c/773: Bugs with -gdwarf options

[Joseph Myers <jsm28 at cam dot ac dot uk>]

>Number:         773
>Category:       c
>Synopsis:       Bugs with -gdwarf options
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Nov 11 05:56:00 PST 2000
>Closed-Date:
>Last-Modified:
>Originator:     Joseph S. Myers
>Release:        2.97 20001111 (experimental)
>Organization:
none
>Environment:
System: Linux decomino 2.2.17 #1 Mon Sep 4 20:22:16 UTC 2000 i686 unknown
Architecture: i686

	
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
>Description:

There are some problems with the various options beginning -gdwarf:

GCC no longer accepts -gdwarf2 meaning DWARF version 1 debug level 2,
presumably to avoid confusion.  However, the documentation has not
been updated for this; it still includes

@itemx -gdwarf@var{level}

Error messages from -gdwarf2 are duplicated:

$ gcc -c -gdwarf2 -o /dev/null t.c
cc1: use -gdwarf -g2 for DWARF v1, level 2
cc1: use -gdwarf-2   for DWARF v2
cc1: use -gdwarf -g2 for DWARF v1, level 2
cc1: use -gdwarf-2   for DWARF v2
$

So are those from -gdwarf1:

$ gcc -c -gdwarf1 -o /dev/null t.c
cc1: use -gdwarf -g1 for DWARF v1, level 1
cc1: use -gdwarf -g1 for DWARF v1, level 1
$

Some nonsense usages, such as -gdwarf-17, are not detected:

$ gcc -c -gdwarf-17 -o /dev/null t.c
$

>How-To-Repeat:

See examples above.

>Fix:

Update documentation; ensure that messages are only given once; give
an appropriate error for -gdwarf-17.
>Release-Note:
>Audit-Trail:
>Unformatted: