[clang] Fix a crash when CTAD fails

[hokein]

Thanks!

clang/test/Sema/check-arg-alignment.cpp

1

I'd move this test case to the existing file llvm-project/clang/test/SemaCXX/cxx1z-class-template-argument-deduction.cpp

[kadircet]

• Move test into existing file.

clang/lib/Sema/SemaChecking.cpp

void Sema::CheckArgAlignment(SourceLocation Loc, NamedDecl *FDecl,
   if (ParamTy->isPointerType())
     ArgTy = ArgTy->getPointeeType();
 
   // Remove reference or pointer
   ParamTy = ParamTy->getPointeeType();
 
   // Find expected alignment, and the actual alignment of the passed object.
   // getTypeAlignInChars requires complete types
-  if (ParamTy->isIncompleteType() || ArgTy->isIncompleteType())
+  if (ParamTy->isIncompleteType() || ArgTy->isIncompleteType() ||
+      ParamTy->isUndeducedType() || ArgTy->isUndeducedType())
     return;
 
   CharUnits ParamAlign = Context.getTypeAlignInChars(ParamTy);
   CharUnits ArgAlign = Context.getTypeAlignInChars(ArgTy);
 
   // If the argument is less aligned than the parameter, there is a
   // potential alignment issue.
   if (ArgAlign < ParamAlign)

clang/test/Sema/check-arg-alignment.cpp

+// Ensure we don't crash when CTAD fails.
+// RUN: %clang_cc1 -std=c++17 -verify %s
+template <typename T1, typename T2>
+struct Foo {   // expected-note{{candidate function template not viable}}
+  Foo(T1, T2); // expected-note{{candidate function template not viable}}
+};
+
+template <typename... Args>
+void insert(Args &&...args);
+
+void foo() {
+  insert(Foo(2, 2, 2)); // expected-error{{no viable constructor or deduction guide}}
+}