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dbe1260b54
We'll need this for our lightning invoice view Signed-off-by: William Casarin <jb55@jb55.com>
65 lines
2.4 KiB
C
65 lines
2.4 KiB
C
/* CC0 (Public domain) - see LICENSE file for details */
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#ifndef CCAN_CHECK_TYPE_H
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#define CCAN_CHECK_TYPE_H
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#include "config.h"
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/**
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* check_type - issue a warning or build failure if type is not correct.
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* @expr: the expression whose type we should check (not evaluated).
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* @type: the exact type we expect the expression to be.
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*
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* This macro is usually used within other macros to try to ensure that a macro
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* argument is of the expected type. No type promotion of the expression is
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* done: an unsigned int is not the same as an int!
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*
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* check_type() always evaluates to 0.
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*
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* If your compiler does not support typeof, then the best we can do is fail
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* to compile if the sizes of the types are unequal (a less complete check).
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*
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* Example:
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* // They should always pass a 64-bit value to _set_some_value!
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* #define set_some_value(expr) \
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* _set_some_value((check_type((expr), uint64_t), (expr)))
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*/
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/**
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* check_types_match - issue a warning or build failure if types are not same.
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* @expr1: the first expression (not evaluated).
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* @expr2: the second expression (not evaluated).
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*
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* This macro is usually used within other macros to try to ensure that
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* arguments are of identical types. No type promotion of the expressions is
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* done: an unsigned int is not the same as an int!
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*
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* check_types_match() always evaluates to 0.
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*
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* If your compiler does not support typeof, then the best we can do is fail
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* to compile if the sizes of the types are unequal (a less complete check).
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*
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* Example:
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* // Do subtraction to get to enclosing type, but make sure that
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* // pointer is of correct type for that member.
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* #define container_of(mbr_ptr, encl_type, mbr) \
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* (check_types_match((mbr_ptr), &((encl_type *)0)->mbr), \
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* ((encl_type *) \
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* ((char *)(mbr_ptr) - offsetof(encl_type, mbr))))
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*/
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#if HAVE_TYPEOF
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#define check_type(expr, type) \
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((typeof(expr) *)0 != (type *)0)
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#define check_types_match(expr1, expr2) \
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((typeof(expr1) *)0 != (typeof(expr2) *)0)
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#else
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#include <ccan/build_assert/build_assert.h>
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/* Without typeof, we can only test the sizes. */
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#define check_type(expr, type) \
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BUILD_ASSERT_OR_ZERO(sizeof(expr) == sizeof(type))
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#define check_types_match(expr1, expr2) \
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BUILD_ASSERT_OR_ZERO(sizeof(expr1) == sizeof(expr2))
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#endif /* HAVE_TYPEOF */
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#endif /* CCAN_CHECK_TYPE_H */
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