Reinstate r173952, this time limiting it to exactly the form

  #define X X

for which there is no point warning, ever.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173991 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 14 insertions, 2 deletions

diff --git a/lib/Lex/PPMacroExpansion.cpp b/lib/Lex/PPMacroExpansion.cpp
index 6379144885..bda31ed294 100644
--- a/lib/Lex/PPMacroExpansion.cpp
+++ b/lib/Lex/PPMacroExpansion.cpp
@@ -459,7 +459,10 @@ bool Preprocessor::HandleMacroExpandedIdentifier(Token &Identifier,
       if (MacroInfo *NewMI = getMacroInfo(NewII))
         if (!NewMI->isEnabled() || NewMI == MI) {
           Identifier.setFlag(Token::DisableExpand);
-          Diag(Identifier, diag::pp_disabled_macro_expansion);
+          // Don't warn for "#define X X" like "#define bool bool" from
+          // stdbool.h.
+          if (NewMI != MI || MI->isFunctionLike())
+            Diag(Identifier, diag::pp_disabled_macro_expansion);
         }
     }
 
diff --git a/test/Headers/stdbool.cpp b/test/Headers/stdbool.cpp
index a252cca1a6..7c927db441 100644
--- a/test/Headers/stdbool.cpp
+++ b/test/Headers/stdbool.cpp
@@ -1,5 +1,6 @@
 // RUN: %clang_cc1 -E -dM %s | FileCheck --check-prefix=CHECK-GNU-COMPAT %s
 // RUN: %clang_cc1 -std=c++98 -E -dM %s | FileCheck --check-prefix=CHECK-CONFORMING %s
+// RUN: %clang_cc1 -fsyntax-only -std=gnu++98 -verify -Weverything %s
 #include <stdbool.h>
 #define zzz
 
@@ -12,3 +13,7 @@
 // CHECK-CONFORMING: #define __CHAR_BIT__
 // CHECK-CONFORMING-NOT: #define false false
 // CHECK-CONFORMING: #define zzz
+
+zzz
+// expected-no-diagnostics
+extern bool x;
diff --git a/test/Preprocessor/warn-disabled-macro-expansion.c b/test/Preprocessor/warn-disabled-macro-expansion.c
index b01b63f6b3..21a3b7e4f1 100644
--- a/test/Preprocessor/warn-disabled-macro-expansion.c
+++ b/test/Preprocessor/warn-disabled-macro-expansion.c
@@ -14,9 +14,10 @@
 
 #define c(x) x(0)
 
+#define y(x) y
 #define z(x) (z)(x)
 
-p // expected-warning {{recursive macro}}
+p // no warning
 
 a // expected-warning {{recursive macro}}
 
@@ -28,4 +29,7 @@ h(0) // expected-warning {{recursive macro}}
 
 c(c) // expected-warning {{recursive macro}}
 
+y(5) // expected-warning {{recursive macro}}
+
 z(z) // ok
+