diff --git a/clang/unittests/StaticAnalyzer/CallDescriptionTest.cpp b/clang/unittests/StaticAnalyzer/CallDescriptionTest.cpp
@@ -488,11 +488,10 @@ TEST(CallDescription, NegativeMatchQualifiedNames) {
 }
 
 TEST(CallDescription, MatchBuiltins) {
-  // Test CDF_MaybeBuiltin - a flag that allows matching weird builtins.
+  // Test CDM::CLibrary - a flag that allows matching weird builtins.
   EXPECT_TRUE(tooling::runToolOnCode(
       std::unique_ptr<FrontendAction>(new CallDescriptionAction<>(
-          {{{{"memset"}, 3}, false},
-           {{CDF_MaybeBuiltin, {"memset"}, 3}, true}})),
+          {{{{"memset"}, 3}, false}, {{CDM::CLibrary, {"memset"}, 3}, true}})),
       "void foo() {"
       "  int x;"
       "  __builtin___memset_chk(&x, 0, sizeof(x),"
@@ -503,8 +502,8 @@ TEST(CallDescription, MatchBuiltins) {
     SCOPED_TRACE("multiple similar builtins");
     EXPECT_TRUE(tooling::runToolOnCode(
         std::unique_ptr<FrontendAction>(new CallDescriptionAction<>(
-            {{{CDF_MaybeBuiltin, {"memcpy"}, 3}, false},
-             {{CDF_MaybeBuiltin, {"wmemcpy"}, 3}, true}})),
+            {{{CDM::CLibrary, {"memcpy"}, 3}, false},
+             {{CDM::CLibrary, {"wmemcpy"}, 3}, true}})),
         R"(void foo(wchar_t *x, wchar_t *y) {
             __builtin_wmemcpy(x, y, sizeof(wchar_t));
           })"));
@@ -513,17 +512,17 @@ TEST(CallDescription, MatchBuiltins) {
     SCOPED_TRACE("multiple similar builtins reversed order");
     EXPECT_TRUE(tooling::runToolOnCode(
         std::unique_ptr<FrontendAction>(new CallDescriptionAction<>(
-            {{{CDF_MaybeBuiltin, {"wmemcpy"}, 3}, true},
-             {{CDF_MaybeBuiltin, {"memcpy"}, 3}, false}})),
+            {{{CDM::CLibrary, {"wmemcpy"}, 3}, true},
+             {{CDM::CLibrary, {"memcpy"}, 3}, false}})),
         R"(void foo(wchar_t *x, wchar_t *y) {
             __builtin_wmemcpy(x, y, sizeof(wchar_t));
           })"));
   }
   {
     SCOPED_TRACE("lookbehind and lookahead mismatches");
     EXPECT_TRUE(tooling::runToolOnCode(
-        std::unique_ptr<FrontendAction>(new CallDescriptionAction<>(
-            {{{CDF_MaybeBuiltin, {"func"}}, false}})),
+        std::unique_ptr<FrontendAction>(
+            new CallDescriptionAction<>({{{CDM::CLibrary, {"func"}}, false}})),
         R"(
           void funcXXX();
           void XXXfunc();
@@ -537,8 +536,8 @@ TEST(CallDescription, MatchBuiltins) {
   {
     SCOPED_TRACE("lookbehind and lookahead matches");
     EXPECT_TRUE(tooling::runToolOnCode(
-        std::unique_ptr<FrontendAction>(new CallDescriptionAction<>(
-            {{{CDF_MaybeBuiltin, {"func"}}, true}})),
+        std::unique_ptr<FrontendAction>(
+            new CallDescriptionAction<>({{{CDM::CLibrary, {"func"}}, true}})),
         R"(
           void func();
           void func_XXX();

diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -190,6 +190,7 @@ set(GENERIC_SOURCES
 
 # We only build BF16 files when "__bf16" is available.
 set(BF16_SOURCES
+    extendbfsf2.c
     truncdfbf2.c
     truncsfbf2.c
 )

diff --git a/clang/lib/AST/Interp/ByteCodeGenError.cpp → compiler-rt/lib/builtins/extendbfsf2.c b/clang/lib/AST/Interp/ByteCodeGenError.cpp → compiler-rt/lib/builtins/extendbfsf2.c
@@ -1,14 +1,13 @@
-//===--- ByteCodeGenError.h - Byte code generation error --------*- C++ -*-===//
+//===-- lib/extendbfsf2.c - bfloat -> single conversion -----------*- C -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
-#include "ByteCodeGenError.h"
+#define SRC_BFLOAT16
+#define DST_SINGLE
+#include "fp_extend_impl.inc"
 
-using namespace clang;
-using namespace clang::interp;
-
-char ByteCodeGenError::ID;
+COMPILER_RT_ABI float __extendbfsf2(src_t a) { return __extendXfYf2__(a); }
diff --git a/compiler-rt/lib/builtins/fp_extend.h b/compiler-rt/lib/builtins/fp_extend.h
@@ -81,6 +81,21 @@ static inline int src_rep_t_clz_impl(src_rep_t a) {
 
 #define src_rep_t_clz src_rep_t_clz_impl
 
+#elif defined SRC_BFLOAT16
+#ifdef COMPILER_RT_HAS_BFLOAT16
+typedef __bf16 src_t;
+#else
+typedef uint16_t src_t;
+#endif
+typedef uint16_t src_rep_t;
+#define SRC_REP_C UINT16_C
+static const int srcBits = sizeof(src_t) * CHAR_BIT;
+static const int srcSigFracBits = 7;
+// -1 accounts for the sign bit.
+// srcBits - srcSigFracBits - 1
+static const int srcExpBits = 8;
+#define src_rep_t_clz __builtin_clz
+
 #else
 #error Source should be half, single, or double precision!
 #endif // end source precision

diff --git a/flang/docs/conf.py b/flang/docs/conf.py
@@ -22,13 +22,24 @@
 # Add any Sphinx extension module names here, as strings. They can be extensions
 # coming with Sphinx (named 'sphinx.ext.*') or your custom ones.
 extensions = [
-    "myst_parser",
     "sphinx.ext.todo",
     "sphinx.ext.mathjax",
     "sphinx.ext.intersphinx",
     "sphinx.ext.autodoc",
 ]
 
+# When building man pages, we do not use the markdown pages,
+# So, we can continue without the myst_parser dependencies.
+# Doing so reduces dependencies of some packaged llvm distributions.
+try:
+    import myst_parser
+
+    extensions.append("myst_parser")
+except ImportError:
+    if not tags.has("builder-man"):
+        raise
+
+
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ["_templates"]
 myst_heading_anchors = 6

diff --git a/flang/include/flang/Optimizer/CodeGen/CodeGen.h b/flang/include/flang/Optimizer/CodeGen/CodeGen.h
@@ -18,6 +18,8 @@
 
 namespace fir {
 
+class LLVMTypeConverter;
+
 struct NameUniquer;
 
 #define GEN_PASS_DECL_FIRTOLLVMLOWERING
@@ -80,6 +82,11 @@ std::unique_ptr<mlir::Pass> createLLVMDialectToLLVMPass(
 std::unique_ptr<mlir::Pass> createBoxedProcedurePass();
 std::unique_ptr<mlir::Pass> createBoxedProcedurePass(bool useThunks);
 
+/// Populate the given list with patterns that convert from FIR to LLVM.
+void populateFIRToLLVMConversionPatterns(fir::LLVMTypeConverter &converter,
+                                         mlir::RewritePatternSet &patterns,
+                                         fir::FIRToLLVMPassOptions &options);
+
 // declarative passes
 #define GEN_PASS_REGISTRATION
 #include "flang/Optimizer/CodeGen/CGPasses.h.inc"

diff --git a/flang/lib/Optimizer/CodeGen/CodeGen.cpp b/flang/lib/Optimizer/CodeGen/CodeGen.cpp
@@ -3937,30 +3937,7 @@ class FIRToLLVMLowering
                                          options.applyTBAA || applyTBAA,
                                          options.forceUnifiedTBAATree, *dl};
     mlir::RewritePatternSet pattern(context);
-    pattern.insert<
-        AbsentOpConversion, AddcOpConversion, AddrOfOpConversion,
-        AllocaOpConversion, AllocMemOpConversion, BoxAddrOpConversion,
-        BoxCharLenOpConversion, BoxDimsOpConversion, BoxEleSizeOpConversion,
-        BoxIsAllocOpConversion, BoxIsArrayOpConversion, BoxIsPtrOpConversion,
-        BoxOffsetOpConversion, BoxProcHostOpConversion, BoxRankOpConversion,
-        BoxTypeCodeOpConversion, BoxTypeDescOpConversion, CallOpConversion,
-        CmpcOpConversion, ConstcOpConversion, ConvertOpConversion,
-        CoordinateOpConversion, DTEntryOpConversion, DivcOpConversion,
-        EmboxOpConversion, EmboxCharOpConversion, EmboxProcOpConversion,
-        ExtractValueOpConversion, FieldIndexOpConversion, FirEndOpConversion,
-        FreeMemOpConversion, GlobalLenOpConversion, GlobalOpConversion,
-        HasValueOpConversion, InsertOnRangeOpConversion,
-        InsertValueOpConversion, IsPresentOpConversion,
-        LenParamIndexOpConversion, LoadOpConversion, MulcOpConversion,
-        NegcOpConversion, NoReassocOpConversion, SelectCaseOpConversion,
-        SelectOpConversion, SelectRankOpConversion, SelectTypeOpConversion,
-        ShapeOpConversion, ShapeShiftOpConversion, ShiftOpConversion,
-        SliceOpConversion, StoreOpConversion, StringLitOpConversion,
-        SubcOpConversion, TypeDescOpConversion, TypeInfoOpConversion,
-        UnboxCharOpConversion, UnboxProcOpConversion, UndefOpConversion,
-        UnreachableOpConversion, UnrealizedConversionCastOpConversion,
-        XArrayCoorOpConversion, XEmboxOpConversion, XReboxOpConversion,
-        ZeroOpConversion>(typeConverter, options);
+    fir::populateFIRToLLVMConversionPatterns(typeConverter, pattern, options);
     mlir::populateFuncToLLVMConversionPatterns(typeConverter, pattern);
     mlir::populateOpenMPToLLVMConversionPatterns(typeConverter, pattern);
     mlir::arith::populateArithToLLVMConversionPatterns(typeConverter, pattern);
@@ -4072,3 +4049,32 @@ fir::createLLVMDialectToLLVMPass(llvm::raw_ostream &output,
                                  fir::LLVMIRLoweringPrinter printer) {
   return std::make_unique<LLVMIRLoweringPass>(output, printer);
 }
+
+void fir::populateFIRToLLVMConversionPatterns(
+    fir::LLVMTypeConverter &converter, mlir::RewritePatternSet &patterns,
+    fir::FIRToLLVMPassOptions &options) {
+  patterns.insert<
+      AbsentOpConversion, AddcOpConversion, AddrOfOpConversion,
+      AllocaOpConversion, AllocMemOpConversion, BoxAddrOpConversion,
+      BoxCharLenOpConversion, BoxDimsOpConversion, BoxEleSizeOpConversion,
+      BoxIsAllocOpConversion, BoxIsArrayOpConversion, BoxIsPtrOpConversion,
+      BoxOffsetOpConversion, BoxProcHostOpConversion, BoxRankOpConversion,
+      BoxTypeCodeOpConversion, BoxTypeDescOpConversion, CallOpConversion,
+      CmpcOpConversion, ConstcOpConversion, ConvertOpConversion,
+      CoordinateOpConversion, DTEntryOpConversion, DivcOpConversion,
+      EmboxOpConversion, EmboxCharOpConversion, EmboxProcOpConversion,
+      ExtractValueOpConversion, FieldIndexOpConversion, FirEndOpConversion,
+      FreeMemOpConversion, GlobalLenOpConversion, GlobalOpConversion,
+      HasValueOpConversion, InsertOnRangeOpConversion, InsertValueOpConversion,
+      IsPresentOpConversion, LenParamIndexOpConversion, LoadOpConversion,
+      MulcOpConversion, NegcOpConversion, NoReassocOpConversion,
+      SelectCaseOpConversion, SelectOpConversion, SelectRankOpConversion,
+      SelectTypeOpConversion, ShapeOpConversion, ShapeShiftOpConversion,
+      ShiftOpConversion, SliceOpConversion, StoreOpConversion,
+      StringLitOpConversion, SubcOpConversion, TypeDescOpConversion,
+      TypeInfoOpConversion, UnboxCharOpConversion, UnboxProcOpConversion,
+      UndefOpConversion, UnreachableOpConversion,
+      UnrealizedConversionCastOpConversion, XArrayCoorOpConversion,
+      XEmboxOpConversion, XReboxOpConversion, ZeroOpConversion>(converter,
+                                                                options);
+}
diff --git a/flang/lib/Optimizer/Transforms/MemoryAllocation.cpp b/flang/lib/Optimizer/Transforms/MemoryAllocation.cpp
@@ -200,7 +200,8 @@ class MemoryAllocationOpt
       return keepStackAllocation(alloca, &func.front(), options);
     });
 
-    patterns.insert<AllocaOpConversion>(context, analysis.getReturns(func));
+    llvm::SmallVector<mlir::Operation *> returnOps = analysis.getReturns(func);
+    patterns.insert<AllocaOpConversion>(context, returnOps);
     if (mlir::failed(
             mlir::applyPartialConversion(func, target, std::move(patterns)))) {
       mlir::emitError(func.getLoc(),

diff --git a/flang/test/Fir/memory-allocation-opt.fir b/flang/test/Fir/memory-allocation-opt.fir
@@ -1,4 +1,6 @@
 // RUN: fir-opt --memory-allocation-opt="dynamic-array-on-heap=true maximum-array-alloc-size=1024" %s | FileCheck %s
+// FIXME: started crashing on windows https://github.com/llvm/llvm-project/issues/83534
+// UNSUPPORTED: system-windows
 
 // Test for size of array being too big.
 

diff --git a/libc/include/llvm-libc-types/float128.h b/libc/include/llvm-libc-types/float128.h
@@ -19,18 +19,17 @@
 //   https://github.com/llvm/llvm-project/issues/80195
 #if defined(__STDC_IEC_60559_BFP__) && !defined(__clang__) &&                  \
     !defined(__cplusplus)
-// Use _Float128 C23 type.
-#define LIBC_COMPILER_HAS_C23_FLOAT128
+#define LIBC_TYPES_HAS_FLOAT128
 typedef _Float128 float128;
 #elif defined(__FLOAT128__) || defined(__SIZEOF_FLOAT128__)
 // Use __float128 type.  gcc and clang sometime use __SIZEOF_FLOAT128__ to
 // notify the availability of __float128.
 // clang also uses __FLOAT128__ macro to notify the availability of __float128
 // type: https://reviews.llvm.org/D15120
-#define LIBC_COMPILER_HAS_FLOAT128_EXTENSION
+#define LIBC_TYPES_HAS_FLOAT128
 typedef __float128 float128;
 #elif (LDBL_MANT_DIG == 113)
-// Use long double.
+#define LIBC_TYPES_HAS_FLOAT128
 typedef long double float128;
 #endif
 

diff --git a/libc/src/__support/FPUtil/ManipulationFunctions.h b/libc/src/__support/FPUtil/ManipulationFunctions.h
@@ -233,8 +233,8 @@ LIBC_INLINE T nextafter(T from, U to) {
 } // namespace fputil
 } // namespace LIBC_NAMESPACE
 
-#ifdef LIBC_LONG_DOUBLE_IS_X86_FLOAT80
+#ifdef LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80
 #include "x86_64/NextAfterLongDouble.h"
-#endif // LIBC_LONG_DOUBLE_IS_X86_FLOAT80
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80
 
 #endif // LLVM_LIBC_SRC___SUPPORT_FPUTIL_MANIPULATIONFUNCTIONS_H
diff --git a/libc/src/__support/FPUtil/NormalFloat.h b/libc/src/__support/FPUtil/NormalFloat.h
@@ -172,7 +172,7 @@ template <typename T> struct NormalFloat {
   }
 };
 
-#ifdef LIBC_LONG_DOUBLE_IS_X86_FLOAT80
+#ifdef LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80
 template <>
 LIBC_INLINE void
 NormalFloat<long double>::init_from_bits(FPBits<long double> bits) {
@@ -261,7 +261,7 @@ template <> LIBC_INLINE NormalFloat<long double>::operator long double() const {
   result.set_implicit_bit(1);
   return result.get_val();
 }
-#endif // LIBC_LONG_DOUBLE_IS_X86_FLOAT80
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80
 
 } // namespace fputil
 } // namespace LIBC_NAMESPACE

diff --git a/libc/src/__support/FPUtil/dyadic_float.h b/libc/src/__support/FPUtil/dyadic_float.h
@@ -19,7 +19,7 @@
 
 namespace LIBC_NAMESPACE::fputil {
 
-// A generic class to perform comuptations of high precision floating points.
+// A generic class to perform computations of high precision floating points.
 // We store the value in dyadic format, including 3 fields:
 //   sign    : boolean value - false means positive, true means negative
 //   exponent: the exponent value of the least significant bit of the mantissa.

diff --git a/libc/src/__support/FPUtil/generic/sqrt.h b/libc/src/__support/FPUtil/generic/sqrt.h
@@ -27,11 +27,11 @@ template <typename T> struct SpecialLongDouble {
   static constexpr bool VALUE = false;
 };
 
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
 template <> struct SpecialLongDouble<long double> {
   static constexpr bool VALUE = true;
 };
-#endif // LIBC_LONG_DOUBLE_IS_X86_FLOAT80
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80
 
 template <typename T>
 LIBC_INLINE void normalize(int &exponent,
@@ -43,12 +43,12 @@ LIBC_INLINE void normalize(int &exponent,
   mantissa <<= shift;
 }
 
-#ifdef LIBC_LONG_DOUBLE_IS_FLOAT64
+#ifdef LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64
 template <>
 LIBC_INLINE void normalize<long double>(int &exponent, uint64_t &mantissa) {
   normalize<double>(exponent, mantissa);
 }
-#elif !defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#elif !defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
 template <>
 LIBC_INLINE void normalize<long double>(int &exponent, UInt128 &mantissa) {
   const uint64_t hi_bits = static_cast<uint64_t>(mantissa >> 64);

diff --git a/libc/src/__support/FPUtil/generic/sqrt_80_bit_long_double.h b/libc/src/__support/FPUtil/generic/sqrt_80_bit_long_double.h
@@ -34,7 +34,7 @@ LIBC_INLINE long double sqrt(long double x);
 
 // Correctly rounded SQRT for all rounding modes.
 // Shift-and-add algorithm.
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
 LIBC_INLINE long double sqrt(long double x) {
   using LDBits = FPBits<long double>;
   using StorageType = typename LDBits::StorageType;
@@ -130,7 +130,7 @@ LIBC_INLINE long double sqrt(long double x) {
     return out.get_val();
   }
 }
-#endif // LIBC_LONG_DOUBLE_IS_X86_FLOAT80
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80
 
 } // namespace x86
 } // namespace fputil

diff --git a/libc/src/__support/FPUtil/x86_64/sqrt.h b/libc/src/__support/FPUtil/x86_64/sqrt.h
@@ -33,7 +33,7 @@ template <> LIBC_INLINE double sqrt<double>(double x) {
   return result;
 }
 
-#ifdef LIBC_LONG_DOUBLE_IS_FLOAT64
+#ifdef LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64
 template <> LIBC_INLINE long double sqrt<long double>(long double x) {
   long double result;
   __asm__ __volatile__("sqrtsd %x1, %x0" : "=x"(result) : "x"(x));

diff --git a/libc/src/__support/float_to_string.h b/libc/src/__support/float_to_string.h
@@ -615,7 +615,7 @@ class FloatToString {
   }
 };
 
-#if !defined(LIBC_LONG_DOUBLE_IS_FLOAT64) &&                                   \
+#if !defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64) &&                             \
     !defined(LIBC_COPT_FLOAT_TO_STR_NO_SPECIALIZE_LD)
 // --------------------------- LONG DOUBLE FUNCTIONS ---------------------------
 
@@ -837,7 +837,7 @@ template <> class FloatToString<long double> {
   }
 };
 
-#endif // !LIBC_LONG_DOUBLE_IS_FLOAT64 &&
+#endif // !LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64 &&
        // !LIBC_COPT_FLOAT_TO_STR_NO_SPECIALIZE_LD
 
 } // namespace LIBC_NAMESPACE

diff --git a/libc/src/__support/macros/properties/types.h b/libc/src/__support/macros/properties/types.h
@@ -19,14 +19,14 @@
 
 // 'long double' properties.
 #if (LDBL_MANT_DIG == 53)
-#define LIBC_LONG_DOUBLE_IS_FLOAT64
+#define LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64
 #elif (LDBL_MANT_DIG == 64)
-#define LIBC_LONG_DOUBLE_IS_X86_FLOAT80
+#define LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80
 #elif (LDBL_MANT_DIG == 113)
-#define LIBC_LONG_DOUBLE_IS_FLOAT128
+#define LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128
 #endif
 
-// float16 support.
+// -- float16 support ---------------------------------------------------------
 // TODO: move this logic to "llvm-libc-types/float16.h"
 #if defined(LIBC_TARGET_ARCH_IS_X86_64) && defined(LIBC_TARGET_CPU_HAS_SSE2)
 #if (defined(LIBC_COMPILER_CLANG_VER) && (LIBC_COMPILER_CLANG_VER >= 1500)) || \
@@ -50,11 +50,8 @@ using float16 = _Float16;
 #endif
 #endif
 
-// float128 support.
-#if defined(LIBC_COMPILER_HAS_C23_FLOAT128) ||                                 \
-    defined(LIBC_COMPILER_HAS_FLOAT128_EXTENSION) ||                           \
-    defined(LIBC_LONG_DOUBLE_IS_FLOAT128)
-#define LIBC_TYPES_HAS_FLOAT128
-#endif
+// -- float128 support --------------------------------------------------------
+// LIBC_TYPES_HAS_FLOAT128 and 'float128' type are provided by
+// "include/llvm-libc-types/float128.h"
 
 #endif // LLVM_LIBC_SRC___SUPPORT_MACROS_PROPERTIES_TYPES_H
diff --git a/libc/src/__support/str_to_float.h b/libc/src/__support/str_to_float.h
@@ -51,13 +51,13 @@ template <class T> LIBC_INLINE void set_implicit_bit(fputil::FPBits<T> &) {
   return;
 }
 
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
 template <>
 LIBC_INLINE void
 set_implicit_bit<long double>(fputil::FPBits<long double> &result) {
   result.set_implicit_bit(result.get_biased_exponent() != 0);
 }
-#endif
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80
 
 // This Eisel-Lemire implementation is based on the algorithm described in the
 // paper Number Parsing at a Gigabyte per Second, Software: Practice and
@@ -176,7 +176,7 @@ eisel_lemire(ExpandedFloat<T> init_num,
   return output;
 }
 
-#if !defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#if !defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
 template <>
 LIBC_INLINE cpp::optional<ExpandedFloat<long double>>
 eisel_lemire<long double>(ExpandedFloat<long double> init_num,
@@ -297,7 +297,7 @@ eisel_lemire<long double>(ExpandedFloat<long double> init_num,
   output.exponent = exp2;
   return output;
 }
-#endif
+#endif // !defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
 
 // The nth item in POWERS_OF_TWO represents the greatest power of two less than
 // 10^n. This tells us how much we can safely shift without overshooting.
@@ -460,7 +460,7 @@ template <> class ClingerConsts<double> {
   static constexpr double MAX_EXACT_INT = 9007199254740991.0;
 };
 
-#if defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
 template <> class ClingerConsts<long double> {
 public:
   static constexpr long double POWERS_OF_TEN_ARRAY[] = {
@@ -473,7 +473,7 @@ template <> class ClingerConsts<long double> {
   static constexpr long double MAX_EXACT_INT =
       ClingerConsts<double>::MAX_EXACT_INT;
 };
-#elif defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
 template <> class ClingerConsts<long double> {
 public:
   static constexpr long double POWERS_OF_TEN_ARRAY[] = {
@@ -484,7 +484,7 @@ template <> class ClingerConsts<long double> {
   static constexpr int32_t DIGITS_IN_MANTISSA = 21;
   static constexpr long double MAX_EXACT_INT = 18446744073709551615.0L;
 };
-#else
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
 template <> class ClingerConsts<long double> {
 public:
   static constexpr long double POWERS_OF_TEN_ARRAY[] = {
@@ -498,6 +498,8 @@ template <> class ClingerConsts<long double> {
   static constexpr long double MAX_EXACT_INT =
       10384593717069655257060992658440191.0L;
 };
+#else
+#error "Unknown long double type"
 #endif
 
 // Take an exact mantissa and exponent and attempt to convert it using only

diff --git a/libc/test/src/__support/FPUtil/fpbits_test.cpp b/libc/test/src/__support/FPUtil/fpbits_test.cpp
@@ -503,7 +503,7 @@ TEST(LlvmLibcFPBitsTest, X86LongDoubleType) {
 }
 #else
 TEST(LlvmLibcFPBitsTest, LongDoubleType) {
-#if defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
   return; // The tests for the "double" type cover for this case.
 #else
   using LongDoubleBits = FPBits<long double>;

diff --git a/libc/test/src/__support/str_to_long_double_test.cpp b/libc/test/src/__support/str_to_long_double_test.cpp
@@ -7,13 +7,13 @@ namespace LIBC_NAMESPACE {
 using LlvmLibcStrToLongDblTest = LlvmLibcStrToFloatTest<long double>;
 using LIBC_NAMESPACE::operator""_u128;
 
-#if defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
 
 TEST_F(LlvmLibcStrToLongDblTest, EiselLemireFloat64AsLongDouble) {
   eisel_lemire_test(123, 0, 0x1EC00000000000, 1029);
 }
 
-#elif defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
 
 TEST_F(LlvmLibcStrToLongDblTest, EiselLemireFloat80Simple) {
   eisel_lemire_test(123, 0, 0xf600000000000000, 16389);
@@ -54,7 +54,7 @@ TEST_F(LlvmLibcStrToLongDblTest, EiselLemireFloat80Fallback) {
   ASSERT_FALSE(internal::eisel_lemire<long double>({1, -1000}).has_value());
 }
 
-#else // Quad precision long double
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
 
 TEST_F(LlvmLibcStrToLongDblTest, EiselLemireFloat128Simple) {
   eisel_lemire_test(123, 0, 0x1ec00'00000000'00000000'00000000_u128, 16389);
@@ -77,6 +77,8 @@ TEST_F(LlvmLibcStrToLongDblTest, EiselLemireFloat128Fallback) {
                    .has_value());
 }
 
+#else
+#error "Unknown long double type"
 #endif
 
 } // namespace LIBC_NAMESPACE
diff --git a/libc/test/src/math/smoke/nanl_test.cpp b/libc/test/src/math/smoke/nanl_test.cpp
@@ -12,12 +12,14 @@
 #include "test/UnitTest/Test.h"
 #include <signal.h>
 
-#if defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
 #define SELECT_LONG_DOUBLE(val, _, __) val
-#elif defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
 #define SELECT_LONG_DOUBLE(_, val, __) val
-#else
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
 #define SELECT_LONG_DOUBLE(_, __, val) val
+#else
+#error "Unknown long double type"
 #endif
 
 class LlvmLibcNanlTest : public LIBC_NAMESPACE::testing::Test {

diff --git a/libc/test/src/stdio/sprintf_test.cpp b/libc/test/src/stdio/sprintf_test.cpp
@@ -775,29 +775,29 @@ TEST_F(LlvmLibcSPrintfTest, FloatHexExpConv) {
   // Length Modifier Tests.
 
   written = LIBC_NAMESPACE::sprintf(buff, "%La", 0.1L);
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
   ASSERT_STREQ_LEN(written, buff, "0xc.ccccccccccccccdp-7");
-#elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
   ASSERT_STREQ_LEN(written, buff, "0x1.999999999999ap-4");
-#else // 128 bit long double
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
   ASSERT_STREQ_LEN(written, buff, "0x1.999999999999999999999999999ap-4");
 #endif
 
   written = LIBC_NAMESPACE::sprintf(buff, "%La", 1.0e1000L);
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
   ASSERT_STREQ_LEN(written, buff, "0xf.38db1f9dd3dac05p+3318");
-#elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
   ASSERT_STREQ_LEN(written, buff, "inf");
-#else // 128 bit long double
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
   ASSERT_STREQ_LEN(written, buff, "0x1.e71b63f3ba7b580af1a52d2a7379p+3321");
 #endif
 
   written = LIBC_NAMESPACE::sprintf(buff, "%La", 1.0e-1000L);
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
   ASSERT_STREQ_LEN(written, buff, "0x8.68a9188a89e1467p-3325");
-#elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
   ASSERT_STREQ_LEN(written, buff, "0x0p+0");
-#else // 128 bit long double
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
   ASSERT_STREQ_LEN(written, buff, "0x1.0d152311513c28ce202627c06ec2p-3322");
 #endif
 
@@ -899,20 +899,20 @@ TEST_F(LlvmLibcSPrintfTest, FloatHexExpConv) {
   ASSERT_STREQ_LEN(written, buff, "0x0p+0");
 
   written = LIBC_NAMESPACE::sprintf(buff, "%.1La", 0.1L);
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
   ASSERT_STREQ_LEN(written, buff, "0xc.dp-7");
-#elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
   ASSERT_STREQ_LEN(written, buff, "0x1.ap-4");
-#else // 128 bit long double
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
   ASSERT_STREQ_LEN(written, buff, "0x1.ap-4");
 #endif
 
   written = LIBC_NAMESPACE::sprintf(buff, "%.1La", 0xf.fffffffffffffffp16380L);
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
   ASSERT_STREQ_LEN(written, buff, "0x1.0p+16384");
-#elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
   ASSERT_STREQ_LEN(written, buff, "inf");
-#else // 128 bit long double
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
   ASSERT_STREQ_LEN(written, buff, "0x2.0p+16383");
 #endif
 
@@ -1158,8 +1158,8 @@ TEST_F(LlvmLibcSPrintfTest, FloatDecimalConv) {
 
 // Some float128 systems (specifically the ones used for aarch64 buildbots)
 // don't respect signs for long double NaNs.
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80) ||                                \
-    defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80) ||                          \
+    defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
   written = LIBC_NAMESPACE::sprintf(buff, "%LF", -ld_nan);
   ASSERT_STREQ_LEN(written, buff, "-NAN");
 #endif
@@ -1354,20 +1354,20 @@ TEST_F(LlvmLibcSPrintfTest, FloatDecimalConv) {
 
   /*
     written = LIBC_NAMESPACE::sprintf(buff, "%.1La", 0.1L);
-  #if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+  #if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
     ASSERT_STREQ_LEN(written, buff, "0xc.dp-7");
-  #elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
     ASSERT_STREQ_LEN(written, buff, "0x1.ap-4");
-  #else // 128 bit long double
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
     ASSERT_STREQ_LEN(written, buff, "0x1.ap-4");
   #endif
 
     written = LIBC_NAMESPACE::sprintf(buff, "%.1La",
-  0xf.fffffffffffffffp16380L); #if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
-    ASSERT_STREQ_LEN(written, buff, "0x1.0p+16384");
-  #elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+  0xf.fffffffffffffffp16380L); #if
+  defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80) ASSERT_STREQ_LEN(written, buff,
+  "0x1.0p+16384"); #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
     ASSERT_STREQ_LEN(written, buff, "inf");
-  #else // 128 bit long double
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
     ASSERT_STREQ_LEN(written, buff, "0x2.0p+16383");
   #endif
   */
@@ -1603,8 +1603,8 @@ TEST_F(LlvmLibcSPrintfTest, FloatDecimalLongDoubleConv) {
 
   // Length Modifier Tests.
 
-  // TODO(michaelrj): Add tests for LIBC_LONG_DOUBLE_IS_FLOAT64 and 128 bit long
-  // double systems.
+  // TODO(michaelrj): Add tests for LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64 and 128
+  // bit long double systems.
   // TODO(michaelrj): Fix the tests to only depend on the digits the long double
   // is accurate for.
 
@@ -1614,7 +1614,7 @@ TEST_F(LlvmLibcSPrintfTest, FloatDecimalLongDoubleConv) {
   written = LIBC_NAMESPACE::sprintf(buff, "%.Lf", -2.5L);
   ASSERT_STREQ_LEN(written, buff, "-2");
 
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
 
   written = LIBC_NAMESPACE::sprintf(buff, "%Lf", 1e100L);
   ASSERT_STREQ_LEN(written, buff,
@@ -1930,7 +1930,7 @@ TEST_F(LlvmLibcSPrintfTest, FloatDecimalLongDoubleConv) {
       "570449525088342437216896462077260223998756027453411520977536701491759878"
       "422771447006016890777855573925295187921971811871399320142563330377888532"
       "179817332113");
-#endif // LIBC_LONG_DOUBLE_IS_X86_FLOAT80
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80
 }
 
 TEST_F(LlvmLibcSPrintfTest, FloatExponentConv) {
@@ -2171,20 +2171,20 @@ TEST_F(LlvmLibcSPrintfTest, FloatExponentConv) {
 
   /*
     written = LIBC_NAMESPACE::sprintf(buff, "%.1La", 0.1L);
-  #if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+  #if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
     ASSERT_STREQ_LEN(written, buff, "0xc.dp-7");
-  #elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
     ASSERT_STREQ_LEN(written, buff, "0x1.ap-4");
-  #else // 128 bit long double
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
     ASSERT_STREQ_LEN(written, buff, "0x1.ap-4");
   #endif
 
     written = LIBC_NAMESPACE::sprintf(buff, "%.1La",
-  0xf.fffffffffffffffp16380L); #if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
-    ASSERT_STREQ_LEN(written, buff, "0x1.0p+16384");
-  #elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+  0xf.fffffffffffffffp16380L); #if
+  defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80) ASSERT_STREQ_LEN(written, buff,
+  "0x1.0p+16384"); #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
     ASSERT_STREQ_LEN(written, buff, "inf");
-  #else // 128 bit long double
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
     ASSERT_STREQ_LEN(written, buff, "0x2.0p+16383");
   #endif
   */
@@ -2423,7 +2423,7 @@ TEST_F(LlvmLibcSPrintfTest, FloatExponentLongDoubleConv) {
   ForceRoundingMode r(RoundingMode::Nearest);
   // Length Modifier Tests.
 
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
   written = LIBC_NAMESPACE::sprintf(buff, "%.9Le", 1000000000500000000.1L);
   ASSERT_STREQ_LEN(written, buff, "1.000000001e+18");
 
@@ -2783,34 +2783,34 @@ TEST_F(LlvmLibcSPrintfTest, FloatAutoConv) {
   written = LIBC_NAMESPACE::sprintf(buff, "%.10g", 0x1.0p-1074);
   ASSERT_STREQ_LEN(written, buff, "4.940656458e-324");
 
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
 
   written = LIBC_NAMESPACE::sprintf(buff, "%.60Lg", 0xa.aaaaaaaaaaaaaabp-7L);
   ASSERT_STREQ_LEN(
       written, buff,
       "0.0833333333333333333355920878593448009041821933351457118988037");
 
-#endif // LIBC_LONG_DOUBLE_IS_X86_FLOAT80
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80
 
   // Long double precision tests.
   // These are currently commented out because they require long double support
   // that isn't ready yet.
   /*
     written = LIBC_NAMESPACE::sprintf(buff, "%.1La", 0.1L);
-  #if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+  #if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
     ASSERT_STREQ_LEN(written, buff, "0xc.dp-7");
-  #elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
     ASSERT_STREQ_LEN(written, buff, "0x1.ap-4");
-  #else // 128 bit long double
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
     ASSERT_STREQ_LEN(written, buff, "0x1.ap-4");
   #endif
 
     written = LIBC_NAMESPACE::sprintf(buff, "%.1La",
-  0xf.fffffffffffffffp16380L); #if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
-    ASSERT_STREQ_LEN(written, buff, "0x1.0p+16384");
-  #elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+  0xf.fffffffffffffffp16380L); #if
+  defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80) ASSERT_STREQ_LEN(written, buff,
+  "0x1.0p+16384"); #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
     ASSERT_STREQ_LEN(written, buff, "inf");
-  #else // 128 bit long double
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
     ASSERT_STREQ_LEN(written, buff, "0x2.0p+16383");
   #endif
   */
@@ -3053,7 +3053,7 @@ TEST_F(LlvmLibcSPrintfTest, FloatAutoLongDoubleConv) {
 
   // Length Modifier Tests.
 
-#if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
 
   written = LIBC_NAMESPACE::sprintf(buff, "%Lg", 0xf.fffffffffffffffp+16380L);
   ASSERT_STREQ_LEN(written, buff, "1.18973e+4932");
@@ -3064,7 +3064,7 @@ TEST_F(LlvmLibcSPrintfTest, FloatAutoLongDoubleConv) {
   written = LIBC_NAMESPACE::sprintf(buff, "%Lg", 9.99999999999e-100L);
   ASSERT_STREQ_LEN(written, buff, "1e-99");
 
-#endif // LIBC_LONG_DOUBLE_IS_X86_FLOAT80
+#endif // LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80
 
   // TODO: Uncomment the below tests after long double support is added
   /*
@@ -3171,29 +3171,29 @@ TEST_F(LlvmLibcSPrintfTest, FloatAutoLongDoubleConv) {
 */
   /*
     written = LIBC_NAMESPACE::sprintf(buff, "%La", 0.1L);
-  #if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+  #if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
     ASSERT_STREQ_LEN(written, buff, "0xc.ccccccccccccccdp-7");
-  #elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
     ASSERT_STREQ_LEN(written, buff, "0x1.999999999999ap-4");
-  #else // 128 bit long double
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
     ASSERT_STREQ_LEN(written, buff, "0x1.999999999999999999999999999ap-4");
   #endif
 
     written = LIBC_NAMESPACE::sprintf(buff, "%La", 1.0e1000L);
-  #if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+  #if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
     ASSERT_STREQ_LEN(written, buff, "0xf.38db1f9dd3dac05p+3318");
-  #elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
     ASSERT_STREQ_LEN(written, buff, "inf");
-  #else // 128 bit long double
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
     ASSERT_STREQ_LEN(written, buff, "0x1.e71b63f3ba7b580af1a52d2a7379p+3321");
   #endif
 
     written = LIBC_NAMESPACE::sprintf(buff, "%La", 1.0e-1000L);
-  #if defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+  #if defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
     ASSERT_STREQ_LEN(written, buff, "0x8.68a9188a89e1467p-3325");
-  #elif defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
     ASSERT_STREQ_LEN(written, buff, "0x0p+0");
-  #else // 128 bit long double
+  #elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
     ASSERT_STREQ_LEN(written, buff, "0x1.0d152311513c28ce202627c06ec2p-3322");
   #endif
   */

diff --git a/libc/test/src/stdio/sscanf_test.cpp b/libc/test/src/stdio/sscanf_test.cpp
@@ -322,7 +322,7 @@ TEST(LlvmLibcSScanfTest, FloatConvLengthModifier) {
   EXPECT_EQ(ret_val, 1);
 // 1e600 may be larger than the maximum long double (if long double is double).
 // In that case both of these should be evaluated as inf.
-#ifdef LIBC_LONG_DOUBLE_IS_FLOAT64
+#ifdef LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64
   EXPECT_FP_EQ(ld_result, d_inf);
 #else
   EXPECT_FP_EQ(ld_result, 1.0e600L);

diff --git a/libc/test/src/stdlib/strtold_test.cpp b/libc/test/src/stdlib/strtold_test.cpp
@@ -15,17 +15,19 @@
 
 #include <stddef.h>
 
-#if defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
 #define SELECT_CONST(val, _, __) val
-#elif defined(LIBC_LONG_DOUBLE_IS_X86_FLOAT80)
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_X86_FLOAT80)
 #define SELECT_CONST(_, val, __) val
-#else
+#elif defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT128)
 #define SELECT_CONST(_, __, val) val
+#else
+#error "Unknown long double type"
 #endif
 
 class LlvmLibcStrToLDTest : public LIBC_NAMESPACE::testing::Test {
 public:
-#if defined(LIBC_LONG_DOUBLE_IS_FLOAT64)
+#if defined(LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64)
   void run_test(const char *inputString, const ptrdiff_t expectedStrLen,
                 const uint64_t expectedRawData, const int expectedErrno = 0)
 #else

diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
@@ -431,7 +431,7 @@ set(files
   __fwd/bit_reference.h
   __fwd/complex.h
   __fwd/fstream.h
-  __fwd/hash.h
+  __fwd/functional.h
   __fwd/ios.h
   __fwd/istream.h
   __fwd/mdspan.h

diff --git a/libcxx/include/__filesystem/path.h b/libcxx/include/__filesystem/path.h
@@ -14,9 +14,8 @@
 #include <__algorithm/replace_copy.h>
 #include <__availability>
 #include <__config>
-#include <__functional/hash.h>
 #include <__functional/unary_function.h>
-#include <__fwd/hash.h>
+#include <__fwd/functional.h>
 #include <__iterator/back_insert_iterator.h>
 #include <__iterator/iterator_traits.h>
 #include <__type_traits/decay.h>

diff --git a/libcxx/include/__format/parser_std_format_spec.h b/libcxx/include/__format/parser_std_format_spec.h
@@ -355,10 +355,10 @@ class _LIBCPP_TEMPLATE_VIS __parser {
   _LIBCPP_HIDE_FROM_ABI constexpr typename _ParseContext::iterator __parse(_ParseContext& __ctx, __fields __fields) {
     auto __begin = __ctx.begin();
     auto __end   = __ctx.end();
-    if (__begin == __end || *__begin == _CharT('}'))
+    if (__begin == __end || *__begin == _CharT('}') || (__fields.__use_range_fill_ && *__begin == _CharT(':')))
       return __begin;
 
-    if (__parse_fill_align(__begin, __end, __fields.__use_range_fill_) && __begin == __end)
+    if (__parse_fill_align(__begin, __end) && __begin == __end)
       return __begin;
 
     if (__fields.__sign_) {
@@ -574,12 +574,10 @@ class _LIBCPP_TEMPLATE_VIS __parser {
     return false;
   }
 
-  _LIBCPP_HIDE_FROM_ABI constexpr void __validate_fill_character(_CharT __fill, bool __use_range_fill) {
+  _LIBCPP_HIDE_FROM_ABI constexpr void __validate_fill_character(_CharT __fill) {
     // The forbidden fill characters all code points formed from a single code unit, thus the
     // check can be omitted when more code units are used.
-    if (__use_range_fill && (__fill == _CharT('{') || __fill == _CharT(':')))
-      std::__throw_format_error("The fill option contains an invalid value");
-    else if (__fill == _CharT('{'))
+    if (__fill == _CharT('{'))
       std::__throw_format_error("The fill option contains an invalid value");
   }
 
@@ -590,7 +588,7 @@ class _LIBCPP_TEMPLATE_VIS __parser {
 #    ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
           || (same_as<_CharT, wchar_t> && sizeof(wchar_t) == 2)
 #    endif
-  _LIBCPP_HIDE_FROM_ABI constexpr bool __parse_fill_align(_Iterator& __begin, _Iterator __end, bool __use_range_fill) {
+  _LIBCPP_HIDE_FROM_ABI constexpr bool __parse_fill_align(_Iterator& __begin, _Iterator __end) {
     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
         __begin != __end,
         "when called with an empty input the function will cause "
@@ -606,7 +604,7 @@ class _LIBCPP_TEMPLATE_VIS __parser {
         // The forbidden fill characters all are code points encoded
         // in one code unit, thus the check can be omitted when more
         // code units are used.
-        __validate_fill_character(*__begin, __use_range_fill);
+        __validate_fill_character(*__begin);
 
       std::copy_n(__begin, __code_units, std::addressof(__fill_.__data[0]));
       __begin += __code_units + 1;
@@ -623,7 +621,7 @@ class _LIBCPP_TEMPLATE_VIS __parser {
 #    ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
   template <contiguous_iterator _Iterator>
     requires(same_as<_CharT, wchar_t> && sizeof(wchar_t) == 4)
-  _LIBCPP_HIDE_FROM_ABI constexpr bool __parse_fill_align(_Iterator& __begin, _Iterator __end, bool __use_range_fill) {
+  _LIBCPP_HIDE_FROM_ABI constexpr bool __parse_fill_align(_Iterator& __begin, _Iterator __end) {
     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
         __begin != __end,
         "when called with an empty input the function will cause "
@@ -632,7 +630,7 @@ class _LIBCPP_TEMPLATE_VIS __parser {
       if (!__unicode::__is_scalar_value(*__begin))
         std::__throw_format_error("The fill option contains an invalid value");
 
-      __validate_fill_character(*__begin, __use_range_fill);
+      __validate_fill_character(*__begin);
 
       __fill_.__data[0] = *__begin;
       __begin += 2;
@@ -651,14 +649,14 @@ class _LIBCPP_TEMPLATE_VIS __parser {
 #  else // _LIBCPP_HAS_NO_UNICODE
   // range-fill and tuple-fill are identical
   template <contiguous_iterator _Iterator>
-  _LIBCPP_HIDE_FROM_ABI constexpr bool __parse_fill_align(_Iterator& __begin, _Iterator __end, bool __use_range_fill) {
+  _LIBCPP_HIDE_FROM_ABI constexpr bool __parse_fill_align(_Iterator& __begin, _Iterator __end) {
     _LIBCPP_ASSERT_VALID_ELEMENT_ACCESS(
         __begin != __end,
         "when called with an empty input the function will cause "
         "undefined behavior by evaluating data not in the input");
     if (__begin + 1 != __end) {
       if (__parse_alignment(*(__begin + 1))) {
-        __validate_fill_character(*__begin, __use_range_fill);
+        __validate_fill_character(*__begin);
 
         __fill_.__data[0] = *__begin;
         __begin += 2;

diff --git a/libcxx/include/__functional/bind.h b/libcxx/include/__functional/bind.h
@@ -13,6 +13,7 @@
 #include <__config>
 #include <__functional/invoke.h>
 #include <__functional/weak_result_type.h>
+#include <__fwd/functional.h>
 #include <__type_traits/decay.h>
 #include <__type_traits/is_reference_wrapper.h>
 #include <__type_traits/is_void.h>

diff --git a/libcxx/include/__functional/hash.h b/libcxx/include/__functional/hash.h
@@ -12,7 +12,7 @@
 #include <__config>
 #include <__functional/invoke.h>
 #include <__functional/unary_function.h>
-#include <__fwd/hash.h>
+#include <__fwd/functional.h>
 #include <__tuple/sfinae_helpers.h>
 #include <__type_traits/is_copy_constructible.h>
 #include <__type_traits/is_default_constructible.h>

diff --git a/libcxx/include/__functional/identity.h b/libcxx/include/__functional/identity.h
@@ -11,7 +11,7 @@
 #define _LIBCPP___FUNCTIONAL_IDENTITY_H
 
 #include <__config>
-#include <__functional/reference_wrapper.h>
+#include <__fwd/functional.h>
 #include <__type_traits/integral_constant.h>
 #include <__utility/forward.h>
 

diff --git a/libcxx/include/__fwd/hash.h → libcxx/include/__fwd/functional.h b/libcxx/include/__fwd/hash.h → libcxx/include/__fwd/functional.h
@@ -6,8 +6,8 @@
 //
 //===---------------------------------------------------------------------===//
 
-#ifndef _LIBCPP___FWD_HASH_H
-#define _LIBCPP___FWD_HASH_H
+#ifndef _LIBCPP___FWD_FUNCTIONAL_H
+#define _LIBCPP___FWD_FUNCTIONAL_H
 
 #include <__config>
 
@@ -20,6 +20,9 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 template <class>
 struct _LIBCPP_TEMPLATE_VIS hash;
 
+template <class>
+class _LIBCPP_TEMPLATE_VIS reference_wrapper;
+
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // _LIBCPP___FWD_HASH_H
+#endif // _LIBCPP___FWD_FUNCTIONAL_H
diff --git a/libcxx/include/__thread/id.h b/libcxx/include/__thread/id.h
@@ -12,7 +12,7 @@
 
 #include <__compare/ordering.h>
 #include <__config>
-#include <__fwd/hash.h>
+#include <__fwd/functional.h>
 #include <__fwd/ostream.h>
 #include <__thread/support.h>
 

diff --git a/libcxx/include/__thread/support/pthread.h b/libcxx/include/__thread/support/pthread.h
@@ -14,7 +14,6 @@
 #include <__chrono/convert_to_timespec.h>
 #include <__chrono/duration.h>
 #include <__config>
-#include <__fwd/hash.h>
 #include <ctime>
 #include <errno.h>
 #include <pthread.h>

diff --git a/libcxx/include/__type_traits/is_reference_wrapper.h b/libcxx/include/__type_traits/is_reference_wrapper.h
@@ -10,6 +10,7 @@
 #define _LIBCPP___TYPE_TRAITS_IS_REFERENCE_WRAPPER_H
 
 #include <__config>
+#include <__fwd/functional.h>
 #include <__type_traits/integral_constant.h>
 #include <__type_traits/remove_cv.h>
 
@@ -19,9 +20,6 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-template <class _Tp>
-class _LIBCPP_TEMPLATE_VIS reference_wrapper;
-
 template <class _Tp>
 struct __is_reference_wrapper_impl : public false_type {};
 template <class _Tp>

diff --git a/libcxx/include/__type_traits/remove_cv.h b/libcxx/include/__type_traits/remove_cv.h
@@ -19,22 +19,17 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if __has_builtin(__remove_cv) && !defined(_LIBCPP_COMPILER_GCC)
 template <class _Tp>
 struct remove_cv {
   using type _LIBCPP_NODEBUG = __remove_cv(_Tp);
 };
 
+#if defined(_LIBCPP_COMPILER_GCC)
 template <class _Tp>
-using __remove_cv_t = __remove_cv(_Tp);
+using __remove_cv_t = typename remove_cv<_Tp>::type;
 #else
 template <class _Tp>
-struct _LIBCPP_TEMPLATE_VIS remove_cv {
-  typedef __remove_volatile_t<__remove_const_t<_Tp> > type;
-};
-
-template <class _Tp>
-using __remove_cv_t = __remove_volatile_t<__remove_const_t<_Tp> >;
+using __remove_cv_t = __remove_cv(_Tp);
 #endif // __has_builtin(__remove_cv)
 
 #if _LIBCPP_STD_VER >= 14

diff --git a/libcxx/include/__type_traits/remove_cvref.h b/libcxx/include/__type_traits/remove_cvref.h
@@ -20,21 +20,26 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if __has_builtin(__remove_cvref) && !defined(_LIBCPP_COMPILER_GCC)
+#if defined(_LIBCPP_COMPILER_GCC)
 template <class _Tp>
-using __remove_cvref_t _LIBCPP_NODEBUG = __remove_cvref(_Tp);
+struct __remove_cvref_gcc {
+  using type = __remove_cvref(_Tp);
+};
+
+template <class _Tp>
+using __remove_cvref_t _LIBCPP_NODEBUG = typename __remove_cvref_gcc<_Tp>::type;
 #else
 template <class _Tp>
-using __remove_cvref_t _LIBCPP_NODEBUG = __remove_cv_t<__libcpp_remove_reference_t<_Tp> >;
+using __remove_cvref_t _LIBCPP_NODEBUG = __remove_cvref(_Tp);
 #endif // __has_builtin(__remove_cvref)
 
 template <class _Tp, class _Up>
-struct __is_same_uncvref : _IsSame<__remove_cvref_t<_Tp>, __remove_cvref_t<_Up> > {};
+using __is_same_uncvref = _IsSame<__remove_cvref_t<_Tp>, __remove_cvref_t<_Up> >;
 
 #if _LIBCPP_STD_VER >= 20
 template <class _Tp>
 struct remove_cvref {
-  using type _LIBCPP_NODEBUG = __remove_cvref_t<_Tp>;
+  using type _LIBCPP_NODEBUG = __remove_cvref(_Tp);
 };
 
 template <class _Tp>

diff --git a/libcxx/include/__type_traits/unwrap_ref.h b/libcxx/include/__type_traits/unwrap_ref.h
@@ -10,6 +10,7 @@
 #define _LIBCPP___TYPE_TRAITS_UNWRAP_REF_H
 
 #include <__config>
+#include <__fwd/functional.h>
 #include <__type_traits/decay.h>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
@@ -23,17 +24,11 @@ struct __unwrap_reference {
   typedef _LIBCPP_NODEBUG _Tp type;
 };
 
-template <class _Tp>
-class reference_wrapper;
-
 template <class _Tp>
 struct __unwrap_reference<reference_wrapper<_Tp> > {
   typedef _LIBCPP_NODEBUG _Tp& type;
 };
 
-template <class _Tp>
-struct decay;
-
 #if _LIBCPP_STD_VER >= 20
 template <class _Tp>
 struct unwrap_reference : __unwrap_reference<_Tp> {};

diff --git a/libcxx/include/experimental/propagate_const b/libcxx/include/experimental/propagate_const
@@ -108,7 +108,7 @@
 */
 
 #include <__functional/operations.h>
-#include <__fwd/hash.h>
+#include <__fwd/functional.h>
 #include <__type_traits/conditional.h>
 #include <__type_traits/decay.h>
 #include <__type_traits/enable_if.h>

diff --git a/libcxx/include/filesystem b/libcxx/include/filesystem
@@ -564,6 +564,7 @@ inline constexpr bool std::ranges::enable_view<std::filesystem::recursive_direct
 #if !defined(_LIBCPP_REMOVE_TRANSITIVE_INCLUDES) && _LIBCPP_STD_VER <= 20
 #  include <concepts>
 #  include <cstdlib>
+#  include <cstring>
 #  include <iosfwd>
 #  include <new>
 #  include <system_error>

diff --git a/libcxx/include/fstream b/libcxx/include/fstream
@@ -279,6 +279,9 @@ public:
 #  endif //  _LIBCPP_STD_VER >= 26
 
   _LIBCPP_HIDE_FROM_ABI inline static const char* __make_mdstring(ios_base::openmode __mode) _NOEXCEPT;
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
+  _LIBCPP_HIDE_FROM_ABI inline static const wchar_t* __make_mdwstring(ios_base::openmode __mode) _NOEXCEPT;
+#  endif
 
 protected:
   // 27.9.1.5 Overridden virtual functions:
@@ -314,6 +317,26 @@ private:
   void __write_mode();
 
   _LIBCPP_EXPORTED_FROM_ABI friend FILE* __get_ostream_file(ostream&);
+
+  // There are multiple (__)open function, they use different C-API open
+  // function. After that call these functions behave the same. This function
+  // does that part and determines the final return value.
+  _LIBCPP_HIDE_FROM_ABI basic_filebuf* __do_open(FILE* __file, ios_base::openmode __mode) {
+    __file_ = __file;
+    if (!__file_)
+      return nullptr;
+
+    __om_ = __mode;
+    if (__mode & ios_base::ate) {
+      if (fseek(__file_, 0, SEEK_END)) {
+        fclose(__file_);
+        __file_ = nullptr;
+        return nullptr;
+      }
+    }
+
+    return this;
+  }
 };
 
 template <class _CharT, class _Traits>
@@ -548,140 +571,93 @@ const char* basic_filebuf<_CharT, _Traits>::__make_mdstring(ios_base::openmode _
   __libcpp_unreachable();
 }
 
+#  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
 template <class _CharT, class _Traits>
-basic_filebuf<_CharT, _Traits>* basic_filebuf<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode) {
-  basic_filebuf<_CharT, _Traits>* __rt = nullptr;
-  if (__file_ == nullptr) {
-    if (const char* __mdstr = __make_mdstring(__mode)) {
-      __rt    = this;
-      __file_ = fopen(__s, __mdstr);
-      if (__file_) {
-        __om_ = __mode;
-        if (__mode & ios_base::ate) {
-          if (fseek(__file_, 0, SEEK_END)) {
-            fclose(__file_);
-            __file_ = nullptr;
-            __rt    = nullptr;
-          }
-        }
-      } else
-        __rt = nullptr;
-    }
+const wchar_t* basic_filebuf<_CharT, _Traits>::__make_mdwstring(ios_base::openmode __mode) _NOEXCEPT {
+  switch (__mode & ~ios_base::ate) {
+  case ios_base::out:
+  case ios_base::out | ios_base::trunc:
+    return L"w";
+  case ios_base::out | ios_base::app:
+  case ios_base::app:
+    return L"a";
+  case ios_base::in:
+    return L"r";
+  case ios_base::in | ios_base::out:
+    return L"r+";
+  case ios_base::in | ios_base::out | ios_base::trunc:
+    return L"w+";
+  case ios_base::in | ios_base::out | ios_base::app:
+  case ios_base::in | ios_base::app:
+    return L"a+";
+  case ios_base::out | ios_base::binary:
+  case ios_base::out | ios_base::trunc | ios_base::binary:
+    return L"wb";
+  case ios_base::out | ios_base::app | ios_base::binary:
+  case ios_base::app | ios_base::binary:
+    return L"ab";
+  case ios_base::in | ios_base::binary:
+    return L"rb";
+  case ios_base::in | ios_base::out | ios_base::binary:
+    return L"r+b";
+  case ios_base::in | ios_base::out | ios_base::trunc | ios_base::binary:
+    return L"w+b";
+  case ios_base::in | ios_base::out | ios_base::app | ios_base::binary:
+  case ios_base::in | ios_base::app | ios_base::binary:
+    return L"a+b";
+#    if _LIBCPP_STD_VER >= 23
+  case ios_base::out | ios_base::noreplace:
+  case ios_base::out | ios_base::trunc | ios_base::noreplace:
+    return L"wx";
+  case ios_base::in | ios_base::out | ios_base::trunc | ios_base::noreplace:
+    return L"w+x";
+  case ios_base::out | ios_base::binary | ios_base::noreplace:
+  case ios_base::out | ios_base::trunc | ios_base::binary | ios_base::noreplace:
+    return L"wbx";
+  case ios_base::in | ios_base::out | ios_base::trunc | ios_base::binary | ios_base::noreplace:
+    return L"w+bx";
+#    endif // _LIBCPP_STD_VER >= 23
+  default:
+    return nullptr;
   }
-  return __rt;
+  __libcpp_unreachable();
+}
+#  endif
+
+template <class _CharT, class _Traits>
+basic_filebuf<_CharT, _Traits>* basic_filebuf<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode) {
+  if (__file_)
+    return nullptr;
+  const char* __mdstr = __make_mdstring(__mode);
+  if (!__mdstr)
+    return nullptr;
+
+  return __do_open(fopen(__s, __mdstr), __mode);
 }
 
 template <class _CharT, class _Traits>
 inline basic_filebuf<_CharT, _Traits>* basic_filebuf<_CharT, _Traits>::__open(int __fd, ios_base::openmode __mode) {
-  basic_filebuf<_CharT, _Traits>* __rt = nullptr;
-  if (__file_ == nullptr) {
-    if (const char* __mdstr = __make_mdstring(__mode)) {
-      __rt    = this;
-      __file_ = fdopen(__fd, __mdstr);
-      if (__file_) {
-        __om_ = __mode;
-        if (__mode & ios_base::ate) {
-          if (fseek(__file_, 0, SEEK_END)) {
-            fclose(__file_);
-            __file_ = nullptr;
-            __rt    = nullptr;
-          }
-        }
-      } else
-        __rt = nullptr;
-    }
-  }
-  return __rt;
+  if (__file_)
+    return nullptr;
+  const char* __mdstr = __make_mdstring(__mode);
+  if (!__mdstr)
+    return nullptr;
+
+  return __do_open(fdopen(__fd, __mdstr), __mode);
 }
 
 #  ifdef _LIBCPP_HAS_OPEN_WITH_WCHAR
 // This is basically the same as the char* overload except that it uses _wfopen
 // and long mode strings.
 template <class _CharT, class _Traits>
 basic_filebuf<_CharT, _Traits>* basic_filebuf<_CharT, _Traits>::open(const wchar_t* __s, ios_base::openmode __mode) {
-  basic_filebuf<_CharT, _Traits>* __rt = nullptr;
-  if (__file_ == nullptr) {
-    __rt = this;
-    const wchar_t* __mdstr;
-    switch (__mode & ~ios_base::ate) {
-    case ios_base::out:
-    case ios_base::out | ios_base::trunc:
-      __mdstr = L"w";
-      break;
-    case ios_base::out | ios_base::app:
-    case ios_base::app:
-      __mdstr = L"a";
-      break;
-    case ios_base::in:
-      __mdstr = L"r";
-      break;
-    case ios_base::in | ios_base::out:
-      __mdstr = L"r+";
-      break;
-    case ios_base::in | ios_base::out | ios_base::trunc:
-      __mdstr = L"w+";
-      break;
-    case ios_base::in | ios_base::out | ios_base::app:
-    case ios_base::in | ios_base::app:
-      __mdstr = L"a+";
-      break;
-    case ios_base::out | ios_base::binary:
-    case ios_base::out | ios_base::trunc | ios_base::binary:
-      __mdstr = L"wb";
-      break;
-    case ios_base::out | ios_base::app | ios_base::binary:
-    case ios_base::app | ios_base::binary:
-      __mdstr = L"ab";
-      break;
-    case ios_base::in | ios_base::binary:
-      __mdstr = L"rb";
-      break;
-    case ios_base::in | ios_base::out | ios_base::binary:
-      __mdstr = L"r+b";
-      break;
-    case ios_base::in | ios_base::out | ios_base::trunc | ios_base::binary:
-      __mdstr = L"w+b";
-      break;
-    case ios_base::in | ios_base::out | ios_base::app | ios_base::binary:
-    case ios_base::in | ios_base::app | ios_base::binary:
-      __mdstr = L"a+b";
-      break;
-#    if _LIBCPP_STD_VER >= 23
-    case ios_base::out | ios_base::noreplace:
-    case ios_base::out | ios_base::trunc | ios_base::noreplace:
-      __mdstr = L"wx";
-      break;
-    case ios_base::in | ios_base::out | ios_base::trunc | ios_base::noreplace:
-      __mdstr = L"w+x";
-      break;
-    case ios_base::out | ios_base::binary | ios_base::noreplace:
-    case ios_base::out | ios_base::trunc | ios_base::binary | ios_base::noreplace:
-      __mdstr = L"wbx";
-      break;
-    case ios_base::in | ios_base::out | ios_base::trunc | ios_base::binary | ios_base::noreplace:
-      __mdstr = L"w+bx";
-      break;
-#    endif // _LIBCPP_STD_VER >= 23
-    default:
-      __rt = nullptr;
-      break;
-    }
-    if (__rt) {
-      __file_ = _wfopen(__s, __mdstr);
-      if (__file_) {
-        __om_ = __mode;
-        if (__mode & ios_base::ate) {
-          if (fseek(__file_, 0, SEEK_END)) {
-            fclose(__file_);
-            __file_ = nullptr;
-            __rt    = nullptr;
-          }
-        }
-      } else
-        __rt = nullptr;
-    }
-  }
-  return __rt;
+  if (__file_)
+    return nullptr;
+  const wchar_t* __mdstr = __make_mdwstring(__mode);
+  if (!__mdstr)
+    return nullptr;
+
+  return __do_open(_wfopen(__s, __mdstr), __mode);
 }
 #  endif
 

diff --git a/libcxx/include/libcxx.imp b/libcxx/include/libcxx.imp
@@ -426,7 +426,7 @@
   { include: [ "<__fwd/bit_reference.h>", "private", "<vector>", "public" ] },
   { include: [ "<__fwd/complex.h>", "private", "<complex>", "public" ] },
   { include: [ "<__fwd/fstream.h>", "private", "<iosfwd>", "public" ] },
-  { include: [ "<__fwd/hash.h>", "private", "<functional>", "public" ] },
+  { include: [ "<__fwd/functional.h>", "private", "<functional>", "public" ] },
   { include: [ "<__fwd/ios.h>", "private", "<iosfwd>", "public" ] },
   { include: [ "<__fwd/istream.h>", "private", "<iosfwd>", "public" ] },
   { include: [ "<__fwd/mdspan.h>", "private", "<mdspan>", "public" ] },

diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
@@ -1365,7 +1365,7 @@ module std_private_functional_hash                       [system] {
   export std_private_type_traits_underlying_type
   export std_private_utility_pair
 }
-module std_private_functional_hash_fwd                   [system] { header "__fwd/hash.h" }
+module std_private_functional_fwd                        [system] { header "__fwd/functional.h" }
 module std_private_functional_identity                   [system] { header "__functional/identity.h" }
 module std_private_functional_invoke                     [system] {
   header "__functional/invoke.h"

diff --git a/libcxx/include/optional b/libcxx/include/optional
@@ -186,8 +186,8 @@ namespace std {
 #include <__exception/exception.h>
 #include <__functional/hash.h>
 #include <__functional/invoke.h>
-#include <__functional/reference_wrapper.h>
 #include <__functional/unary_function.h>
+#include <__fwd/functional.h>
 #include <__memory/addressof.h>
 #include <__memory/construct_at.h>
 #include <__tuple/sfinae_helpers.h>

diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
@@ -418,7 +418,7 @@ namespace std
 */
 
 #include <__config>
-#include <__fwd/hash.h> // This is https://llvm.org/PR56938
+#include <__fwd/functional.h> // This is https://llvm.org/PR56938
 #include <__type_traits/add_const.h>
 #include <__type_traits/add_cv.h>
 #include <__type_traits/add_lvalue_reference.h>

diff --git a/libcxx/src/iostream.cpp b/libcxx/src/iostream.cpp
@@ -21,83 +21,75 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-_ALIGNAS_TYPE(istream)
-_LIBCPP_EXPORTED_FROM_ABI char cin[sizeof(istream)]
+alignas(istream) _LIBCPP_EXPORTED_FROM_ABI char cin[sizeof(istream)]
 #if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
     __asm__("?cin@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_istream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR
             "@std@@@12@A")
 #endif
         ;
-_ALIGNAS_TYPE(__stdinbuf<char>) static char __cin[sizeof(__stdinbuf<char>)];
+alignas(__stdinbuf<char>) static char __cin[sizeof(__stdinbuf<char>)];
 static mbstate_t mb_cin;
 
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-_ALIGNAS_TYPE(wistream)
-_LIBCPP_EXPORTED_FROM_ABI char wcin[sizeof(wistream)]
+alignas(wistream) _LIBCPP_EXPORTED_FROM_ABI char wcin[sizeof(wistream)]
 #  if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
     __asm__("?wcin@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_istream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR
             "@std@@@12@A")
 #  endif
         ;
-_ALIGNAS_TYPE(__stdinbuf<wchar_t>) static char __wcin[sizeof(__stdinbuf<wchar_t>)];
+alignas(__stdinbuf<wchar_t>) static char __wcin[sizeof(__stdinbuf<wchar_t>)];
 static mbstate_t mb_wcin;
 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
 
-_ALIGNAS_TYPE(ostream)
-_LIBCPP_EXPORTED_FROM_ABI char cout[sizeof(ostream)]
+alignas(ostream) _LIBCPP_EXPORTED_FROM_ABI char cout[sizeof(ostream)]
 #if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
     __asm__("?cout@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR
             "@std@@@12@A")
 #endif
         ;
-_ALIGNAS_TYPE(__stdoutbuf<char>) static char __cout[sizeof(__stdoutbuf<char>)];
+alignas(__stdoutbuf<char>) static char __cout[sizeof(__stdoutbuf<char>)];
 static mbstate_t mb_cout;
 
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-_ALIGNAS_TYPE(wostream)
-_LIBCPP_EXPORTED_FROM_ABI char wcout[sizeof(wostream)]
+alignas(wostream) _LIBCPP_EXPORTED_FROM_ABI char wcout[sizeof(wostream)]
 #  if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
     __asm__("?wcout@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR
             "@std@@@12@A")
 #  endif
         ;
-_ALIGNAS_TYPE(__stdoutbuf<wchar_t>) static char __wcout[sizeof(__stdoutbuf<wchar_t>)];
+alignas(__stdoutbuf<wchar_t>) static char __wcout[sizeof(__stdoutbuf<wchar_t>)];
 static mbstate_t mb_wcout;
 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
 
-_ALIGNAS_TYPE(ostream)
-_LIBCPP_EXPORTED_FROM_ABI char cerr[sizeof(ostream)]
+alignas(ostream) _LIBCPP_EXPORTED_FROM_ABI char cerr[sizeof(ostream)]
 #if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
     __asm__("?cerr@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR
             "@std@@@12@A")
 #endif
         ;
-_ALIGNAS_TYPE(__stdoutbuf<char>) static char __cerr[sizeof(__stdoutbuf<char>)];
+alignas(__stdoutbuf<char>) static char __cerr[sizeof(__stdoutbuf<char>)];
 static mbstate_t mb_cerr;
 
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-_ALIGNAS_TYPE(wostream)
-_LIBCPP_EXPORTED_FROM_ABI char wcerr[sizeof(wostream)]
+alignas(wostream) _LIBCPP_EXPORTED_FROM_ABI char wcerr[sizeof(wostream)]
 #  if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
     __asm__("?wcerr@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR
             "@std@@@12@A")
 #  endif
         ;
-_ALIGNAS_TYPE(__stdoutbuf<wchar_t>) static char __wcerr[sizeof(__stdoutbuf<wchar_t>)];
+alignas(__stdoutbuf<wchar_t>) static char __wcerr[sizeof(__stdoutbuf<wchar_t>)];
 static mbstate_t mb_wcerr;
 #endif // _LIBCPP_HAS_NO_WIDE_CHARACTERS
 
-_ALIGNAS_TYPE(ostream)
-_LIBCPP_EXPORTED_FROM_ABI char clog[sizeof(ostream)]
+alignas(ostream) _LIBCPP_EXPORTED_FROM_ABI char clog[sizeof(ostream)]
 #if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
     __asm__("?clog@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@DU?$char_traits@D@" _LIBCPP_ABI_NAMESPACE_STR
             "@std@@@12@A")
 #endif
         ;
 
 #ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
-_ALIGNAS_TYPE(wostream)
-_LIBCPP_EXPORTED_FROM_ABI char wclog[sizeof(wostream)]
+alignas(wostream) _LIBCPP_EXPORTED_FROM_ABI char wclog[sizeof(wostream)]
 #  if defined(_LIBCPP_ABI_MICROSOFT) && defined(__clang__)
     __asm__("?wclog@" _LIBCPP_ABI_NAMESPACE_STR "@std@@3V?$basic_ostream@_WU?$char_traits@_W@" _LIBCPP_ABI_NAMESPACE_STR
             "@std@@@12@A")

diff --git a/libcxx/test/libcxx/transitive_includes/cxx23.csv b/libcxx/test/libcxx/transitive_includes/cxx23.csv
@@ -178,7 +178,6 @@ experimental/utility utility
 filesystem compare
 filesystem cstddef
 filesystem cstdint
-filesystem cstring
 filesystem ctime
 filesystem iomanip
 filesystem limits

diff --git a/libcxx/test/libcxx/transitive_includes/cxx26.csv b/libcxx/test/libcxx/transitive_includes/cxx26.csv
@@ -178,7 +178,6 @@ experimental/utility utility
 filesystem compare
 filesystem cstddef
 filesystem cstdint
-filesystem cstring
 filesystem ctime
 filesystem iomanip
 filesystem limits

diff --git a/...test/std/containers/container.adaptors/container.adaptors.format/format.functions.tests.h b/...test/std/containers/container.adaptors/container.adaptors.format/format.functions.tests.h
@@ -35,8 +35,10 @@ void test_char_default(TestFunction check, ExceptionTest check_exception, auto&&
 
   // when one is present there is no escaping,
   check(SV("[H, e, l, l, o]"), SV("{::}"), input);
+  check(SV("[H, e, l, l, o]"), SV("{::<}"), input);
   // unless forced by the type specifier.
   check(SV("['H', 'e', 'l', 'l', 'o']"), SV("{::?}"), input);
+  check(SV("['H', 'e', 'l', 'l', 'o']"), SV("{::<?}"), input);
 
   // ***** underlying has no format-spec
 
@@ -53,7 +55,6 @@ void test_char_default(TestFunction check, ExceptionTest check_exception, auto&&
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -153,7 +154,6 @@ void test_char_string(TestFunction check, ExceptionTest check_exception, auto&&
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<s}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<s}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<s}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-s}"), input);
@@ -177,6 +177,7 @@ void test_char_string(TestFunction check, ExceptionTest check_exception, auto&&
 
   // *** type ***
   check_exception("Type m requires a pair or a tuple with two elements", SV("{:m}"), input);
+  check_exception("The type option contains an invalid value for a character formatting argument", SV("{::<s}"), input);
 
   // ***** Only underlying has a format-spec
   check_exception("Type s and an underlying format specification can't be used together", SV("{:s:}"), input);
@@ -206,7 +207,7 @@ void test_char_escaped_string(TestFunction check, ExceptionTest check_exception,
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<?s}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<?s}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<?s}"), input);
+  check_exception("The format specifier should consume the input or end with a '}'", SV("{::<?s}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-?s}"), input);
@@ -324,7 +325,6 @@ void test_bool(TestFunction check, ExceptionTest check_exception, auto&& input)
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -440,7 +440,6 @@ void test_int(TestFunction check, ExceptionTest check_exception, auto&& input) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -550,7 +549,6 @@ void test_floating_point(TestFunction check, ExceptionTest check_exception, auto
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -688,7 +686,6 @@ void test_pointer(TestFunction check, ExceptionTest check_exception, auto&& inpu
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -798,7 +795,6 @@ void test_string(TestFunction check, ExceptionTest check_exception, auto&& input
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -910,7 +906,6 @@ void test_status(TestFunction check, ExceptionTest check_exception, auto&& input
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);

diff --git a/libcxx/test/std/containers/sequences/vector.bool/vector.bool.fmt/format.functions.tests.h b/libcxx/test/std/containers/sequences/vector.bool/vector.bool.fmt/format.functions.tests.h
@@ -34,7 +34,6 @@ void format_test_vector_bool(TestFunction check, ExceptionTest check_exception,
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);

diff --git a/libcxx/test/std/utilities/format/format.range/format.range.fmtmap/format.functions.tests.h b/libcxx/test/std/utilities/format/format.range/format.range.fmtmap/format.functions.tests.h
@@ -45,7 +45,6 @@ void test_char(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -87,7 +86,6 @@ void test_char(TestFunction check, ExceptionTest check_exception) {
   check(SV("{__'a': 'A'___, __'b': 'B'___, __'c': 'C'___}"), SV("{::_^{}}"), input, 13);
   check(SV("{#####'a': 'A', #####'b': 'B', #####'c': 'C'}"), SV("{::#>{}}"), input, 13);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 
@@ -157,7 +155,6 @@ void test_char_to_wchar(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -198,7 +195,6 @@ void test_char_to_wchar(TestFunction check, ExceptionTest check_exception) {
   check(SV("{__'a': 'A'___, __'b': 'B'___, __'c': 'C'___}"), SV("{::_^{}}"), input, 13);
   check(SV("{#####'a': 'A', #####'b': 'B', #####'c': 'C'}"), SV("{::#>{}}"), input, 13);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 
@@ -267,7 +263,6 @@ void test_bool(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -308,7 +303,6 @@ void test_bool(TestFunction check, ExceptionTest check_exception) {
   check(SV("{_false: 0_, _true: 42_, _true: 1__}"), SV("{::_^{}}"), input, 10);
   check(SV("{##false: 0, ##true: 42, ###true: 1}"), SV("{::#>{}}"), input, 10);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 
@@ -369,7 +363,6 @@ void test_int(TestFunction check, ExceptionTest check_exception, auto&& input) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -410,7 +403,6 @@ void test_int(TestFunction check, ExceptionTest check_exception, auto&& input) {
   check(SV("{_-42: 42__, __1: -1___, _42: -42__}"), SV("{::_^{}}"), input, 10);
   check(SV("{###-42: 42, #####1: -1, ###42: -42}"), SV("{::#>{}}"), input, 10);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 
@@ -478,7 +470,6 @@ void test_floating_point(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -519,7 +510,6 @@ void test_floating_point(TestFunction check, ExceptionTest check_exception) {
   check(SV("{_-42: 42__, __1: -1___}"), SV("{::_^{}}"), input, 10);
   check(SV("{###-42: 42, #####1: -1}"), SV("{::#>{}}"), input, 10);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 
@@ -582,7 +572,6 @@ void test_pointer(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:#}"), input);
@@ -621,7 +610,6 @@ void test_pointer(TestFunction check, ExceptionTest check_exception) {
   check(SV("{__0x0: 0x0___}"), SV("{::_^{}}"), input, 13);
   check(SV("{#####0x0: 0x0}"), SV("{::#>{}}"), input, 13);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 
@@ -685,7 +673,6 @@ void test_string(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:#}"), input);
@@ -724,7 +711,6 @@ void test_string(TestFunction check, ExceptionTest check_exception) {
   check(SV(R"({__"hello": "HELLO"___, __"world": "WORLD"___})"), SV("{::_^{}}"), input, 21);
   check(SV(R"({#####"hello": "HELLO", #####"world": "WORLD"})"), SV("{::#>{}}"), input, 21);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 
@@ -788,7 +774,6 @@ void test_status(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);

diff --git a/libcxx/test/std/utilities/format/format.range/format.range.fmtset/format.functions.tests.h b/libcxx/test/std/utilities/format/format.range/format.range.fmtset/format.functions.tests.h
@@ -34,8 +34,10 @@ void test_char_default(TestFunction check, ExceptionTest check_exception) {
   check(SV("{'a', 'b', 'c'}^42"), SV("{:}^42"), input);
   // when one is present there is no escaping,
   check(SV("{a, b, c}"), SV("{::}"), input);
+  check(SV("{a, b, c}"), SV("{::<}"), input);
   // unless forced by the type specifier.
   check(SV("{'a', 'b', 'c'}"), SV("{::?}"), input);
+  check(SV("{'a', 'b', 'c'}"), SV("{::<?}"), input);
 
   // ***** underlying has no format-spec
 
@@ -52,7 +54,6 @@ void test_char_default(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -156,7 +157,6 @@ void test_char_string(TestFunction check, [[maybe_unused]] ExceptionTest check_e
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<s}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<s}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<s}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-s}"), input);
@@ -180,6 +180,7 @@ void test_char_string(TestFunction check, [[maybe_unused]] ExceptionTest check_e
 
   // *** type ***
   check_exception("Type m requires a pair or a tuple with two elements", SV("{:m}"), input);
+  check_exception("The type option contains an invalid value for a character formatting argument", SV("{::<s}"), input);
 
   // ***** Only underlying has a format-spec
   check_exception("Type s and an underlying format specification can't be used together", SV("{:s:}"), input);
@@ -215,7 +216,7 @@ void test_char_escaped_string(TestFunction check, [[maybe_unused]] ExceptionTest
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<?s}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<?s}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<?s}"), input);
+  check_exception("The format specifier should consume the input or end with a '}'", SV("{::<?s}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-?s}"), input);
@@ -271,8 +272,10 @@ void test_char_to_wchar(TestFunction check, ExceptionTest check_exception) {
   check(SV("{'a', 'b', 'c'}^42"), SV("{:}^42"), input);
   // when one is present there is no escaping,
   check(SV("{a, b, c}"), SV("{::}"), input);
+  check(SV("{a, b, c}"), SV("{::<}"), input);
   // unless forced by the type specifier.
   check(SV("{'a', 'b', 'c'}"), SV("{::?}"), input);
+  check(SV("{'a', 'b', 'c'}"), SV("{::<?}"), input);
 
   // ***** underlying has no format-spec
 
@@ -289,7 +292,6 @@ void test_char_to_wchar(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -405,7 +407,6 @@ void test_bool(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -512,7 +513,6 @@ void test_bool_multiset(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -621,7 +621,6 @@ void test_int(TestFunction check, ExceptionTest check_exception, auto&& input) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -730,7 +729,6 @@ void test_floating_point(TestFunction check, ExceptionTest check_exception, auto
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -868,7 +866,6 @@ void test_pointer(TestFunction check, ExceptionTest check_exception, auto&& inpu
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:#}"), input);
@@ -978,7 +975,6 @@ void test_string(TestFunction check, ExceptionTest check_exception, auto&& input
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:#}"), input);
@@ -1091,7 +1087,6 @@ void test_status(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -1160,7 +1155,6 @@ void test_pair_tuple(TestFunction check, ExceptionTest check_exception, auto&& i
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -1202,7 +1196,6 @@ void test_pair_tuple(TestFunction check, ExceptionTest check_exception, auto&& i
   check(SV("{_(1, 'a')__, _(42, '*')_}"), SV("{::_^{}}"), input, 11);
   check(SV("{###(1, 'a'), ##(42, '*')}"), SV("{::#>{}}"), input, 11);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 
@@ -1284,7 +1277,6 @@ void test_tuple_int(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -1325,7 +1317,6 @@ void test_tuple_int(TestFunction check, ExceptionTest check_exception) {
   check(SV("{_(42)__, _(99)__}"), SV("{::_^{}}"), input, 7);
   check(SV("{###(42), ###(99)}"), SV("{::#>{}}"), input, 7);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 
@@ -1394,7 +1385,6 @@ void test_tuple_int_int_int(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -1435,7 +1425,6 @@ void test_tuple_int_int_int(TestFunction check, ExceptionTest check_exception) {
   check(SV("{_(1, 10, 100)_, _(42, 99, 0)__}"), SV("{::_^{}}"), input, 14);
   check(SV("{##(1, 10, 100), ###(42, 99, 0)}"), SV("{::#>{}}"), input, 14);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 

diff --git a/libcxx/test/std/utilities/format/format.range/format.range.fmtstr/format.functions.tests.h b/libcxx/test/std/utilities/format/format.range/format.range.fmtstr/format.functions.tests.h
@@ -137,7 +137,6 @@ void test_range_string(TestFunction check, ExceptionTest check_exception, auto&&
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -327,7 +326,6 @@ void test_range_debug_string(TestFunction check, ExceptionTest check_exception,
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);

diff --git a/...xx/test/std/utilities/format/format.range/format.range.formatter/format.functions.tests.h b/...xx/test/std/utilities/format/format.range/format.range.formatter/format.functions.tests.h
@@ -39,8 +39,10 @@ void test_char_default(TestFunction check, ExceptionTest check_exception, auto&&
 
   // when one is present there is no escaping,
   check(SV("[H, e, l, l, o]"), SV("{::}"), input);
+  check(SV("[H, e, l, l, o]"), SV("{::<}"), input);
   // unless forced by the type specifier.
   check(SV("['H', 'e', 'l', 'l', 'o']"), SV("{::?}"), input);
+  check(SV("['H', 'e', 'l', 'l', 'o']"), SV("{::<?}"), input);
 
   // ***** underlying has no format-spec
 
@@ -57,7 +59,6 @@ void test_char_default(TestFunction check, ExceptionTest check_exception, auto&&
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -157,7 +158,6 @@ void test_char_string(TestFunction check, ExceptionTest check_exception, auto&&
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<s}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<s}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<s}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-s}"), input);
@@ -181,6 +181,7 @@ void test_char_string(TestFunction check, ExceptionTest check_exception, auto&&
 
   // *** type ***
   check_exception("Type m requires a pair or a tuple with two elements", SV("{:m}"), input);
+  check_exception("The type option contains an invalid value for a character formatting argument", SV("{::<s}"), input);
 
   // ***** Only underlying has a format-spec
   check_exception("Type s and an underlying format specification can't be used together", SV("{:s:}"), input);
@@ -210,7 +211,7 @@ void test_char_escaped_string(TestFunction check, ExceptionTest check_exception,
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<?s}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<?s}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<?s}"), input);
+  check_exception("The format specifier should consume the input or end with a '}'", SV("{::<?s}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-?s}"), input);
@@ -315,7 +316,6 @@ void test_bool(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -423,7 +423,6 @@ void test_int(TestFunction check, ExceptionTest check_exception, auto&& input) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -534,7 +533,6 @@ void test_floating_point(TestFunction check, ExceptionTest check_exception, auto
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -673,7 +671,6 @@ void test_pointer(TestFunction check, ExceptionTest check_exception, auto&& inpu
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:#}"), input);
@@ -782,7 +779,6 @@ void test_string(TestFunction check, ExceptionTest check_exception, auto&& input
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:#}"), input);
@@ -895,7 +891,6 @@ void test_status(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -978,7 +973,6 @@ void test_pair_tuple(TestFunction check, ExceptionTest check_exception, auto&& i
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -1019,7 +1013,6 @@ void test_pair_tuple(TestFunction check, ExceptionTest check_exception, auto&& i
   check(SV("[_(1, 'a')__, _(42, '*')_]"), SV("{::_^{}}"), input, 11);
   check(SV("[###(1, 'a'), ##(42, '*')]"), SV("{::#>{}}"), input, 11);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 
@@ -1098,7 +1091,6 @@ void test_tuple_int(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -1138,7 +1130,6 @@ void test_tuple_int(TestFunction check, ExceptionTest check_exception) {
   check(SV("[_(42)__, _(99)__]"), SV("{::_^{}}"), input, 7);
   check(SV("[###(42), ###(99)]"), SV("{::#>{}}"), input, 7);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 
@@ -1203,7 +1194,6 @@ void test_tuple_int_int_int(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -1243,7 +1233,6 @@ void test_tuple_int_int_int(TestFunction check, ExceptionTest check_exception) {
   check(SV("[_(42, 99, 0)__, _(1, 10, 100)_]"), SV("{::_^{}}"), input, 14);
   check(SV("[###(42, 99, 0), ##(1, 10, 100)]"), SV("{::#>{}}"), input, 14);
 
-  check_exception("The fill option contains an invalid value", SV("{:::<}"), input);
   check_exception("The format string contains an invalid escape sequence", SV("{::}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{::{<}"), input);
 

diff --git a/libcxx/test/std/utilities/format/format.tuple/format.functions.tests.h b/libcxx/test/std/utilities/format/format.tuple/format.functions.tests.h
@@ -46,7 +46,6 @@ void test_tuple_or_pair_int_int(TestFunction check, ExceptionTest check_exceptio
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -95,7 +94,6 @@ void test_tuple_or_pair_int_string(TestFunction check, ExceptionTest check_excep
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -187,7 +185,6 @@ void test_tuple_int(TestFunction check, ExceptionTest check_exception) {
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -238,7 +235,6 @@ void test_tuple_int_string_color(TestFunction check, ExceptionTest check_excepti
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);
@@ -313,7 +309,6 @@ void test_nested(TestFunction check, ExceptionTest check_exception, Nested&& inp
 
   check_exception("The format string contains an invalid escape sequence", SV("{:}<}"), input);
   check_exception("The fill option contains an invalid value", SV("{:{<}"), input);
-  check_exception("The fill option contains an invalid value", SV("{::<}"), input);
 
   // *** sign ***
   check_exception("The format specifier should consume the input or end with a '}'", SV("{:-}"), input);

diff --git a/libcxx/utils/generate_iwyu_mapping.py b/libcxx/utils/generate_iwyu_mapping.py
@@ -34,8 +34,6 @@ def IWYU_mapping(header: str) -> typing.Optional[typing.List[str]]:
         return ["atomic", "mutex", "semaphore", "thread"]
     elif header == "__tree":
         return ["map", "set"]
-    elif header == "__fwd/hash.h":
-        return ["functional"]
     elif header == "__fwd/pair.h":
         return ["utility"]
     elif header == "__fwd/subrange.h":

diff --git a/libcxx/utils/libcxx/test/format.py b/libcxx/utils/libcxx/test/format.py
@@ -265,7 +265,6 @@ def getTestsForPath(self, testSuite, pathInSuite, litConfig, localConfig):
             "[.]sh[.][^.]+$",
             "[.]gen[.][^.]+$",
             "[.]verify[.]cpp$",
-            "[.]fail[.]cpp$",
         ]
 
         sourcePath = testSuite.getSourcePath(pathInSuite)

diff --git a/llvm/docs/Contributing.rst b/llvm/docs/Contributing.rst
@@ -89,10 +89,9 @@ in order to update the last commit with all pending changes.
   ``clang/tools/clang-format/git-clang-format``.
 
 The LLVM project has migrated to GitHub Pull Requests as its review process.
-We still have an active :ref:`Phabricator <phabricator-reviews>`
-instance for the duration of the migration. If you want to contribute to LLVM
-now, please use GitHub. For more information about the workflow of using GitHub
-Pull Requests see our :ref:`GitHub <github-reviews>` documentation.
+For more information about the workflow of using GitHub Pull Requests see our
+:ref:`GitHub <github-reviews>` documentation. We still have an read-only
+`LLVM's Phabricator <https://reviews.llvm.org>`_ instance.
 
 To make sure the right people see your patch, please select suitable reviewers
 and add them to your patch when requesting a review. Suitable reviewers are the
@@ -185,5 +184,5 @@ of LLVM's high-level design, as well as its internals:
 .. _clang-format-diff.py: https://reviews.llvm.org/source/llvm-github/browse/main/clang/tools/clang-format/clang-format-diff.py
 .. _git-clang-format: https://reviews.llvm.org/source/llvm-github/browse/main/clang/tools/clang-format/git-clang-format
 .. _LLVM's GitHub: https://github.com/llvm/llvm-project
-.. _LLVM's Phabricator (deprecated): https://reviews.llvm.org/
+.. _LLVM's Phabricator (read-only): https://reviews.llvm.org/
 .. _LLVM's Open Projects page: https://llvm.org/OpenProjects.html#what
diff --git a/llvm/docs/DeveloperPolicy.rst b/llvm/docs/DeveloperPolicy.rst
@@ -129,8 +129,8 @@ awareness of. For such changes, the following should be done:
 
 .. warning::
 
-  Phabricator is deprecated and will be switched to read-only mode in October
-  2023, for new code contributions use :ref:`GitHub Pull Requests <github-reviews>`.
+  Phabricator is deprecated is available in read-only mode,
+  for new code contributions use :ref:`GitHub Pull Requests <github-reviews>`.
   This section contains old information that needs to be updated.
 
 * When performing the code review for the change, please add any applicable