`__GNUC__` 4, `__GNUC_MINOR__` 2 and `__GNUC_PATCHLEVEL__` 1 too old and not consistent than the macro `__VERSION__` Clang 22.1.4

[forchid]

In the GCC toolchain from MinGW-Builds project, these macros look correct and consistent, but these aren't in the llvm-mingw.

the test

cc\version>g++ -o gnu-version gccv.cc

cc\version>.\gnu-version
GNU Compiler Collection version: 15.2.0
Full version string: 15.2.0

cc\version>mingw-llvmenv
cc\version>g++ -o llvm-version gccv.cc

cc\version>.\llvm-version
GNU Compiler Collection version: 4.2.1
Full version string: Clang 22.1.4 (https://github.com/llvm/llvm-project.git 35990504507d79e0b9deb809c8ee5e1b34ceef20)

the source

#include <iostream>

int main() {
    std::cout << "GNU Compiler Collection version: ";
    std::cout << __GNUC__ << "." << __GNUC_MINOR__ << "." << __GNUC_PATCHLEVEL__ << std::endl;
    std::cout << "Full version string: " << __VERSION__ << std::endl;
    return 0;
}

[mstorsjo]

This issue is in no way specific to llvm-mingw, but goes for any build of Clang. For issues not specific to llvm-mingw, I suggest filing them at https://github.com/llvm/llvm-project/issues instead.

__GNUC__ and __GNUC_MINOR__ are not intended to convey what version of Clang it is - it is intended to indicate what version of GCC that it is compatible with. There's lots of code out there checking these defines, and if high enough, it assumes that all the features of GCC from that version are available. While Clang is compatible with GCC in general, there are features/extensions from more modern versions of GCC that aren't implemented in Clang. (There can of course also be features from even older GCC versions that aren't implemented, but which aren't used much in the wild, and might not be used with such checks for the GCC version.)

See https://discourse.llvm.org/t/whats-the-rationale-to-continue-declare-compatibility-with-gcc-4-2-1/52530, llvm/llvm-project#42162 and llvm/llvm-project#99804 for more discussion about what version Clang should declare through these macros. There's clearly people thinking it should be raised - but exactly to what value, and amount of broken third party software by that change to tolerate, is an open question.