Silence -Wc2y-extensions warning around __COUNTER__ (#2108)

clang-23 in pedantic mode now warns that __COUNTER__ macro is c2y
extension. This patch silences this warning around uses of this
macro.

Co-authored-by: dominic <510002+dmah42@users.noreply.github.com>

AUTHORS

diff --git a/AUTHORS b/AUTHORS
index ef90553..11d28f7 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -44,6 +44,7 @@
 Jussi Knuuttila <jussi.knuuttila@gmail.com>
 Kaito Udagawa <umireon@gmail.com>
 Kishan Kumar <kumar.kishan@outlook.com>
+Kostiantyn Lazukin <konstantin.lazukin@gmail.com>
 Lei Xu <eddyxu@gmail.com>
 Marcel Jacobse <mjacobse@uni-bremen.de>
 Matt Clarkson <mattyclarkson@gmail.com>

CONTRIBUTORS

diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 4b01592..52e49cc 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -67,6 +67,7 @@
 Kaito Udagawa <umireon@gmail.com>
 Kai Wolf <kai.wolf@gmail.com>
 Kishan Kumar <kumar.kishan@outlook.com>
+Kostiantyn Lazukin <konstantin.lazukin@gmail.com>
 Lei Xu <eddyxu@gmail.com>
 Marcel Jacobse <mjacobse@uni-bremen.de>
 Matt Clarkson <mattyclarkson@gmail.com>

include/benchmark/benchmark.h

diff --git a/include/benchmark/benchmark.h b/include/benchmark/benchmark.h
index a67a24e..f7d1341 100644
--- a/include/benchmark/benchmark.h
+++ b/include/benchmark/benchmark.h
@@ -1484,14 +1484,29 @@
 // ------------------------------------------------------
 // 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_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_COUNTER_WARNING
 
 // Helpers for generating unique variable names
 #define BENCHMARK_PRIVATE_NAME(...)                                      \
@@ -1505,9 +1520,10 @@
   BaseClass##_##Method##_Benchmark
 
 #define BENCHMARK_PRIVATE_DECLARE(n)                                   \
+  BENCHMARK_DISABLE_COUNTER_WARNING                                    \
   /* NOLINTNEXTLINE(misc-use-anonymous-namespace) */                   \
   static ::benchmark::Benchmark const* const BENCHMARK_PRIVATE_NAME(n) \
-      BENCHMARK_UNUSED
+      BENCHMARK_RESTORE_COUNTER_WARNING BENCHMARK_UNUSED
 
 #define BENCHMARK(...)                                   \
   BENCHMARK_PRIVATE_DECLARE(_benchmark_) =               \
@@ -1695,9 +1711,11 @@
           ::benchmark::internal::make_unique<UniqueName>()))
 
 #define BENCHMARK_TEMPLATE_INSTANTIATE_F(BaseClass, Method, ...)    \
+  BENCHMARK_DISABLE_COUNTER_WARNING                                 \
   BENCHMARK_TEMPLATE_PRIVATE_INSTANTIATE_F(                         \
       BaseClass, Method, BENCHMARK_PRIVATE_NAME(BaseClass##Method), \
-      __VA_ARGS__)
+      __VA_ARGS__)                                                  \
+  BENCHMARK_RESTORE_COUNTER_WARNING
 
 // This macro will define and register a benchmark within a fixture class.
 #define BENCHMARK_F(BaseClass, Method)           \