8311c83f91
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.
37 lines
1.6 KiB
C
37 lines
1.6 KiB
C
/* The array_length and array_end macros.
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Copyright (C) 2017-2019 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#ifndef _ARRAY_LENGTH_H
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#define _ARRAY_LENGTH_H
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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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(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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#define array_end(var) (&(var)[array_length (var)])
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#endif /* _ARRAY_LENGTH_H */
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