PR21706: -Wunsequenced was missing warnings when leaving a sequenced region that contained side effects.

llvm-svn: 223184

1 files changed, 6 insertions, 5 deletions

diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index 91ba91e4f53..8e5592564f5 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -7014,11 +7014,12 @@ class SequenceChecker : public EvaluatedExprVisitor<SequenceChecker> {
       Self.ModAsSideEffect = &ModAsSideEffect;
     }
     ~SequencedSubexpression() {
-      for (unsigned I = 0, E = ModAsSideEffect.size(); I != E; ++I) {
-        UsageInfo &U = Self.UsageMap[ModAsSideEffect[I].first];
-        U.Uses[UK_ModAsSideEffect] = ModAsSideEffect[I].second;
-        Self.addUsage(U, ModAsSideEffect[I].first,
-                      ModAsSideEffect[I].second.Use, UK_ModAsValue);
+      for (auto MI = ModAsSideEffect.rbegin(), ME = ModAsSideEffect.rend();
+           MI != ME; ++MI) {
+        UsageInfo &U = Self.UsageMap[MI->first];
+        auto &SideEffectUsage = U.Uses[UK_ModAsSideEffect];
+        Self.addUsage(U, MI->first, SideEffectUsage.Use, UK_ModAsValue);
+        SideEffectUsage = MI->second;
       }
       Self.ModAsSideEffect = OldModAsSideEffect;
     }