[gcc r13-4149] libcpp: Avoid remapping filenames within directives

[Jeff Law <law@gcc.gnu.org>]

https://gcc.gnu.org/g:11543b27fe16d81ca5483ecb98ec7a5b2426e0c0

commit r13-4149-g11543b27fe16d81ca5483ecb98ec7a5b2426e0c0
Author: Richard Purdie <richard.purdie@linuxfoundation.org>
Date:   Fri Nov 18 13:13:50 2022 -0700

    libcpp: Avoid remapping filenames within directives
    
    Code such as:
    
     #include __FILE__
    
    can interact poorly with the *-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 allows avoiding such failures.
    
    Fix this to improve such usage and then document this against file-prefix-map
    (referenced by the other *-prefix-map options) to make the behaviour clear
    and defined.
    
    libcpp/ChangeLog:
    
            * macro.cc (_cpp_builtin_macro_text): Don't remap filenames within
            directives.
    
    gcc/ChangeLog:
    
            * doc/invoke.texi: Document prefix-maps don't affect directives.

Diff:
---
 gcc/doc/invoke.texi | 3 ++-
 libcpp/macro.cc     | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 31d031cd25c..0f6a1833ef1 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -2201,7 +2201,8 @@ any references to them in the result of the compilation as if the
 files resided in directory @file{@var{new}} instead.  Specifying this
 option is equivalent to specifying all the individual
 @option{-f*-prefix-map} options.  This can be used to make reproducible
-builds that are location independent.  See also
+builds that are location independent.  Directories referenced by
+directives are not affected by these options. See also
 @option{-fmacro-prefix-map}, @option{-fdebug-prefix-map} and
 @option{-fprofile-prefix-map}.
 
diff --git a/libcpp/macro.cc b/libcpp/macro.cc
index 8ebf360c03c..7d5a0d0fd2e 100644
--- a/libcpp/macro.cc
+++ b/libcpp/macro.cc
@@ -563,7 +563,7 @@ _cpp_builtin_macro_text (cpp_reader *pfile, cpp_hashnode *node,
 	    if (!name)
 	      abort ();
 	  }
-	if (pfile->cb.remap_filename)
+	if (pfile->cb.remap_filename && !pfile->state.in_directive)
 	  name = pfile->cb.remap_filename (name);
 	len = strlen (name);
 	buf = _cpp_unaligned_alloc (pfile, len * 2 + 3);