implement the microsoft/gnu "__COUNTER__" macro: rdar://4329310


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@68933 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Lex/PPMacroExpansion.cpp b/lib/Lex/PPMacroExpansion.cpp
index b23311a..797a5bf 100644
--- a/lib/Lex/PPMacroExpansion.cpp
+++ b/lib/Lex/PPMacroExpansion.cpp
@@ -55,6 +55,7 @@
   Ident__FILE__ = RegisterBuiltinMacro("__FILE__");
   Ident__DATE__ = RegisterBuiltinMacro("__DATE__");
   Ident__TIME__ = RegisterBuiltinMacro("__TIME__");
+  Ident__COUNTER__ = RegisterBuiltinMacro("__COUNTER__");
   Ident_Pragma  = RegisterBuiltinMacro("_Pragma");
   
   // GCC Extensions.
@@ -557,6 +558,13 @@
     TmpBuffer[Len] = '"';  // Replace the newline with a quote.
     Tok.setKind(tok::string_literal);
     CreateString(TmpBuffer, Len+1, Tok, Tok.getLocation());
+  } else if (II == Ident__COUNTER__) {
+    Diag(Tok, diag::ext_pp_counter);
+    
+    // __COUNTER__ expands to a simple numeric value.
+    sprintf(TmpBuffer, "%u", CounterValue++);
+    Tok.setKind(tok::numeric_constant);
+    CreateString(TmpBuffer, strlen(TmpBuffer), Tok, Tok.getLocation());
   } else {
     assert(0 && "Unknown identifier!");
   }
diff --git a/lib/Lex/Preprocessor.cpp b/lib/Lex/Preprocessor.cpp
index 097b454..2c9b0b9 100644
--- a/lib/Lex/Preprocessor.cpp
+++ b/lib/Lex/Preprocessor.cpp
@@ -53,7 +53,8 @@
     SourceMgr(SM), HeaderInfo(Headers), Identifiers(opts, IILookup),
     CurPPLexer(0), CurDirLookup(0), Callbacks(0) {
   ScratchBuf = new ScratchBuffer(SourceMgr);
-
+  CounterValue = 0; // __COUNTER__ starts at 0.
+      
   // Clear stats.
   NumDirectives = NumDefined = NumUndefined = NumPragma = 0;
   NumIf = NumElse = NumEndif = 0;