Merge from gnulib.
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Paul Eggert
parent
122b0c8643
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1 changed files with 79 additions and 51 deletions
130
lib/verify.h
130
lib/verify.h
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@ -17,42 +17,37 @@
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/* Written by Paul Eggert, Bruno Haible, and Jim Meyering. */
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#ifndef VERIFY_H
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# define VERIFY_H 1
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#ifndef _GL_VERIFY_H
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# define _GL_VERIFY_H
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/* Define HAVE__STATIC_ASSERT to 1 if _Static_assert works as per the
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/* Define _GL_HAVE__STATIC_ASSERT to 1 if _Static_assert works as per the
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C1X draft N1548 section 6.7.10. This is supported by GCC 4.6.0 and
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later, in C mode, and its use here generates easier-to-read diagnostics
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when verify (R) fails.
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Define HAVE_STATIC_ASSERT to 1 if static_assert works as per the
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C1X draft N1548 section 7.2 or the C++0X draft N3242 section 7.(4).
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Define _GL_HAVE_STATIC_ASSERT to 1 if static_assert works as per the
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C++0X draft N3242 section 7.(4).
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This will likely be supported by future GCC versions, in C++ mode.
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For now, use this only with GCC. Eventually whether _Static_assert
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and static_assert works should be determined by 'configure'. */
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Use this only with GCC. If we were willing to slow 'configure'
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down we could also use it with other compilers, but since this
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affects only the quality of diagnostics, why bother? */
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# if (4 < __GNUC__ || (__GNUC__ == 4 && 6 <= __GNUC_MINOR__)) && !defined __cplusplus
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# define HAVE__STATIC_ASSERT 1
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# define _GL_HAVE__STATIC_ASSERT 1
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# endif
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/* The condition (99 < __GNUC__) is temporary, until we know about the
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first G++ release that supports static_assert. */
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# if (99 < __GNUC__) && defined __cplusplus
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# define HAVE_STATIC_ASSERT 1
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# define _GL_HAVE_STATIC_ASSERT 1
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# endif
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/* Each of these macros verifies that its argument R is nonzero. To
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be portable, R should be an integer constant expression. Unlike
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assert (R), there is no run-time overhead.
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There are two macros, since no single macro can be used in all
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contexts in C. verify_true (R) is for scalar contexts, including
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integer constant expression contexts. verify (R) is for declaration
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contexts, e.g., the top level.
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Symbols ending in "__" are private to this header.
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If _Static_assert works, verify (R) uses it directly. Similarly,
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verify_true (R) works by packaging a _Static_assert inside a struct
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_GL_VERIFY_TRUE works by packaging a _Static_assert inside a struct
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that is an operand of sizeof.
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The code below uses several ideas for C++ compilers, and for C
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@ -64,7 +59,9 @@
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constant and nonnegative.
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* Next this expression W is wrapped in a type
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struct verify_type__ { unsigned int verify_error_if_negative_size__: W; }.
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struct _gl_verify_type {
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unsigned int _gl_verify_error_if_negative: W;
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}.
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If W is negative, this yields a compile-time error. No compiler can
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deal with a bit-field of negative size.
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@ -78,7 +75,7 @@
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void function (int n) { verify (n < 0); }
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* For the verify macro, the struct verify_type__ will need to
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* For the verify macro, the struct _gl_verify_type will need to
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somehow be embedded into a declaration. To be portable, this
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declaration must declare an object, a constant, a function, or a
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typedef name. If the declared entity uses the type directly,
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@ -116,11 +113,11 @@
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Which of the following alternatives can be used?
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extern int dummy [sizeof (struct {...})];
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extern int dummy [sizeof (struct verify_type__ {...})];
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extern int dummy [sizeof (struct _gl_verify_type {...})];
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extern void dummy (int [sizeof (struct {...})]);
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extern void dummy (int [sizeof (struct verify_type__ {...})]);
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extern void dummy (int [sizeof (struct _gl_verify_type {...})]);
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extern int (*dummy (void)) [sizeof (struct {...})];
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extern int (*dummy (void)) [sizeof (struct verify_type__ {...})];
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extern int (*dummy (void)) [sizeof (struct _gl_verify_type {...})];
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In the second and sixth case, the struct type is exported to the
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outer scope; two such declarations therefore collide. GCC warns
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@ -159,44 +156,75 @@
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possible. */
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# define _GL_GENSYM(prefix) _GL_CONCAT (prefix, _GL_COUNTER)
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/* Verify requirement R at compile-time, as an integer constant expression.
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Return 1. */
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/* Verify requirement R at compile-time, as an integer constant expression
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that returns 1. If R is false, fail at compile-time, preferably
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with a diagnostic that includes the string-literal DIAGNOSTIC. */
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# define _GL_VERIFY_TRUE(R, DIAGNOSTIC) \
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(!!sizeof (_GL_VERIFY_TYPE (R, DIAGNOSTIC)))
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# ifdef __cplusplus
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template <int w>
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struct verify_type__ { unsigned int verify_error_if_negative_size__: w; };
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# define verify_true(R) \
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(!!sizeof (verify_type__<(R) ? 1 : -1>))
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# elif HAVE__STATIC_ASSERT
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# define verify_true(R) \
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(!!sizeof \
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(struct { \
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_Static_assert (R, "verify_true (" #R ")"); \
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int verify_dummy__; \
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}))
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# elif HAVE_STATIC_ASSERT
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# define verify_true(R) \
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(!!sizeof \
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(struct { \
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static_assert (R, "verify_true (" #R ")"); \
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int verify_dummy__; \
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}))
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struct _gl_verify_type {
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unsigned int _gl_verify_error_if_negative: w;
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};
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# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
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_gl_verify_type<(R) ? 1 : -1>
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# elif defined _GL_HAVE__STATIC_ASSERT
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# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
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struct { \
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_Static_assert (R, DIAGNOSTIC); \
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int _gl_dummy; \
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}
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# else
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# define verify_true(R) \
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(!!sizeof \
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(struct { unsigned int verify_error_if_negative_size__: (R) ? 1 : -1; }))
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# define _GL_VERIFY_TYPE(R, DIAGNOSTIC) \
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struct { unsigned int _gl_verify_error_if_negative: (R) ? 1 : -1; }
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# endif
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/* Verify requirement R at compile-time, as a declaration without a
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trailing ';'. If R is false, fail at compile-time, preferably
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with a diagnostic that includes the string-literal DIAGNOSTIC.
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Unfortunately, unlike C1X, this implementation must appear as an
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ordinary declaration, and cannot appear inside struct { ... }. */
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# ifdef _GL_HAVE__STATIC_ASSERT
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# define _GL_VERIFY _Static_assert
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# else
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# define _GL_VERIFY(R, DIAGNOSTIC) \
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extern int (*_GL_GENSYM (_gl_verify_function) (void)) \
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[_GL_VERIFY_TRUE (R, DIAGNOSTIC)]
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# endif
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/* _GL_STATIC_ASSERT_H is defined if this code is copied into assert.h. */
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# ifdef _GL_STATIC_ASSERT_H
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# if !defined _GL_HAVE__STATIC_ASSERT && !defined _Static_assert
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# define _Static_assert(R, DIAGNOSTIC) _GL_VERIFY (R, DIAGNOSTIC)
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# endif
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# if !defined _GL_HAVE_STATIC_ASSERT && !defined static_assert
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# define static_assert _Static_assert /* Draft C1X requires this #define. */
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# endif
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# else
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/* Each of these macros verifies that its argument R is nonzero. To
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be portable, R should be an integer constant expression. Unlike
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assert (R), there is no run-time overhead.
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There are two macros, since no single macro can be used in all
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contexts in C. verify_true (R) is for scalar contexts, including
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integer constant expression contexts. verify (R) is for declaration
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contexts, e.g., the top level. */
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/* Verify requirement R at compile-time, as an integer constant expression.
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Return 1. */
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# define verify_true(R) _GL_VERIFY_TRUE (R, "verify_true (" #R ")")
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/* Verify requirement R at compile-time, as a declaration without a
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trailing ';'. */
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# if HAVE__STATIC_ASSERT
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# define verify(R) _Static_assert (R, "verify (" #R ")")
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# elif HAVE_STATIC_ASSERT
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# define verify(R) static_assert (R, "verify (" #R ")")
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# else
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# define verify(R) \
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extern int (* _GL_GENSYM (verify_function) (void)) [verify_true (R)]
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# define verify(R) _GL_VERIFY (R, "verify (" #R ")")
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# endif
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#endif
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