[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 6a439dd61803e7da91a7791453ca7b9acb90b1b6 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Mon, 26 Feb 2024 22:39:05 +0100
Subject: [PATCH] [Clang] Fix __has_cpp_attribute and C++11 attributes with
 arguments in C++03

---
 clang/test/Preprocessor/has_attribute.cpp |  4 +++-
 clang/test/SemaCXX/attr-gnu.cpp           | 28 +++++++++++------------
 clang/test/SemaCXX/cxx03-cxx11-attr.cpp   |  9 ++++++++
 clang/utils/TableGen/ClangAttrEmitter.cpp | 12 +---------
 4 files changed, 27 insertions(+), 26 deletions(-)
 create mode 100644 clang/test/SemaCXX/cxx03-cxx11-attr.cpp

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/attr-gnu.cpp b/clang/test/SemaCXX/attr-gnu.cpp
index c257c2b029127b..e7063ce020e2b7 100644
--- a/clang/test/SemaCXX/attr-gnu.cpp
+++ b/clang/test/SemaCXX/attr-gnu.cpp
@@ -1,7 +1,7 @@
-// RUN: %clang_cc1 -std=gnu++17 -fsyntax-only -fms-compatibility -verify %s
-
-void f() {
-  // GNU-style attributes are prohibited in this position.
+// RUN: %clang_cc1 -std=gnu++17 -fsyntax-only -fms-compatibility -verify %s
+
+void f() {
+  // GNU-style attributes are prohibited in this position.
   auto P = new int * __attribute__((vector_size(8))); // expected-error {{an attribute list cannot appear here}} \
                                                       // expected-error {{invalid vector element type 'int *'}}
 
@@ -47,13 +47,13 @@ void tuTest1(Tu<int> u); // expected-note {{candidate function not viable: no kn
 void tuTest2(Tu3 u); // expected-note {{candidate function not viable: no known conversion from 'int' to 'Tu3' for 1st argument}}
 void tu() {
   int x = 2;
-  tuTest1(x); // expected-error {{no matching function for call to 'tuTest1'}}
-  tuTest2(x); // expected-error {{no matching function for call to 'tuTest2'}}
-}
-
-[[gnu::__const__]] int f2() { return 12; }
-[[__gnu__::__const__]] int f3() { return 12; }
-[[using __gnu__ : __const__]] int f4() { return 12; }
-
-static_assert(__has_cpp_attribute(gnu::__const__));
-static_assert(__has_cpp_attribute(__gnu__::__const__));
+  tuTest1(x); // expected-error {{no matching function for call to 'tuTest1'}}
+  tuTest2(x); // expected-error {{no matching function for call to 'tuTest2'}}
+}
+
+[[gnu::__const__]] int f2() { return 12; }
+[[__gnu__::__const__]] int f3() { return 12; }
+[[using __gnu__ : __const__]] int f4() { return 12; }
+
+static_assert(__has_cpp_attribute(gnu::__const__));
+static_assert(__has_cpp_attribute(__gnu__::__const__));
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"