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41 lines
1.2 KiB
C
41 lines
1.2 KiB
C
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/* CC0 (Public domain) - see ccan/licenses/CC0 file for details */
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#ifndef CCAN_BUILD_ASSERT_H
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#define CCAN_BUILD_ASSERT_H
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/**
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* BUILD_ASSERT - assert a build-time dependency.
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* @cond: the compile-time condition which must be true.
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*
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* Your compile will fail if the condition isn't true, or can't be evaluated
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* by the compiler. This can only be used within a function.
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*
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* Example:
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* #include <stddef.h>
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* ...
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* static char *foo_to_char(struct foo *foo)
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* {
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* // This code needs string to be at start of foo.
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* BUILD_ASSERT(offsetof(struct foo, string) == 0);
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* return (char *)foo;
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* }
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*/
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#define BUILD_ASSERT(cond) \
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do { (void) sizeof(char [1 - 2*!(cond)]); } while(0)
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/**
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* BUILD_ASSERT_OR_ZERO - assert a build-time dependency, as an expression.
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* @cond: the compile-time condition which must be true.
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*
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* Your compile will fail if the condition isn't true, or can't be evaluated
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* by the compiler. This can be used in an expression: its value is "0".
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*
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* Example:
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* #define foo_to_char(foo) \
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* ((char *)(foo) \
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* + BUILD_ASSERT_OR_ZERO(offsetof(struct foo, string) == 0))
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*/
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#define BUILD_ASSERT_OR_ZERO(cond) \
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(sizeof(char [1 - 2*!(cond)]) - 1)
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#endif /* CCAN_BUILD_ASSERT_H */
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