[Sema] Add deprecation warnings for some compiler provided __has_* ty…

…pe traits Some compiler provided type traits like __has_trivial_constructor have been documented as deprecated for quite some time. Still, some people apparently still use them, even though mixing them with concepts and with deleted functions leads to weird results. There's also disagreement about some edge cases between GCC (which Clang claims to follow) and MSVC. This patch adds deprecation warnings for the usage of those builtins, except for __has_trivial_destructor which doesn't have a GCC alternative. I made the warning on by default, so I had to silence it for some tests but it's not too many. Some (decade old) history of issues with those builtins: #18187 #18559 #22161 #33063 The abseil usage of them that triggered me to add this warning: abseil/abseil-cpp#1201 Weird interaction of those builtins with C++20's conditionally trivial special member functions: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106085 Reviewed By: #clang-language-wg, aaron.ballman Differential Revision: https://reviews.llvm.org/D129170
llvm · Jul 12, 2022 · 0b89d1d · 0b89d1d
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diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
@@ -312,6 +312,10 @@ Non-comprehensive list of changes in this release
   - ASAN_OPTIONS=detect_stack_use_after_return=1 (only on Linux).
   - MSAN_OPTIONS=poison_in_dtor=1.
 
+- Some type-trait builtins, such as ``__has_trivial_assign``, have been documented
+  as deprecated for a while because their semantics don't mix well with post-C++11 type-traits.
+  Clang now emits deprecation warnings for them under the flag ``-Wdeprecated-builtins``.
+
 New Compiler Flags
 ------------------
 - Added the ``-fno-knr-functions`` flag to allow users to opt into the C2x

diff --git a/clang/include/clang/Basic/DiagnosticGroups.td b/clang/include/clang/Basic/DiagnosticGroups.td
@@ -188,6 +188,7 @@ def UnguardedAvailability : DiagGroup<"unguarded-availability",
 def : DiagGroup<"partial-availability", [UnguardedAvailability]>;
 def DeprecatedDynamicExceptionSpec
     : DiagGroup<"deprecated-dynamic-exception-spec">;
+def DeprecatedBuiltins : DiagGroup<"deprecated-builtins">;
 def DeprecatedImplementations :DiagGroup<"deprecated-implementations">;
 def DeprecatedIncrementBool : DiagGroup<"deprecated-increment-bool">;
 def DeprecatedRegister : DiagGroup<"deprecated-register">;
@@ -210,6 +211,7 @@ def Deprecated : DiagGroup<"deprecated", [DeprecatedAnonEnumEnumConversion,
                                           DeprecatedEnumCompareConditional,
                                           DeprecatedEnumEnumConversion,
                                           DeprecatedEnumFloatConversion,
+                                          DeprecatedBuiltins,
                                           DeprecatedIncrementBool,
                                           DeprecatedPragma,
                                           DeprecatedRegister,

diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -5562,6 +5562,9 @@ def warn_deprecated_def : Warning<
 def warn_unavailable_def : Warning<
   "implementing unavailable method">,
   InGroup<DeprecatedImplementations>, DefaultIgnore;
+def warn_deprecated_builtin : Warning<
+  "builtin %0 is deprecated; use %1 instead">,
+  InGroup<DeprecatedBuiltins>;
 def err_unavailable : Error<"%0 is unavailable">;
 def err_property_method_unavailable :
     Error<"property access is using %0 method which is unavailable">;

diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
@@ -5394,6 +5394,39 @@ static bool evaluateTypeTrait(Sema &S, TypeTrait Kind, SourceLocation KWLoc,
   return false;
 }
 
+namespace {
+void DiagnoseBuiltinDeprecation(Sema& S, TypeTrait Kind,
+                                SourceLocation KWLoc) {
+  TypeTrait Replacement;
+  switch (Kind) {
+    case UTT_HasNothrowAssign:
+    case UTT_HasNothrowMoveAssign:
+      Replacement = BTT_IsNothrowAssignable;
+      break;
+    case UTT_HasNothrowCopy:
+    case UTT_HasNothrowConstructor:
+      Replacement = TT_IsNothrowConstructible;
+      break;
+    case UTT_HasTrivialAssign:
+    case UTT_HasTrivialMoveAssign:
+      Replacement = BTT_IsTriviallyAssignable;
+      break;
+    case UTT_HasTrivialCopy:
+    case UTT_HasTrivialDefaultConstructor:
+    case UTT_HasTrivialMoveConstructor:
+      Replacement = TT_IsTriviallyConstructible;
+      break;
+    case UTT_HasTrivialDestructor:
+      Replacement = UTT_IsTriviallyDestructible;
+      break;
+    default:
+      return;
+  }
+  S.Diag(KWLoc, diag::warn_deprecated_builtin)
+    << getTraitSpelling(Kind) << getTraitSpelling(Replacement);
+}
+}
+
 ExprResult Sema::BuildTypeTrait(TypeTrait Kind, SourceLocation KWLoc,
                                 ArrayRef<TypeSourceInfo *> Args,
                                 SourceLocation RParenLoc) {
@@ -5403,6 +5436,8 @@ ExprResult Sema::BuildTypeTrait(TypeTrait Kind, SourceLocation KWLoc,
                                *this, Kind, KWLoc, Args[0]->getType()))
     return ExprError();
 
+  DiagnoseBuiltinDeprecation(*this, Kind, KWLoc);
+
   bool Dependent = false;
   for (unsigned I = 0, N = Args.size(); I != N; ++I) {
     if (Args[I]->getType()->isDependentType()) {

diff --git a/clang/test/CXX/dcl.decl/dcl.init/p5.cpp b/clang/test/CXX/dcl.decl/dcl.init/p5.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -fsyntax-only -verify -std=c++98 %s
-// RUN: %clang_cc1 -fsyntax-only -verify -std=c++11 %s
-// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-deprecated-builtins -std=c++98 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-deprecated-builtins -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -verify -Wno-deprecated-builtins %s
 
 //   A program that calls for default-initialization or value-initialization of
 //   an entity of reference type is illformed. If T is a cv-qualified type, the

diff --git a/clang/test/CXX/drs/dr18xx.cpp b/clang/test/CXX/drs/dr18xx.cpp
@@ -1,8 +1,8 @@
-// RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++17 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++2a -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++17 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++2a -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
 
 #if __cplusplus < 201103L
 // expected-error@+1 {{variadic macro}}

diff --git a/clang/test/CXX/drs/dr21xx.cpp b/clang/test/CXX/drs/dr21xx.cpp
@@ -1,7 +1,7 @@
-// RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++1z -triple x86_64-unknown-unknown %s -verify -fexceptions -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++1z -triple x86_64-unknown-unknown %s -verify -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
 
 #if __cplusplus < 201103L
 // expected-error@+1 {{variadic macro}}

diff --git a/clang/test/CXX/special/class.copy/p12-0x.cpp b/clang/test/CXX/special/class.copy/p12-0x.cpp
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -std=c++11 -verify %s -Wno-defaulted-function-deleted
-// RUN: %clang_cc1 -std=c++11 -verify %s -Wno-defaulted-function-deleted -fclang-abi-compat=14 -DCLANG_ABI_COMPAT=14
+// RUN: %clang_cc1 -std=c++11 -verify %s -Wno-deprecated-builtins -Wno-defaulted-function-deleted
+// RUN: %clang_cc1 -std=c++11 -verify %s -Wno-deprecated-builtins -Wno-defaulted-function-deleted -fclang-abi-compat=14 -DCLANG_ABI_COMPAT=14
 
 // expected-no-diagnostics
 

diff --git a/clang/test/CXX/special/class.copy/p25-0x.cpp b/clang/test/CXX/special/class.copy/p25-0x.cpp
@@ -1,5 +1,5 @@
-// RUN: %clang_cc1 -std=c++11 -verify %s
-// RUN: %clang_cc1 -std=c++11 -verify %s -fclang-abi-compat=14 -DCLANG_ABI_COMPAT=14
+// RUN: %clang_cc1 -std=c++11 -verify %s -Wno-deprecated-builtins
+// RUN: %clang_cc1 -std=c++11 -verify %s -Wno-deprecated-builtins -fclang-abi-compat=14 -DCLANG_ABI_COMPAT=14
 
 // expected-no-diagnostics
 

diff --git a/clang/test/CXX/special/class.ctor/p5-0x.cpp b/clang/test/CXX/special/class.ctor/p5-0x.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++11 -Wno-defaulted-function-deleted
+// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++11 -Wno-deprecated-builtins -Wno-defaulted-function-deleted
 
 struct DefaultedDefCtor1 {};
 struct DefaultedDefCtor2 { DefaultedDefCtor2() = default; };

diff --git a/clang/test/Modules/cxx-decls.cpp b/clang/test/Modules/cxx-decls.cpp
@@ -1,6 +1,6 @@
 // RUN: rm -rf %t
-// RUN: %clang_cc1 -x objective-c++ -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -I %S/Inputs %s -verify -std=c++11
-// RUN: %clang_cc1 -x objective-c++ -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -I %S/Inputs %s -ast-dump -ast-dump-filter merge -std=c++11 | FileCheck %s
+// RUN: %clang_cc1 -x objective-c++ -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -Wno-deprecated-builtins -I %S/Inputs %s -verify -std=c++11
+// RUN: %clang_cc1 -x objective-c++ -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -Wno-deprecated-builtins -I %S/Inputs %s -ast-dump -ast-dump-filter merge -std=c++11 | FileCheck %s
 
 // expected-no-diagnostics
 

diff --git a/clang/test/SemaCXX/cxx0x-defaulted-functions.cpp b/clang/test/SemaCXX/cxx0x-defaulted-functions.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -fcxx-exceptions %s
+// RUN: %clang_cc1 -std=c++11 -fsyntax-only -verify -fcxx-exceptions -Wno-deprecated-builtins %s
 
 void fn() = default; // expected-error {{only special member}}
 struct foo {

diff --git a/clang/test/SemaCXX/cxx11-crashes.cpp b/clang/test/SemaCXX/cxx11-crashes.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++11 -verify %s
+// RUN: %clang_cc1 -std=c++11 -verify %s -Wno-deprecated-builtins
 
 // rdar://12240916 stack overflow.
 namespace rdar12240916 {

diff --git a/clang/test/SemaCXX/deprecated-builtins.cpp b/clang/test/SemaCXX/deprecated-builtins.cpp
@@ -0,0 +1,19 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+
+struct A {};
+
+void f() {
+    bool a;
+
+    a = __has_nothrow_assign(A);  // expected-warning-re {{__has_nothrow_assign {{.*}} use __is_nothrow_assignable}}
+    a = __has_nothrow_move_assign(A);  // expected-warning-re {{__has_nothrow_move_assign {{.*}} use __is_nothrow_assignable}}
+    a = __has_nothrow_copy(A);  // expected-warning-re {{__has_nothrow_copy {{.*}} use __is_nothrow_constructible}}
+    a = __has_nothrow_constructor(A);  // expected-warning-re {{__has_nothrow_constructor {{.*}} use __is_nothrow_constructible}}
+    a = __has_trivial_assign(A);  // expected-warning-re {{__has_trivial_assign {{.*}} use __is_trivially_assignable}}
+    a = __has_trivial_move_assign(A);  // expected-warning-re {{__has_trivial_move_assign {{.*}} use __is_trivially_assignable}}
+    a = __has_trivial_copy(A);  // expected-warning-re {{__has_trivial_copy {{.*}} use __is_trivially_constructible}}
+    a = __has_trivial_constructor(A);  // expected-warning-re {{__has_trivial_constructor {{.*}} use __is_trivially_constructible}}
+    a = __has_trivial_move_constructor(A);  // expected-warning-re {{__has_trivial_move_constructor {{.*}} use __is_trivially_constructible}}
+    a = __has_trivial_destructor(A);  // expected-warning-re {{__has_trivial_destructor {{.*}} use __is_trivially_destructible}}
+
+}
diff --git a/clang/test/SemaCXX/sizeless-1.cpp b/clang/test/SemaCXX/sizeless-1.cpp
@@ -1,7 +1,7 @@
-// RUN: %clang_cc1 -fcxx-exceptions -fsyntax-only -verify -W -Wall -Wno-unused-but-set-variable -Wrange-loop-analysis -triple arm64-linux-gnu -target-feature +sve -std=c++98 %s
-// RUN: %clang_cc1 -fcxx-exceptions -fsyntax-only -verify -W -Wall -Wno-unused-but-set-variable -Wrange-loop-analysis -triple arm64-linux-gnu -target-feature +sve -std=c++11 %s
-// RUN: %clang_cc1 -fcxx-exceptions -fsyntax-only -verify -W -Wall -Wno-unused-but-set-variable -Wrange-loop-analysis -triple arm64-linux-gnu -target-feature +sve -std=c++17 %s
-// RUN: %clang_cc1 -fcxx-exceptions -fsyntax-only -verify -W -Wall -Wno-unused-but-set-variable -Wrange-loop-analysis -triple arm64-linux-gnu -target-feature +sve -std=gnu++17 %s
+// RUN: %clang_cc1 -fcxx-exceptions -fsyntax-only -verify -W -Wall -Wno-deprecated-builtins -Wno-unused-but-set-variable -Wrange-loop-analysis -triple arm64-linux-gnu -target-feature +sve -std=c++98 %s
+// RUN: %clang_cc1 -fcxx-exceptions -fsyntax-only -verify -W -Wall -Wno-deprecated-builtins -Wno-unused-but-set-variable -Wrange-loop-analysis -triple arm64-linux-gnu -target-feature +sve -std=c++11 %s
+// RUN: %clang_cc1 -fcxx-exceptions -fsyntax-only -verify -W -Wall -Wno-deprecated-builtins -Wno-unused-but-set-variable -Wrange-loop-analysis -triple arm64-linux-gnu -target-feature +sve -std=c++17 %s
+// RUN: %clang_cc1 -fcxx-exceptions -fsyntax-only -verify -W -Wall -Wno-deprecated-builtins -Wno-unused-but-set-variable -Wrange-loop-analysis -triple arm64-linux-gnu -target-feature +sve -std=gnu++17 %s
 
 namespace std {
 struct type_info;

diff --git a/clang/test/SemaCXX/trivial-constructor.cpp b/clang/test/SemaCXX/trivial-constructor.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++11
+// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++11 -Wno-deprecated-builtins
 // expected-no-diagnostics
 struct T1 {
 };

diff --git a/clang/test/SemaCXX/trivial-destructor.cpp b/clang/test/SemaCXX/trivial-destructor.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++11
+// RUN: %clang_cc1 -fsyntax-only -verify %s -std=c++11 -Wno-deprecated-builtins
 // expected-no-diagnostics
 struct T1 {
 };

diff --git a/clang/test/SemaCXX/type-traits.cpp b/clang/test/SemaCXX/type-traits.cpp
@@ -1,6 +1,6 @@
-// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify -std=gnu++11 -fms-extensions -Wno-microsoft %s
-// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify -std=gnu++14 -fms-extensions -Wno-microsoft %s
-// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify -std=gnu++1z -fms-extensions -Wno-microsoft %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify -std=gnu++11 -Wno-deprecated-builtins -fms-extensions -Wno-microsoft %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify -std=gnu++14 -Wno-deprecated-builtins -fms-extensions -Wno-microsoft %s
+// RUN: %clang_cc1 -triple x86_64-apple-darwin10 -fsyntax-only -verify -std=gnu++1z -Wno-deprecated-builtins -fms-extensions -Wno-microsoft %s
 
 #define T(b) (b) ? 1 : -1
 #define F(b) (b) ? -1 : 1

diff --git a/clang/test/SemaObjCXX/arc-type-traits.mm b/clang/test/SemaObjCXX/arc-type-traits.mm
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -fobjc-arc -fobjc-runtime-has-weak -verify -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -fobjc-arc -fobjc-runtime-has-weak -verify -std=c++11 %s -Wno-deprecated-builtins
 // expected-no-diagnostics
 
 // Check the results of the various type-trait query functions on

diff --git a/clang/test/SemaObjCXX/objc-weak-type-traits.mm b/clang/test/SemaObjCXX/objc-weak-type-traits.mm
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -fobjc-weak -fobjc-runtime-has-weak -verify -std=c++11 %s
+// RUN: %clang_cc1 -fsyntax-only -fobjc-weak -fobjc-runtime-has-weak -verify -std=c++11 %s -Wno-deprecated-builtins
 // expected-no-diagnostics
 
 // Check the results of the various type-trait query functions on