Eric Blake <ebl...@redhat.com> writes:
> We've started using the _GL_ prefix, rather than GL_, because the
> package OpenGL uses the GL_ prefix....
> s/one one/one/ ...
> Do you also want to check that it actually increments? And wouldn't
> __LINE__ be a slightly better fallback than 0?...
All good points, thanks; I pushed the following further patch.
> The trailing __ of the old version was nice to avoid inadvertent
> collisions with normal namespace; should we be using
> GL_GENSYM(verify_function__) in the new version?
It might not hurt, I suppose, but surely the names verify_function0 etc.
are not that much more likely than verify_function__0 etc.
Further improvements to verify.h, suggested by Eric Blake.
* lib/verify.h (_GL_CONCAT, _GL_CONCAT0, _GL_GENSYM): Renamed from
the GL_* versions, to avoid collision with OpenGL.
(_GL_COUNTER): New macro, so that we can fall back on __LINE__ if
__COUNTER__ doesn't work. Test that __COUNTER__ increments rather
than testing merely whether it's defined.
diff --git a/lib/verify.h b/lib/verify.h
index dbca35c..a0849a8 100644
--- a/lib/verify.h
+++ b/lib/verify.h
@@ -69,9 +69,9 @@
if the entity names are not disambiguated. A workaround is to
attach the current line number to the entity name:
- #define GL_CONCAT0(x, y) x##y
- #define GL_CONCAT(x, y) GL_CONCAT0 (x, y)
- extern struct {...} * GL_CONCAT(dummy,__LINE__);
+ #define _GL_CONCAT0(x, y) x##y
+ #define _GL_CONCAT(x, y) _GL_CONCAT0 (x, y)
+ extern struct {...} * _GL_CONCAT(dummy,__LINE__);
But this has the problem that two invocations of verify from
within the same macro would collide, since the __LINE__ value
@@ -123,19 +123,22 @@
Use a template type to work around the problem. */
/* Concatenate two preprocessor tokens. */
-# define GL_CONCAT(x, y) GL_CONCAT0 (x, y)
-# define GL_CONCAT0(x, y) x##y
-
-/* __COUNTER__ evaluates to 0, 1, 2,..., adding one one each time the
- preprocessor uses it. If the preprocessor doesn't support this
- builtin macro, define it to 0. */
-# ifndef __COUNTER__
-# define __COUNTER__ 0
+# define _GL_CONCAT(x, y) _GL_CONCAT0 (x, y)
+# 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. */
+# if defined __COUNTER__ && __COUNTER__ != __COUNTER__
+# define _GL_COUNTER __COUNTER__
+# else
+# define _GL_COUNTER __LINE__
# endif
/* Generate a symbol with the given prefix, making it unique if
possible. */
-# define GL_GENSYM(prefix) GL_CONCAT(prefix, __COUNTER__)
+# define _GL_GENSYM(prefix) _GL_CONCAT(prefix, _GL_COUNTER)
/* Verify requirement R at compile-time, as an integer constant expression.
Return 1. */
@@ -155,6 +158,6 @@ template <int w>
trailing ';'. */
# define verify(R) \
- extern int (* GL_GENSYM(verify_function) (void)) [verify_true (R)]
+ extern int (* _GL_GENSYM(verify_function) (void)) [verify_true (R)]
#endif
