Sema: Don't diagnose string + int if the int is value dependent

Don't send a value dependent expression into the expression evaluator,
HandleSizeof would crash.  Making HandleSizeof handle dependent types
would noisily warn about the operation even if everything turns out OK
after instantiation.

This fixes PR21848.

llvm-svn: 224240

2 files changed, 6 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index c04b99d464c..876e5b71e01 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -7282,7 +7282,7 @@ static void diagnoseStringPlusInt(Sema &Self, SourceLocation OpLoc,
 
   bool IsStringPlusInt = StrExpr &&
       IndexExpr->getType()->isIntegralOrUnscopedEnumerationType();
-  if (!IsStringPlusInt)
+  if (!IsStringPlusInt || IndexExpr->isValueDependent())
     return;
 
   llvm::APSInt index;
diff --git a/clang/test/SemaCXX/string-plus-int.cpp b/clang/test/SemaCXX/string-plus-int.cpp
index 5752f8f9663..fe9c7194969 100644
--- a/clang/test/SemaCXX/string-plus-int.cpp
+++ b/clang/test/SemaCXX/string-plus-int.cpp
@@ -64,3 +64,8 @@ void f(int index) {
   consume(A B + sizeof(A) - 1);
 }
 
+template <typename T>
+void PR21848() {
+  (void)(sizeof(T) + ""); // expected-warning {{to a string does not append to the string}} expected-note {{use array indexing to silence this warning}}
+}
+template void PR21848<int>(); // expected-note {{in instantiation of function template specialization 'PR21848<int>' requested here}}