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commit 8311c83f91a3127ccd2fe684e25bc60c5178d23b
Author: Florian Weimer <fweimer@redhat.com>
Date: Thu Feb 7 09:03:02 2019 +0100
array_length: Make usable as a constant expression
Do not use a statement expression in array_length, so that
array_length can be used at file scope and as a constant expression.
Instead, put the _Static_assert into a struct (as a declaration),
and nest this in the expression using a sizeof expression.
diff --git a/include/array_length.h b/include/array_length.h
index cb4a8b2a56bca3ad..ccb253c1dc1641cf 100644
--- a/include/array_length.h
+++ b/include/array_length.h
@@ -22,12 +22,12 @@
/* array_length (VAR) is the number of elements in the array VAR. VAR
must evaluate to an array, not a pointer. */
#define array_length(var) \
- __extension__ ({ \
- _Static_assert (!__builtin_types_compatible_p \
- (__typeof (var), __typeof (&(var)[0])), \
- "argument must be an array"); \
- sizeof (var) / sizeof ((var)[0]); \
- })
+ (sizeof (var) / sizeof ((var)[0]) \
+ + 0 * sizeof (struct { \
+ _Static_assert (!__builtin_types_compatible_p \
+ (__typeof (var), __typeof (&(var)[0])), \
+ "argument must be an array"); \
+ }))
/* array_end (VAR) is a pointer one past the end of the array VAR.
VAR must evaluate to an array, not a pointer. */