[Bug c++/109988] New: -iwithprefix doesn't add folder to end of search list

[Bug c++/109988] New: -iwithprefix doesn't add folder to end of search list

[ivan.lazaric.gcc at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109988

            Bug ID: 109988
           Summary: -iwithprefix doesn't add folder to end of search list
           Product: gcc
           Version: 11.3.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ivan.lazaric.gcc at gmail dot com
  Target Milestone: ---

```
echo | g++ -iprefix "./" -iwithprefix "."  -E -v -
```

Snippet of output:
```
#include <...> search starts here:
 ./.
 /usr/lib/gcc/x86_64-linux-gnu/11/include
 /usr/local/include
 /usr/include/x86_64-linux-gnu
 /usr/include
End of search list.
```

Issue is that "./." is at the front of the list, should be at bottom.

Snippet of `man g++`:
```
-iprefix prefix
           Specify prefix as the prefix for subsequent -iwithprefix options. 
If the prefix
           represents a directory, you should include the final /.

       -iwithprefix dir
       -iwithprefixbefore dir
           Append dir to the prefix specified previously with -iprefix, and add
the
           resulting directory to the include search path.  -iwithprefixbefore
puts it in
           the same place -I would; -iwithprefix puts it where -idirafter
would.
```

^ implying `-iwithprefix` should behave like `-idirafter`

`echo | g++ -idirafter "./." -E -v -`:
```
#include <...> search starts here:
 /usr/lib/gcc/x86_64-linux-gnu/11/include
 /usr/local/include
 /usr/include/x86_64-linux-gnu
 /usr/include
 ./.
End of search list.
```

Related to: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=34502

[Bug c++/109988] -iwithprefix doesn't add folder to end of search list

[ivan.lazaric.gcc at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109988

--- Comment #1 from Ivan Lazaric <ivan.lazaric.gcc at gmail dot com> ---
In `gcc/c-family/c-opts.cc`:
```
    case OPT_iwithprefix:
      add_prefixed_path (arg, INC_SYSTEM);
      break;
```

Should `INC_SYSTEM` actually be `INC_AFTER` ?

[Bug preprocessor/109988] -iwithprefix doesn't add folder to end of search list

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109988

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2023-05-26
           Keywords|                            |documentation
          Component|c++                         |preprocessor
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
It has been the same as -isystem since at least r0-21114-g0b22d65c9a10ce (March
1999).
The documentation was changed (added to) at r0-35796-gf3c9b8530c78ce (June
2001) to specify the same as -idirafter even though the implementation was
something different ....

I don't know what the correct thing to do really since it has been almost 22
years of having the documentation not match the implementation ...
Maybe just update the documentation ....

Confirmed either way.

[Bug preprocessor/109988] -iwithprefix doesn't add folder to end of search list

[ivan.lazaric.gcc at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109988

--- Comment #3 from Ivan Lazaric <ivan.lazaric.gcc at gmail dot com> ---
Note that clang has the same flags and behaves according to the documentation,
might be some value in matching it.

If it's considered too breaking of a change, I would recommend introducing a
-iwithprefixafter flag that would add the directory to the end of the include
search list.