[Mingw-users] Mingw gcc does not handle -DVAR=value correctly.

[Mo D. <su...@ba...>]

Hi all.

I seem to have run into a little problem with the mingw version of gcc.
I am using gcc version 2.95.3-6 from the 1.1 release of mingw on a
Win 98 system. I am running mingw gcc under msys (1.0.5) in case
that matters.

First, the results I get from the Cygwin version of gcc. Don't worry
I am not mixing runtimes or anything. I also get these good results
when using mingw gcc version 2.95.2.

$ cat one.c
#ifdef HAVE_ONE_ERROR
#error ONE
#endif

void foo() {}

$ gcc -c one.c

$ gcc -c one.c -DHAVE_ONE_ERROR
one.c:2: #error ONE

$ gcc -c one.c -DHAVE_ONE_ERROR=1
one.c:2: #error ONE


Now for the bad result from mingw gcc:

$ gcc -c one.c

$ gcc -c one.c -DHAVE_ONE_ERROR
one.c:2: #error ONE

$ gcc -c one.c -DHAVE_ONE_ERROR=1

When the =1 is added to the -D flag, the symbol is not
defined at all! This is a very serious problem because
autoconf tends to pass -DFLAG=1 as a result of feature
tests. Strange miscompiles when using autoconf is what
lead me to this problem in the first place.

thanks much
Mo DeJong