[PATCH 2/2] libcpp: Avoid remapping filenames within directives

[Jeff Law]

On 8/17/22 06:15, Richard Purdie via Gcc-patches wrote:
> Code such as:
#include __FILE__
>
> can interact poorly with file-prefix-map options when cross compiling. In
> general you're after to remap filenames for use in target context but the
> local paths should be used to find include files at compile time. Ingoring
> filename remapping for directives is one way to avoid such failures.
>
> libcpp/ChangeLog:
>
>      * macro.cc (_cpp_builtin_macro_text): Don't remap filenames within directives

So I went back and reviewed the old PR which introduced this code.  It 
was actually the Yocto project that got this code in to begin with :-)  
There wasn't really any discussion AFAICT about whether or not to remap 
in directives that I saw in the PR.


ISTM that given the change in behavior, we should probably document that 
we don't remap in directives.  Probably doc/invoke.texi.

With suitable documentation, this should be fine.  It seems like it 
ought to be independent of the first patch in this series which adds 
support for remapping relative paths.


jeff