10 Migrating to HP Fortran

A major feature of HP Fortran is its compatibility with standard-conforming HP FORTRAN 77. Both source files and object files from existing HP FORTRAN 77 applications can be migrated to HP Fortran with comparatively little effort. However, some command-line options and nonstandard extensions in HP FORTRAN 77 programs may have to be changed to compile and execute correctly under HP Fortran.

To smooth the migration path, HP Fortran includes a number of extensions that are compatible with HP FORTRAN 77. HP Fortran also includes extensions that are designed to ease the job of porting applications from other vendors' Fortran dialects. For a summary list of all HP Fortran extensions, see the HP Fortran Programmer's Reference. For information about porting other vendors’ Fortran programs to HP Fortran, see “Porting to HP Fortran” (page 141).

This chapter discusses the following topics:

•Incompatibilities with HP FORTRAN 77

•Migration issues

•Approaches to migration

Incompatibilities with HP FORTRAN 77

The following sections describe known incompatibilities between HP Fortran and HP FORTRAN

77.These incompatibilities include both source-level and object-code incompatibilities. A subset of these are detected by the HP fid tool, which is described in “Fortran incompatibilities detector” (page 139).

Compiler limits

HP Fortran supports format field widths up to 32767. HP FORTRAN 77 allows format field widths up to 2147483639, which is close to 2*31.

Command-line options not supported

The HP Fortran compiler does not accept the f77command-line options listed in Table 10-1, and the f77 options listed in Table 10-2 have been renamed for f90. In addition, HP Fortran code may not link correctly with HP FORTRAN 77 object files that were compiled with these options; see “Object code issues” (page 138).

Table 37 f77 options not supported by f90

+800

+e

+N

+A

+I[24]

+R

+A3

+L8

+U

+A8

+LA

-w66-

+apollo

-lisam

 

+E

+mr

 

Table 38 f77 options replaced by f90 options

f77 option

f90 replacement

 

 

-A

+langlvla

 

 

-a

+langlvla

 

 

+autodblpad

+autodbla

 

 

+B

+escape

 

 

Incompatibilities with HP FORTRAN 77 131