An ISO C commitee document contains a portability study regarding the
__COUNTER__ macro.
2025-04-07 Bruno Haible <br...@clisp.org>
verify: Enhance a comment.
* lib/verify.h (_GL_COUNTER): Reference portability study regarding
__COUNTER__.
diff --git a/lib/verify.h b/lib/verify.h
index 96fde0b9c8..3b01d7c2fb 100644
--- a/lib/verify.h
+++ b/lib/verify.h
@@ -157,9 +157,10 @@
#define _GL_CONCAT0(x, y) x##y
/* _GL_COUNTER is an integer, preferably one that changes each time we
- use it. Use __COUNTER__ if it works, falling back on __LINE__
- otherwise. __LINE__ isn't perfect, but it's better than a
- constant. */
+ use it. Use __COUNTER__ if it works (it does so with most compilers,
+ see <https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3457.htm>),
+ falling back on __LINE__ otherwise. __LINE__ isn't perfect, but it's
+ better than a constant. */
#if defined __COUNTER__ && __COUNTER__ != __COUNTER__
# define _GL_COUNTER __COUNTER__
#else
