preprocessor/6521: -MG creates dependency with wrong path

[rspier@pobox.com]

>Number:         6521
>Category:       preprocessor
>Synopsis:       -MG creates dependency with wrong path
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Apr 30 13:36:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     rspier@pobox.com
>Release:        gcc2.95, gcc2.96rh, egcs 1.1.2 (gcc 2.91), gcc 3.0.2
>Organization:
>Environment:
Linux
>Description:
gcc or g++ -MG outputs incorrect dependency information when there is a nonexistent header file specified in angle brackets.  (i.e. #include <...>)

It uses the path of the first specified -I argument (or the first system directory, if no directory is specified.)

The attached script demonstrates the problem.  

#include "some/header.h"
#include <nonexistent.h>
int main() {
}
gcc3 -M -MG /tmp/_16336//test.c -I/tmp/_16336//not/a/real/path
test.o: /tmp/_16336/test.c some/header.h \
  /tmp/_16336/not/a/real/path/nonexistent.h
>How-To-Repeat:
(Run attached script.)
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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