[Bug 1618799] Re: gfortran and equivalence produces internal compiler error

[Matthias Klose]

(gdb) bt
#0  0x0000000000643a8e in ?? ()
#1  0x0000000000643898 in ?? ()
#2  0x00000000006427f2 in ?? ()
#3  0x0000000000d4e6fe in gfc_generate_function_code(gfc_namespace*) ()
#4  0x0000000000d2c6b6 in gfc_parse_file() ()
#5  0x00000000011e6166 in ?? ()
#6  0x0000000001236373 in ?? ()
#7  0x0000000000d0ca69 in toplev::main(int, char**) ()
#8  0x0000000000d0cdba in main ()

this is fixed in gcc-5 in zesty and in gcc-6.


** Changed in: gcc-5 (Ubuntu)
   Importance: Undecided => Medium

** Changed in: gcc-5 (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1618799

Title:
  gfortran and equivalence produces internal compiler error

Status in gcc-5 package in Ubuntu:
  Confirmed

Bug description:
  Hello,

  I encountered an internal compiler error with gfortran (Ubuntu
  5.4.0-6ubuntu1~16.04.2) and the error message suggests to submit a GCC
  bug report:

  -----------
  gfortran gfortran_test_equivalence.f90
  gfortran_test_equivalence.f90:14:0:

   PROGRAM test
   1
  internal compiler error: Segmentation fault
  Please submit a full bug report,
  with preprocessed source if appropriate.
  See <file:///usr/share/doc/gcc-5/README.Bugs> for instructions.
  -----------

  I was able to boil down the problem to the following simple code:

  -----------
  MODULE test_equivalence
    REAL, PRIVATE, DIMENSION(100) :: array1
    REAL, PRIVATE, DIMENSION(100) :: array2
    EQUIVALENCE(array1(1),array2(1))
  END MODULE test_equivalence

  MODULE mymodule
    USE test_equivalence
    ! declare a local variable with the same name as the (private!)
    ! variable in module test_equivalence:
    REAL, DIMENSION(:), ALLOCATABLE :: array1
  END MODULE mymodule

  PROGRAM test
    USE mymodule
  END PROGRAM test
  -----------

  AFAICS, this code is correct Fortran90. The private arrays in MODULE
  test_equivalence should be separate from those in MODULE mymodule.
  However, it seems that gfortran turns array1 into a public variable
  because of the EQUIVALENCE statement.

  Asking a colleague, I was told that the bug also occurs in version 6.2.0
  but not in 4.3.4, 4.8.1, and 4.9.4.

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