[clang] d930ed1 - Disallow use of __has_c_attribute in C++ mode.

[Aaron Ballman via cfe-commits]

Author: Aaron Ballman
Date: 2019-11-25T17:35:12-05:00
New Revision: d930ed1acc0ea49d4b3aae7e95b4c6d9cd310578

URL: https://github.com/llvm/llvm-project/commit/d930ed1acc0ea49d4b3aae7e95b4c6d9cd310578
DIFF: https://github.com/llvm/llvm-project/commit/d930ed1acc0ea49d4b3aae7e95b4c6d9cd310578.diff

LOG: Disallow use of __has_c_attribute in C++ mode.

__has_cpp_attribute is not available in C mode, and __has_c_attribute
should not be available in C++ mode. This also adds a test to
demonstrate that we properly handle scoped attribute tokens even in C
mode.

Added: 
    clang/test/Preprocessor/has_c_attribute.cpp

Modified: 
    clang/lib/Lex/PPMacroExpansion.cpp
    clang/test/Preprocessor/has_c_attribute.c

Removed: 
    


################################################################################
diff  --git a/clang/lib/Lex/PPMacroExpansion.cpp b/clang/lib/Lex/PPMacroExpansion.cpp
index e6e00b1c1700..a69c4dbb3a2a 100644
--- a/clang/lib/Lex/PPMacroExpansion.cpp
+++ b/clang/lib/Lex/PPMacroExpansion.cpp
@@ -370,7 +370,11 @@ void Preprocessor::RegisterBuiltinMacros() {
   Ident__has_extension    = RegisterBuiltinMacro(*this, "__has_extension");
   Ident__has_builtin      = RegisterBuiltinMacro(*this, "__has_builtin");
   Ident__has_attribute    = RegisterBuiltinMacro(*this, "__has_attribute");
-  Ident__has_c_attribute  = RegisterBuiltinMacro(*this, "__has_c_attribute");
+  if (!LangOpts.CPlusPlus)
+    Ident__has_c_attribute = RegisterBuiltinMacro(*this, "__has_c_attribute");
+  else
+    Ident__has_c_attribute = nullptr;
+
   Ident__has_declspec = RegisterBuiltinMacro(*this, "__has_declspec_attribute");
   Ident__has_include      = RegisterBuiltinMacro(*this, "__has_include");
   Ident__has_include_next = RegisterBuiltinMacro(*this, "__has_include_next");

diff  --git a/clang/test/Preprocessor/has_c_attribute.c b/clang/test/Preprocessor/has_c_attribute.c
index 843a67a2646c..f8b0b364faa5 100644
--- a/clang/test/Preprocessor/has_c_attribute.c
+++ b/clang/test/Preprocessor/has_c_attribute.c
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fdouble-square-bracket-attributes -std=c11 -E %s -o - | FileCheck %s
+// RUN: %clang_cc1 -std=c2x -E %s -o - | FileCheck %s
 
 // CHECK: has_fallthrough
 #if __has_c_attribute(fallthrough)
@@ -14,3 +15,8 @@
 #if __has_c_attribute(__nodiscard__)
   int has_nodiscard_underscore();
 #endif
+
+// CHECK: has_clang_annotate
+#if __has_c_attribute(clang::annotate)
+  int has_clang_annotate();
+#endif

diff  --git a/clang/test/Preprocessor/has_c_attribute.cpp b/clang/test/Preprocessor/has_c_attribute.cpp
new file mode 100644
index 000000000000..0bde73067178
--- /dev/null
+++ b/clang/test/Preprocessor/has_c_attribute.cpp
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -std=c++11 %s -verify
+
+#if __has_c_attribute(fallthrough) // expected-error {{function-like macro '__has_c_attribute' is not defined}}
+#endif
+
+#if __has_c_attribute(gnu::transparent_union) // expected-error {{function-like macro '__has_c_attribute' is not defined}}
+#endif
+