[Bug driver/22231] New: -MG ignores missing headers even with -c

[Bug driver/22231] New: -MG ignores missing headers even with -c

[js at linuxtv dot org]

I just spent half an hour to debug mysterious build failures
(make complaining about missing dependencies) in some
third party code. (The reason was a missing -Ipath.)

Given what the documentation of -MG
in the preprocessor says I'm not sure this is a real bug,
but as an enhancement request I think gcc shouldn't
pass -MG to the preprocessor if it is used in combination
with -c (or -S etc.), or produce an error (it doesn't
really make sense to use -MG with -c).

This behaviour is the same in gcc --version:
gcc-3.3 (GCC) 3.3.6 (Debian 1:3.3.6-7)
gcc-3.4 (GCC) 3.4.5 20050613 (prerelease) (Debian 3.4.4-1)
gcc-4.0 (GCC) 4.0.1 20050617 (prerelease) (Debian 4.0.0-10)

$ cat >t.c
#include "foo.h"
$ gcc -MD -c t.c
t.c:1:17: foo.h: No such file or directory
$ ls -l t.*
-rw-r--r--  1 js js 17 Jun 29 15:35 t.c
-rw-r--r--  1 js js  0 Jun 29 15:36 t.d
$ gcc -MD -MG -c t.c
$ ls -l t.*
-rw-r--r--  1 js js  17 Jun 29 15:35 t.c
-rw-r--r--  1 js js  15 Jun 29 15:35 t.d
-rw-r--r--  1 js js 637 Jun 29 15:35 t.o
$ cat t.d
t.o: t.c foo.h
$

-- 
           Summary: -MG ignores missing headers even with -c
           Product: gcc
           Version: 4.0.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: driver
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: js at linuxtv dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22231

[Bug preprocessor/22231] -MG ignores missing headers even with -c

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|driver                      |preprocessor


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22231

[Bug preprocessor/22231] -MG ignores missing headers even with -c

[tromey at gcc dot gnu dot org]

------- Comment #5 from tromey at gcc dot gnu dot org  2008-05-09 22:18 -------
Fixed on trunk.
It is very unlikely that this will be back-ported, so I'm closing the bug.


-- 

tromey at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22231

[Bug preprocessor/22231] -MG ignores missing headers even with -c

[tromey at gcc dot gnu dot org]

------- Comment #4 from tromey at gcc dot gnu dot org  2008-05-09 22:17 -------
Subject: Bug 22231

Author: tromey
Date: Fri May  9 22:17:00 2008
New Revision: 135128

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=135128
Log:
gcc
        PR preprocessor/22231:
        * c-opts.c (sanitize_cpp_opts): Disallow -MG if compilation is
        proceeding.
gcc/testsuite
        PR preprocessor/22231:
        * gcc.dg/pr22231.c: New file.

Added:
    trunk/gcc/testsuite/gcc.dg/pr22231.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/c-opts.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22231

[Bug preprocessor/22231] -MG ignores missing headers even with -c

[tromey at gcc dot gnu dot org]

------- Comment #3 from tromey at gcc dot gnu dot org  2008-05-08 16:40 -------
I finally submitted this patch.
http://gcc.gnu.org/ml/gcc-patches/2008-05/msg00520.html


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22231

[Bug preprocessor/22231] -MG ignores missing headers even with -c

[tromey at gcc dot gnu dot org]

------- Comment #2 from tromey at gcc dot gnu dot org  2007-01-21 03:09 -------
I am testing a patch for this.


-- 

tromey at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |tromey at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED
   Last reconfirmed|2007-01-08 01:54:32         |2007-01-21 03:09:47
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22231

[Bug preprocessor/22231] -MG ignores missing headers even with -c

[tromey at gcc dot gnu dot org]

------- Comment #1 from tromey at gcc dot gnu dot org  2007-01-08 01:54 -------
Confirmed.
I'm inclined to agree that we should disallow -MG in this situation.
Perhaps this is best done in c-opts.c:sanitize_cpp_opts()


-- 

tromey at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at gcc dot gnu dot
                   |                            |org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-01-08 01:54:32
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22231