[clang-cl][Windows] consteval compilation error occurs when compiling the open source third-party library fmt

[jiangxinhaha]

Clang version: 20.1.5

When compiling the open source third-party library fmt, support for c++20 was set, but consteval compilation errors still occurred. The Clang used is already the latest version。

1，The following is the compilation error code snippet：

2，The error message:

[frederick-vs-ja]

Could you post your formatter specialization for detail::bigint? It seems that the format function you posted lacks const.

[jiangxinhaha]

Could you post your formatter specialization for detail::bigint? It seems that the format function you posted lacks const.
From the error message, the problem is with this call statement:

I did some testing and found that the official 19.1.5 and 19.1.7 versions are OK, but there are problems with the 20+ versions.
It seems that there are problems with the new version. Please take a look at this question

[tbaederr]

What about your formatter specialization? What's on line 2930 of your core.h?

[jiangxinhaha]

What about your formatter specialization? What's on line 2930 of your core.h?

After reading the code, the 2930th line of code in core.h is as follows:

basic_format_string -> check_format_string -> parse_format_string -> on_format_specs;

This is an open source third-party library (https://github.com/fmtlib/fmt/tree/master).
I am not familiar with the detailed code in it.
However, the compilation was OK before version 19.1.7, and problems occurred in the new version after that.

[tbaederr]

This could be a duplicate of #113517, can you reproduce the problem on godbolt, e.g. https://godbolt.org/z/4zGfdqP6z with fmtlib trunk?

[jiangxinhaha]

This could be a duplicate of #113517, can you reproduce the problem on godbolt, e.g. https://godbolt.org/z/4zGfdqP6z with fmtlib trunk?

@tbaederr I've looked at the issue #113517. If it's a bug in fmtlib, why is it that versions of Windows Clang prior to 19.1.7 work fine while versions after that have problems? Moreover, fmtlib can be compiled without issues using Apple Clang and NDK Clang.

[tbaederr]

Because clang changed. Can you reproduce your issue in godbolt?

[jiangxinhaha]

Because clang changed. Can you reproduce your issue in godbolt?

I will try it, thanks!

[jiangxinhaha]

fmtlib trunk is ok.