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preprocessor/9203: preprocessor
- From: michael at moria dot de
- To: gcc-gnats at gcc dot gnu dot org
- Date: 6 Jan 2003 22:26:03 -0000
- Subject: preprocessor/9203: preprocessor
>Number: 9203
>Category: preprocessor
>Synopsis: preprocessor
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: unassigned
>State: open
>Class: change-request
>Submitter-Id: net
>Arrival-Date: Mon Jan 06 14:36:00 PST 2003
>Closed-Date:
>Last-Modified:
>Originator: Michael Haardt
>Release: 3.2
>Organization:
>Environment:
System: Linux palantir 2.4.20-rc1 #8 Wed Nov 6 23:26:07 CET 2002 i686 unknown
Architecture: i686
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ../gcc-3.2/configure --prefix=/usr
>Description:
The preprocessor allows to compare numbers with identifiers. I am not
sure if it's a bug or required by the standard, but even if it is legal,
a warning just would have saved me some time. According to the ANSI C
grammar (K&R, 2nd edition), the syntax allows the comparison. I can't
find a reference concerning semantics.
>How-To-Repeat:
michael@elrond; cat a.c
#if 123<ABC
number less than identifier
#else
number greater than identifier
#endif
michael@elrond; gcc -E -Wall -ansi -pedantic a.c
# 1 "a.c"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "a.c"
number greater than identifier
>Fix:
Even if it is legal, which I doubt but can not tell, -Wall should
issue a warning. Otherwise of course an error would be nice.
The above happened in a comparison of #define constants, of which
one was spelled wrong, so it was not substituted. That can easily
happen and I would appreciate gcc telling me so.
Michael
>Release-Note:
>Audit-Trail:
>Unformatted: