11.2 Compilers Other Than f2c

On systems with Fortran compilers other than f2c and g77, code compiled by g77 is not expected to work well with code compiled by the native compiler. (This is true for f2c-compiled objects as well.) Libraries compiled with the native compiler probably will have to be recompiled with g77 to be used with g77-compiled code.

Reasons for such incompatibilities include:

• There might be differences in the way names of Fortran procedures are translated for use in the system's object-file format. For example, the statement `CALL FOO' might be compiled by g77 to call a procedure the linker ld sees given the name `_foo_', while the apparently corresponding statement `SUBROUTINE FOO' might be compiled by the native compiler to define the linker-visible name `_foo', or `_FOO_', and so on.
• There might be subtle type mismatches which cause subroutine arguments and function return values to get corrupted.

  This is why simply getting g77 to transform procedure names the same way a native compiler does is not usually a good idea—unless some effort has been made to ensure that, aside from the way the two compilers transform procedure names, everything else about the way they generate code for procedure interfaces is identical.

• Native compilers use libraries of private I/O routines which will not be available at link time unless you have the native compiler—and you would have to explicitly ask for them.

  For example, on the Sun you would have to add `-L/usr/lang/SCx.x -lF77 -lV77' to the link command.