preprocessor bug...

["Marc W. Mengel" <mengel at fnal dot gov>]

On with gcc-2.95.2, sparc-sun-solaris-2.6, The following program:

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#ifndef FROM_DOT
#include <X11/Xmd.h>
#else
#include "./Xmd.h"
#endif

SIZEOF(nag)
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with a symlink ./Xmd.h -> /usr/include/X11/Xmd.h
Gives differing results with

  gcc -E bug.c

versus

  gcc -E -DFROM_DOT bug.c

to wit (according to diff):

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3,5c3
<
<
< # 1 "Xmd.h" 1
---
> # 1 "/usr/include/X11/Xmd.h" 1 3
105c103
< # 117 "Xmd.h"
---
> # 117 "/usr/include/X11/Xmd.h" 3
119d116
< typedef signed char    INT8;
121a119
> typedef char           INT8;
143c141
< # 164 "Xmd.h"
---
> # 164 "/usr/include/X11/Xmd.h" 3
172c170
< # 4 "bug.c" 2
---
> # 2 "bug.c" 2
176c174,176
< sz_nag
---
>
>
> sz_  nag
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Now, of course, the differing pathnames I expect, but the
differing typedef and SIZEOF(nag) expansion seem completely wrong.

For those keeping score, the definitions  in question are (of course) in #if
constructs:

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#if __STDC__ || defined(sgi) || defined(AIXV3)
typedef signed char    INT8;
#else
typedef char           INT8;
#endif
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#if ((__STDC__ || defined(__cplusplus) || defined(c_plusplus)) && !defined(UNIXCPP)) || defined(ANSICPP)
#define _SIZEOF(x) sz_##x
#define SIZEOF(x) _SIZEOF(x)
#else
#define SIZEOF(x) sz_/**/x
#endif /* if ANSI C compiler else not */
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so it would appear that the definition of __STDC__ is on or off
depending on the pathname through which the file is located???