Crash in homebrew fmt 11.1.0 from homebrew ccache 4.10.2

[ADKaster]

This appears to be an ABI break(?) or at least difference between fmt 11.0.2 and 11.1.0.

Feel free to close this if it's entirely homebrew's fault though :)

With older homebrew's build of 11.0.2, this issue does not reproduce.

However, on current latest versions, I see the following behavior:

ccache --version: 👍
ccahe --help : 💥

Here's the brew issue I opened: https://github.com/orgs/Homebrew/discussions/5830

And the backtrace:

$ lldb ccache
(lldb) target create "ccache"
Current executable set to '/opt/homebrew/bin/ccache' (arm64).
(lldb) run --help
Process 85982 launched: '/opt/homebrew/bin/ccache' (arm64)
Process 85982 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x8)
    frame #0: 0x000000010000e350 ccache`fmt::v11::basic_appender<char> fmt::v11::detail::write_padded<char, (fmt::v11::align::type)1, fmt::v11::basic_appender<char>, fmt::v11::basic_appender<char> fmt::v11::detail::write<char, fmt::v11::basic_appender<char>>(fmt::v11::basic_appender<char>, fmt::v11::basic_string_view<char>, fmt::v11::format_specs const&)::'lambda'(fmt::v11::basic_appender<char>)>(fmt::v11::basic_appender<char>, fmt::v11::format_specs const&, unsigned long, unsigned long, fmt::v11::basic_appender<char> fmt::v11::detail::write<char, fmt::v11::basic_appender<char>>(fmt::v11::basic_appender<char>, fmt::v11::basic_string_view<char>, fmt::v11::format_specs const&)::'lambda'(fmt::v11::basic_appender<char>)&&) + 64
ccache`fmt::v11::detail::write_padded<char, (fmt::v11::align::type)1, fmt::v11::basic_appender<char>, fmt::v11::basic_appender<char> fmt::v11::detail::write<char, fmt::v11::basic_appender<char>>(fmt::v11::basic_appender<char>, fmt::v11::basic_string_view<char>, fmt::v11::format_specs const&)::'lambda'(fmt::v11::basic_appender<char>)>:
->  0x10000e350 <+64>: ldp    x8, x9, [x0, #0x8]
    0x10000e354 <+68>: add    x8, x8, x2
    0x10000e358 <+72>: add    x21, x1, #0xb
    0x10000e35c <+76>: ldrb   w10, [x1, #0xf]
Target 0: (ccache) stopped.
(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x8)
  * frame #0: 0x000000010000e350 ccache`fmt::v11::basic_appender<char> fmt::v11::detail::write_padded<char, (fmt::v11::align::type)1, fmt::v11::basic_appender<char>, fmt::v11::basic_appender<char> fmt::v11::detail::write<char, fmt::v11::basic_appender<char>>(fmt::v11::basic_appender<char>, fmt::v11::basic_string_view<char>, fmt::v11::format_specs const&)::'lambda'(fmt::v11::basic_appender<char>)>(fmt::v11::basic_appender<char>, fmt::v11::format_specs const&, unsigned long, unsigned long, fmt::v11::basic_appender<char> fmt::v11::detail::write<char, fmt::v11::basic_appender<char>>(fmt::v11::basic_appender<char>, fmt::v11::basic_string_view<char>, fmt::v11::format_specs const&)::'lambda'(fmt::v11::basic_appender<char>)&&) + 64
    frame #1: 0x000000010000e274 ccache`fmt::v11::basic_appender<char> fmt::v11::detail::write<char, fmt::v11::basic_appender<char>>(fmt::v11::basic_appender<char>, fmt::v11::basic_string_view<char>, fmt::v11::format_specs const&) + 232
    frame #2: 0x000000010000d7a8 ccache`auto fmt::v11::formatter<std::__1::__fs::filesystem::path, char, void>::format<fmt::v11::context>(std::__1::__fs::filesystem::path const&, fmt::v11::context&) const + 108
    frame #3: 0x000000010000d6fc ccache`void fmt::v11::detail::value<fmt::v11::context>::format_custom_arg<std::__1::__fs::filesystem::path, fmt::v11::formatter<std::__1::__fs::filesystem::path, char, void>>(void*, fmt::v11::basic_format_parse_context<char>&, fmt::v11::context&) + 112
    frame #4: 0x000000010018b39c libfmt.11.dylib`void fmt::v11::detail::parse_format_string<char, fmt::v11::detail::format_handler<char>>(fmt::v11::basic_string_view<char>, fmt::v11::detail::format_handler<char>&&) + 1264
    frame #5: 0x000000010018ac64 libfmt.11.dylib`fmt::v11::detail::vformat_to(fmt::v11::detail::buffer<char>&, fmt::v11::basic_string_view<char>, fmt::v11::basic_format_args<fmt::v11::context>, fmt::v11::detail::locale_ref) + 76
    frame #6: 0x000000010018b62c libfmt.11.dylib`fmt::v11::vprint(__sFILE*, fmt::v11::basic_string_view<char>, fmt::v11::basic_format_args<fmt::v11::context>) + 84
    frame #7: 0x000000010004be88 ccache`core::process_main_options(int, char const* const*) + 4116
    frame #8: 0x0000000100021a9c ccache`ccache_main(int, char const* const*) + 144
    frame #9: 0x0000000195210274 dyld`start + 2840

This appears to be an issue upgrading from 11.0.2 to 11.1.0, which feels unexpected from fmtlib's perspective.

fmt info

$ brew info fmt
==> fmt: stable 11.1.0 (bottled), HEAD
Open-source formatting library for C++
https://fmt.dev/
Installed
/opt/homebrew/Cellar/fmt/11.1.0 (29 files, 1MB) *
  Poured from bottle using the formulae.brew.sh API on 2024-12-26 at 09:32:49
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/f/fmt.rb
License: MIT
==> Dependencies
Build: cmake ✔
==> Options
--HEAD
	Install HEAD version
==> Analytics
install: 18,699 (30 days), 61,427 (90 days), 237,794 (365 days)
install-on-request: 634 (30 days), 3,807 (90 days), 14,685 (365 days)
build-error: 0 (30 days)

[phprus]

@vitaut

It looks like class context has changed ABI:

4fa533c#diff-1441eec7746106c0c58dbb3a207f93cd1cec6d991e4d40b0056b1ad7f5930f58L2764

[vitaut]

Thanks for reporting! I managed to repro the issue and here's a tentative fix: 3e04222. @ADKaster, could you confirm that it fixes the problem?

[ADKaster]

@vitaut yes, your commit fixes the issue on my machine.

After configuring with cmake -GNinja -DBUILD_SHARED_LIBS=ON -Bbuild and building the project, the following test now works:

andrew@Andrews-MacBook-Pro-2:~/Source/fmt$ git rev-parse HEAD
3e04222d53e683f60a4ad79016a9c6d82186bbb5
andrew@Andrews-MacBook-Pro-2:~/Source/fmt$  ccache --help
Segmentation fault: 11
andrew@Andrews-MacBook-Pro-2:~/Source/fmt$ DYLD_LIBRARY_PATH=$PWD/build ccache --help
Usage:
    ccache [ccache options]
    ccache [KEY=VALUE ...] compiler [compiler options]
    compiler [compiler options]

    The first form takes options described below. The second form invokes the
    compiler, optionally using configuration options from KEY=VALUE arguments.
    In the third form, ccache is masquerading as the compiler.

[ADKaster]

Note that homebrew did up-rev their ccache package: Homebrew/homebrew-core#202493

[vitaut]

Thanks for checking! I've merged the fix and will put together a corrective release. Thanks, @phprus, for investigating this as well.

[phprus]

@vitaut
The absence of FMT_NO_UNIQUE_ADDRESS will not affect the ABI?

[vitaut]

The absence of FMT_NO_UNIQUE_ADDRESS will not affect the ABI?

Good catch, re-added in feb7212.

[vitaut]

Patch release: https://github.com/fmtlib/fmt/releases/tag/11.1.1