diff --git a/clang-tools-extra/clangd/unittests/ParsedASTTests.cpp b/clang-tools-extra/clangd/unittests/ParsedASTTests.cpp
@@ -12,10 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "../../clang-tidy/ClangTidyCheck.h"
-#include "../../clang-tidy/ClangTidyModule.h"
-#include "../../clang-tidy/ClangTidyModuleRegistry.h"
 #include "AST.h"
-#include "CompileCommands.h"
 #include "Compiler.h"
 #include "Config.h"
 #include "Diagnostics.h"
@@ -32,7 +29,6 @@
 #include "clang/Basic/SourceLocation.h"
 #include "clang/Basic/SourceManager.h"
 #include "clang/Basic/TokenKinds.h"
-#include "clang/Lex/PPCallbacks.h"
 #include "clang/Tooling/Syntax/Tokens.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Testing/Annotations/Annotations.h"
@@ -41,6 +37,7 @@
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 #include <memory>
+#include <string_view>
 #include <utility>
 #include <vector>
 
@@ -347,9 +344,8 @@ TEST(ParsedASTTest, CollectsMainFileMacroExpansions) {
   }
   for (const auto &R : AST.getMacros().UnknownMacros)
     MacroExpansionPositions.push_back(R.StartOffset);
-  EXPECT_THAT(
-      MacroExpansionPositions,
-      testing::UnorderedElementsAreArray(TestCase.points()));
+  EXPECT_THAT(MacroExpansionPositions,
+              testing::UnorderedElementsAreArray(TestCase.points()));
 }
 
 MATCHER_P(withFileName, Inc, "") { return arg.FileName == Inc; }
@@ -768,6 +764,35 @@ TEST(ParsedASTTest, GracefulFailureOnAssemblyFile) {
       << "Should not try to build AST for assembly source file";
 }
 
+TEST(ParsedASTTest, PreambleWithDifferentTarget) {
+  constexpr std::string_view kPreambleTarget = "x86_64";
+  // Specifically picking __builtin_va_list as it triggers crashes when
+  // switching to wasm.
+  // It's due to different predefined types in different targets.
+  auto TU = TestTU::withHeaderCode("void foo(__builtin_va_list);");
+  TU.Code = "void bar() { foo(2); }";
+  TU.ExtraArgs.emplace_back("-target");
+  TU.ExtraArgs.emplace_back(kPreambleTarget);
+  const auto Preamble = TU.preamble();
+
+  // Switch target to wasm.
+  TU.ExtraArgs.pop_back();
+  TU.ExtraArgs.emplace_back("wasm32");
+
+  IgnoreDiagnostics Diags;
+  MockFS FS;
+  auto Inputs = TU.inputs(FS);
+  auto CI = buildCompilerInvocation(Inputs, Diags);
+  ASSERT_TRUE(CI) << "Failed to build compiler invocation";
+
+  auto AST = ParsedAST::build(testPath(TU.Filename), std::move(Inputs),
+                              std::move(CI), {}, Preamble);
+
+  ASSERT_TRUE(AST);
+  // We use the target from preamble, not with the most-recent flags.
+  EXPECT_EQ(AST->getASTContext().getTargetInfo().getTriple().getArchName(),
+            llvm::StringRef(kPreambleTarget));
+}
 } // namespace
 } // namespace clangd
 } // namespace clang
diff --git a/clang-tools-extra/docs/ReleaseNotes.rst b/clang-tools-extra/docs/ReleaseNotes.rst
@@ -147,10 +147,18 @@ Changes in existing checks
   <clang-tidy/checks/bugprone/assert-side-effect>` check by detecting side
   effect from calling a method with non-const reference parameters.
 
+- Improved :doc:`bugprone-forwarding-reference-overload
+  <clang-tidy/checks/bugprone/forwarding-reference-overload>`
+  check to ignore deleted constructors which won't hide other overloads.
+
 - Improved :doc:`bugprone-inc-dec-in-conditions
   <clang-tidy/checks/bugprone/inc-dec-in-conditions>` check to ignore code
   within unevaluated contexts, such as ``decltype``.
 
+- Improved :doc:`bugprone-lambda-function-name<clang-tidy/checks/bugprone/lambda-function-name>`
+  check by ignoring ``__func__`` macro in lambda captures, initializers of
+  default parameters and nested function declarations.
+
 - Improved :doc:`bugprone-non-zero-enum-to-bool-conversion
   <clang-tidy/checks/bugprone/non-zero-enum-to-bool-conversion>` check by
   eliminating false positives resulting from direct usage of bitwise operators
@@ -221,6 +229,10 @@ Changes in existing checks
   <clang-tidy/checks/llvm/header-guard>` check by replacing the local
   option `HeaderFileExtensions` by the global option of the same name.
 
+- Improved :doc:`misc-const-correctness
+  <clang-tidy/checks/misc/const-correctness>` check by avoiding infinite recursion
+  for recursive forwarding reference.
+
 - Improved :doc:`misc-definitions-in-headers
   <clang-tidy/checks/misc/definitions-in-headers>` check by replacing the local
   option `HeaderFileExtensions` by the global option of the same name.

diff --git a/clang-tools-extra/docs/clang-tidy/checks/bugprone/sizeof-expression.rst b/clang-tools-extra/docs/clang-tidy/checks/bugprone/sizeof-expression.rst
@@ -190,6 +190,6 @@ Options
 
 .. option:: WarnOnSizeOfPointerToAggregate
 
-   When `true, the check will warn on an expression like
+   When `true`, the check will warn on an expression like
    ``sizeof(expr)`` where the expression is a pointer
    to aggregate. Default is `true`.
diff --git a/clang-tools-extra/docs/clang-tidy/checks/list.rst b/clang-tools-extra/docs/clang-tidy/checks/list.rst
@@ -341,9 +341,9 @@ Clang-Tidy Checks
    :doc:`portability-std-allocator-const <portability/std-allocator-const>`,
    :doc:`readability-avoid-const-params-in-decls <readability/avoid-const-params-in-decls>`, "Yes"
    :doc:`readability-avoid-nested-conditional-operator <readability/avoid-nested-conditional-operator>`,
-   :doc:`readability-avoid-return-with-void-value <readability/avoid-return-with-void-value>`,
+   :doc:`readability-avoid-return-with-void-value <readability/avoid-return-with-void-value>`, "Yes"
    :doc:`readability-avoid-unconditional-preprocessor-if <readability/avoid-unconditional-preprocessor-if>`,
-   :doc:`readability-braces-around-statements <readability/braces-around-statements>`, "Yes"
+   :doc:`readability-braces-around-statements <readability/braces-around-statements>`,
    :doc:`readability-const-return-type <readability/const-return-type>`, "Yes"
    :doc:`readability-container-contains <readability/container-contains>`, "Yes"
    :doc:`readability-container-data-pointer <readability/container-data-pointer>`, "Yes"
@@ -529,12 +529,12 @@ Clang-Tidy Checks
    :doc:`cppcoreguidelines-non-private-member-variables-in-classes <cppcoreguidelines/non-private-member-variables-in-classes>`, :doc:`misc-non-private-member-variables-in-classes <misc/non-private-member-variables-in-classes>`,
    :doc:`cppcoreguidelines-use-default-member-init <cppcoreguidelines/use-default-member-init>`, :doc:`modernize-use-default-member-init <modernize/use-default-member-init>`, "Yes"
    :doc:`fuchsia-header-anon-namespaces <fuchsia/header-anon-namespaces>`, :doc:`google-build-namespaces <google/build-namespaces>`,
-   :doc:`google-readability-braces-around-statements <google/readability-braces-around-statements>`, :doc:`readability-braces-around-statements <readability/braces-around-statements>`, "Yes"
+   :doc:`google-readability-braces-around-statements <google/readability-braces-around-statements>`, :doc:`readability-braces-around-statements <readability/braces-around-statements>`,
    :doc:`google-readability-function-size <google/readability-function-size>`, :doc:`readability-function-size <readability/function-size>`,
    :doc:`google-readability-namespace-comments <google/readability-namespace-comments>`, :doc:`llvm-namespace-comment <llvm/namespace-comment>`,
    :doc:`hicpp-avoid-c-arrays <hicpp/avoid-c-arrays>`, :doc:`modernize-avoid-c-arrays <modernize/avoid-c-arrays>`,
    :doc:`hicpp-avoid-goto <hicpp/avoid-goto>`, :doc:`cppcoreguidelines-avoid-goto <cppcoreguidelines/avoid-goto>`,
-   :doc:`hicpp-braces-around-statements <hicpp/braces-around-statements>`, :doc:`readability-braces-around-statements <readability/braces-around-statements>`, "Yes"
+   :doc:`hicpp-braces-around-statements <hicpp/braces-around-statements>`, :doc:`readability-braces-around-statements <readability/braces-around-statements>`,
    :doc:`hicpp-deprecated-headers <hicpp/deprecated-headers>`, :doc:`modernize-deprecated-headers <modernize/deprecated-headers>`, "Yes"
    :doc:`hicpp-explicit-conversions <hicpp/explicit-conversions>`, :doc:`google-explicit-constructor <google/explicit-constructor>`, "Yes"
    :doc:`hicpp-function-size <hicpp/function-size>`, :doc:`readability-function-size <readability/function-size>`,

diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/forwarding-reference-overload.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/forwarding-reference-overload.cpp
@@ -251,3 +251,13 @@ class Test10 {
   Test10(T &&Item, E e)
       : e(e){}
 };
+
+// A deleted ctor cannot hide anything
+class Test11 {
+public:
+  template <typename T>
+  Test11(T&&) = delete;
+
+  Test11(const Test11 &) = default;
+  Test11(Test11 &&) = default;
+};
diff --git a/clang-tools-extra/test/clang-tidy/checkers/bugprone/lambda-function-name.cpp b/clang-tools-extra/test/clang-tidy/checkers/bugprone/lambda-function-name.cpp
@@ -19,6 +19,22 @@ void Positives() {
   // CHECK-MESSAGES-NO-CONFIG: :[[@LINE-1]]:8: warning: inside a lambda, '__FUNCTION__' expands to the name of the function call operator; consider capturing the name of the enclosing function explicitly [bugprone-lambda-function-name]
   [] { EMBED_IN_ANOTHER_MACRO1; }();
   // CHECK-MESSAGES-NO-CONFIG: :[[@LINE-1]]:8: warning: inside a lambda, '__func__' expands to the name of the function call operator; consider capturing the name of the enclosing function explicitly [bugprone-lambda-function-name]
+  [] {
+    __func__;
+  // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: inside a lambda, '__func__' expands to the name of the function call operator; consider capturing the name of the enclosing function explicitly [bugprone-lambda-function-name]
+    struct S {
+      void f() {
+        __func__;
+        [] {
+          __func__;
+  // CHECK-MESSAGES: :[[@LINE-1]]:11: warning: inside a lambda, '__func__' expands to the name of the function call operator; consider capturing the name of the enclosing function explicitly [bugprone-lambda-function-name]
+        }();
+        __func__;
+      }
+    };
+    __func__;
+  // CHECK-MESSAGES: :[[@LINE-1]]:5: warning: inside a lambda, '__func__' expands to the name of the function call operator; consider capturing the name of the enclosing function explicitly [bugprone-lambda-function-name]
+  }();
 }
 
 #define FUNC_MACRO_WITH_FILE_AND_LINE Foo(__func__, __FILE__, __LINE__)
@@ -40,4 +56,7 @@ void Negatives() {
   [] { FUNC_MACRO_WITH_FILE_AND_LINE; }();
   [] { FUNCTION_MACRO_WITH_FILE_AND_LINE; }();
   [] { EMBED_IN_ANOTHER_MACRO2; }();
+
+  [] (const char* func = __func__) { func; }();
+  [func=__func__] { func; }();
 }
diff --git a/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-templates.cpp b/clang-tools-extra/test/clang-tidy/checkers/misc/const-correctness-templates.cpp
@@ -58,3 +58,18 @@ void concatenate3(Args... args)
     (..., (stream << args));
 }
 } // namespace gh70323
+
+namespace gh60895 {
+
+template <class T> void f1(T &&a);
+template <class T> void f2(T &&a);
+template <class T> void f1(T &&a) { f2<T>(a); }
+template <class T> void f2(T &&a) { f1<T>(a); }
+void f() {
+  int x = 0;
+  // CHECK-MESSAGES:[[@LINE-1]]:3: warning: variable 'x' of type 'int' can be declared 'const'
+  // CHECK-FIXES: int const x = 0;
+  f1(x);
+}
+
+} // namespace gh60895
diff --git a/clang/cmake/caches/Apple-stage2.cmake b/clang/cmake/caches/Apple-stage2.cmake
@@ -16,6 +16,7 @@ set(LLVM_ENABLE_BACKTRACES OFF CACHE BOOL "")
 set(LLVM_ENABLE_MODULES ON CACHE BOOL "")
 set(LLVM_EXTERNALIZE_DEBUGINFO ON CACHE BOOL "")
 set(LLVM_ENABLE_EXPORTED_SYMBOLS_IN_EXECUTABLES OFF CACHE BOOL "")
+set(LLVM_PLUGIN_SUPPORT OFF CACHE BOOL "")
 set(CLANG_PLUGIN_SUPPORT OFF CACHE BOOL "")
 set(CLANG_SPAWN_CC1 ON CACHE BOOL "")
 set(BUG_REPORT_URL "http://developer.apple.com/bugreporter/" CACHE STRING "")

diff --git a/clang/cmake/caches/Fuchsia.cmake b/clang/cmake/caches/Fuchsia.cmake
@@ -65,7 +65,6 @@ set(_FUCHSIA_BOOTSTRAP_PASSTHROUGH
   LLDB_EMBED_PYTHON_HOME
   LLDB_PYTHON_HOME
   LLDB_PYTHON_RELATIVE_PATH
-  LLDB_TEST_USE_VENDOR_PACKAGES
   LLDB_TEST_USER_ARGS
   Python3_EXECUTABLE
   Python3_LIBRARIES

diff --git a/clang/docs/ClangOffloadBundler.rst b/clang/docs/ClangOffloadBundler.rst
@@ -518,11 +518,14 @@ The compressed offload bundle begins with a header followed by the compressed bi
     This is a unique identifier to distinguish compressed offload bundles. The value is the string 'CCOB' (Compressed Clang Offload Bundle).
 
 - **Version Number (16-bit unsigned int)**:
-    This denotes the version of the compressed offload bundle format. The current version is `1`.
+    This denotes the version of the compressed offload bundle format. The current version is `2`.
 
 - **Compression Method (16-bit unsigned int)**:
     This field indicates the compression method used. The value corresponds to either `zlib` or `zstd`, represented as a 16-bit unsigned integer cast from the LLVM compression enumeration.
 
+- **Total File Size (32-bit unsigned int)**:
+    This is the total size (in bytes) of the file, including the header. Available in version 2 and above.
+
 - **Uncompressed Binary Size (32-bit unsigned int)**:
     This is the size (in bytes) of the binary data before it was compressed.
 

diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
@@ -3466,6 +3466,54 @@ Query for this feature with ``__has_builtin(__builtin_trap)``.
 
 ``__builtin_arm_trap`` is lowered to the ``llvm.aarch64.break`` builtin, and then to ``brk #payload``.
 
+``__builtin_allow_runtime_check``
+---------------------------------
+
+``__builtin_allow_runtime_check`` return true if the check at the current
+program location should be executed. It is expected to be used to implement
+``assert`` like checks which can be safely removed by optimizer.
+
+**Syntax**:
+
+.. code-block:: c++
+
+    bool __builtin_allow_runtime_check(const char* kind)
+
+**Example of use**:
+
+.. code-block:: c++
+
+  if (__builtin_allow_runtime_check("mycheck") && !ExpensiveCheck()) {
+     abort();
+  }
+
+**Description**
+
+``__builtin_allow_runtime_check`` is lowered to ` ``llvm.allow.runtime.check``
+<https://llvm.org/docs/LangRef.html#llvm-allow-runtime-check-intrinsic>`_
+builtin.
+
+The ``__builtin_allow_runtime_check()`` is expected to be used with control
+flow conditions such as in ``if`` to guard expensive runtime checks. The
+specific rules for selecting permitted checks can differ and are controlled by
+the compiler options.
+
+Flags to control checks:
+* ``-mllvm -lower-allow-check-percentile-cutoff-hot=N`` where N is PGO hotness
+cutoff in range ``[0, 999999]`` to disallow checks in hot code.
+* ``-mllvm -lower-allow-check-random-rate=P`` where P is number in range
+``[0.0, 1.0]`` representation probability of keeping a check.
+* If both flags are specified, ``-lower-allow-check-random-rate`` takes
+precedence.
+* If none is specified, ``__builtin_allow_runtime_check`` is lowered as
+``true``, allowing all checks.
+
+Parameter ``kind`` is a string literal representing a user selected kind for
+guarded check. It's unused now. It will enable kind-specific lowering in future.
+E.g. a higher hotness cutoff can be used for more expensive kind of check.
+
+Query for this feature with ``__has_builtin(__builtin_allow_runtime_check)``.
+
 ``__builtin_nondeterministic_value``
 ------------------------------------
 

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
@@ -68,7 +68,7 @@ AST Dumping Potentially Breaking Changes
 
 Clang Frontend Potentially Breaking Changes
 -------------------------------------------
-- Removed support for constructing on-stack ``TemplateArgumentList``s; interfaces should instead
+- Removed support for constructing on-stack ``TemplateArgumentList``\ s; interfaces should instead
   use ``ArrayRef<TemplateArgument>`` to pass template arguments. Transitioning internal uses to
   ``ArrayRef<TemplateArgument>`` reduces AST memory usage by 0.4% when compiling clang, and is
   expected to show similar improvements on other workloads.
@@ -179,6 +179,9 @@ C23 Feature Support
 - Clang now supports `N3018 The constexpr specifier for object definitions`
   <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3018.htm>`_.
 
+- Properly promote bit-fields of bit-precise integer types to the field's type
+  rather than to ``int``. #GH87641
+
 Non-comprehensive list of changes in this release
 -------------------------------------------------
 
@@ -203,12 +206,6 @@ Non-comprehensive list of changes in this release
 - ``__typeof_unqual__`` is available in all C modes as an extension, which behaves
   like ``typeof_unqual`` from C23, similar to ``__typeof__`` and ``typeof``.
 
-- Improved stack usage with C++ initialization code. This allows significantly
-  more levels of recursive initialization before reaching stack exhaustion
-  limits. This will positively impact recursive template instantiation code,
-  but should also reduce memory overhead for initializations in general.
-  Fixes #GH88330
-
 New Compiler Flags
 ------------------
 - ``-fsanitize=implicit-bitfield-conversion`` checks implicit truncation and
@@ -220,6 +217,9 @@ New Compiler Flags
   This diagnostic can be disabled to make ``-Wmissing-field-initializers`` behave
   like it did before Clang 18.x. Fixes #GH56628
 
+- ``-fexperimental-modules-reduced-bmi`` enables the Reduced BMI for C++20 named modules.
+  See the document of standard C++ modules for details.
+
 Deprecated Compiler Flags
 -------------------------
 
@@ -290,6 +290,9 @@ Attribute Changes in Clang
   This allows the ``_Nullable`` and ``_Nonnull`` family of type attributes to
   apply to this class.
 
+- Clang now warns that the ``exclude_from_explicit_instantiation`` attribute
+  is ignored when applied to a local class or a member thereof.
+
 Improvements to Clang's diagnostics
 -----------------------------------
 - Clang now applies syntax highlighting to the code snippets it
@@ -367,6 +370,8 @@ Improvements to Clang's diagnostics
 - Clang now uses the correct type-parameter-key (``class`` or ``typename``) when printing
   template template parameter declarations.
 
+- Clang now diagnoses requires expressions with explicit object parameters.
+
 Improvements to Clang's time-trace
 ----------------------------------
 
@@ -425,6 +430,14 @@ Bug Fixes in This Version
 
 - Fixed an assertion failure on invalid InitListExpr in C89 mode (#GH88008).
 
+- Clang will no longer diagnose an erroneous non-dependent ``switch`` condition
+  during instantiation, and instead will only diagnose it once, during checking
+  of the function template.
+
+- Clang now allows the value of unroll count to be zero in ``#pragma GCC unroll`` and ``#pragma unroll``.
+  The values of 0 and 1 block any unrolling of the loop. This keeps the same behavior with GCC.
+  Fixes (`#88624 <https://github.com/llvm/llvm-project/issues/88624>`_).
+
 Bug Fixes to Compiler Builtins
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -528,6 +541,8 @@ Bug Fixes to C++ Support
 - Fix an issue caused by not handling invalid cases when substituting into the parameter mapping of a constraint. Fixes (#GH86757).
 - Fixed a bug that prevented member function templates of class templates declared with a deduced return type
   from being explicitly specialized for a given implicit instantiation of the class template.
+- Fixed a crash when ``this`` is used in a dependent class scope function template specialization
+  that instantiates to a static member function.
 
 - Fix crash when inheriting from a cv-qualified type. Fixes #GH35603
 - Fix a crash when the using enum declaration uses an anonymous enumeration. Fixes (#GH86790).
@@ -537,7 +552,9 @@ Bug Fixes to C++ Support
   Fixes (#GH70604), (#GH79754), (#GH84163), (#GH84425), (#GH86054), (#GH86398), and (#GH86399).
 - Fix a crash when deducing ``auto`` from an invalid dereference (#GH88329).
 - Fix a crash in requires expression with templated base class member function. Fixes (#GH84020).
-- Placement new initializes typedef array with correct size (#GH41441)
+- Fix a crash caused by defined struct in a type alias template when the structure
+  has fields with dependent type. Fixes (#GH75221).
+- Fix the Itanium mangling of lambdas defined in a member of a local class (#GH88906)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -547,6 +564,9 @@ Bug Fixes to AST Handling
 Miscellaneous Bug Fixes
 ^^^^^^^^^^^^^^^^^^^^^^^
 
+- Fixed an infinite recursion in ASTImporter, on return type declared inside
+  body of C++11 lambda without trailing return (#GH68775).
+
 Miscellaneous Clang Crashes Fixed
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
@@ -682,6 +702,10 @@ Static Analyzer
   but not under any case blocks if ``unroll-loops=true`` analyzer config is
   set. (#GH68819)
 - Support C++23 static operator calls. (#GH84972)
+- Fixed a crash in ``security.cert.env.InvalidPtr`` checker when accidentally
+  matched user-defined ``strerror`` and similar library functions. (GH#88181)
+- Fixed a crash when storing through an address that refers to the address of
+  a label. (GH#89185)
 
 New features
 ^^^^^^^^^^^^

diff --git a/clang/docs/StandardCPlusPlusModules.rst b/clang/docs/StandardCPlusPlusModules.rst
@@ -483,6 +483,13 @@ violations with the flag enabled.
 ABI Impacts
 -----------
 
+This section describes the new ABI changes brought by modules.
+
+Only Itanium C++ ABI related change are mentioned
+
+Mangling Names
+~~~~~~~~~~~~~~
+
 The declarations in a module unit which are not in the global module fragment have new linkage names.
 
 For example,
@@ -520,6 +527,129 @@ is attached to the global module fragments. For example:
 
 Now the linkage name of ``NS::foo()`` will be ``_ZN2NS3fooEv``.
 
+Module Initializers
+~~~~~~~~~~~~~~~~~~~
+
+All the importable module units are required to emit an initializer function.
+The initializer function should contain calls to importing modules first and
+all the dynamic-initializers in the current module unit then.
+
+Translation units explicitly or implicitly importing named modules must call
+the initializer functions of the imported named modules within the sequence of
+the dynamic-initializers in the TU. Initializations of entities at namespace
+scope are appearance-ordered. This (recursively) extends into imported modules
+at the point of appearance of the import declaration.
+
+It is allowed to omit calls to importing modules if it is known empty.
+
+It is allowed to omit calls to importing modules for which is known to be called.
+
+Reduced BMI
+-----------
+
+To support the 2 phase compilation model, Clang chose to put everything needed to
+produce an object into the BMI. But every consumer of the BMI, except itself, doesn't
+need such informations. It makes the BMI to larger and so may introduce unnecessary
+dependencies into the BMI. To mitigate the problem, we decided to reduce the information
+contained in the BMI.
+
+To be clear, we call the default BMI as Full BMI and the new introduced BMI as Reduced
+BMI.
+
+Users can use ``-fexperimental-modules-reduced-bmi`` flag to enable the Reduced BMI.
+
+For one phase compilation model (CMake implements this model), with
+``-fexperimental-modules-reduced-bmi``, the generated BMI will be Reduced BMI automatically.
+(The output path of the BMI is specified by ``-fmodule-output=`` as usual one phase
+compilation model).
+
+It is still possible to support Reduced BMI in two phase compilation model. With
+``-fexperimental-modules-reduced-bmi``, ``--precompile`` and ``-fmodule-output=`` specified,
+the generated BMI specified by ``-o`` will be full BMI and the BMI specified by
+``-fmodule-output=`` will be Reduced BMI. The dependency graph may be:
+
+.. code-block:: none
+
+  module-unit.cppm --> module-unit.full.pcm -> module-unit.o
+                    |
+                    -> module-unit.reduced.pcm -> consumer1.cpp
+                                               -> consumer2.cpp
+                                               -> ...
+                                               -> consumer_n.cpp
+
+We don't emit diagnostics if ``-fexperimental-modules-reduced-bmi`` is used with a non-module
+unit. This design helps the end users of one phase compilation model to perform experiments
+early without asking for the help of build systems. The users of build systems which supports
+two phase compilation model still need helps from build systems.
+
+Within Reduced BMI, we won't write unreachable entities from GMF, definitions of non-inline
+functions and non-inline variables. This may not be a transparent change.
+`[module.global.frag]ex2 <https://eel.is/c++draft/module.global.frag#example-2>`_ may be a good
+example:
+
+.. code-block:: c++
+
+  // foo.h
+  namespace N {
+    struct X {};
+    int d();
+    int e();
+    inline int f(X, int = d()) { return e(); }
+    int g(X);
+    int h(X);
+  }
+
+  // M.cppm
+  module;
+  #include "foo.h"
+  export module M;
+  template<typename T> int use_f() {
+    N::X x;                       // N::X, N, and :: are decl-reachable from use_f
+    return f(x, 123);             // N::f is decl-reachable from use_f,
+                                  // N::e is indirectly decl-reachable from use_f
+                                  //   because it is decl-reachable from N::f, and
+                                  // N::d is decl-reachable from use_f
+                                  //   because it is decl-reachable from N::f
+                                  //   even though it is not used in this call
+  }
+  template<typename T> int use_g() {
+    N::X x;                       // N::X, N, and :: are decl-reachable from use_g
+    return g((T(), x));           // N::g is not decl-reachable from use_g
+  }
+  template<typename T> int use_h() {
+    N::X x;                       // N::X, N, and :: are decl-reachable from use_h
+    return h((T(), x));           // N::h is not decl-reachable from use_h, but
+                                  // N::h is decl-reachable from use_h<int>
+  }
+  int k = use_h<int>();
+    // use_h<int> is decl-reachable from k, so
+    // N::h is decl-reachable from k
+
+  // M-impl.cpp
+  module M;
+  int a = use_f<int>();           // OK
+  int b = use_g<int>();           // error: no viable function for call to g;
+                                  // g is not decl-reachable from purview of
+                                  // module M's interface, so is discarded
+  int c = use_h<int>();           // OK
+
+In the above example, the function definition of ``N::g`` is elided from the Reduced
+BMI of ``M.cppm``. Then the use of ``use_g<int>`` in ``M-impl.cpp`` fails
+to instantiate. For such issues, users can add references to ``N::g`` in the module purview
+of ``M.cppm`` to make sure it is reachable, e.g., ``using N::g;``.
+
+We think the Reduced BMI is the correct direction. But given it is a drastic change,
+we'd like to make it experimental first to avoid breaking existing users. The roadmap
+of Reduced BMI may be:
+
+1. ``-fexperimental-modules-reduced-bmi`` is opt in for 1~2 releases. The period depends
+on testing feedbacks.
+2. We would announce Reduced BMI is not experimental and introduce ``-fmodules-reduced-bmi``.
+and suggest users to enable this mode. This may takes 1~2 releases too.
+3. Finally we will enable this by default. When that time comes, the term BMI will refer to
+the reduced BMI today and the Full BMI will only be meaningful to build systems which
+loves to support two phase compilations.
+
 Performance Tips
 ----------------
 

diff --git a/clang/include/clang/AST/ASTMutationListener.h b/clang/include/clang/AST/ASTMutationListener.h
@@ -27,6 +27,7 @@ namespace clang {
   class FunctionTemplateDecl;
   class Module;
   class NamedDecl;
+  class NamespaceDecl;
   class ObjCCategoryDecl;
   class ObjCContainerDecl;
   class ObjCInterfaceDecl;
@@ -35,6 +36,7 @@ namespace clang {
   class QualType;
   class RecordDecl;
   class TagDecl;
+  class TranslationUnitDecl;
   class ValueDecl;
   class VarDecl;
   class VarTemplateDecl;
@@ -147,6 +149,31 @@ class ASTMutationListener {
   virtual void AddedAttributeToRecord(const Attr *Attr,
                                       const RecordDecl *Record) {}
 
+  /// The parser find the named module declaration.
+  virtual void EnteringModulePurview() {}
+
+  /// An mangling number was added to a Decl
+  ///
+  /// \param D The decl that got a mangling number
+  ///
+  /// \param Number The mangling number that was added to the Decl
+  virtual void AddedManglingNumber(const Decl *D, unsigned Number) {}
+
+  /// An static local number was added to a Decl
+  ///
+  /// \param D The decl that got a static local number
+  ///
+  /// \param Number The static local number that was added to the Decl
+  virtual void AddedStaticLocalNumbers(const Decl *D, unsigned Number) {}
+
+  /// An anonymous namespace was added the translation unit decl
+  ///
+  /// \param TU The translation unit decl that got a new anonymous namespace
+  ///
+  /// \param AnonNamespace The anonymous namespace that was added
+  virtual void AddedAnonymousNamespace(const TranslationUnitDecl *TU,
+                                       NamespaceDecl *AnonNamespace) {}
+
   // NOTE: If new methods are added they should also be added to
   // MultiplexASTMutationListener.
 };

diff --git a/clang/include/clang/AST/ASTNodeTraverser.h b/clang/include/clang/AST/ASTNodeTraverser.h
@@ -851,6 +851,12 @@ class ASTNodeTraverser
       Visit(R);
   }
 
+  void VisitTypeTraitExpr(const TypeTraitExpr *E) {
+    // Argument types are not children of the TypeTraitExpr.
+    for (auto *A : E->getArgs())
+      Visit(A->getType());
+  }
+
   void VisitLambdaExpr(const LambdaExpr *Node) {
     if (Traversal == TK_IgnoreUnlessSpelledInSource) {
       for (unsigned I = 0, N = Node->capture_size(); I != N; ++I) {

diff --git a/clang/include/clang/AST/Decl.h b/clang/include/clang/AST/Decl.h
@@ -120,7 +120,7 @@ class TranslationUnitDecl : public Decl,
   ASTContext &getASTContext() const { return Ctx; }
 
   NamespaceDecl *getAnonymousNamespace() const { return AnonymousNamespace; }
-  void setAnonymousNamespace(NamespaceDecl *D) { AnonymousNamespace = D; }
+  void setAnonymousNamespace(NamespaceDecl *D);
 
   static TranslationUnitDecl *Create(ASTContext &C);
 
@@ -157,7 +157,7 @@ class PragmaCommentDecl final
                                    SourceLocation CommentLoc,
                                    PragmaMSCommentKind CommentKind,
                                    StringRef Arg);
-  static PragmaCommentDecl *CreateDeserialized(ASTContext &C, unsigned ID,
+  static PragmaCommentDecl *CreateDeserialized(ASTContext &C, DeclID ID,
                                                unsigned ArgSize);
 
   PragmaMSCommentKind getCommentKind() const { return CommentKind; }
@@ -192,7 +192,7 @@ class PragmaDetectMismatchDecl final
                                           SourceLocation Loc, StringRef Name,
                                           StringRef Value);
   static PragmaDetectMismatchDecl *
-  CreateDeserialized(ASTContext &C, unsigned ID, unsigned NameValueSize);
+  CreateDeserialized(ASTContext &C, DeclID ID, unsigned NameValueSize);
 
   StringRef getName() const { return getTrailingObjects<char>(); }
   StringRef getValue() const { return getTrailingObjects<char>() + ValueStart; }
@@ -518,7 +518,7 @@ class LabelDecl : public NamedDecl {
   static LabelDecl *Create(ASTContext &C, DeclContext *DC,
                            SourceLocation IdentL, IdentifierInfo *II,
                            SourceLocation GnuLabelL);
-  static LabelDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static LabelDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   LabelStmt *getStmt() const { return TheStmt; }
   void setStmt(LabelStmt *T) { TheStmt = T; }
@@ -581,7 +581,7 @@ class NamespaceDecl : public NamedDecl, public DeclContext,
                                IdentifierInfo *Id, NamespaceDecl *PrevDecl,
                                bool Nested);
 
-  static NamespaceDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static NamespaceDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   using redecl_range = redeclarable_base::redecl_range;
   using redecl_iterator = redeclarable_base::redecl_iterator;
@@ -1146,7 +1146,7 @@ class VarDecl : public DeclaratorDecl, public Redeclarable<VarDecl> {
                          const IdentifierInfo *Id, QualType T,
                          TypeSourceInfo *TInfo, StorageClass S);
 
-  static VarDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static VarDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 
@@ -1728,7 +1728,7 @@ class ImplicitParamDecl : public VarDecl {
   static ImplicitParamDecl *Create(ASTContext &C, QualType T,
                                    ImplicitParamKind ParamKind);
 
-  static ImplicitParamDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ImplicitParamDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   ImplicitParamDecl(ASTContext &C, DeclContext *DC, SourceLocation IdLoc,
                     const IdentifierInfo *Id, QualType Type,
@@ -1782,7 +1782,7 @@ class ParmVarDecl : public VarDecl {
                              TypeSourceInfo *TInfo, StorageClass S,
                              Expr *DefArg);
 
-  static ParmVarDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ParmVarDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 
@@ -2178,7 +2178,7 @@ class FunctionDecl : public DeclaratorDecl,
          bool hasWrittenPrototype, ConstexprSpecKind ConstexprKind,
          Expr *TrailingRequiresClause);
 
-  static FunctionDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static FunctionDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   DeclarationNameInfo getNameInfo() const {
     return DeclarationNameInfo(getDeclName(), getLocation(), DNLoc);
@@ -3136,7 +3136,7 @@ class FieldDecl : public DeclaratorDecl, public Mergeable<FieldDecl> {
                            TypeSourceInfo *TInfo, Expr *BW, bool Mutable,
                            InClassInitStyle InitStyle);
 
-  static FieldDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static FieldDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   /// Returns the index of this field within its record,
   /// as appropriate for passing to ASTRecordLayout::getFieldOffset.
@@ -3149,7 +3149,7 @@ class FieldDecl : public DeclaratorDecl, public Mergeable<FieldDecl> {
   bool isBitField() const { return BitField; }
 
   /// Determines whether this is an unnamed bitfield.
-  bool isUnnamedBitfield() const { return isBitField() && !getDeclName(); }
+  bool isUnnamedBitField() const { return isBitField() && !getDeclName(); }
 
   /// Determines whether this field is a
   /// representative for an anonymous struct or union. Such fields are
@@ -3311,7 +3311,7 @@ class EnumConstantDecl : public ValueDecl,
                                   SourceLocation L, IdentifierInfo *Id,
                                   QualType T, Expr *E,
                                   const llvm::APSInt &V);
-  static EnumConstantDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static EnumConstantDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   const Expr *getInitExpr() const { return (const Expr*) Init; }
   Expr *getInitExpr() { return (Expr*) Init; }
@@ -3357,7 +3357,7 @@ class IndirectFieldDecl : public ValueDecl,
                                    QualType T,
                                    llvm::MutableArrayRef<NamedDecl *> CH);
 
-  static IndirectFieldDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static IndirectFieldDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   using chain_iterator = ArrayRef<NamedDecl *>::const_iterator;
 
@@ -3542,7 +3542,7 @@ class TypedefDecl : public TypedefNameDecl {
   static TypedefDecl *Create(ASTContext &C, DeclContext *DC,
                              SourceLocation StartLoc, SourceLocation IdLoc,
                              const IdentifierInfo *Id, TypeSourceInfo *TInfo);
-  static TypedefDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static TypedefDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 
@@ -3567,7 +3567,7 @@ class TypeAliasDecl : public TypedefNameDecl {
   static TypeAliasDecl *Create(ASTContext &C, DeclContext *DC,
                                SourceLocation StartLoc, SourceLocation IdLoc,
                                const IdentifierInfo *Id, TypeSourceInfo *TInfo);
-  static TypeAliasDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static TypeAliasDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 
@@ -3977,7 +3977,7 @@ class EnumDecl : public TagDecl {
                           IdentifierInfo *Id, EnumDecl *PrevDecl,
                           bool IsScoped, bool IsScopedUsingClassTag,
                           bool IsFixed);
-  static EnumDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static EnumDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   /// Overrides to provide correct range when there's an enum-base specifier
   /// with forward declarations.
@@ -4182,7 +4182,7 @@ class RecordDecl : public TagDecl {
   static RecordDecl *Create(const ASTContext &C, TagKind TK, DeclContext *DC,
                             SourceLocation StartLoc, SourceLocation IdLoc,
                             IdentifierInfo *Id, RecordDecl* PrevDecl = nullptr);
-  static RecordDecl *CreateDeserialized(const ASTContext &C, unsigned ID);
+  static RecordDecl *CreateDeserialized(const ASTContext &C, DeclID ID);
 
   RecordDecl *getPreviousDecl() {
     return cast_or_null<RecordDecl>(
@@ -4433,7 +4433,7 @@ class FileScopeAsmDecl : public Decl {
                                   StringLiteral *Str, SourceLocation AsmLoc,
                                   SourceLocation RParenLoc);
 
-  static FileScopeAsmDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static FileScopeAsmDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceLocation getAsmLoc() const { return getLocation(); }
   SourceLocation getRParenLoc() const { return RParenLoc; }
@@ -4469,7 +4469,7 @@ class TopLevelStmtDecl : public Decl, public DeclContext {
 
 public:
   static TopLevelStmtDecl *Create(ASTContext &C, Stmt *Statement);
-  static TopLevelStmtDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static TopLevelStmtDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY;
   Stmt *getStmt() { return Statement; }
@@ -4563,7 +4563,7 @@ class BlockDecl : public Decl, public DeclContext {
 
 public:
   static BlockDecl *Create(ASTContext &C, DeclContext *DC, SourceLocation L);
-  static BlockDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static BlockDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceLocation getCaretLocation() const { return getLocation(); }
 
@@ -4717,7 +4717,7 @@ class CapturedDecl final
 
   static CapturedDecl *Create(ASTContext &C, DeclContext *DC,
                               unsigned NumParams);
-  static CapturedDecl *CreateDeserialized(ASTContext &C, unsigned ID,
+  static CapturedDecl *CreateDeserialized(ASTContext &C, DeclID ID,
                                           unsigned NumParams);
 
   Stmt *getBody() const override;
@@ -4851,7 +4851,7 @@ class ImportDecl final : public Decl,
                                     SourceLocation EndLoc);
 
   /// Create a new, deserialized module import declaration.
-  static ImportDecl *CreateDeserialized(ASTContext &C, unsigned ID,
+  static ImportDecl *CreateDeserialized(ASTContext &C, DeclID ID,
                                         unsigned NumLocations);
 
   /// Retrieve the module that was imported by the import declaration.
@@ -4892,7 +4892,7 @@ class ExportDecl final : public Decl, public DeclContext {
 public:
   static ExportDecl *Create(ASTContext &C, DeclContext *DC,
                             SourceLocation ExportLoc);
-  static ExportDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ExportDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceLocation getExportLoc() const { return getLocation(); }
   SourceLocation getRBraceLoc() const { return RBraceLoc; }
@@ -4931,7 +4931,7 @@ class EmptyDecl : public Decl {
 public:
   static EmptyDecl *Create(ASTContext &C, DeclContext *DC,
                            SourceLocation L);
-  static EmptyDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static EmptyDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
   static bool classofKind(Kind K) { return K == Empty; }
@@ -4957,7 +4957,7 @@ class HLSLBufferDecl final : public NamedDecl, public DeclContext {
                                 bool CBuffer, SourceLocation KwLoc,
                                 IdentifierInfo *ID, SourceLocation IDLoc,
                                 SourceLocation LBrace);
-  static HLSLBufferDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static HLSLBufferDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY {
     return SourceRange(getLocStart(), RBraceLoc);

diff --git a/clang/include/clang/AST/DeclBase.h b/clang/include/clang/AST/DeclBase.h
@@ -349,6 +349,8 @@ class alignas(8) Decl {
   LLVM_PREFERRED_TYPE(Linkage)
   mutable unsigned CacheValidAndLinkage : 3;
 
+  using DeclID = uint32_t;
+
   /// Allocate memory for a deserialized declaration.
   ///
   /// This routine must be used to allocate memory for any declaration that is
@@ -358,7 +360,7 @@ class alignas(8) Decl {
   /// \param Ctx The context in which we will allocate memory.
   /// \param ID The global ID of the deserialized declaration.
   /// \param Extra The amount of extra space to allocate after the object.
-  void *operator new(std::size_t Size, const ASTContext &Ctx, unsigned ID,
+  void *operator new(std::size_t Size, const ASTContext &Ctx, DeclID ID,
                      std::size_t Extra = 0);
 
   /// Allocate memory for a non-deserialized declaration.

diff --git a/clang/include/clang/AST/DeclCXX.h b/clang/include/clang/AST/DeclCXX.h
@@ -120,7 +120,7 @@ class AccessSpecDecl : public Decl {
     return new (C, DC) AccessSpecDecl(AS, DC, ASLoc, ColonLoc);
   }
 
-  static AccessSpecDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static AccessSpecDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
@@ -579,7 +579,7 @@ class CXXRecordDecl : public RecordDecl {
                                      TypeSourceInfo *Info, SourceLocation Loc,
                                      unsigned DependencyKind, bool IsGeneric,
                                      LambdaCaptureDefault CaptureDefault);
-  static CXXRecordDecl *CreateDeserialized(const ASTContext &C, unsigned ID);
+  static CXXRecordDecl *CreateDeserialized(const ASTContext &C, DeclID ID);
 
   bool isDynamicClass() const {
     return data().Polymorphic || data().NumVBases != 0;
@@ -1980,7 +1980,7 @@ class CXXDeductionGuideDecl : public FunctionDecl {
          CXXConstructorDecl *Ctor = nullptr,
          DeductionCandidate Kind = DeductionCandidate::Normal);
 
-  static CXXDeductionGuideDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static CXXDeductionGuideDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   ExplicitSpecifier getExplicitSpecifier() { return ExplicitSpec; }
   const ExplicitSpecifier getExplicitSpecifier() const { return ExplicitSpec; }
@@ -2035,7 +2035,7 @@ class RequiresExprBodyDecl : public Decl, public DeclContext {
   static RequiresExprBodyDecl *Create(ASTContext &C, DeclContext *DC,
                                       SourceLocation StartLoc);
 
-  static RequiresExprBodyDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static RequiresExprBodyDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
@@ -2078,7 +2078,7 @@ class CXXMethodDecl : public FunctionDecl {
          ConstexprSpecKind ConstexprKind, SourceLocation EndLocation,
          Expr *TrailingRequiresClause = nullptr);
 
-  static CXXMethodDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static CXXMethodDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   bool isStatic() const;
   bool isInstance() const { return !isStatic(); }
@@ -2579,7 +2579,7 @@ class CXXConstructorDecl final
   friend class ASTDeclWriter;
   friend TrailingObjects;
 
-  static CXXConstructorDecl *CreateDeserialized(ASTContext &C, unsigned ID,
+  static CXXConstructorDecl *CreateDeserialized(ASTContext &C, DeclID ID,
                                                 uint64_t AllocKind);
   static CXXConstructorDecl *
   Create(ASTContext &C, CXXRecordDecl *RD, SourceLocation StartLoc,
@@ -2822,7 +2822,7 @@ class CXXDestructorDecl : public CXXMethodDecl {
          bool UsesFPIntrin, bool isInline, bool isImplicitlyDeclared,
          ConstexprSpecKind ConstexprKind,
          Expr *TrailingRequiresClause = nullptr);
-  static CXXDestructorDecl *CreateDeserialized(ASTContext & C, unsigned ID);
+  static CXXDestructorDecl *CreateDeserialized(ASTContext & C, DeclID ID);
 
   void setOperatorDelete(FunctionDecl *OD, Expr *ThisArg);
 
@@ -2881,7 +2881,7 @@ class CXXConversionDecl : public CXXMethodDecl {
          bool UsesFPIntrin, bool isInline, ExplicitSpecifier ES,
          ConstexprSpecKind ConstexprKind, SourceLocation EndLocation,
          Expr *TrailingRequiresClause = nullptr);
-  static CXXConversionDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static CXXConversionDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   ExplicitSpecifier getExplicitSpecifier() {
     return getCanonicalDecl()->ExplicitSpec;
@@ -2948,7 +2948,7 @@ class LinkageSpecDecl : public Decl, public DeclContext {
                                  SourceLocation ExternLoc,
                                  SourceLocation LangLoc,
                                  LinkageSpecLanguageIDs Lang, bool HasBraces);
-  static LinkageSpecDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static LinkageSpecDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   /// Return the language specified by this linkage specification.
   LinkageSpecLanguageIDs getLanguage() const {
@@ -3096,7 +3096,7 @@ class UsingDirectiveDecl : public NamedDecl {
                                     SourceLocation IdentLoc,
                                     NamedDecl *Nominated,
                                     DeclContext *CommonAncestor);
-  static UsingDirectiveDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static UsingDirectiveDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY {
     return SourceRange(UsingLoc, getLocation());
@@ -3157,7 +3157,7 @@ class NamespaceAliasDecl : public NamedDecl,
                                     SourceLocation IdentLoc,
                                     NamedDecl *Namespace);
 
-  static NamespaceAliasDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static NamespaceAliasDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   using redecl_range = redeclarable_base::redecl_range;
   using redecl_iterator = redeclarable_base::redecl_iterator;
@@ -3254,7 +3254,7 @@ class LifetimeExtendedTemporaryDecl final
         LifetimeExtendedTemporaryDecl(Temp, EDec, Mangling);
   }
   static LifetimeExtendedTemporaryDecl *CreateDeserialized(ASTContext &C,
-                                                           unsigned ID) {
+                                                           DeclID ID) {
     return new (C, ID) LifetimeExtendedTemporaryDecl(EmptyShell{});
   }
 
@@ -3357,7 +3357,7 @@ class UsingShadowDecl : public NamedDecl, public Redeclarable<UsingShadowDecl> {
         UsingShadowDecl(UsingShadow, C, DC, Loc, Name, Introducer, Target);
   }
 
-  static UsingShadowDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static UsingShadowDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   using redecl_range = redeclarable_base::redecl_range;
   using redecl_iterator = redeclarable_base::redecl_iterator;
@@ -3566,7 +3566,7 @@ class UsingDecl : public BaseUsingDecl, public Mergeable<UsingDecl> {
                            const DeclarationNameInfo &NameInfo,
                            bool HasTypenameKeyword);
 
-  static UsingDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static UsingDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 
@@ -3645,7 +3645,7 @@ class ConstructorUsingShadowDecl final : public UsingShadowDecl {
                                             UsingDecl *Using, NamedDecl *Target,
                                             bool IsVirtual);
   static ConstructorUsingShadowDecl *CreateDeserialized(ASTContext &C,
-                                                        unsigned ID);
+                                                        DeclID ID);
 
   /// Override the UsingShadowDecl's getIntroducer, returning the UsingDecl that
   /// introduced this.
@@ -3757,7 +3757,7 @@ class UsingEnumDecl : public BaseUsingDecl, public Mergeable<UsingEnumDecl> {
                                SourceLocation UsingL, SourceLocation EnumL,
                                SourceLocation NameL, TypeSourceInfo *EnumType);
 
-  static UsingEnumDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static UsingEnumDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 
@@ -3830,7 +3830,7 @@ class UsingPackDecl final
                                NamedDecl *InstantiatedFrom,
                                ArrayRef<NamedDecl *> UsingDecls);
 
-  static UsingPackDecl *CreateDeserialized(ASTContext &C, unsigned ID,
+  static UsingPackDecl *CreateDeserialized(ASTContext &C, DeclID ID,
                                            unsigned NumExpansions);
 
   SourceRange getSourceRange() const override LLVM_READONLY {
@@ -3924,7 +3924,7 @@ class UnresolvedUsingValueDecl : public ValueDecl,
            const DeclarationNameInfo &NameInfo, SourceLocation EllipsisLoc);
 
   static UnresolvedUsingValueDecl *
-  CreateDeserialized(ASTContext &C, unsigned ID);
+  CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 
@@ -4015,7 +4015,7 @@ class UnresolvedUsingTypenameDecl
            SourceLocation EllipsisLoc);
 
   static UnresolvedUsingTypenameDecl *
-  CreateDeserialized(ASTContext &C, unsigned ID);
+  CreateDeserialized(ASTContext &C, DeclID ID);
 
   /// Retrieves the canonical declaration of this declaration.
   UnresolvedUsingTypenameDecl *getCanonicalDecl() override {
@@ -4045,7 +4045,7 @@ class UnresolvedUsingIfExistsDecl final : public NamedDecl {
                                              SourceLocation Loc,
                                              DeclarationName Name);
   static UnresolvedUsingIfExistsDecl *CreateDeserialized(ASTContext &Ctx,
-                                                         unsigned ID);
+                                                         DeclID ID);
 
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
   static bool classofKind(Kind K) { return K == Decl::UnresolvedUsingIfExists; }
@@ -4073,7 +4073,7 @@ class StaticAssertDecl : public Decl {
                                   SourceLocation StaticAssertLoc,
                                   Expr *AssertExpr, Expr *Message,
                                   SourceLocation RParenLoc, bool Failed);
-  static StaticAssertDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static StaticAssertDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   Expr *getAssertExpr() { return AssertExprAndFailed.getPointer(); }
   const Expr *getAssertExpr() const { return AssertExprAndFailed.getPointer(); }
@@ -4120,7 +4120,7 @@ class BindingDecl : public ValueDecl {
 
   static BindingDecl *Create(ASTContext &C, DeclContext *DC,
                              SourceLocation IdLoc, IdentifierInfo *Id);
-  static BindingDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static BindingDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   /// Get the expression to which this declaration is bound. This may be null
   /// in two different cases: while parsing the initializer for the
@@ -4189,7 +4189,7 @@ class DecompositionDecl final
                                    QualType T, TypeSourceInfo *TInfo,
                                    StorageClass S,
                                    ArrayRef<BindingDecl *> Bindings);
-  static DecompositionDecl *CreateDeserialized(ASTContext &C, unsigned ID,
+  static DecompositionDecl *CreateDeserialized(ASTContext &C, DeclID ID,
                                                unsigned NumBindings);
 
   ArrayRef<BindingDecl *> bindings() const {
@@ -4246,7 +4246,7 @@ class MSPropertyDecl : public DeclaratorDecl {
                                 SourceLocation L, DeclarationName N, QualType T,
                                 TypeSourceInfo *TInfo, SourceLocation StartL,
                                 IdentifierInfo *Getter, IdentifierInfo *Setter);
-  static MSPropertyDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static MSPropertyDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   static bool classof(const Decl *D) { return D->getKind() == MSProperty; }
 
@@ -4300,7 +4300,7 @@ class MSGuidDecl : public ValueDecl,
   MSGuidDecl(DeclContext *DC, QualType T, Parts P);
 
   static MSGuidDecl *Create(const ASTContext &C, QualType T, Parts P);
-  static MSGuidDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static MSGuidDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   // Only ASTContext::getMSGuidDecl and deserialization create these.
   friend class ASTContext;
@@ -4353,7 +4353,7 @@ class UnnamedGlobalConstantDecl : public ValueDecl,
   static UnnamedGlobalConstantDecl *Create(const ASTContext &C, QualType T,
                                            const APValue &APVal);
   static UnnamedGlobalConstantDecl *CreateDeserialized(ASTContext &C,
-                                                       unsigned ID);
+                                                       DeclID ID);
 
   // Only ASTContext::getUnnamedGlobalConstantDecl and deserialization create
   // these.

diff --git a/clang/include/clang/AST/DeclFriend.h b/clang/include/clang/AST/DeclFriend.h
@@ -112,7 +112,7 @@ class FriendDecl final
   Create(ASTContext &C, DeclContext *DC, SourceLocation L, FriendUnion Friend_,
          SourceLocation FriendL,
          ArrayRef<TemplateParameterList *> FriendTypeTPLists = std::nullopt);
-  static FriendDecl *CreateDeserialized(ASTContext &C, unsigned ID,
+  static FriendDecl *CreateDeserialized(ASTContext &C, DeclID ID,
                                         unsigned FriendTypeNumTPLists);
 
   /// If this friend declaration names an (untemplated but possibly

diff --git a/clang/include/clang/AST/DeclObjC.h b/clang/include/clang/AST/DeclObjC.h
@@ -236,7 +236,7 @@ class ObjCMethodDecl : public NamedDecl, public DeclContext {
          ObjCImplementationControl impControl = ObjCImplementationControl::None,
          bool HasRelatedResultType = false);
 
-  static ObjCMethodDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ObjCMethodDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   ObjCMethodDecl *getCanonicalDecl() override;
   const ObjCMethodDecl *getCanonicalDecl() const {
@@ -614,7 +614,7 @@ class ObjCTypeParamDecl : public TypedefNameDecl {
                                    IdentifierInfo *name,
                                    SourceLocation colonLoc,
                                    TypeSourceInfo *boundInfo);
-  static ObjCTypeParamDecl *CreateDeserialized(ASTContext &ctx, unsigned ID);
+  static ObjCTypeParamDecl *CreateDeserialized(ASTContext &ctx, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 
@@ -789,7 +789,7 @@ class ObjCPropertyDecl : public NamedDecl {
                                   TypeSourceInfo *TSI,
                                   PropertyControl propControl = None);
 
-  static ObjCPropertyDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ObjCPropertyDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceLocation getAtLoc() const { return AtLoc; }
   void setAtLoc(SourceLocation L) { AtLoc = L; }
@@ -1279,7 +1279,7 @@ class ObjCInterfaceDecl : public ObjCContainerDecl
          ObjCInterfaceDecl *PrevDecl,
          SourceLocation ClassLoc = SourceLocation(), bool isInternal = false);
 
-  static ObjCInterfaceDecl *CreateDeserialized(const ASTContext &C, unsigned ID);
+  static ObjCInterfaceDecl *CreateDeserialized(const ASTContext &C, DeclID ID);
 
   /// Retrieve the type parameters of this class.
   ///
@@ -1969,7 +1969,7 @@ class ObjCIvarDecl : public FieldDecl {
                               TypeSourceInfo *TInfo, AccessControl ac,
                               Expr *BW = nullptr, bool synthesized = false);
 
-  static ObjCIvarDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ObjCIvarDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   /// Return the class interface that this ivar is logically contained
   /// in; this is either the interface where the ivar was declared, or the
@@ -2039,7 +2039,7 @@ class ObjCAtDefsFieldDecl : public FieldDecl {
                                      SourceLocation IdLoc, IdentifierInfo *Id,
                                      QualType T, Expr *BW);
 
-  static ObjCAtDefsFieldDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ObjCAtDefsFieldDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
@@ -2142,7 +2142,7 @@ class ObjCProtocolDecl : public ObjCContainerDecl,
                                   SourceLocation atStartLoc,
                                   ObjCProtocolDecl *PrevDecl);
 
-  static ObjCProtocolDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ObjCProtocolDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   const ObjCProtocolList &getReferencedProtocols() const {
     assert(hasDefinition() && "No definition available!");
@@ -2361,7 +2361,7 @@ class ObjCCategoryDecl : public ObjCContainerDecl {
          ObjCTypeParamList *typeParamList,
          SourceLocation IvarLBraceLoc = SourceLocation(),
          SourceLocation IvarRBraceLoc = SourceLocation());
-  static ObjCCategoryDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ObjCCategoryDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   ObjCInterfaceDecl *getClassInterface() { return ClassInterface; }
   const ObjCInterfaceDecl *getClassInterface() const { return ClassInterface; }
@@ -2558,7 +2558,7 @@ class ObjCCategoryImplDecl : public ObjCImplDecl {
   Create(ASTContext &C, DeclContext *DC, const IdentifierInfo *Id,
          ObjCInterfaceDecl *classInterface, SourceLocation nameLoc,
          SourceLocation atStartLoc, SourceLocation CategoryNameLoc);
-  static ObjCCategoryImplDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ObjCCategoryImplDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   ObjCCategoryDecl *getCategoryDecl() const;
 
@@ -2640,7 +2640,7 @@ class ObjCImplementationDecl : public ObjCImplDecl {
                                         SourceLocation IvarLBraceLoc=SourceLocation(),
                                         SourceLocation IvarRBraceLoc=SourceLocation());
 
-  static ObjCImplementationDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ObjCImplementationDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   /// init_iterator - Iterates through the ivar initializer list.
   using init_iterator = CXXCtorInitializer **;
@@ -2780,7 +2780,7 @@ class ObjCCompatibleAliasDecl : public NamedDecl {
                                          ObjCInterfaceDecl* aliasedClass);
 
   static ObjCCompatibleAliasDecl *CreateDeserialized(ASTContext &C,
-                                                     unsigned ID);
+                                                     DeclID ID);
 
   const ObjCInterfaceDecl *getClassInterface() const { return AliasedClass; }
   ObjCInterfaceDecl *getClassInterface() { return AliasedClass; }
@@ -2851,7 +2851,7 @@ class ObjCPropertyImplDecl : public Decl {
                                       ObjCIvarDecl *ivarDecl,
                                       SourceLocation ivarLoc);
 
-  static ObjCPropertyImplDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ObjCPropertyImplDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 

diff --git a/clang/include/clang/AST/DeclOpenMP.h b/clang/include/clang/AST/DeclOpenMP.h
@@ -133,7 +133,7 @@ class OMPThreadPrivateDecl final : public OMPDeclarativeDirective<Decl> {
                                       SourceLocation L,
                                       ArrayRef<Expr *> VL);
   static OMPThreadPrivateDecl *CreateDeserialized(ASTContext &C,
-                                                  unsigned ID, unsigned N);
+                                                  DeclID ID, unsigned N);
 
   typedef MutableArrayRef<Expr *>::iterator varlist_iterator;
   typedef ArrayRef<const Expr *>::iterator varlist_const_iterator;
@@ -214,7 +214,7 @@ class OMPDeclareReductionDecl final : public ValueDecl, public DeclContext {
          QualType T, OMPDeclareReductionDecl *PrevDeclInScope);
   /// Create deserialized declare reduction node.
   static OMPDeclareReductionDecl *CreateDeserialized(ASTContext &C,
-                                                     unsigned ID);
+                                                     DeclID ID);
 
   /// Get combiner expression of the declare reduction construct.
   Expr *getCombiner() { return Combiner; }
@@ -318,7 +318,7 @@ class OMPDeclareMapperDecl final : public OMPDeclarativeDirective<ValueDecl>,
                                       ArrayRef<OMPClause *> Clauses,
                                       OMPDeclareMapperDecl *PrevDeclInScope);
   /// Creates deserialized declare mapper node.
-  static OMPDeclareMapperDecl *CreateDeserialized(ASTContext &C, unsigned ID,
+  static OMPDeclareMapperDecl *CreateDeserialized(ASTContext &C, DeclID ID,
                                                   unsigned N);
 
   using clauselist_iterator = MutableArrayRef<OMPClause *>::iterator;
@@ -397,7 +397,7 @@ class OMPCapturedExprDecl final : public VarDecl {
                                      IdentifierInfo *Id, QualType T,
                                      SourceLocation StartLoc);
 
-  static OMPCapturedExprDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static OMPCapturedExprDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   SourceRange getSourceRange() const override LLVM_READONLY;
 
@@ -427,7 +427,7 @@ class OMPRequiresDecl final : public OMPDeclarativeDirective<Decl> {
   static OMPRequiresDecl *Create(ASTContext &C, DeclContext *DC,
                                  SourceLocation L, ArrayRef<OMPClause *> CL);
   /// Create deserialized requires node.
-  static OMPRequiresDecl *CreateDeserialized(ASTContext &C, unsigned ID,
+  static OMPRequiresDecl *CreateDeserialized(ASTContext &C, DeclID ID,
                                              unsigned N);
 
   using clauselist_iterator = MutableArrayRef<OMPClause *>::iterator;
@@ -495,7 +495,7 @@ class OMPAllocateDecl final : public OMPDeclarativeDirective<Decl> {
   static OMPAllocateDecl *Create(ASTContext &C, DeclContext *DC,
                                  SourceLocation L, ArrayRef<Expr *> VL,
                                  ArrayRef<OMPClause *> CL);
-  static OMPAllocateDecl *CreateDeserialized(ASTContext &C, unsigned ID,
+  static OMPAllocateDecl *CreateDeserialized(ASTContext &C, DeclID ID,
                                              unsigned NVars, unsigned NClauses);
 
   typedef MutableArrayRef<Expr *>::iterator varlist_iterator;

diff --git a/clang/include/clang/AST/DeclTemplate.h b/clang/include/clang/AST/DeclTemplate.h
@@ -1087,7 +1087,7 @@ class FunctionTemplateDecl : public RedeclarableTemplateDecl {
                                       NamedDecl *Decl);
 
   /// Create an empty function template node.
-  static FunctionTemplateDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static FunctionTemplateDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   // Implement isa/cast/dyncast support
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
@@ -1204,9 +1204,9 @@ class TemplateTypeParmDecl final : public TypeDecl,
          bool Typename, bool ParameterPack, bool HasTypeConstraint = false,
          std::optional<unsigned> NumExpanded = std::nullopt);
   static TemplateTypeParmDecl *CreateDeserialized(const ASTContext &C,
-                                                  unsigned ID);
+                                                  DeclID ID);
   static TemplateTypeParmDecl *CreateDeserialized(const ASTContext &C,
-                                                  unsigned ID,
+                                                  DeclID ID,
                                                   bool HasTypeConstraint);
 
   /// Whether this template type parameter was declared with
@@ -1414,10 +1414,10 @@ class NonTypeTemplateParmDecl final
          ArrayRef<TypeSourceInfo *> ExpandedTInfos);
 
   static NonTypeTemplateParmDecl *CreateDeserialized(ASTContext &C,
-                                                     unsigned ID,
+                                                     DeclID ID,
                                                      bool HasTypeConstraint);
   static NonTypeTemplateParmDecl *CreateDeserialized(ASTContext &C,
-                                                     unsigned ID,
+                                                     DeclID ID,
                                                      unsigned NumExpandedTypes,
                                                      bool HasTypeConstraint);
 
@@ -1632,9 +1632,9 @@ class TemplateTemplateParmDecl final
          ArrayRef<TemplateParameterList *> Expansions);
 
   static TemplateTemplateParmDecl *CreateDeserialized(ASTContext &C,
-                                                      unsigned ID);
+                                                      DeclID ID);
   static TemplateTemplateParmDecl *CreateDeserialized(ASTContext &C,
-                                                      unsigned ID,
+                                                      DeclID ID,
                                                       unsigned NumExpansions);
 
   using TemplateParmPosition::getDepth;
@@ -1858,7 +1858,7 @@ class ClassTemplateSpecializationDecl
          ArrayRef<TemplateArgument> Args,
          ClassTemplateSpecializationDecl *PrevDecl);
   static ClassTemplateSpecializationDecl *
-  CreateDeserialized(ASTContext &C, unsigned ID);
+  CreateDeserialized(ASTContext &C, DeclID ID);
 
   void getNameForDiagnostic(raw_ostream &OS, const PrintingPolicy &Policy,
                             bool Qualified) const override;
@@ -2110,7 +2110,7 @@ class ClassTemplatePartialSpecializationDecl
          ClassTemplatePartialSpecializationDecl *PrevDecl);
 
   static ClassTemplatePartialSpecializationDecl *
-  CreateDeserialized(ASTContext &C, unsigned ID);
+  CreateDeserialized(ASTContext &C, DeclID ID);
 
   ClassTemplatePartialSpecializationDecl *getMostRecentDecl() {
     return cast<ClassTemplatePartialSpecializationDecl>(
@@ -2306,7 +2306,7 @@ class ClassTemplateDecl : public RedeclarableTemplateDecl {
                                    NamedDecl *Decl);
 
   /// Create an empty class template node.
-  static ClassTemplateDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ClassTemplateDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   /// Return the specialization with the provided arguments if it exists,
   /// otherwise return the insertion point.
@@ -2472,7 +2472,7 @@ class FriendTemplateDecl : public Decl {
          MutableArrayRef<TemplateParameterList *> Params, FriendUnion Friend,
          SourceLocation FriendLoc);
 
-  static FriendTemplateDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static FriendTemplateDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   /// If this friend declaration names a templated type (or
   /// a dependent member type of a templated type), return that
@@ -2573,7 +2573,7 @@ class TypeAliasTemplateDecl : public RedeclarableTemplateDecl {
                                        NamedDecl *Decl);
 
   /// Create an empty alias template node.
-  static TypeAliasTemplateDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static TypeAliasTemplateDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   // Implement isa/cast/dyncast support
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
@@ -2670,7 +2670,7 @@ class VarTemplateSpecializationDecl : public VarDecl,
          TypeSourceInfo *TInfo, StorageClass S,
          ArrayRef<TemplateArgument> Args);
   static VarTemplateSpecializationDecl *CreateDeserialized(ASTContext &C,
-                                                           unsigned ID);
+                                                           DeclID ID);
 
   void getNameForDiagnostic(raw_ostream &OS, const PrintingPolicy &Policy,
                             bool Qualified) const override;
@@ -2901,7 +2901,7 @@ class VarTemplatePartialSpecializationDecl
          const TemplateArgumentListInfo &ArgInfos);
 
   static VarTemplatePartialSpecializationDecl *CreateDeserialized(ASTContext &C,
-                                                                  unsigned ID);
+                                                                  DeclID ID);
 
   VarTemplatePartialSpecializationDecl *getMostRecentDecl() {
     return cast<VarTemplatePartialSpecializationDecl>(
@@ -3078,7 +3078,7 @@ class VarTemplateDecl : public RedeclarableTemplateDecl {
                                  VarDecl *Decl);
 
   /// Create an empty variable template node.
-  static VarTemplateDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static VarTemplateDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   /// Return the specialization with the provided arguments if it exists,
   /// otherwise return the insertion point.
@@ -3183,7 +3183,7 @@ class ConceptDecl : public TemplateDecl, public Mergeable<ConceptDecl> {
                              SourceLocation L, DeclarationName Name,
                              TemplateParameterList *Params,
                              Expr *ConstraintExpr);
-  static ConceptDecl *CreateDeserialized(ASTContext &C, unsigned ID);
+  static ConceptDecl *CreateDeserialized(ASTContext &C, DeclID ID);
 
   Expr *getConstraintExpr() const {
     return ConstraintExpr;
@@ -3232,7 +3232,7 @@ class ImplicitConceptSpecializationDecl final
   Create(const ASTContext &C, DeclContext *DC, SourceLocation SL,
          ArrayRef<TemplateArgument> ConvertedArgs);
   static ImplicitConceptSpecializationDecl *
-  CreateDeserialized(const ASTContext &C, unsigned ID,
+  CreateDeserialized(const ASTContext &C, DeclID ID,
                      unsigned NumTemplateArgs);
 
   ArrayRef<TemplateArgument> getTemplateArguments() const {
@@ -3275,7 +3275,7 @@ class TemplateParamObjectDecl : public ValueDecl,
   static TemplateParamObjectDecl *Create(const ASTContext &C, QualType T,
                                          const APValue &V);
   static TemplateParamObjectDecl *CreateDeserialized(ASTContext &C,
-                                                     unsigned ID);
+                                                     DeclID ID);
 
   /// Only ASTContext::getTemplateParamObjectDecl and deserialization
   /// create these.

diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
@@ -3198,7 +3198,6 @@ class UnresolvedLookupExpr final
                        NestedNameSpecifierLoc QualifierLoc,
                        SourceLocation TemplateKWLoc,
                        const DeclarationNameInfo &NameInfo, bool RequiresADL,
-                       bool Overloaded,
                        const TemplateArgumentListInfo *TemplateArgs,
                        UnresolvedSetIterator Begin, UnresolvedSetIterator End,
                        bool KnownDependent);
@@ -3218,8 +3217,9 @@ class UnresolvedLookupExpr final
   static UnresolvedLookupExpr *
   Create(const ASTContext &Context, CXXRecordDecl *NamingClass,
          NestedNameSpecifierLoc QualifierLoc,
-         const DeclarationNameInfo &NameInfo, bool RequiresADL, bool Overloaded,
-         UnresolvedSetIterator Begin, UnresolvedSetIterator End);
+         const DeclarationNameInfo &NameInfo, bool RequiresADL,
+         UnresolvedSetIterator Begin, UnresolvedSetIterator End,
+         bool KnownDependent);
 
   // After canonicalization, there may be dependent template arguments in
   // CanonicalConverted But none of Args is dependent. When any of
@@ -3240,9 +3240,6 @@ class UnresolvedLookupExpr final
   /// argument-dependent lookup.
   bool requiresADL() const { return UnresolvedLookupExprBits.RequiresADL; }
 
-  /// True if this lookup is overloaded.
-  bool isOverloaded() const { return UnresolvedLookupExprBits.Overloaded; }
-
   /// Gets the 'naming class' (in the sense of C++0x
   /// [class.access.base]p5) of the lookup.  This is the scope
   /// that was looked in to find these results.

diff --git a/clang/include/clang/AST/OpenACCClause.h b/clang/include/clang/AST/OpenACCClause.h
@@ -156,6 +156,111 @@ class OpenACCSelfClause : public OpenACCClauseWithCondition {
                                    Expr *ConditionExpr, SourceLocation EndLoc);
 };
 
+/// Represents a clause that has one or more IntExprs.  It does not own the
+/// IntExprs, but provides 'children' and other accessors.
+class OpenACCClauseWithIntExprs : public OpenACCClauseWithParams {
+  MutableArrayRef<Expr *> IntExprs;
+
+protected:
+  OpenACCClauseWithIntExprs(OpenACCClauseKind K, SourceLocation BeginLoc,
+                            SourceLocation LParenLoc, SourceLocation EndLoc)
+      : OpenACCClauseWithParams(K, BeginLoc, LParenLoc, EndLoc) {}
+
+  /// Used only for initialization, the leaf class can initialize this to
+  /// trailing storage.
+  void setIntExprs(MutableArrayRef<Expr *> NewIntExprs) {
+    assert(IntExprs.empty() && "Cannot change IntExprs list");
+    IntExprs = NewIntExprs;
+  }
+
+  /// Gets the entire list of integer expressions, but leave it to the
+  /// individual clauses to expose this how they'd like.
+  llvm::ArrayRef<Expr *> getIntExprs() const { return IntExprs; }
+
+public:
+  child_range children() {
+    return child_range(reinterpret_cast<Stmt **>(IntExprs.begin()),
+                       reinterpret_cast<Stmt **>(IntExprs.end()));
+  }
+
+  const_child_range children() const {
+    child_range Children =
+        const_cast<OpenACCClauseWithIntExprs *>(this)->children();
+    return const_child_range(Children.begin(), Children.end());
+  }
+};
+
+class OpenACCNumGangsClause final
+    : public OpenACCClauseWithIntExprs,
+      public llvm::TrailingObjects<OpenACCNumGangsClause, Expr *> {
+
+  OpenACCNumGangsClause(SourceLocation BeginLoc, SourceLocation LParenLoc,
+                        ArrayRef<Expr *> IntExprs, SourceLocation EndLoc)
+      : OpenACCClauseWithIntExprs(OpenACCClauseKind::NumGangs, BeginLoc,
+                                  LParenLoc, EndLoc) {
+    std::uninitialized_copy(IntExprs.begin(), IntExprs.end(),
+                            getTrailingObjects<Expr *>());
+    setIntExprs(MutableArrayRef(getTrailingObjects<Expr *>(), IntExprs.size()));
+  }
+
+public:
+  static OpenACCNumGangsClause *
+  Create(const ASTContext &C, SourceLocation BeginLoc, SourceLocation LParenLoc,
+         ArrayRef<Expr *> IntExprs, SourceLocation EndLoc);
+
+  llvm::ArrayRef<Expr *> getIntExprs() {
+    return OpenACCClauseWithIntExprs::getIntExprs();
+  }
+
+  llvm::ArrayRef<Expr *> getIntExprs() const {
+    return OpenACCClauseWithIntExprs::getIntExprs();
+  }
+};
+
+/// Represents one of a handful of clauses that have a single integer
+/// expression.
+class OpenACCClauseWithSingleIntExpr : public OpenACCClauseWithIntExprs {
+  Expr *IntExpr;
+
+protected:
+  OpenACCClauseWithSingleIntExpr(OpenACCClauseKind K, SourceLocation BeginLoc,
+                                 SourceLocation LParenLoc, Expr *IntExpr,
+                                 SourceLocation EndLoc)
+      : OpenACCClauseWithIntExprs(K, BeginLoc, LParenLoc, EndLoc),
+        IntExpr(IntExpr) {
+    setIntExprs(MutableArrayRef<Expr *>{&this->IntExpr, 1});
+  }
+
+public:
+  bool hasIntExpr() const { return !getIntExprs().empty(); }
+  const Expr *getIntExpr() const {
+    return hasIntExpr() ? getIntExprs()[0] : nullptr;
+  }
+
+  Expr *getIntExpr() { return hasIntExpr() ? getIntExprs()[0] : nullptr; };
+};
+
+class OpenACCNumWorkersClause : public OpenACCClauseWithSingleIntExpr {
+  OpenACCNumWorkersClause(SourceLocation BeginLoc, SourceLocation LParenLoc,
+                          Expr *IntExpr, SourceLocation EndLoc);
+
+public:
+  static OpenACCNumWorkersClause *Create(const ASTContext &C,
+                                         SourceLocation BeginLoc,
+                                         SourceLocation LParenLoc,
+                                         Expr *IntExpr, SourceLocation EndLoc);
+};
+
+class OpenACCVectorLengthClause : public OpenACCClauseWithSingleIntExpr {
+  OpenACCVectorLengthClause(SourceLocation BeginLoc, SourceLocation LParenLoc,
+                            Expr *IntExpr, SourceLocation EndLoc);
+
+public:
+  static OpenACCVectorLengthClause *
+  Create(const ASTContext &C, SourceLocation BeginLoc, SourceLocation LParenLoc,
+         Expr *IntExpr, SourceLocation EndLoc);
+};
+
 template <class Impl> class OpenACCClauseVisitor {
   Impl &getDerived() { return static_cast<Impl &>(*this); }
 

diff --git a/clang/include/clang/AST/Stmt.h b/clang/include/clang/AST/Stmt.h
@@ -1067,11 +1067,6 @@ class alignas(void *) Stmt {
     /// argument-dependent lookup if this is the operand of a function call.
     LLVM_PREFERRED_TYPE(bool)
     unsigned RequiresADL : 1;
-
-    /// True if these lookup results are overloaded.  This is pretty trivially
-    /// rederivable if we urgently need to kill this field.
-    LLVM_PREFERRED_TYPE(bool)
-    unsigned Overloaded : 1;
   };
   static_assert(sizeof(UnresolvedLookupExprBitfields) <= 4,
                 "UnresolvedLookupExprBitfields must be <= than 4 bytes to"

diff --git a/clang/include/clang/Analysis/Analyses/ExprMutationAnalyzer.h b/clang/include/clang/Analysis/Analyses/ExprMutationAnalyzer.h
@@ -8,11 +8,9 @@
 #ifndef LLVM_CLANG_ANALYSIS_ANALYSES_EXPRMUTATIONANALYZER_H
 #define LLVM_CLANG_ANALYSIS_ANALYSES_EXPRMUTATIONANALYZER_H
 
-#include <type_traits>
-
-#include "clang/AST/AST.h"
 #include "clang/ASTMatchers/ASTMatchers.h"
 #include "llvm/ADT/DenseMap.h"
+#include <memory>
 
 namespace clang {
 
@@ -21,75 +19,127 @@ class FunctionParmMutationAnalyzer;
 /// Analyzes whether any mutative operations are applied to an expression within
 /// a given statement.
 class ExprMutationAnalyzer {
+  friend class FunctionParmMutationAnalyzer;
+
 public:
+  struct Memoized {
+    using ResultMap = llvm::DenseMap<const Expr *, const Stmt *>;
+    using FunctionParaAnalyzerMap =
+        llvm::SmallDenseMap<const FunctionDecl *,
+                            std::unique_ptr<FunctionParmMutationAnalyzer>>;
+
+    ResultMap Results;
+    ResultMap PointeeResults;
+    FunctionParaAnalyzerMap FuncParmAnalyzer;
+
+    void clear() {
+      Results.clear();
+      PointeeResults.clear();
+      FuncParmAnalyzer.clear();
+    }
+  };
+  struct Analyzer {
+    Analyzer(const Stmt &Stm, ASTContext &Context, Memoized &Memorized)
+        : Stm(Stm), Context(Context), Memorized(Memorized) {}
+
+    const Stmt *findMutation(const Expr *Exp);
+    const Stmt *findMutation(const Decl *Dec);
+
+    const Stmt *findPointeeMutation(const Expr *Exp);
+    const Stmt *findPointeeMutation(const Decl *Dec);
+    static bool isUnevaluated(const Stmt *Smt, const Stmt &Stm,
+                              ASTContext &Context);
+
+  private:
+    using MutationFinder = const Stmt *(Analyzer::*)(const Expr *);
+
+    const Stmt *findMutationMemoized(const Expr *Exp,
+                                     llvm::ArrayRef<MutationFinder> Finders,
+                                     Memoized::ResultMap &MemoizedResults);
+    const Stmt *tryEachDeclRef(const Decl *Dec, MutationFinder Finder);
+
+    bool isUnevaluated(const Expr *Exp);
+
+    const Stmt *findExprMutation(ArrayRef<ast_matchers::BoundNodes> Matches);
+    const Stmt *findDeclMutation(ArrayRef<ast_matchers::BoundNodes> Matches);
+    const Stmt *
+    findExprPointeeMutation(ArrayRef<ast_matchers::BoundNodes> Matches);
+    const Stmt *
+    findDeclPointeeMutation(ArrayRef<ast_matchers::BoundNodes> Matches);
+
+    const Stmt *findDirectMutation(const Expr *Exp);
+    const Stmt *findMemberMutation(const Expr *Exp);
+    const Stmt *findArrayElementMutation(const Expr *Exp);
+    const Stmt *findCastMutation(const Expr *Exp);
+    const Stmt *findRangeLoopMutation(const Expr *Exp);
+    const Stmt *findReferenceMutation(const Expr *Exp);
+    const Stmt *findFunctionArgMutation(const Expr *Exp);
+
+    const Stmt &Stm;
+    ASTContext &Context;
+    Memoized &Memorized;
+  };
+
   ExprMutationAnalyzer(const Stmt &Stm, ASTContext &Context)
-      : Stm(Stm), Context(Context) {}
+      : Memorized(), A(Stm, Context, Memorized) {}
 
   bool isMutated(const Expr *Exp) { return findMutation(Exp) != nullptr; }
   bool isMutated(const Decl *Dec) { return findMutation(Dec) != nullptr; }
-  const Stmt *findMutation(const Expr *Exp);
-  const Stmt *findMutation(const Decl *Dec);
+  const Stmt *findMutation(const Expr *Exp) { return A.findMutation(Exp); }
+  const Stmt *findMutation(const Decl *Dec) { return A.findMutation(Dec); }
 
   bool isPointeeMutated(const Expr *Exp) {
     return findPointeeMutation(Exp) != nullptr;
   }
   bool isPointeeMutated(const Decl *Dec) {
     return findPointeeMutation(Dec) != nullptr;
   }
-  const Stmt *findPointeeMutation(const Expr *Exp);
-  const Stmt *findPointeeMutation(const Decl *Dec);
+  const Stmt *findPointeeMutation(const Expr *Exp) {
+    return A.findPointeeMutation(Exp);
+  }
+  const Stmt *findPointeeMutation(const Decl *Dec) {
+    return A.findPointeeMutation(Dec);
+  }
+
   static bool isUnevaluated(const Stmt *Smt, const Stmt &Stm,
-                            ASTContext &Context);
+                            ASTContext &Context) {
+    return Analyzer::isUnevaluated(Smt, Stm, Context);
+  }
 
 private:
-  using MutationFinder = const Stmt *(ExprMutationAnalyzer::*)(const Expr *);
-  using ResultMap = llvm::DenseMap<const Expr *, const Stmt *>;
-
-  const Stmt *findMutationMemoized(const Expr *Exp,
-                                   llvm::ArrayRef<MutationFinder> Finders,
-                                   ResultMap &MemoizedResults);
-  const Stmt *tryEachDeclRef(const Decl *Dec, MutationFinder Finder);
-
-  bool isUnevaluated(const Expr *Exp);
-
-  const Stmt *findExprMutation(ArrayRef<ast_matchers::BoundNodes> Matches);
-  const Stmt *findDeclMutation(ArrayRef<ast_matchers::BoundNodes> Matches);
-  const Stmt *
-  findExprPointeeMutation(ArrayRef<ast_matchers::BoundNodes> Matches);
-  const Stmt *
-  findDeclPointeeMutation(ArrayRef<ast_matchers::BoundNodes> Matches);
-
-  const Stmt *findDirectMutation(const Expr *Exp);
-  const Stmt *findMemberMutation(const Expr *Exp);
-  const Stmt *findArrayElementMutation(const Expr *Exp);
-  const Stmt *findCastMutation(const Expr *Exp);
-  const Stmt *findRangeLoopMutation(const Expr *Exp);
-  const Stmt *findReferenceMutation(const Expr *Exp);
-  const Stmt *findFunctionArgMutation(const Expr *Exp);
-
-  const Stmt &Stm;
-  ASTContext &Context;
-  llvm::DenseMap<const FunctionDecl *,
-                 std::unique_ptr<FunctionParmMutationAnalyzer>>
-      FuncParmAnalyzer;
-  ResultMap Results;
-  ResultMap PointeeResults;
+  Memoized Memorized;
+  Analyzer A;
 };
 
 // A convenient wrapper around ExprMutationAnalyzer for analyzing function
 // params.
 class FunctionParmMutationAnalyzer {
 public:
-  FunctionParmMutationAnalyzer(const FunctionDecl &Func, ASTContext &Context);
+  static FunctionParmMutationAnalyzer *
+  getFunctionParmMutationAnalyzer(const FunctionDecl &Func, ASTContext &Context,
+                                  ExprMutationAnalyzer::Memoized &Memorized) {
+    auto it = Memorized.FuncParmAnalyzer.find(&Func);
+    if (it == Memorized.FuncParmAnalyzer.end())
+      it =
+          Memorized.FuncParmAnalyzer
+              .try_emplace(&Func, std::unique_ptr<FunctionParmMutationAnalyzer>(
+                                      new FunctionParmMutationAnalyzer(
+                                          Func, Context, Memorized)))
+              .first;
+    return it->getSecond().get();
+  }
 
   bool isMutated(const ParmVarDecl *Parm) {
     return findMutation(Parm) != nullptr;
   }
   const Stmt *findMutation(const ParmVarDecl *Parm);
 
 private:
-  ExprMutationAnalyzer BodyAnalyzer;
+  ExprMutationAnalyzer::Analyzer BodyAnalyzer;
   llvm::DenseMap<const ParmVarDecl *, const Stmt *> Results;
+
+  FunctionParmMutationAnalyzer(const FunctionDecl &Func, ASTContext &Context,
+                               ExprMutationAnalyzer::Memoized &Memorized);
 };
 
 } // namespace clang

diff --git a/clang/include/clang/Analysis/FlowSensitive/ASTOps.h b/clang/include/clang/Analysis/FlowSensitive/ASTOps.h
@@ -56,6 +56,7 @@ class RecordInitListHelper {
 public:
   // `InitList` must have record type.
   RecordInitListHelper(const InitListExpr *InitList);
+  RecordInitListHelper(const CXXParenListInitExpr *ParenInitList);
 
   // Base classes with their associated initializer expressions.
   ArrayRef<std::pair<const CXXBaseSpecifier *, Expr *>> base_inits() const {
@@ -68,6 +69,9 @@ class RecordInitListHelper {
   }
 
 private:
+  RecordInitListHelper(QualType Ty, std::vector<const FieldDecl *> Fields,
+                       ArrayRef<Expr *> Inits);
+
   SmallVector<std::pair<const CXXBaseSpecifier *, Expr *>> BaseInits;
   SmallVector<std::pair<const FieldDecl *, Expr *>> FieldInits;
 
@@ -92,6 +96,9 @@ struct ReferencedDecls {
 /// Returns declarations that are declared in or referenced from `FD`.
 ReferencedDecls getReferencedDecls(const FunctionDecl &FD);
 
+/// Returns declarations that are declared in or referenced from `S`.
+ReferencedDecls getReferencedDecls(const Stmt &S);
+
 } // namespace dataflow
 } // namespace clang
 

diff --git a/clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h b/clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h
@@ -84,7 +84,7 @@ class Environment {
     virtual ComparisonResult compare(QualType Type, const Value &Val1,
                                      const Environment &Env1, const Value &Val2,
                                      const Environment &Env2) {
-      // FIXME: Consider adding QualType to RecordValue and removing the Type
+      // FIXME: Consider adding `QualType` to `Value` and removing the `Type`
       // argument here.
       return ComparisonResult::Unknown;
     }
@@ -407,20 +407,15 @@ class Environment {
   /// storage locations and values for indirections until it finds a
   /// non-pointer/non-reference type.
   ///
-  /// If `Type` is a class, struct, or union type, creates values for all
-  /// modeled fields (including synthetic fields) and calls `setValue()` to
-  /// associate the `RecordValue` with its storage location
-  /// (`RecordValue::getLoc()`).
-  ///
   /// If `Type` is one of the following types, this function will always return
   /// a non-null pointer:
   /// - `bool`
   /// - Any integer type
-  /// - Any class, struct, or union type
   ///
   /// Requirements:
   ///
-  ///  `Type` must not be null.
+  ///  - `Type` must not be null.
+  ///  - `Type` must not be a reference type or record type.
   Value *createValue(QualType Type);
 
   /// Creates an object (i.e. a storage location with an associated value) of
@@ -452,6 +447,7 @@ class Environment {
   /// Initializes the fields (including synthetic fields) of `Loc` with values,
   /// unless values of the field type are not supported or we hit one of the
   /// limits at which we stop producing values.
+  /// If a field already has a value, that value is preserved.
   /// If `Type` is provided, initializes only those fields that are modeled for
   /// `Type`; this is intended for use in cases where `Loc` is a derived type
   /// and we only want to initialize the fields of a base type.
@@ -461,6 +457,10 @@ class Environment {
   }
 
   /// Assigns `Val` as the value of `Loc` in the environment.
+  ///
+  /// Requirements:
+  ///
+  ///  `Loc` must not be a `RecordStorageLocation`.
   void setValue(const StorageLocation &Loc, Value &Val);
 
   /// Clears any association between `Loc` and a value in the environment.
@@ -470,20 +470,24 @@ class Environment {
   ///
   /// Requirements:
   ///
-  ///  - `E` must be a prvalue
-  ///  - If `Val` is a `RecordValue`, its `RecordStorageLocation` must be
-  ///    `getResultObjectLocation(E)`. An exception to this is if `E` is an
-  ///    expression that originally creates a `RecordValue` (such as a
-  ///    `CXXConstructExpr` or `CallExpr`), as these establish the location of
-  ///    the result object in the first place.
+  ///  - `E` must be a prvalue.
+  ///  - `E` must not have record type.
   void setValue(const Expr &E, Value &Val);
 
   /// Returns the value assigned to `Loc` in the environment or null if `Loc`
   /// isn't assigned a value in the environment.
+  ///
+  /// Requirements:
+  ///
+  ///  `Loc` must not be a `RecordStorageLocation`.
   Value *getValue(const StorageLocation &Loc) const;
 
   /// Equivalent to `getValue(getStorageLocation(D))` if `D` is assigned a
   /// storage location in the environment, otherwise returns null.
+  ///
+  /// Requirements:
+  ///
+  ///  `D` must not have record type.
   Value *getValue(const ValueDecl &D) const;
 
   /// Equivalent to `getValue(getStorageLocation(E, SP))` if `E` is assigned a
@@ -775,12 +779,6 @@ RecordStorageLocation *getImplicitObjectLocation(const CXXMemberCallExpr &MCE,
 RecordStorageLocation *getBaseObjectLocation(const MemberExpr &ME,
                                              const Environment &Env);
 
-/// Associates a new `RecordValue` with `Loc` and returns the new value.
-RecordValue &refreshRecordValue(RecordStorageLocation &Loc, Environment &Env);
-
-/// Associates a new `RecordValue` with `Expr` and returns the new value.
-RecordValue &refreshRecordValue(const Expr &Expr, Environment &Env);
-
 } // namespace dataflow
 } // namespace clang
 

diff --git a/clang/include/clang/Analysis/FlowSensitive/Value.h b/clang/include/clang/Analysis/FlowSensitive/Value.h
@@ -35,7 +35,6 @@ class Value {
   enum class Kind {
     Integer,
     Pointer,
-    Record,
 
     // TODO: Top values should not be need to be type-specific.
     TopBool,
@@ -67,7 +66,6 @@ class Value {
   /// Properties may not be set on `RecordValue`s; use synthetic fields instead
   /// (for details, see documentation for `RecordStorageLocation`).
   void setProperty(llvm::StringRef Name, Value &Val) {
-    assert(getKind() != Kind::Record);
     Properties.insert_or_assign(Name, &Val);
   }
 
@@ -184,45 +182,6 @@ class PointerValue final : public Value {
   StorageLocation &PointeeLoc;
 };
 
-/// Models a value of `struct` or `class` type.
-/// In C++, prvalues of class type serve only a limited purpose: They can only
-/// be used to initialize a result object. It is not possible to access member
-/// variables or call member functions on a prvalue of class type.
-/// Correspondingly, `RecordValue` also serves only a limited purpose: It
-/// conveys a prvalue of class type from the place where the object is
-/// constructed to the result object that it initializes.
-///
-/// When creating a prvalue of class type, we already need a storage location
-/// for `this`, even though prvalues are otherwise not associated with storage
-/// locations. `RecordValue` is therefore essentially a wrapper for a storage
-/// location, which is then used to set the storage location for the result
-/// object when we process the AST node for that result object.
-///
-/// For example:
-///    MyStruct S = MyStruct(3);
-///
-/// In this example, `MyStruct(3) is a prvalue, which is modeled as a
-/// `RecordValue` that wraps a `RecordStorageLocation`. This
-/// `RecordStorageLocation` is then used as the storage location for `S`.
-///
-/// Over time, we may eliminate `RecordValue` entirely. See also the discussion
-/// here: https://reviews.llvm.org/D155204#inline-1503204
-class RecordValue final : public Value {
-public:
-  explicit RecordValue(RecordStorageLocation &Loc)
-      : Value(Kind::Record), Loc(Loc) {}
-
-  static bool classof(const Value *Val) {
-    return Val->getKind() == Kind::Record;
-  }
-
-  /// Returns the storage location that this `RecordValue` is associated with.
-  RecordStorageLocation &getLoc() const { return Loc; }
-
-private:
-  RecordStorageLocation &Loc;
-};
-
 raw_ostream &operator<<(raw_ostream &OS, const Value &Val);
 
 } // namespace dataflow

diff --git a/clang/include/clang/Basic/Builtins.td b/clang/include/clang/Basic/Builtins.td
@@ -1164,6 +1164,12 @@ def Unreachable : Builtin {
   let Prototype = "void()";
 }
 
+def AllowRuntimeCheck : Builtin {
+  let Spellings = ["__builtin_allow_runtime_check"];
+  let Attributes = [NoThrow, Pure, Const];
+  let Prototype = "bool(char const*)";
+}
+
 def ShuffleVector : Builtin {
   let Spellings = ["__builtin_shufflevector"];
   let Attributes = [NoThrow, Const, CustomTypeChecking];

diff --git a/clang/include/clang/Basic/DebugOptions.def b/clang/include/clang/Basic/DebugOptions.def
@@ -129,6 +129,9 @@ DEBUGOPT(CodeViewCommandLine, 1, 0)
 /// Whether emit extra debug info for sample pgo profile collection.
 DEBUGOPT(DebugInfoForProfiling, 1, 0)
 
+/// Whether to emit DW_TAG_template_alias for template aliases.
+DEBUGOPT(DebugTemplateAlias, 1, 0)
+
 /// Whether to emit .debug_gnu_pubnames section instead of .debug_pubnames.
 DEBUGOPT(DebugNameTable, 2, 0)
 

diff --git a/clang/include/clang/Basic/DiagnosticInstallAPIKinds.td b/clang/include/clang/Basic/DiagnosticInstallAPIKinds.td
@@ -24,6 +24,7 @@ def err_no_matching_target : Error<"no matching target found for target variant
 def err_unsupported_vendor : Error<"vendor '%0' is not supported: '%1'">;
 def err_unsupported_environment : Error<"environment '%0' is not supported: '%1'">;
 def err_unsupported_os : Error<"os '%0' is not supported: '%1'">;
+def err_cannot_read_alias_list : Error<"could not read alias list '%0': %1">;
 } // end of command line category.
 
 let CategoryName = "Verification" in {

diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -863,6 +863,8 @@ def err_empty_requires_expr : Error<
   "a requires expression must contain at least one requirement">;
 def err_requires_expr_parameter_list_ellipsis : Error<
   "varargs not allowed in requires expression">;
+def err_requires_expr_explicit_object_parameter: Error<
+  "a requires expression cannot have an explicit object parameter">;
 def err_expected_semi_requirement : Error<
   "expected ';' at end of requirement">;
 def err_requires_expr_missing_arrow : Error<

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -3669,6 +3669,9 @@ def warn_attribute_dllexport_explicit_instantiation_decl : Warning<
 def warn_attribute_dllexport_explicit_instantiation_def : Warning<
   "'dllexport' attribute ignored on explicit instantiation definition">,
   InGroup<IgnoredAttributes>;
+def warn_attribute_exclude_from_explicit_instantiation_local_class : Warning<
+  "%0 attribute ignored on local class%select{| member}1">,
+  InGroup<IgnoredAttributes>;
 def warn_invalid_initializer_from_system_header : Warning<
   "invalid constructor from class in system header, should not be explicit">,
   InGroup<DiagGroup<"invalid-initializer-from-system-header">>;
@@ -12278,4 +12281,21 @@ def warn_acc_if_self_conflict
     : Warning<"OpenACC construct 'self' has no effect when an 'if' clause "
               "evaluates to true">,
       InGroup<DiagGroup<"openacc-self-if-potential-conflict">>;
+def err_acc_int_expr_requires_integer
+    : Error<"OpenACC %select{clause|directive}0 '%1' requires expression of "
+            "integer type (%2 invalid)">;
+def err_acc_int_expr_incomplete_class_type
+    : Error<"OpenACC integer expression has incomplete class type %0">;
+def err_acc_int_expr_explicit_conversion
+    : Error<"OpenACC integer expression type %0 requires explicit conversion "
+            "to %1">;
+def note_acc_int_expr_conversion
+    : Note<"conversion to %select{integral|enumeration}0 type %1">;
+def err_acc_int_expr_multiple_conversions
+    : Error<"multiple conversions from expression type %0 to an integral type">;
+def err_acc_num_gangs_num_args
+    : Error<"%select{no|too many}0 integer expression arguments provided to "
+            "OpenACC 'num_gangs' "
+            "%select{|clause: '%1' directive expects maximum of %2, %3 were "
+            "provided}0">;
 } // end of sema component.
diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
@@ -224,6 +224,11 @@ class LangOptionsBase {
     ///   - the parameter list of a template template parameter
     Ver17,
 
+    /// Attempt to be ABI-compatible with code generated by Clang 18.0.x.
+    /// This causes clang to revert some fixes to the mangling of lambdas
+    /// in the initializers of members of local classes.
+    Ver18,
+
     /// Conform to the underlying platform's C and C++ ABIs as closely
     /// as we can.
     Latest

diff --git a/clang/include/clang/Basic/OpenACCClauses.def b/clang/include/clang/Basic/OpenACCClauses.def
@@ -18,5 +18,8 @@
 VISIT_CLAUSE(Default)
 VISIT_CLAUSE(If)
 VISIT_CLAUSE(Self)
+VISIT_CLAUSE(NumGangs)
+VISIT_CLAUSE(NumWorkers)
+VISIT_CLAUSE(VectorLength)
 
 #undef VISIT_CLAUSE
diff --git a/clang/include/clang/Basic/arm_fp16.td b/clang/include/clang/Basic/arm_fp16.td
@@ -14,7 +14,7 @@
 include "arm_neon_incl.td"
 
 // ARMv8.2-A FP16 intrinsics.
-let ArchGuard = "defined(__aarch64__)", TargetGuard = "fullfp16" in {
+let ArchGuard = "defined(__aarch64__) || defined(__arm64ec__)", TargetGuard = "fullfp16" in {
 
   // Negate
   def VNEGSH          : SInst<"vneg", "11", "Sh">;