[clang] [Clang] Fix __has_cpp_attribute and C++11 attributes with arguments in C++03 (PR #83065)

[Nikolas Klauser via cfe-commits]

https://github.com/philnik777 updated https://github.com/llvm/llvm-project/pull/83065

>From 497b6639231f9d3141cc3278b3e476edd1d642d2 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Tue, 27 Feb 2024 14:40:42 +0100
Subject: [PATCH] [Clang] Fix __has_cpp_attribute and C++11 attributes with
 arguments in C++03

---
 clang/docs/ReleaseNotes.rst                      |  1 +
 clang/test/Preprocessor/has_attribute.cpp        |  4 +++-
 clang/test/SemaCXX/constant-expression-cxx11.cpp |  2 +-
 clang/test/SemaCXX/cxx03-cxx11-attr.cpp          |  9 +++++++++
 clang/utils/TableGen/ClangAttrEmitter.cpp        | 12 +-----------
 5 files changed, 15 insertions(+), 13 deletions(-)
 create mode 100644 clang/test/SemaCXX/cxx03-cxx11-attr.cpp

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 45ace4191592d3..4e0b28cb21ce27 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -267,6 +267,7 @@ Bug Fixes to C++ Support
   was only accepted at namespace scope but not at local function scope.
 - Clang no longer tries to call consteval constructors at runtime when they appear in a member initializer.
   (`#782154 <https://github.com/llvm/llvm-project/issues/82154>`_`)
+- Fixes (`#82995 <https://github.com/llvm/llvm-project/issues/82995>`_)
 
 Bug Fixes to AST Handling
 ^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/test/Preprocessor/has_attribute.cpp b/clang/test/Preprocessor/has_attribute.cpp
index 33546dbb175f61..00ec57615c84b8 100644
--- a/clang/test/Preprocessor/has_attribute.cpp
+++ b/clang/test/Preprocessor/has_attribute.cpp
@@ -1,4 +1,6 @@
+// RUN: %clang_cc1 -triple i386-unknown-unknown -fms-compatibility -std=c++03 -E -P %s -o - | FileCheck %s --check-prefixes=CHECK,ITANIUM --implicit-check-not=:
 // RUN: %clang_cc1 -triple i386-unknown-unknown -fms-compatibility -std=c++11 -E -P %s -o - | FileCheck %s --check-prefixes=CHECK,ITANIUM --implicit-check-not=:
+// RUN: %clang_cc1 -triple i386-windows -fms-compatibility -std=c++03 -E -P %s -o - | FileCheck %s --check-prefixes=CHECK,WINDOWS --implicit-check-not=:
 // RUN: %clang_cc1 -triple i386-windows -fms-compatibility -std=c++11 -E -P %s -o - | FileCheck %s --check-prefixes=CHECK,WINDOWS --implicit-check-not=:
 
 #define CXX11(x) x: __has_cpp_attribute(x)
@@ -65,7 +67,7 @@ CXX11(unlikely)
 // CHECK: likely: 201803L
 // CHECK: maybe_unused: 201603L
 // ITANIUM: no_unique_address: 201803L
-// WINDOWS: no_unique_address: 0 
+// WINDOWS: no_unique_address: 0
 // ITANIUM: msvc::no_unique_address: 0
 // WINDOWS: msvc::no_unique_address: 201803L
 // CHECK: nodiscard: 201907L
diff --git a/clang/test/SemaCXX/constant-expression-cxx11.cpp b/clang/test/SemaCXX/constant-expression-cxx11.cpp
index 9e2ae07cbe4c9c..e71659440aa11d 100644
--- a/clang/test/SemaCXX/constant-expression-cxx11.cpp
+++ b/clang/test/SemaCXX/constant-expression-cxx11.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++23 -isystem %S/Inputs -fsyntax-only -verify=expected,cxx20_23,cxx23    -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fcxx-exceptions -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
+// RUN: %clang_cc1 -std=c++23 -isystem %S/Inputs -fexperimental-new-constant-interpreter -fsyntax-only -verify=expected,cxx20_23,cxx23    -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fcxx-exceptions -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
 // RUN: %clang_cc1 -std=c++20 -isystem %S/Inputs -fsyntax-only -verify=expected,cxx11_20,cxx20_23 -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fcxx-exceptions -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
 // RUN: %clang_cc1 -std=c++11 -isystem %S/Inputs -fsyntax-only -verify=expected,cxx11_20,cxx11    -triple x86_64-linux -Wno-string-plus-int -Wno-pointer-arith -Wno-zero-length-array -Wno-c99-designator -fcxx-exceptions -pedantic %s -Wno-comment -Wno-tautological-pointer-compare -Wno-bool-conversion
 
diff --git a/clang/test/SemaCXX/cxx03-cxx11-attr.cpp b/clang/test/SemaCXX/cxx03-cxx11-attr.cpp
new file mode 100644
index 00000000000000..5a273c8fe2534a
--- /dev/null
+++ b/clang/test/SemaCXX/cxx03-cxx11-attr.cpp
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -std=c++03 -fsyntax-only %s
+
+// Ensure that __has_cpp_attribute and argument parsing work in C++03
+
+#if !__has_cpp_attribute(nodiscard)
+#  error
+#endif
+
+[[gnu::assume_aligned(4)]] void* g() { return __nullptr; }
diff --git a/clang/utils/TableGen/ClangAttrEmitter.cpp b/clang/utils/TableGen/ClangAttrEmitter.cpp
index 935b9846990ee5..eb5c34d15693d7 100644
--- a/clang/utils/TableGen/ClangAttrEmitter.cpp
+++ b/clang/utils/TableGen/ClangAttrEmitter.cpp
@@ -3576,10 +3576,6 @@ static void GenerateHasAttrSpellingStringSwitch(
       const Record *R = Attr->getValueAsDef("Target");
       std::vector<StringRef> Arches = R->getValueAsListOfStrings("Arches");
       GenerateTargetSpecificAttrChecks(R, Arches, Test, nullptr);
-
-      // If this is the C++11 variety, also add in the LangOpts test.
-      if (Variety == "CXX11")
-        Test += " && LangOpts.CPlusPlus11";
     } else if (!Attr->getValueAsListOfDefs("TargetSpecificSpellings").empty()) {
       // Add target checks if this spelling is target-specific.
       const std::vector<Record *> TargetSpellings =
@@ -3597,13 +3593,7 @@ static void GenerateHasAttrSpellingStringSwitch(
           }
         }
       }
-
-      if (Variety == "CXX11")
-        Test += " && LangOpts.CPlusPlus11";
-    } else if (Variety == "CXX11")
-      // C++11 mode should be checked against LangOpts, which is presumed to be
-      // present in the caller.
-      Test = "LangOpts.CPlusPlus11";
+    }
 
     std::string TestStr = !Test.empty()
                               ? Test + " ? " + llvm::itostr(Version) + " : 0"