1 files changed, 25 insertions, 0 deletions
diff --git a/clang/lib/Lex/Lexer.cpp b/clang/lib/Lex/Lexer.cpp
index 27b0feb4827..88e7b247806 100644
--- a/clang/lib/Lex/Lexer.cpp
+++ b/clang/lib/Lex/Lexer.cpp
@@ -1000,6 +1000,31 @@ StringRef Lexer::getImmediateMacroName(SourceLocation Loc,
   return ExpansionBuffer.substr(ExpansionInfo.second, MacroTokenLength);
 }
 
+StringRef Lexer::getImmediateMacroNameForDiagnostics(
+    SourceLocation Loc, const SourceManager &SM, const LangOptions &LangOpts) {
+  assert(Loc.isMacroID() && "Only reasonble to call this on macros");
+  // Walk past macro argument expanions.
+  while (SM.isMacroArgExpansion(Loc))
+    Loc = SM.getImmediateExpansionRange(Loc).first;
+
+  // If the macro's spelling has no FileID, then it's actually a token paste
+  // or stringization (or similar) and not a macro at all.
+  if (!SM.getFileEntryForID(SM.getFileID(SM.getSpellingLoc(Loc))))
+    return StringRef();
+
+  // Find the spelling location of the start of the non-argument expansion
+  // range. This is where the macro name was spelled in order to begin
+  // expanding this macro.
+  Loc = SM.getSpellingLoc(SM.getImmediateExpansionRange(Loc).first);
+
+  // Dig out the buffer where the macro name was spelled and the extents of the
+  // name so that we can render it into the expansion note.
+  std::pair<FileID, unsigned> ExpansionInfo = SM.getDecomposedLoc(Loc);
+  unsigned MacroTokenLength = Lexer::MeasureTokenLength(Loc, SM, LangOpts);
+  StringRef ExpansionBuffer = SM.getBufferData(ExpansionInfo.first);
+  return ExpansionBuffer.substr(ExpansionInfo.second, MacroTokenLength);
+}
+
 bool Lexer::isIdentifierBodyChar(char c, const LangOptions &LangOpts) {
   return isIdentifierBody(c, LangOpts.DollarIdents);
 }