Fix isInSystemMacro to handle pasted macros

Token pasted by the preprocessor (through ##) have a Spelling pointing to scratch buffer.
As a result they are not recognized at system macro, even though the pasting happened in
a system macro. Fix that by looking into the parent macro if the original lookup finds a
scratch buffer.

Differential Revision: https://reviews.llvm.org/D55782

This effectively fixes https://bugs.llvm.org/show_bug.cgi?id=35268,

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@352838 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 17 insertions, 1 deletions

diff --git a/include/clang/Basic/SourceManager.h b/include/clang/Basic/SourceManager.h
index ba829a8773..b45357e645 100644
--- a/include/clang/Basic/SourceManager.h
+++ b/include/clang/Basic/SourceManager.h
@@ -1440,6 +1440,12 @@ public:
     return Filename.equals("<command line>");
   }
 
+  /// Returns whether \p Loc is located in a <scratch space> file.
+  bool isWrittenInScratchSpace(SourceLocation Loc) const {
+    StringRef Filename(getPresumedLoc(Loc).getFilename());
+    return Filename.equals("<scratch space>");
+  }
+
   /// Returns if a SourceLocation is in a system header.
   bool isInSystemHeader(SourceLocation Loc) const {
     return isSystem(getFileCharacteristic(Loc));
@@ -1452,7 +1458,17 @@ public:
 
   /// Returns whether \p Loc is expanded from a macro in a system header.
   bool isInSystemMacro(SourceLocation loc) const {
-    return loc.isMacroID() && isInSystemHeader(getSpellingLoc(loc));
+    if(!loc.isMacroID())
+      return false;
+
+    // This happens when the macro is the result of a paste, in that case
+    // its spelling is the scratch memory, so we take the parent context.
+    if (isWrittenInScratchSpace(getSpellingLoc(loc))) {
+      return isInSystemHeader(getSpellingLoc(getImmediateMacroCallerLoc(loc)));
+    }
+    else {
+      return isInSystemHeader(getSpellingLoc(loc));
+    }
   }
 
   /// The size of the SLocEntry that \p FID represents.