[Bug fortran/55069] New: [4.7/4.8 Regression] TRIM incorrectly optimized out for assignment to allocatable string

[quantheory at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55069



             Bug #: 55069

           Summary: [4.7/4.8 Regression] TRIM incorrectly optimized out

                    for assignment to allocatable string

    Classification: Unclassified

           Product: gcc

           Version: 4.7.3

            Status: UNCONFIRMED

          Severity: minor

          Priority: P3

         Component: fortran

        AssignedTo: unassig...@gcc.gnu.org

        ReportedBy: quanthe...@gmail.com





With -ffrontend-optimize turned on, in the following assignments, "str" is

allocated to a larger size than it should have:



  character(len=2) :: blah

  character(len=:), allocatable :: str



  blah = "a"



  ! With -O, str will be set to "a ", else str == "a"

  str = trim(blah)



  ! No effect with -O

  str = trim(str)



  ! With -O str will be set to "ba ", else "ba"

  str = "b"//trim(blah)



  ! This trim cannot be optimized out, so it yields "ab" either way.

  str = trim(blah)//"b"





This problem with allocatable strings is noted in the original enhancement

proposal (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40628), but apparently

not addressed yet?