[llvm] [Benchmark] Fix warnings around usage of __COUNTER__ (PR #184524)

[Aiden Grossman via llvm-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/184524

Premerge CI is currently failing with the following after the update to clang v22:

```
/home/gha/llvm-project/clang-tools-extra/clangd/benchmarks/IndexBenchmark.cpp:92:1: error: '__COUNTER__' is a C2y extension [-Werror,-Wc2y-extensions]
   92 | BENCHMARK(dexQueries);
      | ^
```

Some original work was done around this in
df1d786c460e0e47c9074f3533f098190ebfbc1b, which was then done in upstream Google benchmark in
https://github.com/google/benchmark/commit/d8db2f90b643eb28a12976beb4d57bcfb639911d. The original work done in the patch implementing this feature doesn't seem to account for as many cases as the upstream patch does. This patch reverts the diff in df1d786c460e0e47c9074f3533f098190ebfbc1b and applies the applicable hunks from the upstream patch.

>From 0e6bc2a7c2f591ddcadebcb7b5a6527cd1133477 Mon Sep 17 00:00:00 2001
From: Aiden Grossman <aidengrossman at google.com>
Date: Wed, 4 Mar 2026 00:50:35 +0000
Subject: [PATCH] [Benchmark] Fix warnings around usage of __COUNTER__

Premerge CI is currently failing with the following after the update to
clang v22:

```
/home/gha/llvm-project/clang-tools-extra/clangd/benchmarks/IndexBenchmark.cpp:92:1: error: '__COUNTER__' is a C2y extension [-Werror,-Wc2y-extensions]
   92 | BENCHMARK(dexQueries);
      | ^
```

Some original work was done around this in
df1d786c460e0e47c9074f3533f098190ebfbc1b, which was then done in
upstream Google benchmark in
https://github.com/google/benchmark/commit/d8db2f90b643eb28a12976beb4d57bcfb639911d.
The original work done in the patch implementing this feature doesn't
seem to account for as many cases as the upstream patch does. This patch
reverts the diff in df1d786c460e0e47c9074f3533f098190ebfbc1b and applies
the applicable hunks from the upstream patch.
---
 .../benchmark/include/benchmark/benchmark.h   | 28 +++++++++++--------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/third-party/benchmark/include/benchmark/benchmark.h b/third-party/benchmark/include/benchmark/benchmark.h
index c2debb216d64f..71399d030a846 100644
--- a/third-party/benchmark/include/benchmark/benchmark.h
+++ b/third-party/benchmark/include/benchmark/benchmark.h
@@ -250,10 +250,6 @@ BENCHMARK(BM_test)->Unit(benchmark::kMillisecond);
   _Pragma("GCC diagnostic push")             \
   _Pragma("GCC diagnostic ignored \"-Wdeprecated-declarations\"")
 #define BENCHMARK_RESTORE_DEPRECATED_WARNING _Pragma("GCC diagnostic pop")
-#define BENCHMARK_DISABLE_PEDANTIC_WARNING \
-  _Pragma("GCC diagnostic push")             \
-  _Pragma("GCC diagnostic ignored \"-Wpedantic\"")
-#define BENCHMARK_RESTORE_PEDANTIC_WARNING _Pragma("GCC diagnostic pop")
 #elif defined(__NVCOMPILER)
 #define BENCHMARK_BUILTIN_EXPECT(x, y) __builtin_expect(x, y)
 #define BENCHMARK_DEPRECATED_MSG(msg) __attribute__((deprecated(msg)))
@@ -261,8 +257,6 @@ BENCHMARK(BM_test)->Unit(benchmark::kMillisecond);
   _Pragma("diagnostic push") \
   _Pragma("diag_suppress deprecated_entity_with_custom_message")
 #define BENCHMARK_RESTORE_DEPRECATED_WARNING _Pragma("diagnostic pop")
-#define BENCHMARK_DISABLE_PEDANTIC_WARNING
-#define BENCHMARK_RESTORE_PEDANTIC_WARNING
 #else
 #define BENCHMARK_BUILTIN_EXPECT(x, y) x
 #define BENCHMARK_DEPRECATED_MSG(msg)
@@ -271,8 +265,6 @@ BENCHMARK(BM_test)->Unit(benchmark::kMillisecond);
       __LINE__) ") : warning note: " msg))
 #define BENCHMARK_DISABLE_DEPRECATED_WARNING
 #define BENCHMARK_RESTORE_DEPRECATED_WARNING
-#define BENCHMARK_DISABLE_PEDANTIC_WARNING
-#define BENCHMARK_RESTORE_PEDANTIC_WARNING
 #endif
 // clang-format on
 
@@ -1467,16 +1459,29 @@ class Fixture : public internal::Benchmark {
 // ------------------------------------------------------
 // Macro to register benchmarks
 
+// clang-format off
+#if defined(__clang__)
+#define BENCHMARK_DISABLE_COUNTER_WARNING                        \
+  _Pragma("GCC diagnostic push")                                 \
+  _Pragma("GCC diagnostic ignored \"-Wunknown-warning-option\"") \
+  _Pragma("GCC diagnostic ignored \"-Wc2y-extensions\"")
+#define BENCHMARK_RESTORE_COUNTER_WARNING _Pragma("GCC diagnostic pop")
+#else
+#define BENCHMARK_DISABLE_COUNTER_WARNING
+#define BENCHMARK_RESTORE_COUNTER_WARNING
+#endif
+// clang-format on
+
 // Check that __COUNTER__ is defined and that __COUNTER__ increases by 1
 // every time it is expanded. X + 1 == X + 0 is used in case X is defined to be
 // empty. If X is empty the expression becomes (+1 == +0).
-BENCHMARK_DISABLE_PEDANTIC_WARNING
+BENCHMARK_DISABLE_COUNTER_WARNING
 #if defined(__COUNTER__) && (__COUNTER__ + 1 == __COUNTER__ + 0)
 #define BENCHMARK_PRIVATE_UNIQUE_ID __COUNTER__
 #else
 #define BENCHMARK_PRIVATE_UNIQUE_ID __LINE__
 #endif
-BENCHMARK_RESTORE_PEDANTIC_WARNING
+BENCHMARK_RESTORE_COUNTER_WARNING
 
 // Helpers for generating unique variable names
 #ifdef BENCHMARK_HAS_CXX11
@@ -1495,8 +1500,9 @@ BENCHMARK_RESTORE_PEDANTIC_WARNING
   BaseClass##_##Method##_Benchmark
 
 #define BENCHMARK_PRIVATE_DECLARE(n)                                 \
+  BENCHMARK_DISABLE_COUNTER_WARNING                                  \
   static ::benchmark::internal::Benchmark* BENCHMARK_PRIVATE_NAME(n) \
-      BENCHMARK_UNUSED
+      BENCHMARK_RESTORE_COUNTER_WARNING BENCHMARK_UNUSED
 
 #ifdef BENCHMARK_HAS_CXX11
 #define BENCHMARK(...)                                               \