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* Re: preprocessor/3872: gcc -M... ignores "-o"
@ 2002-03-15 3:28 neil
0 siblings, 0 replies; 3+ messages in thread
From: neil @ 2002-03-15 3:28 UTC (permalink / raw)
To: D.Yu.Bolkhovityanov, gcc-bugs, gcc-prs, neil, nobody
Synopsis: gcc -M... ignores "-o"
Responsible-Changed-From-To: unassigned->neil
Responsible-Changed-By: neil
Responsible-Changed-When: Fri Mar 15 03:28:28 2002
Responsible-Changed-Why:
FWIW this was fixed in 3.0.5 and 3.1.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=3872
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: preprocessor/3872: gcc -M... ignores "-o"
@ 2001-07-30 0:48 neil
0 siblings, 0 replies; 3+ messages in thread
From: neil @ 2001-07-30 0:48 UTC (permalink / raw)
To: D.Yu.Bolkhovityanov, gcc-bugs, gcc-prs, nobody
Synopsis: gcc -M... ignores "-o"
State-Changed-From-To: open->closed
State-Changed-By: neil
State-Changed-When: Mon Jul 30 00:48:30 2001
State-Changed-Why:
Could you report bugs in Red Hat's compiler to Red Hat?
Dependency generation was improved substantially in the months before GCC 3.0 was released. A new option -MF allows you to specify
an output file, and semantics w.r.t. -o were changed and made more
consistent. See
http://gcc.gnu.org/news/dependencies.html
for a brief and incomplete overview. If you still have problems with 3.0,
please file another PR.
http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view&pr=3872&database=gcc
^ permalink raw reply [flat|nested] 3+ messages in thread
* preprocessor/3872: gcc -M... ignores "-o"
@ 2001-07-30 0:36 D.Yu.Bolkhovityanov
0 siblings, 0 replies; 3+ messages in thread
From: D.Yu.Bolkhovityanov @ 2001-07-30 0:36 UTC (permalink / raw)
To: gcc-gnats
>Number: 3872
>Category: preprocessor
>Synopsis: gcc -M... ignores "-o"
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: unassigned
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Mon Jul 30 00:36:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator: D.Yu.Bolkhovityanov@inp.nsk.su
>Release: gcc version 2.96 20000731 (Red Hat Linux 7.1 2.96-85)
>Organization:
>Environment:
>Description:
When gcc is ran with a following command line
gcc -M sourcefile.c -o depfile.dep
it prints a list of dependencies to stdout instead of "depfile.dep" (any "-M..." option may be used instead of just "-M" -- e.g. "-MM").
What it uses "-o" for is a filename before ":" in depfile -- i.e. there will be "depfile.dep: ..." instead of "sourcefile.o: ...".
In earlier versions (since ancient and at least up to egcs-2.91) this worked as expected. Such a behaviour seems even more strange if taking into account a note in ChangeLog.CPP for 2001-01-08: "If -o given, use it as the target of any -M options" (or is *that* a cause of the bug?)
Sure, one can use ">depfile.dep" instead, but that's not a good idea, and I'll try to explain why.
When "gcc -M ..." is run from Makefile, and when cpp encounters an error (e.g. missing file in #include), in case of working "-o depfile.dep" it wouldn't touch depfile.dep, while in case of ">depfile.dep" the timestamp on the latter will become more recent than that of "sourcefile.c", and hence the immediately repeated "make" will "succeed" (since it wouldn't run "gcc -M..." at all). Of course, the subsequent "gcc" w/o "-M" will fail, but such behaviour is undesired anyway.
>How-To-Repeat:
Issue the following commands:
echo "#include <stdio.h>" >sourcefile.c
gcc -E -M sourcefile.c -o depfile.dep
and you'll get a text describing "depfile.dep" (!!!) dependant on many system headers. The "depfile.dep" isn't created as it should.
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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2002-03-15 3:28 preprocessor/3872: gcc -M... ignores "-o" neil
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2001-07-30 0:48 neil
2001-07-30 0:36 D.Yu.Bolkhovityanov
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