On Sat, 6 Dec 2025 at 09:14, Jason Merrill jason@redhat.com wrote:

On 12/6/25 11:52 AM, ci_notify@linaro.org wrote:

...

Dear contributor,

Our automatic CI has detected problems related to your patch(es). Please find some details below.

In arm-eabi v7-a softfp, after: | commit gcc-16-5581-g3ad2e2d707c3 | Author: Jason Merrill jason@redhat.com | Date: Tue Nov 11 15:58:01 2025 +0530 | | driver/c++: add --compile-std-module | | For simple testcases that want to use the std module, it would be useful to | have a reasonably short way to request building the binary module form | before the testcase. So with this patch users can write | ... 31 lines of the commit log omitted.

Produces 1 regression: | | regressions.sum: | Running g++:g++.dg/modules/modules.exp ... | FAIL: g++.dg/modules/compile-std1.C -std=c++26 (test for excess errors)

It seems that module std doesn't compile on arm-eabi, which is good to know.

There seem to be two general issues: first, that some of the <stdio.h> functions that <print> relies on aren't declared:

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/home/tcwg-buildslave/workspace/tcwg_gnu_1/abe/builds/x86_64-pc-linux-gnu/arm-eabi/gcc-gcc.git~master-sta\ ge2/arm-eabi/libstdc++-v3/include/print: In member function 'virtual void std::__format::_File_sink::_M_o\ verflow()': /home/tcwg-buildslave/workspace/tcwg_gnu_1/abe/builds/x86_64-pc-linux-gnu/arm-eabi/gcc-gcc.git~master-sta\ ge2/arm-eabi/libstdc++-v3/include/print:197:20: error: '::fwrite_unlocked' has not been declared; did you\ mean '_fwrite_unlocked_r'? /home/tcwg-buildslave/workspace/tcwg_gnu_1/abe/builds/x86_64-pc-linux-gnu/arm-eabi/gcc-gcc.git~master-sta\ ge2/arm-eabi/libstdc++-v3/include/print: In constructor 'std::__format::_File_sink::_File_sink(FILE*, boo\ l)': /home/tcwg-buildslave/workspace/tcwg_gnu_1/abe/builds/x86_64-pc-linux-gnu/arm-eabi/gcc-gcc.git~master-sta\ ge2/arm-eabi/libstdc++-v3/include/print:212:9: error: '::flockfile' has not been declared; did you mean '\ _flockfile'? /home/tcwg-buildslave/workspace/tcwg_gnu_1/abe/builds/x86_64-pc-linux-gnu/arm-eabi/gcc-gcc.git~master-sta\ ge2/arm-eabi/libstdc++-v3/include/print: In destructor 'std::__format::_File_sink::~_File_sink()': /home/tcwg-buildslave/workspace/tcwg_gnu_1/abe/builds/x86_64-pc-linux-gnu/arm-eabi/gcc-gcc.git~master-sta\ ge2/arm-eabi/libstdc++-v3/include/print:218:11: error: '::putc_unlocked' has not been declared; did you m\ ean '_putc_unlocked_r'? /home/tcwg-buildslave/workspace/tcwg_gnu_1/abe/builds/x86_64-pc-linux-gnu/arm-eabi/gcc-gcc.git~master-sta\ ge2/arm-eabi/libstdc++-v3/include/print:219:9: error: '::funlockfile' has not been declared; did you mean\ '_funlockfile'?

It seems that newlib doesn't declare these functions under -std=c++26, only -std=gnu++26. I don't know what the right approach to this is.

and then a bunch of "not declared" exports, such as

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/home/tcwg-buildslave/workspace/tcwg_gnu_1/abe/builds/x86_64-pc-linux-gnu/arm-eabi/gcc-gcc.git~master-sta\ ge2/arm-eabi/libstdc++-v3/include/bits/std.cc:1002:14: error: 'condition_variable' has not been declared \ in 'std'

This looks like just needing to add more #if to std.cc, as below. OK for trunk?

OK

I keep going back and forth on whether we should provide dumb no-op versions of std::mutex etc. for non-ghtreads targets, so that the types exist they just don't do anything. We provide std::thread for non-gthreads, but it only has a default constructor, so you can't actually create new threads of execution with it.

And for this one we could just define the thread-safe pool as an alias of the unsynchronized pool for non-gthreads:

+#if _GLIBCXX_HAS_GTHREADS using std::pmr::synchronized_pool_resource; +#endif using std::pmr::unsynchronized_pool_resource;

Incidentally, is it expected that arm-eabi doesn't support gthread?

Jason