Re: [PATCH 3/3] Fix gdb.base/completion.exp with --target_board=dwarf4-gdb-index

[Pedro Alves <palves@redhat.com>]

On 02/23/2017 04:02 PM, Yao Qi wrote:
> Pedro Alves <palves@redhat.com> writes:
> 
> Hi Pedro,
> I don't know much about symbtab,
> 
>> -  /* Find the symtab for SRCFILE (this loads it if it was not yet read
>> -     in).  */
>> -  s = lookup_symtab (srcfile);
>> -  if (s == NULL)
>> +  /* Go through symtabs for SRCFILE and check the externs and statics
>> +     for symbols which match.  */
>> +  iterate_over_symtabs (srcfile, [&] (struct symtab *symtab)
>>      {
>> -      /* Maybe they typed the file with leading directories, while the
>> -	 symbol tables record only its basename.  */
>> -      const char *tail = lbasename (srcfile);
>> -
>> -      if (tail > srcfile)
>> -	s = lookup_symtab (tail);
> 
> This is removed, do we have something equivalent in iterate_over_symtabs?

AFAICS, yes, though via other means.

iterate_over_some_symtabs matches both the symtab name, and if that
fails, tries the symtab's resolved fullname.

The path actually fixes a bug related to this, it seems.

Before the patch, any random absolute path would match, like:

 (gdb) b /silly/path/asdfasdfsdafasdfasdfsadfasdfasdfasdfasdfasdf/test.c:<tab>
 a       foo     int     main()  

But then actually setting the breakpoint would fail:

 (gdb) b /silly/path/asdfasdfsdafasdfasdfsadfasdfasdfasdfasdfasdf/test.c:main
 No source file named /silly/path/asdfasdfsdafasdfasdfsadfasdfasdfasdfasdfasdf/test.c.
 Make breakpoint pending on future shared library load? (y or [n]) n

While after the patch, only full paths that gdb can resolve in
find_and_open_source, according to the source lookup rules, match for
completion.  I.e., in my quick test, completing "/home/pedro/tmp/test.c:",
which is the source file's real path, matches for completion, but the
silly path above does not.

If I move the source file elsewhere and use the "dir" command to
point GDB at it, completion now finds it there:

 (gdb) b /home/pedro/tmp2/test.c:<tab>
 #nothing
 (gdb) dir /home/pedro/tmp2/
 Source directories searched: /home/pedro/tmp2:$cdir:$cwd
 (gdb) b /home/pedro/tmp2/test.c:
 a       foo     int     main()  
 (gdb) b /home/pedro/tmp/dirs/ctor.cc:main
 Note: breakpoint 1 also set at pc 0x4005ba.

So this patch makes completion consistent with the rest of
gdb, which seems like a desirable change.

I'll try to come up with a test case for this.

Thanks,
Pedro Alves