AX_C_DECLARE_BLOCK
,
if C variables must be declared at the beginning of a block
Guido U. Draheim <guidod@gmx.de>
guidod's C Support (released)
The macro will compile a test program to see whether the compiler does
allow new variable declarations in the middle of a C statement block,
i.e. after some non-declaration line. New compilers will allow that
which makes the behave a bit more like C++ - the gcc did support it
for quite a time already.
#define DECLARE_BLOCK_NEEDED says they need to be at the beginning of
of a statement block. Additionlly two defines DECLARE_BLOCK { and
DECLARE_END } are being set. That makes it possible to do the following
in your source code (which this macro is really made up for):
#define ___ DECLARE_BLOCK
#define ____ DECLARE_END
int f() {
char buffer[1024];
fgets(buffer, 1024, stdin);
___ int i; int ii = strlen(buffer);
for (i=0; i < ii; i++) {
fputc(buffer[i], stdout);
}____;
}
@licence GPLWithACException
AC_DEFUN([AX_C_DECLARE_BLOCK],[dnl
AC_CACHE_CHECK(
[if C variables must be declared at the beginning of a block],
ax_cv_c_declare_block,[
AC_TRY_COMPILE([#include <stdio.h>
int f() {
char buffer[1024];
fgets(buffer, 1024, stdin);
int i; int ii = strlen(buffer);
for (i=0; i < ii; i++) {
fputc(buffer[i], stdout);
}
}],
[],
ax_cv_c_declare_block=no, ax_cv_c_declare_block=yes)])
if test "$ax_cv_c_declare_block" = yes; then
AC_DEFINE([DECLARE_BLOCK_NEEDED],[1],
[if C variables must be declared at the beginning of a block])
AC_DEFINE([DECLARE_BLOCK],[{],
[set to { if variable declarations need a block start before])
AC_DEFINE([DECLARE_END],[}],
[set to } if variable declarations need a block start before])
fi
])