[Bug testsuite/80221] Contrib script to rewrite testcase from absolute to relative line numbers

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80221

--- Comment #11 from Martin Sebor <msebor at gcc dot gnu.org> ---
That would work too.  Yet another possibility is to surround all the dg-message
directives that apply to the same line in a pair of new directives (analogously
to dg-{begin,end}-multiline-output):

    foobar;
    /* { dg-begin-same-line-output .-1 }
       ...
       { dg-warning "warning for foobar" }
       ...
       { dg-message "note for foobar" }
       ...
       { dg-error "error for foobar" }
       ...
       { dg-end-same-line-output }  */