[Bug fortran/56136] New: Compiler fails when code contains lhs-reallocation of an object with overloaded (elemental) Assignment operator

[alipasha.celeris at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56136

             Bug #: 56136
           Summary: Compiler fails when code contains lhs-reallocation of
                    an object with overloaded (elemental) Assignment
                    operator
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: fortran
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: alipasha.celeris@gmail.com


Created attachment 29299
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29299
The code that causes compiler crash

Upon compiling the following code using GNU Fortran (GCC) 4.8.0 20130128
(experimental):

      MODULE A_TEST_M
        TYPE :: A_TYPE
          CONTAINS
          GENERIC :: ASSIGNMENT (=) => ASGN_A
          PROCEDURE, PRIVATE :: ASGN_A
        END TYPE

        CONTAINS

        ELEMENTAL SUBROUTINE ASGN_A (A, B)
          CLASS (A_TYPE), INTENT (INOUT) :: A
          CLASS (A_TYPE), INTENT (IN) :: B
        END SUBROUTINE
      END MODULE A_TEST_M

      PROGRAM ASGN_REALLOC_TEST
        USE A_TEST_M
        TYPE (A_TYPE), ALLOCATABLE :: A(:)

        ALLOCATE (A(100))
        A(1:50) = A(51:100)
        A = A(1:50)
      END PROGRAM

placed in file "asgn_realloc_test.f" with compile call:

      user@machine:~/../quicktest$ gfortran asgn_realloc_test.f

causes compiler to crash with the following messages: 

asgn_realloc_test.f: In function ‘test’:
asgn_realloc_test.f:22:0: internal compiler error: in gfc_conv_variable, at
fortran/trans-expr.c:1658
         A = A(1:50)
 ^
0x5db000 gfc_conv_variable
    ../.././gcc/fortran/trans-expr.c:1658
0x5d75ca gfc_conv_expr(gfc_se*, gfc_expr*)
    ../.././gcc/fortran/trans-expr.c:6263
0x5dbef3 gfc_conv_expr_reference(gfc_se*, gfc_expr*)
    ../.././gcc/fortran/trans-expr.c:6357
0x5dc2fa gfc_conv_derived_to_class(gfc_se*, gfc_expr*, gfc_typespec,
tree_node*, bool, bool)
    ../.././gcc/fortran/trans-expr.c:305
0x5d426a gfc_conv_procedure_call(gfc_se*, gfc_symbol*, gfc_actual_arglist*,
gfc_expr*, vec<tree_node*, va_gc, vl_embed>*)
    ../.././gcc/fortran/trans-expr.c:4087
0x5ff84c gfc_trans_call(gfc_code*, bool, tree_node*, tree_node*, bool)
    ../.././gcc/fortran/trans-stmt.c:491
0x5a4663 trans_code
    ../.././gcc/fortran/trans.c:1511
0x5cb57e gfc_generate_function_code(gfc_namespace*)
    ../.././gcc/fortran/trans-decl.c:5390
0x564390 translate_all_program_units
    ../.././gcc/fortran/parse.c:4463
0x564390 gfc_parse_file()
    ../.././gcc/fortran/parse.c:4677
0x59fe75 gfc_be_parse_file
    ../.././gcc/fortran/f95-lang.c:189
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.

Note that the line before the reallocating assignment (A(1:50) = A(51:100))
will not cause errors.

Compiler was configured using:

      sudo LIBRARY_PATH=/usr/lib/x86_64-linux-gnu ./configure
--enable-languages=c,c++,fortran --enable-libgomp --enable-lto --enable-gold
--with-plugin-ld=/usr/bin/gold

on Ubuntu:

      Release 12.04 (precise) 64-bit
      Kernel Linux 3.2.0-36-generic