Use of reserved identifiers

[melak47]

A quick scan shows at least __catchResult and ____C_A_T_C_H____T_E_S_T____ being used,
but since these identifiers contain double underscores, they are reserved for
the compiler/stdlib implementation: [lex.name] 2.10.3 ([global.names] 17.6.4.3.2 until C++17)

[horenmar]

Not really a bug, but more of a language lawyer request.

[AndrewPaxie]

LLVM commit b83b23275b745287bf9d3d72a93b593119f53f75 introduces
warning -Wreserved-identifier.
See: https://reviews.llvm.org/D93095
This is devastating to projects using Catch that compile with -Weverything on the Clang command line.
Example: trompeloeil.

[j-stephan]

This is devastating to projects using Catch that compile with -Weverything on the Clang command line.

Indeed. Once clang 14 13 becomes more widely used a lot of people will run into this.

[davidstone]

Trying to set up a new project using the add_subdirectory CMake integration. I immediately run into this error because my project builds with this warning. This is using the Catch2 v3 devel branch.

In file included from /home/david/tm/Catch2/src/catch2/../catch2/catch_test_macros.hpp:11:
In file included from /home/david/tm/Catch2/src/catch2/../catch2/internal/catch_test_macro_impl.hpp:11:
In file included from /home/david/tm/Catch2/src/catch2/../catch2/internal/catch_assertion_handler.hpp:11:
In file included from /home/david/tm/Catch2/src/catch2/../catch2/catch_assertion_info.hpp:13:
/home/david/tm/Catch2/src/catch2/../catch2/internal/catch_stringref.hpp:101:32: error: identifier '_sr' is reserved because it starts with '_' at global scope [-Werror,-Wreserved-identifier]
    constexpr auto operator "" _sr( char const* rawChars, std::size_t size ) noexcept -> StringRef {
                   ~~~~~~~~~~~~^~~
                   operator""_sr
/home/david/tm/Catch2/src/catch2/../catch2/internal/catch_stringref.hpp:106:28: error: identifier '_catch_sr' is reserved because it starts with '_' at global scope [-Werror,-Wreserved-identifier]
constexpr auto operator "" _catch_sr( char const* rawChars, std::size_t size ) noexcept -> Catch::StringRef {
               ~~~~~~~~~~~~^~~~~~~~~
               operator""_catch_sr
2 errors generated.

[melak47]

Not really a bug, but more of a language lawyer request.

I'd be happy to open a PR, if it would be welcome?

[horenmar]

@melak47 It is already done for v3, but I am willing to merge it for v2 (I don't like backporting v3->v2 and IIRC I got bunch of merge conflicts from it).

@davidstone That seems like bad implementation in Clang, because both are UDLs, which are not even allowed to start without a leading _, and _sr is inside a namespace:

Catch2/src/catch2/internal/catch_stringref.hpp

Lines 101 to 103 in 88c27ff

	constexpr auto operator "" _sr( char const* rawChars, std::size_t size ) noexcept -> StringRef {
	return StringRef( rawChars, size );
	}

[AndrewPaxie]

@horenmar Nice to hear v3 provides a fix. I was surprised by the quality of implementation problems in Clang. We will have to hussle to make any meaningful change in Clang-13, least there is another warning that is useless on release. 13.0.0-rc2 is scheduled for release 24 August 2021, -rc3 on 7 September 2021, and final on 21 September 2021, based on the schedule at http://llvm.org.

We can follow the progress of this bug report: https://bugs.llvm.org/show_bug.cgi?id=50644

[davidstone]

@horenmar: The issue is the space between the "" and the UDL name. This causes a warning because having that space there exposes you to macro expansion, see https://bugs.llvm.org/show_bug.cgi?id=50644. Defining your UDLs as operator ""_catch_sr and operator ""_sr make the warning go away.

[bernhardmgruber]

The issue is bigger than just UDLs: https://godbolt.org/z/nG9Mn7hKv. If you use e.g. TEMPLATE_LIST_TEST_CASE, then you get additional errors like:

error: identifier '____C_A_T_C_H____T_E_M_P_L_A_T_E____T_E_S_T____F_U_N_C____0' is reserved because it starts with '__' [-Werror,-Wreserved-identifier]
TEMPLATE_LIST_TEST_CASE("", "", Types) {

[horenmar]

v3 has been fixed for a while and @bernhardmgruber made PR for v2, so this is done.