[Bug c/108753] New: '-Wduplicated-cond' doesn't diagnose duplicated subexpressions

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108753

            Bug ID: 108753
           Summary: '-Wduplicated-cond' doesn't diagnose duplicated
                    subexpressions
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tschwinge at gcc dot gnu.org
                CC: mpolacek at gcc dot gnu.org
  Target Milestone: ---

Created attachment 54448
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54448&action=edit
pr.c

Shouldn't '-Wduplicated-cond' be able to diagnose the XFAILed duplicated
subexpressions?  (In the attached 'pr.c', 'f2' is reduced from real-world
code.)

This works:

    if (a == 5) // { dg-note {previously used here} }
      return 30;
    else if (a == 5) // { dg-warning {duplicated 'if' condition} }
      return 40;

..., but this and similar ones don't:

    if (a == 5) // { dg-note {previously used here} TODO { xfail *-*-* } }
      return 30;
    else if (a == 5 // { dg-warning {duplicated 'if' condition} TODO { xfail
*-*-* } }
             || a == 6)
      return 40;