[clang][Interp] Don't require StmtExpr result to be an expression

It can be a statement containing an expression.

Author: tbaederr

clang/lib/AST/Interp/Compiler.cpp

@@ -3073,13 +3073,13 @@ bool Compiler<Emitter>::VisitStmtExpr(const StmtExpr *E) {
     }
 
     assert(S == Result);
-    // This better produces a value (i.e. is an expression).
     if (const Expr *ResultExpr = dyn_cast<Expr>(S)) {
       if (DiscardResult)
         return this->discard(ResultExpr);
       return this->delegate(ResultExpr);
     }
-    return false;
+
+    return this->visitStmt(S);
   }
 
   return BS.destroyLocals();

clang/test/CodeGenCXX/cxx1z-constexpr-if.cpp

@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -std=c++1z %s -emit-llvm -fblocks -triple x86_64-apple-darwin10 -o - | FileCheck %s --implicit-check-not=should_not_be_used
+// RUN: %clang_cc1 -std=c++1z %s -emit-llvm -fblocks -triple x86_64-apple-darwin10 -o - -fexperimental-new-constant-interpreter | FileCheck %s --implicit-check-not=should_not_be_used
 
 void should_be_used_1();
 void should_be_used_2();