https://gcc.gnu.org/bugzilla/show_bug.cgi?id=127940
--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Jason Merrill <[email protected]>: https://gcc.gnu.org/g:a70f7ee802d9adaf3727d392e7be2f5eacba78ca commit r17-6023-ga70f7ee802d9adaf3727d392e7be2f5eacba78ca Author: Jason Merrill <[email protected]> Date: Sat Nov 7 15:44:28 2026 -0500 libcpp: don't assume an alternate header exists [PR127940] Here when trying to translate a standard library #include into import <bits/stdc++.h> we gave a hard error if stdc++.h did not exist, which breaks using an alternate standard library. Let's make the check fail silently by using the __has_include mode. It's awkward to add a test for this because dejagnu always adds the libstdc++ headers so an -I in the testcase options is never searched; I had to override ALWAYS_CXXFLAGS for this one testcase in module.exp. PR c++/127940 libcpp/ChangeLog: * files.cc (_cpp_stack_include): Use _cpp_FFK_HAS_INCLUDE to check for an alternate header. gcc/testsuite/ChangeLog: * g++.dg/modules/inc-xlate-5.C: New test. * g++.dg/modules/dummy-stdlib/stdexcept: For new test. * g++.dg/modules/modules.exp: Override ALWAYS_CXXFLAGS for it.
