[Sema] Fix using old initializer during switch statement transformation.

It fixes a crash in CodeGen when we are trying to generate code for
initializer expression created before template instantiation, like

    CallExpr '<dependent type>'
    |-UnresolvedLookupExpr '<overloaded function type>' lvalue (ADL) = 'parse'
    `-DeclRefExpr 'Buffer<N>' lvalue ParmVar 'buffer' 'Buffer<N>'

rdar://problem/33888545

Reviewers: rsmith, ahatanak

Reviewed By: ahatanak

Subscribers: aemerson, kristof.beyls, cfe-commits

Differential Revision: https://reviews.llvm.org/D38009

llvm-svn: 313896

2 files changed, 33 insertions, 2 deletions

diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
index ee67e15b9ae..6fb9eca9a9c 100644
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -6601,8 +6601,7 @@ TreeTransform<Derived>::TransformSwitchStmt(SwitchStmt *S) {
 
   // Rebuild the switch statement.
   StmtResult Switch
-    = getDerived().RebuildSwitchStmtStart(S->getSwitchLoc(),
-                                          S->getInit(), Cond);
+    = getDerived().RebuildSwitchStmtStart(S->getSwitchLoc(), Init.get(), Cond);
   if (Switch.isInvalid())
     return StmtError();
 
diff --git a/clang/test/SemaCXX/cxx1z-init-statement-template.cpp b/clang/test/SemaCXX/cxx1z-init-statement-template.cpp
new file mode 100644
index 00000000000..cedd2c720d9
--- /dev/null
+++ b/clang/test/SemaCXX/cxx1z-init-statement-template.cpp
@@ -0,0 +1,32 @@
+// RUN: %clang_cc1 -std=c++1z -verify -emit-llvm-only %s
+// expected-no-diagnostics
+
+// rdar://problem/33888545
+template <unsigned int BUFFER_SIZE> class Buffer {};
+
+class A {
+public:
+  int status;
+};
+
+template <unsigned int N> A parse(Buffer<N> buffer);
+
+template<unsigned int N>
+void init_in_if(Buffer<N> buffer) {
+  if (A a = parse(buffer); a.status > 0) {
+  }
+}
+
+template<unsigned int N>
+void init_in_switch(Buffer<N> buffer) {
+  switch (A a = parse(buffer); a.status) {
+    default:
+      break;
+  }
+}
+
+void test() {
+  Buffer<10> buffer;
+  init_in_if(buffer);
+  init_in_switch(buffer);
+}