[Bug testsuite/115294] New: [15 regression] dg-additional-files-options change broke several testsuites

["ro at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115294

            Bug ID: 115294
           Summary: [15 regression] dg-additional-files-options change
                    broke several testsuites
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: testsuite
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ro at gcc dot gnu.org
                CC: aoliva at gcc dot gnu.org
  Target Milestone: ---

Between 20240529 (18f477980c8597fe3dca2c2e8bd533c0c2b17aa6) and 20240530
(71899d6b4e18145f005046681208db0137c95ede),
several testsuite results were lost completely.

libatomic, libgomp, libitm, and libphobos are affected.  In each case, the
test logs show a variation of

ERROR: tcl error sourcing
/vol/gcc/src/hg/master/local/libatomic/testsuite/../../gcc/testsuite/lib/gcc-dg.exp.
wrong # args: should be "dg-additional-files-options options source dest type"
    while executing
"check_cached_effective_target $prop {
        eval [list check_no_compiler_messages_nocache $prop] $args
    }"
    (procedure "check_no_compiler_messages" line 2)
    invoked from within
"check_no_compiler_messages lto object {
       void foo (void) { }
    } "-flto""
    (procedure "check_effective_target_lto" line 11)
    invoked from within
"check_effective_target_lto"
    invoked from within
"if [info exists TORTURE_OPTIONS] {
    set DG_TORTURE_OPTIONS $TORTURE_OPTIONS
} else {
    # It is theoretically beneficial to group all of the O2/O3..."
    (file
"/vol/gcc/src/hg/master/local/libatomic/testsuite/../../gcc/testsuite/lib/gcc-dg.exp"
line 82)
    invoked from within
"source
/vol/gcc/src/hg/master/local/libatomic/testsuite/../../gcc/testsuite/lib/gcc-dg.exp"
    ("uplevel" body line 1)
    invoked from within
"uplevel #0 source
/vol/gcc/src/hg/master/local/libatomic/testsuite/../../gcc/testsuite/lib/gcc-dg.exp"
    invoked from within
"catch "uplevel #0 source $file""

I'm seeing this on both i386-pc-solaris2.11 and x86_64-pc-linux-gnu; most
likely
this happens everywhere.