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Re: preprocessor/5899: -M disables -dM
- From: neil at gcc dot gnu dot org
- To: gcc-bugs at gcc dot gnu dot org, gcc-prs at gcc dot gnu dot org, nobody at gcc dot gnu dot org, schwab at suse dot de
- Date: 9 Mar 2002 19:40:58 -0000
- Subject: Re: preprocessor/5899: -M disables -dM
- Reply-to: neil at gcc dot gnu dot org, gcc-bugs at gcc dot gnu dot org, gcc-prs at gcc dot gnu dot org, nobody at gcc dot gnu dot org, schwab at suse dot de, gcc-gnats at gcc dot gnu dot org
Synopsis: -M disables -dM
State-Changed-From-To: open->analyzed
State-Changed-By: neil
State-Changed-When: Sat Mar 9 11:40:58 2002
State-Changed-Why:
I'm not sure this behaviour is a good idea. The documentation in 3.0 for -dM begins "Instead of the normal output", and the documentation for -M begins "Instead of outputting the result of preprocessing, output a rule suitable for make". In other words, I think you're relying on undocumented behaviour that just happened to work.
What did 2.95 do? I believe it output both to the same place. I'm waiting for confirmation from Chris Demetriou that the semantics of 3.1 now match 2.95 for -M etc., which is a regression that was fixed, and is pending for 3.0.5. If the 3.0 behaviour is not a regression from 2.95 then I see no reason to preserve it, particularly if it was undocumented.
Neil.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=5899