Sema: Don't leave switch stack inconsistent when recovering

We would exit Sema::ActOnFinishSwitchStmt early if we didn't have a
body.  This would leave an extra SwitchStmt on the SwitchStack.

This fixes PR21841.

llvm-svn: 224237

clang/include/clang/AST/Stmt.h

@@ -1015,7 +1015,7 @@ public:
 
   SourceLocation getLocStart() const LLVM_READONLY { return SwitchLoc; }
   SourceLocation getLocEnd() const LLVM_READONLY {
-    return SubExprs[BODY]->getLocEnd();
+    return SubExprs[BODY] ? SubExprs[BODY]->getLocEnd() : SubExprs[COND]->getLocEnd();
   }
 
   // Iterators

clang/lib/Sema/SemaStmt.cpp

@@ -730,9 +730,10 @@ Sema::ActOnFinishSwitchStmt(SourceLocation SwitchLoc, Stmt *Switch,
   assert(SS == getCurFunction()->SwitchStack.back() &&
          "switch stack missing push/pop!");
 
+  getCurFunction()->SwitchStack.pop_back();
+
   if (!BodyStmt) return StmtError();
   SS->setBody(BodyStmt, SwitchLoc);
-  getCurFunction()->SwitchStack.pop_back();
 
   Expr *CondExpr = SS->getCond();
   if (!CondExpr) return StmtError();

clang/test/Parser/switch-recovery.cpp

@@ -220,3 +220,12 @@ bool bar0() {
   case bar5: ;  // expected-error{{use of undeclared identifier 'bar5'}}
 }
 }
+
+namespace pr21841 {
+void fn1() {
+  switch (0)
+    switch (0  // expected-note{{to match this '('}}
+    {  // expected-error{{expected ')'}}
+    }
+} // expected-error{{expected statement}}
+}