clang-tidy prints warnings from certain macros from system headers

[llvmbot]

Bugzilla Link	45528
Version	unspecified
OS	All
Attachments	Full working example of the issue
Reporter	LLVM Bugzilla Contributor

Extended Description

According to documentation clang-tidy should not print warnings for headers included from system include directories unless --system-headers is specified. This seems to mostly work however I have discovered that warnings from certain macros in Catch2 header (https://github.com/catchorg/Catch2/blob/master/single_include/catch2/catch.hpp):

//main.cpp
#define CATCH_CONFIG_MAIN
#include <Catch2/catch.hpp>

TEST_CASE("") {
REQUIRE(true == true);
}

The command line either:

clang-tidy main.cpp -- -isystem ../include

Or using compilation database entry:

[
{
"directory": "/home/mv/clang-tidy-system/build",
"command": "/usr/bin/clang++-10 -isystem ../include -std=gnu++17 -o CMakeFiles/app.dir/main.cpp.o -c /home/mv/clang-tidy-system/main.cpp",
"file": "/home/mv/clang-tidy-system/main.cpp"
}
]

Specifically it comes from the macro REQUIRE:

~/clang-tidy-system/build$ clang-tidy-10 ../main.cpp
34285 warnings generated.
/home/mv/clang-tidy-system/main.cpp:5:5: warning: do not call c-style vararg functions [hicpp-vararg]
REQUIRE(true == true);
^
../include/Catch2/catch.hpp:17317:24: note: expanded from macro 'REQUIRE'
#define REQUIRE( ... ) INTERNAL_CATCH_TEST( "REQUIRE", Catch::ResultDisposition::Normal, VA_ARGS )
^
../include/Catch2/catch.hpp:2677:9: note: expanded from macro 'INTERNAL_CATCH_TEST'
CATCH_INTERNAL_IGNORE_BUT_WARN(VA_ARGS);
^
../include/Catch2/catch.hpp:154:55: note: expanded from macro 'CATCH_INTERNAL_IGNORE_BUT_WARN'

define CATCH_INTERNAL_IGNORE_BUT_WARN(...) (void)__builtin_constant_p(VA_ARGS) /* NOLINT(cppcoreguidelines-pro-type-vararg) */

                                                  ^

Suppressed 34291 warnings (34284 in non-user code, 7 NOLINT).
Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.

Attached is the complete example I am using to debug this including the Catch2 header.

[PiotrZSL]

Fixed by 670de10