modern-concat-nested-namespaces does not warn on header files

[llvmbot]

Bugzilla Link	41670
Version	unspecified
OS	Linux
Reporter	LLVM Bugzilla Contributor

Extended Description

For header files that pass the -header-filter, the modernize-concat-nested-namespaces check does not generate the expected warning and fix for un-concatenated namespaces.

E.g.,
====a.h===
#pragma once
namespace foo {
namespace bar {
namespace baz {
struct S {};
}
}
}

====a.cpp====
#include "a.h"

namespace foo {
namespace bar {
namespace baz {
void foo(const S&) {}
}
}
}

int main () {
return 0;
}

Running the following command only generates fixes for a.cpp, not the instance in a.h:
clang-tidy -checks="modernize-concat-nested-namespaces" -p path/to/compilation_database.json -header-filter="a.h" -fix-errors a.cpp

If instead, I pass a.h as the last argument, clang-tidy does generate fixes for the header.

I suspect this is due to the early return here:
https://github.com/llvm-mirror/clang-tools-extra/blob/e5a800d6f7b093471c7bb509dfcc3713ef01caf8/clang-tidy/modernize/ConcatNestedNamespacesCheck.cpp#L88

Perhaps we should only return if the location is not in the main file and if it's not a header.

[llvmbot]

https://reviews.llvm.org/D61989

[carlosgalvezp]

Fixed on latest trunk