1 files changed, 22 insertions, 4 deletions
diff --git a/lib/Parse/ParseStmt.cpp b/lib/Parse/ParseStmt.cpp
index 313793c3e8..2974e6a245 100644
--- a/lib/Parse/ParseStmt.cpp
+++ b/lib/Parse/ParseStmt.cpp
@@ -439,7 +439,7 @@ StmtResult Parser::ParseExprStatement() {
 
   // Otherwise, eat the semicolon.
   ExpectAndConsumeSemi(diag::err_expected_semi_after_expr);
-  return Actions.ActOnExprStmt(Expr);
+  return Actions.ActOnExprStmt(Expr, isExprValueDiscarded());
 }
 
 /// ParseSEHTryBlockCommon
@@ -958,6 +958,16 @@ bool Parser::ConsumeNullStmt(StmtVector &Stmts) {
   return true;
 }
 
+bool Parser::isExprValueDiscarded() {
+  if (Actions.isCurCompoundStmtAStmtExpr()) {
+    // Look to see if the next two tokens close the statement expression;
+    // if so, this expression statement is the last statement in a
+    // statment expression.
+    return Tok.isNot(tok::r_brace) || NextToken().isNot(tok::r_paren);
+  }
+  return true;
+}
+
 /// ParseCompoundStatementBody - Parse a sequence of statements and invoke the
 /// ActOnCompoundStmt action.  This expects the '{' to be the current token, and
 /// consume the '}' at the end of the block.  It does not manipulate the scope
@@ -1062,7 +1072,7 @@ StmtResult Parser::ParseCompoundStatementBody(bool isStmtExpr) {
         // Eat the semicolon at the end of stmt and convert the expr into a
         // statement.
         ExpectAndConsumeSemi(diag::err_expected_semi_after_expr);
-        R = Actions.ActOnExprStmt(Res);
+        R = Actions.ActOnExprStmt(Res, isExprValueDiscarded());
       }
     }
 
@@ -1698,8 +1708,16 @@ StmtResult Parser::ParseForStatement(SourceLocation *TrailingElseLoc) {
     if (!Value.isInvalid()) {
       if (ForEach)
         FirstPart = Actions.ActOnForEachLValueExpr(Value.get());
-      else
-        FirstPart = Actions.ActOnExprStmt(Value);
+      else {
+        // We already know this is not an init-statement within a for loop, so
+        // if we are parsing a C++11 range-based for loop, we should treat this
+        // expression statement as being a discarded value expression because
+        // we will err below. This way we do not warn on an unused expression
+        // that was an error in the first place, like with: for (expr : expr);
+        bool IsRangeBasedFor =
+            getLangOpts().CPlusPlus11 && !ForEach && Tok.is(tok::colon);
+        FirstPart = Actions.ActOnExprStmt(Value, !IsRangeBasedFor);
+      }
     }
 
     if (Tok.is(tok::semi)) {