[PATCH] D107125: [Diagnostic] Split 'qualifier on reference type has no effect' out into a new flag

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added a comment.

In D107125#2920989 <https://reviews.llvm.org/D107125#2920989>, @lunasorcery wrote:

> How does this look? I've got a 'control' test to demonstrate the diagnostic as a child of ignored-qualifiers, as well as a test to demonstrate this diagnostic can be disabled in isolation.

The test contents are great, but I had a suggestion for combining the test files.



================
Comment at: clang/test/SemaCXX/ignored-reference-qualifiers-disabled.cpp:1-20
+// RUN: %clang_cc1 %s -std=c++11 -Wignored-qualifiers -Wno-ignored-reference-qualifiers -verify
+
+const int scalar_c(); // expected-warning{{'const' type qualifier on return type has no effect}}
+volatile int scalar_v(); // expected-warning{{'volatile' type qualifier on return type has no effect}}
+const volatile int scalar_cv(); // expected-warning{{'const volatile' type qualifiers on return type have no effect}}
+
+// no warnings expected below here, as we've disabled ignored-reference-qualifiers.
----------------
Given that the test file contents are the same except for expected diagnostics, I would recommend combining them into a single test file with two `// RUN` lines. Something like this (untested, but hopefully it gives you the right idea):
```
// RUN: %clang_cc1 %s -std=c++11 -Wignored-qualifiers -Wno-ignored-reference-qualifiers -verify=both
// RUN: %clang_cc1 %s -std=c++11 -Wignored-qualifiers -verify=both,qual

const int scalar_c(); // both-warning{{'const' type qualifier on return type has no effect}}
volatile int scalar_v(); // both-warning{{'volatile' type qualifier on return type has no effect}}
const volatile int scalar_cv(); // both-warning{{'const volatile' type qualifiers on return type have no effect}}

typedef int& IntRef;

const IntRef ref_c(); // qual-warning{{'const' qualifier on reference type 'IntRef' (aka 'int &') has no effect}}
volatile IntRef ref_v(); // qual-warning{{'volatile' qualifier on reference type 'IntRef' (aka 'int &') has no effect}}
const volatile IntRef ref_cv(); // qual-warning{{'const' qualifier on reference type 'IntRef' (aka 'int &') has no effect}} \
                                qual-warning{{'volatile' qualifier on reference type 'IntRef' (aka 'int &') has no effect}}

template<typename T>
class container {
	using value_type = T;
	using reference  = value_type&;
	reference get();
	const reference get() const; // qual-warning{{'const' qualifier on reference type 'container::reference' (aka 'T &') has no effect}}
};
```


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