[Bug preprocessor/110558] __has_include argument expansion results in unexpected filename

[lhyatt at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110558

Lewis Hyatt <lhyatt at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-12-11
                 CC|                            |lhyatt at gcc dot gnu.org

--- Comment #4 from Lewis Hyatt <lhyatt at gcc dot gnu.org> ---
__has_include was added I think in GCC 5, and re-implemented in GCC 10, but
this issue with padding in the macro expansion was never handled correctly it
seems. I am testing the below which will fix it, will submit it soon with a
testcase. Not sure if it would be eligible for backport or not, but it would
apply cleanly to all active branches also.

diff --git a/libcpp/macro.cc b/libcpp/macro.cc
index 6f24a9d6f3a..15140c60023 100644
--- a/libcpp/macro.cc
+++ b/libcpp/macro.cc
@@ -398,6 +398,8 @@ builtin_has_include (cpp_reader *pfile, cpp_hashnode *op,
bool has_next)
               NODE_NAME (op));

   pfile->state.angled_headers = true;
+  const auto sav_padding = pfile->state.directive_wants_padding;
+  pfile->state.directive_wants_padding = true;
   const cpp_token *token = cpp_get_token_no_padding (pfile);
   bool paren = token->type == CPP_OPEN_PAREN;
   if (paren)
@@ -406,6 +408,7 @@ builtin_has_include (cpp_reader *pfile, cpp_hashnode *op,
bool has_next)
     cpp_error (pfile, CPP_DL_ERROR,
               "missing '(' before \"%s\" operand", NODE_NAME (op));
   pfile->state.angled_headers = false;
+  pfile->state.directive_wants_padding = sav_padding;

   bool bracket = token->type != CPP_STRING;
   char *fname = NULL;