Don't warn for empty 'if' body if there is a macro that expands to nothing, e.g:

  if (condition)
    CALL(0); // empty macro but don't warn for empty body.

Fixes rdar://8436021.

llvm-svn: 119838

1 files changed, 13 insertions, 3 deletions

diff --git a/clang/lib/Parse/ParseStmt.cpp b/clang/lib/Parse/ParseStmt.cpp
index 12444e87bbd..e3c15680c23 100644
--- a/clang/lib/Parse/ParseStmt.cpp
+++ b/clang/lib/Parse/ParseStmt.cpp
@@ -538,7 +538,8 @@ StmtResult Parser::ParseCompoundStatementBody(bool isStmtExpr) {
 bool Parser::ParseParenExprOrCondition(ExprResult &ExprResult,
                                        Decl *&DeclResult,
                                        SourceLocation Loc,
-                                       bool ConvertToBoolean) {
+                                       bool ConvertToBoolean,
+                                       bool *MacroExpandedAfterRParen) {
   bool ParseError = false;
   
   SourceLocation LParenLoc = ConsumeParen();
@@ -567,7 +568,14 @@ bool Parser::ParseParenExprOrCondition(ExprResult &ExprResult,
   }
 
   // Otherwise the condition is valid or the rparen is present.
+
+  // Catch a macro expansion after ')'. This is used to know that there is a
+  // macro for 'if' body and not warn for empty body if the macro is empty.
+  PPMacroExpansionTrap MacroExpansionTrap(PP);
   MatchRHSPunctuation(tok::r_paren, LParenLoc);
+  if (MacroExpandedAfterRParen)
+    *MacroExpandedAfterRParen = MacroExpansionTrap.hasMacroExpansionOccured();
+
   return false;
 }
 
@@ -610,7 +618,9 @@ StmtResult Parser::ParseIfStatement(AttributeList *Attr) {
   // Parse the condition.
   ExprResult CondExp;
   Decl *CondVar = 0;
-  if (ParseParenExprOrCondition(CondExp, CondVar, IfLoc, true))
+  bool MacroExpandedInThenStmt;
+  if (ParseParenExprOrCondition(CondExp, CondVar, IfLoc, true,
+                                &MacroExpandedInThenStmt))
     return StmtError();
 
   FullExprArg FullCondExp(Actions.MakeFullExpr(CondExp.get()));
@@ -694,7 +704,7 @@ StmtResult Parser::ParseIfStatement(AttributeList *Attr) {
     ElseStmt = Actions.ActOnNullStmt(ElseStmtLoc);
 
   return Actions.ActOnIfStmt(IfLoc, FullCondExp, CondVar, ThenStmt.get(),
-                             ElseLoc, ElseStmt.get());
+                             MacroExpandedInThenStmt, ElseLoc, ElseStmt.get());
 }
 
 /// ParseSwitchStatement