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Silence -Wc2y-extensions warning around __COUNTER__#2108

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dmah42 merged 2 commits intogoogle:mainfrom
Sunday111:silence_counter_warning
Jan 21, 2026
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Silence -Wc2y-extensions warning around __COUNTER__#2108
dmah42 merged 2 commits intogoogle:mainfrom
Sunday111:silence_counter_warning

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@Sunday111 Sunday111 commented Jan 21, 2026 •
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clang-23 in pedantic mode now warns that __COUNTER__ macro is c2y extension. This patch silences this warning around uses of this macro.

Fixes #2057

Note: I had to fix this with ifdefs in a few places because __COUNTER__ is used for token generation. Also tried to do this with __extension__ but it simply becomes a part of generated name.

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Sunday111 commented Jan 21, 2026

Tested this locally with
clang version 23.0.0git (https://github.com/llvm/llvm-project ec080ab8bdc66808b0b7bba605b49103f1c82d0a)

cmake -S . -B ./build -G Ninja -DCMAKE_TOOLCHAIN_FILE=~/llvm/generated/llvm-toolchain-static-libcxx.cmake -DBENCHMARK_DOWNLOAD_DEPENDENCIES=ON -DBENCHMARK_ENABLE_TESTING=ON -DCMAKE_BUILD_TYPE=Release
(cmake --build ./build && cd build && ctest)

one test failed, but fails on main as well

99% tests passed, 1 tests failed out of 84

Total Test time (real) =  11.02 sec

The following tests FAILED:
         72 - locale_impermeability_test (Subprocess aborted)
Errors while running CTest

LebedevRI
LebedevRI reviewed Jan 21, 2026
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include/benchmark/benchmark.h Outdated
// Macro to register benchmarks

#if defined(__clang__)
#define BENCHMARK_SILENCE_COUNTER_WARNING_PUSH \
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@LebedevRI LebedevRI Jan 21, 2026

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Let's follow the existing naming scheme for these,
BENCHMARK_DISABLE_COUNTER_WARNING an BENCHMARK_RESTORE_COUNTER_WARNING

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@Sunday111 Sunday111 Jan 21, 2026

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Done

LebedevRI
LebedevRI reviewed Jan 21, 2026
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include/benchmark/benchmark.h Outdated
#if defined(__clang__)
#define BENCHMARK_SILENCE_COUNTER_WARNING_PUSH \
_Pragma("GCC diagnostic push") \
_Pragma("GCC diagnostic ignored \"-Wc2y-extensions\"")
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@LebedevRI LebedevRI Jan 21, 2026

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I'm guessing there is no more fine-grained flag for this specific warning?

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@Sunday111 Sunday111 Jan 21, 2026

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Did not find one

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LebedevRI commented Jan 21, 2026

And of course earlier clang's barf at that diag group,
you'll need to also silence -Wunknown-warning-option or also check clang version...

@Sunday111 Sunday111 force-pushed the silence_counter_warning branch from 8a65006 to fb33aa9 Compare January 21, 2026 11:19
@Sunday111 Sunday111 requested a review from LebedevRI January 21, 2026 11:21
@Sunday111
Silence -Wc2y-extensions warning around __COUNTER__
12250c4 
clang-23 in pedantic mode now warns that __COUNTER__ macro is c2y
extension. This patch silences this warning around uses of this
macro.
@Sunday111 Sunday111 force-pushed the silence_counter_warning branch from fb33aa9 to 12250c4 Compare January 21, 2026 11:48
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dmah42 commented Jan 21, 2026

bazel issues are not related. i'll take a look at that.

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dmah42 commented Jan 21, 2026

bazel issues are not related. i'll take a look at that.

this is due to bazel silently bumping to 9.0.0 which changes how googletest needs to load library rules. i've pinned us to 8.2.1 until googletest upgrades.

@dmah42 dmah42 merged commit d8db2f9 into google:main Jan 21, 2026
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@BrewTestBot BrewTestBot mentioned this pull request Jan 21, 2026
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LebedevRI
LebedevRI reviewed Jan 21, 2026
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include/benchmark/benchmark.h
/* NOLINTNEXTLINE(misc-use-anonymous-namespace) */ \
static ::benchmark::Benchmark const* const BENCHMARK_PRIVATE_NAME(n) \
BENCHMARK_UNUSED
BENCHMARK_RESTORE_COUNTER_WARNING BENCHMARK_UNUSED
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@LebedevRI LebedevRI Jan 21, 2026

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There is no semantical difference, but these should have been on different lines.

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@Sunday111 Sunday111 Jan 24, 2026

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@LebedevRI, yes, sorry I was in a rush to get it done. Would you like another pr to fix that or thats fine?

@Sunday111 Sunday111 deleted the silence_counter_warning branch January 21, 2026 14:54
krzysz00 added a commit to krzysz00/iree that referenced this pull request Feb 20, 2026
@krzysz00
Integrate third-party/benchmark to v1.9.5
af93be0 
This pulls in google/benchmark#2108 , which
fixes a build error when using extremely new Clangs, which can occur
during gfx1250 testing.

Note that this does bump us past
google/benchmark#1836, which gets rid of a
division by number of threads on certain reported time values. I don't
know if this impacts us, but I'm going to flag it anyway.
@krzysz00 krzysz00 mentioned this pull request Feb 20, 2026
Merged
krzysz00 added a commit to iree-org/iree that referenced this pull request Feb 21, 2026
@krzysz00
Integrate third-party/benchmark to v1.9.5 (#23532)
36df853 
This pulls in google/benchmark#2108 , which
fixes a build error when using extremely new Clangs, which can occur
during gfx1250 testing.

Note that this does bump us past
google/benchmark#1836, which gets rid of a
division by number of threads on certain reported time values. I don't
know if this impacts us, but I'm going to flag it anyway.
AaronStGeorge added a commit to AaronStGeorge/fusilli that referenced this pull request Feb 25, 2026
@AaronStGeorge @claude
[Fusilli] Silence -Wc2y-extensions warning around __COUNTER__ usage
a87ac7d 
__COUNTER__ is supported by all major compilers but newer Clangs
flag it as use of upcoming C2y standard. Add diagnostic push/pop
macros around call sites that expand __COUNTER__ for unique names.

Follows the same pattern as google/benchmark#2108.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
AaronStGeorge added a commit to AaronStGeorge/fusilli that referenced this pull request Feb 25, 2026
@AaronStGeorge @claude
[Fusilli] Silence -Wc2y-extensions warning around __COUNTER__ usage
c59e643 
__COUNTER__ is supported by all major compilers but newer Clangs
flag it as use of upcoming C2y standard. Add diagnostic push/pop
macros around call sites that expand __COUNTER__ for unique names.

Follows the same pattern as google/benchmark#2108.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
AaronStGeorge added a commit to AaronStGeorge/fusilli that referenced this pull request Feb 25, 2026
@AaronStGeorge @claude
[Fusilli] Silence -Wc2y-extensions warning around __COUNTER__ usage
7c63efc 
__COUNTER__ is supported by all major compilers but newer Clangs
flag it as use of upcoming C2y standard. Add diagnostic push/pop
macros around call sites that expand __COUNTER__ for unique names.

Follows the same pattern as google/benchmark#2108.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
@AaronStGeorge AaronStGeorge mentioned this pull request Feb 25, 2026
Merged
AaronStGeorge added a commit to AaronStGeorge/fusilli that referenced this pull request Feb 25, 2026
@AaronStGeorge @claude
[Fusilli] Silence -Wc2y-extensions warning around __COUNTER__ usage
aefc01d 
__COUNTER__ is supported by all major compilers but newer Clangs
flag it as use of upcoming C2y standard. Add diagnostic push/pop
macros around call sites that expand __COUNTER__ for unique names.

Follows the same pattern as google/benchmark#2108.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
sjain-stanford pushed a commit to iree-org/fusilli that referenced this pull request Feb 25, 2026
@AaronStGeorge @claude
[Fusilli,FusilliPlugin] Silence -Wc2y-extensions warning around `__…
6098c53 
…COUNTER__` usage (#190)

Fusilli builds using a very new Clang and `-Werror` (for example in
[`TheRock`](https://github.com/ROCm/TheRock/tree/main/iree-libs)) will
fail with `-Wc2y-extensions`. The error is warning about uses of
`__COUNTER__`, which is supported by all major compilers, though
technically unstandardized and part of the upcoming C2y standard. The
`__COUNTER__` use isn't a practical problem, so we can add diagnostic
push/pop macros around call sites that expand `__COUNTER__` to silence
the error.

The other options are for every consumer of fusilli to add
`-Wno-c2y-extensions` to their builds, or to just use `__LINE__`. The
former is pretty annoying, the latter option would probably be fine
though could cause an issue if anyone used multiple
`FUSILLI_ASSIGN_OR_RETURN`s on one line (unlikely).

This PR follows the same pattern as
google/benchmark#2108.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
@PardhavMaradani PardhavMaradani mentioned this pull request Mar 3, 2026
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@romintomasetti romintomasetti mentioned this pull request Mar 12, 2026
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@SeanTAllen SeanTAllen mentioned this pull request Mar 15, 2026
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[BUG] Passing -pedantic -Werror but relying on extensions

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@Sunday111 @LebedevRI @dmah42