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The source code I am working with was originally written for the Intel Fortran compiler so it has preprocessor directives such as
!DEC$ATTRIBUTES DLLEXPORT::MYDLL
!DEC$ATTRIBUTES STDCALL::MYSUBROUTINE
!DEC$ATTRIBUTES ALIAS: 'MYENTRYPOINT'::MYSUBROUTINE

How do I convert this to work with gfortran. Mainly I want to be able to define and name entry points. Right now when I compile with gfortran every subroutine gets exposed as an entry point. Also the entry point name are all lower case with a underscore at the end.

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2 Answers 2

Reset to default
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If you place your routines into a module and put the statement PRIVATE at the top of the module, then PUBLIC :: name1, name2, only the procedures name1 and name2 will be visible outside of the module. This should follow through to a library into which you place object code containing the module. This has been supported since Fortran 90.

As already answered by @janneb, you can use the bind (C,name=X) approach to take complete control of the externally visible name of a procedure, overriding the Fortran name of the procedure. This is part of Fortran 2003 and is supported by numerous compilers for years. A possible issue with the bind(C) approach that it specifies that the calling convention of the routine should be that of C. If this is different from that Fortran and you wish to call these routines from Fortran the complexity increases. Then you would have to specify an interface to inform the calling Fortran routines that they are calling what looks like a C routine. Since people rarely care about the name visible to the linker unless they are calling from C, you might want the C calling convention?

Examples at Private function in Fortran and C/C++, FORTRAN, underscores, and GNU Autotools

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Name visibility in a Fortran module sense and visibility in terms of names exported in object code are essentially unrelated. Consider for example private specific procedures in a public generic interface, or a private function being used in the specification expression for the declaration of the function result of a public function.
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GFortran supports some attributes, see

http://gcc.gnu.org/onlinedocs/gfortran/GNU-Fortran-Compiler-Directives.html#GNU-Fortran-Compiler-Directives

For changing the symbol name, you can use the bind(C, name=) specifier of ISO_C_BINDING, see e.g.

http://gcc.gnu.org/onlinedocs/gfortran/Interoperable-Subroutines-and-Functions.html#Interoperable-Subroutines-and-Functions

http://gcc.gnu.org/onlinedocs/gfortran/Interoperable-Global-Variables.html#Interoperable-Global-Variables

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4 Comments

I have tried adding !GCC$ ATTRIBUTES STDCALL::MYSUBROUTINE but the compiled library still lists every single subroutine as an entry point.
@Reflux: Yes, the attributes to change the calling convention change the calling convention and not the visibility of the symbol.
is there a way to change the visibility?
No, unless the DLLIMPORT/EXPORT things do something wrt. that (I'm not a Windows user, so I haven't used those attributes myself).

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