[Bug debug/47919] New: -fcompare-debug failure with custom flags

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47919

           Summary: -fcompare-debug failure with custom flags
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zsojka@seznam.cz
                CC: aoliva@gcc.gnu.org
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu


Created attachment 23486
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23486
auto-reduced testcase

Compiler output:
$ gfortran -fgcse -frerun-cse-after-loop -O -funroll-loops
-fno-tree-loop-optimize -fno-tree-ter -fno-web -fcompare-debug
testcase-min1.f08 -save-temps
gfortran: error: testcase-min1.f08: -fcompare-debug failure (length)

(interestingly, -funroll-loops is documented to imply -frerun-cse-after-loop,
bug explicit -frerun-cse-after-loop is needed to reproduce)

Tested revisions:
r170522 - fail
4.5 r170013 - fail