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Add G_STATIC_ASSERT_EXPR macro

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https://bugzilla.gnome.org/show_bug.cgi?id=626549
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Ryan Lortie 2011-05-22 12:44:12 -04:00 committed by Matthias Clasen
parent 64d5a0404a
commit c00ef0a17a
2 changed files with 19 additions and 0 deletions
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18
docs/reference/glib/tmpl/macros_misc.sgml
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@ -165,6 +165,24 @@ The macro should only be used once per source code line.
@expr: a constant expression.
@Since: 2.20
<!-- ##### MACRO G_STATIC_ASSERT_EXPR ##### -->
<para>
The G_STATIC_ASSERT_EXPR macro lets the programmer check a condition at
compile time. The condition needs to be compile time computable.
</para>
<para>
Unlike <literal>G_STATIC_ASSERT</literal>, this macro evaluates to an
expression and, as such, can be used in the middle of other expressions.
Its value should be ignored. This can be accomplished by placing it as
the first argument of a comma expression.
</para>
<informalexample><programlisting>
#define ADD_ONE_TO_INT(x) \
(G_STATIC_ASSERT_EXPR(sizeof (x) == sizeof (int)), ((x) + 1))
</programlisting></informalexample>
@expr: a constant expression.
@Since: 2.30
<!-- ##### MACRO G_GNUC_EXTENSION ##### -->
<para>

1
glib/gmacros.h
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@ -147,6 +147,7 @@
#define G_PASTE_ARGS(identifier1,identifier2) identifier1 ## identifier2
#define G_PASTE(identifier1,identifier2) G_PASTE_ARGS (identifier1, identifier2)
#define G_STATIC_ASSERT(expr) typedef struct { char Compile_Time_Assertion[(expr) ? 1 : -1]; } G_PASTE (_GStaticAssert_, __LINE__)
#define G_STATIC_ASSERT_EXPR(expr) ((void) sizeof (char[(expr) ? 1 : -1]))
/* Provide a string identifying the current code position */
#if defined(__GNUC__) && (__GNUC__ < 3) && !defined(__cplusplus)