(automake-1.16.info)Mixing Fortran 77 With C and C++

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8.14.3 Mixing Fortran 77 With C and C++
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Automake currently provides _limited_ support for creating programs and
shared libraries that are a mixture of Fortran 77 and C and/or C++.
However, there are many other issues related to mixing Fortran 77 with
other languages that are _not_ (currently) handled by Automake, but that
are handled by other packages(1).

   Automake can help in two ways:

  1. Automatic selection of the linker depending on which combinations
     of source code.

  2. Automatic selection of the appropriate linker flags (e.g., ‘-L’ and
     ‘-l’) to pass to the automatically selected linker in order to link
     in the appropriate Fortran 77 intrinsic and run-time libraries.

     These extra Fortran 77 linker flags are supplied in the output
     variable ‘FLIBS’ by the ‘AC_F77_LIBRARY_LDFLAGS’ Autoconf macro.
     Note: Fortran Compiler Characteristics.

   If Automake detects that a program or shared library (as mentioned in
some ‘_PROGRAMS’ or ‘_LTLIBRARIES’ primary) contains source code that is
a mixture of Fortran 77 and C and/or C++, then it requires that the
macro ‘AC_F77_LIBRARY_LDFLAGS’ be called in ‘configure.ac’, and that
either ‘$(FLIBS)’ appear in the appropriate ‘_LDADD’ (for programs) or
‘_LIBADD’ (for shared libraries) variables.  It is the responsibility of
the person writing the ‘Makefile.am’ to make sure that ‘$(FLIBS)’
appears in the appropriate ‘_LDADD’ or ‘_LIBADD’ variable.

   For example, consider the following ‘Makefile.am’:

     bin_PROGRAMS = foo
     foo_SOURCES  = main.cc foo.f
     foo_LDADD    = libfoo.la $(FLIBS)

     pkglib_LTLIBRARIES = libfoo.la
     libfoo_la_SOURCES  = bar.f baz.c zardoz.cc
     libfoo_la_LIBADD   = $(FLIBS)

   In this case, Automake will insist that ‘AC_F77_LIBRARY_LDFLAGS’ is
mentioned in ‘configure.ac’.  Also, if ‘$(FLIBS)’ hadn’t been mentioned
in ‘foo_LDADD’ and ‘libfoo_la_LIBADD’, then Automake would have issued a
warning.

How the Linker is Chosen

Automatic linker selection

   ---------- Footnotes ----------

   (1) For example, the cfortran package
(http://www-zeus.desy.de/~burow/cfortran/) addresses all of these
inter-language issues, and runs under nearly all Fortran 77, C and C++
compilers on nearly all platforms.  However, ‘cfortran’ is not yet Free
Software, but it will be in the next major release.