FIX: Mixed Type Expressions Cause F2124: Code Generation Error

MS-DOS              | OS/2

The information in this article applies to:

• Microsoft FORTRAN for MS-DOS, versions 4.0, 4.1, 5.0, and 5.1
• Microsoft FORTRAN for OS/2, versions 4.1, 5.0, 5.1

SYMPTOMS

Using Microsoft FORTRAN 5.0 or 5.1 to compile a program that uses mixed data types in an expression can cause the compiler to hang the machine under DOS, generate a protection violation under OS/2, or result in the following error:

   F2124: Code Generation Error

   fatal error F1001: Internal Compiler Error
               (compiler file '@(#)mactab.c:1.2', line 663)

In some cases, the error is suppressed by optimization (for example, using /Ox, or by not using the /Od compiler option during compilation). In other cases, the problem is more severe when using optimization.

CAUSE

The following sample programs illustrate the problems.

Using COMPLEX and REAL Data Types

       subroutine x(a,c,d)
       complex*16 a, d, b
       b = (1.0,0)
       a = a * (-b) * c * d
       return
       end

Using COMPLEX instead of COMPLEX*16 will generate the following error:

   fatal error F1001: Internal Compiler Error
               (compiler file '@(#)mactab.c:1.2', line 663)

Using REAL and INTEGER Data Types

       real a,b,c
       b = 1.0
       c = 2.0
       a = 4 * b * (-1) * c
       end

   F2124: Code Generation Error

RESOLUTION

Explicitly converting the type of all of the variables or constants to the same type will prevent the errors, as illustrated by the following sample programs:

Using COMPLEX and REAL Data Types

       subroutine x(a,c,d)
       complex*16 a, d, b
       b = (1.0,0)
       a = a * (-b) * dcmplx(c) * d    ! Convert real data type to
                                       ! double precision complex
                                       ! data type to match other
                                       ! types.
       return
       end

Using REAL and INTEGER Data Types

       real a,b,c
       b = 1.0
       c = 2.0
       a = 4.0 * b * (-1.0) * c        ! Convert integer constants
                                       ! to real constants to match
                                       ! other types.
       end

STATUS

Microsoft has confirmed this to be a problem in Microsoft FORTRAN versions 5.0 and 5.1 for MS-DOS and OS/2. This problem was corrected in FORTRAN PowerStation.