[Bug bootstrap/124602] New: [9..16] regression: [unexpected EOF while looking for matching `"'] while /bin/sh is parsing $(BASE_FLAGS_TO_PASS)

[zack+gcc at buhman dot org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124602

            Bug ID: 124602
           Summary: [9..16] regression: [unexpected EOF while looking for
                    matching `"'] while /bin/sh is parsing
                    $(BASE_FLAGS_TO_PASS)
           Product: gcc
           Version: 15.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zack+gcc at buhman dot org
  Target Milestone: ---

Created attachment 63994
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=63994&action=edit
make.log (Makefile trivially edited with `@` removed on line Makefile:11672)

Superficially, the error is:

/usr/bin/sh: -c: line 7: unexpected EOF while looking for matching `"'

This appears to be caused by the combined evaluation of both $(HOST_EXPORTS)
and $(BASE_FLAGS_TO_PASS).

I do not understand why, but it appears one of the values of one of the
variables in HOST_EXPORTS escapes shell quoting in one of the expressions in
BASE_FLAGS_TO_PASS.

This affects every `all-stage1-*:` target that uses the same
$(HOST_EXPORTS)/$(MAKE)/$(BASE_FLAGS_TO_PASS) pattern.