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