/* Written by Paul Eggert, Bruno Haible, and Jim Meyering. */
-#ifndef VERIFY_H
-# define VERIFY_H 1
+#ifndef _GL_VERIFY_H
+# define _GL_VERIFY_H
-/* Define HAVE__STATIC_ASSERT to 1 if _Static_assert works as per the
+
+/* Define _GL_HAVE__STATIC_ASSERT to 1 if _Static_assert works as per the
C1X draft N1548 section 6.7.10. This is supported by GCC 4.6.0 and
later, in C mode, and its use here generates easier-to-read diagnostics
when verify (R) fails.
- Define HAVE_STATIC_ASSERT to 1 if static_assert works as per the
- C1X draft N1548 section 7.2 or the C++0X draft N3242 section 7.(4).
+ Define _GL_HAVE_STATIC_ASSERT to 1 if static_assert works as per the
+ C++0X draft N3242 section 7.(4).
This will likely be supported by future GCC versions, in C++ mode.
- For now, use this only with GCC. Eventually whether _Static_assert
- and static_assert works should be determined by 'configure'. */
+ Use this only with GCC. If we were willing to slow 'configure'
+ down we could also use it with other compilers, but since this
+ affects only the quality of diagnostics, why bother? */
# if (4 < __GNUC__ || (__GNUC__ == 4 && 6 <= __GNUC_MINOR__)) && !defined __cplusplus
-# define HAVE__STATIC_ASSERT 1
+# define _GL_HAVE__STATIC_ASSERT 1
# endif
/* The condition (99 < __GNUC__) is temporary, until we know about the
first G++ release that supports static_assert. */
# if (99 < __GNUC__) && defined __cplusplus
-# define HAVE_STATIC_ASSERT 1
+# define _GL_HAVE_STATIC_ASSERT 1
# endif
/* Each of these macros verifies that its argument R is nonzero. To
be portable, R should be an integer constant expression. Unlike
assert (R), there is no run-time overhead.
- There are two macros, since no single macro can be used in all
- contexts in C. verify_true (R) is for scalar contexts, including
- integer constant expression contexts. verify (R) is for declaration
- contexts, e.g., the top level.
-
- Symbols ending in "__" are private to this header.
-
If _Static_assert works, verify (R) uses it directly. Similarly,
- verify_true (R) works by packaging a _Static_assert inside a struct
+ _GL_VERIFY_TRUE works by packaging a _Static_assert inside a struct
that is an operand of sizeof.
The code below uses several ideas for C++ compilers, and for C
constant and nonnegative.
* Next this expression W is wrapped in a type
- struct verify_type__ { unsigned int verify_error_if_negative_size__: W; }.
+ struct _gl_verify_type {
+ unsigned int _gl_verify_error_if_negative: W;
+ }.
If W is negative, this yields a compile-time error. No compiler can
deal with a bit-field of negative size.
void function (int n) { verify (n < 0); }
- * For the verify macro, the struct verify_type__ will need to
+ * For the verify macro, the struct _gl_verify_type will need to
somehow be embedded into a declaration. To be portable, this
declaration must declare an object, a constant, a function, or a
typedef name. If the declared entity uses the type directly,
Which of the following alternatives can be used?
extern int dummy [sizeof (struct {...})];
- extern int dummy [sizeof (struct verify_type__ {...})];
+ extern int dummy [sizeof (struct _gl_verify_type {...})];
extern void dummy (int [sizeof (struct {...})]);
- extern void dummy (int [sizeof (struct verify_type__ {...})]);
+ extern void dummy (int [sizeof (struct _gl_verify_type {...})]);
extern int (*dummy (void)) [sizeof (struct {...})];
- extern int (*dummy (void)) [sizeof (struct verify_type__ {...})];
+ extern int (*dummy (void)) [sizeof (struct _gl_verify_type {...})];
In the second and sixth case, the struct type is exported to the
outer scope; two such declarations therefore collide. GCC warns
possible. */
# define _GL_GENSYM(prefix) _GL_CONCAT (prefix, _GL_COUNTER)
-/* Verify requirement R at compile-time, as an integer constant expression.
- Return 1. */
+/* Verify requirement R at compile-time, as an integer constant expression
+ that returns 1. If R is false, fail at compile-time, preferably
+ with a diagnostic that includes the string-literal DIAGNOSTIC. */
+
+# define _GL_VERIFY_TRUE(R, DIAGNOSTIC) \
+ (!!sizeof (_GL_VERIFY_TYPE (R, DIAGNOSTIC)))
# ifdef __cplusplus
template <int w>
- struct verify_type__ { unsigned int verify_error_if_negative_size__: w; };
-# define verify_true(R) \
- (!!sizeof (verify_type__<(R) ? 1 : -1>))
-# elif HAVE__STATIC_ASSERT
-# define verify_true(R) \
- (!!sizeof \
- (struct { \
- _Static_assert (R, "verify_true (" #R ")"); \
- int verify_dummy__; \
- }))
-# elif HAVE_STATIC_ASSERT
-# define verify_true(R) \
- (!!sizeof \
- (struct { \
- static_assert (R, "verify_true (" #R ")"); \
- int verify_dummy__; \
- }))
+ struct _gl_verify_type {
+ unsigned int _gl_verify_error_if_negative: w;
+ };
+# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
+ _gl_verify_type<(R) ? 1 : -1>
+# elif defined _GL_HAVE__STATIC_ASSERT
+# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
+ struct { \
+ _Static_assert (R, DIAGNOSTIC); \
+ int _gl_dummy; \
+ }
# else
-# define verify_true(R) \
- (!!sizeof \
- (struct { unsigned int verify_error_if_negative_size__: (R) ? 1 : -1; }))
+# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
+ struct { unsigned int _gl_verify_error_if_negative: (R) ? 1 : -1; }
# endif
/* Verify requirement R at compile-time, as a declaration without a
- trailing ';'. */
+ trailing ';'. If R is false, fail at compile-time, preferably
+ with a diagnostic that includes the string-literal DIAGNOSTIC.
+
+ Unfortunately, unlike C1X, this implementation must appear as an
+ ordinary declaration, and cannot appear inside struct { ... }. */
+
+# ifdef _GL_HAVE__STATIC_ASSERT
+# define _GL_VERIFY _Static_assert
+# else
+# define _GL_VERIFY(R, DIAGNOSTIC) \
+ extern int (*_GL_GENSYM (_gl_verify_function) (void)) \
+ [_GL_VERIFY_TRUE (R, DIAGNOSTIC)]
+# endif
-# if HAVE__STATIC_ASSERT
-# define verify(R) _Static_assert (R, "verify (" #R ")")
-# elif HAVE_STATIC_ASSERT
-# define verify(R) static_assert (R, "verify (" #R ")")
+/* _GL_STATIC_ASSERT_H is defined if this code is copied into assert.h. */
+# ifdef _GL_STATIC_ASSERT_H
+# if !defined _GL_HAVE__STATIC_ASSERT && !defined _Static_assert
+# define _Static_assert(R, DIAGNOSTIC) _GL_VERIFY (R, DIAGNOSTIC)
+# endif
+# if !defined _GL_HAVE_STATIC_ASSERT && !defined static_assert
+# define static_assert _Static_assert /* Draft C1X requires this #define. */
+# endif
# else
-# define verify(R) \
- extern int (* _GL_GENSYM (verify_function) (void)) [verify_true (R)]
+
+/* Each of these macros verifies that its argument R is nonzero. To
+ be portable, R should be an integer constant expression. Unlike
+ assert (R), there is no run-time overhead.
+
+ There are two macros, since no single macro can be used in all
+ contexts in C. verify_true (R) is for scalar contexts, including
+ integer constant expression contexts. verify (R) is for declaration
+ contexts, e.g., the top level. */
+
+/* Verify requirement R at compile-time, as an integer constant expression.
+ Return 1. */
+
+# define verify_true(R) _GL_VERIFY_TRUE (R, "verify_true (" #R ")")
+
+/* Verify requirement R at compile-time, as a declaration without a
+ trailing ';'. */
+
+# define verify(R) _GL_VERIFY (R, "verify (" #R ")")
+
# endif
#endif
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