External Libraries

FoBiS.py supports two approaches for linking external libraries: direct linking by full path, and indirect linking by name with a library search path.

Direct linking (full path)

Use -libs to specify the full path to one or more library files:

fobis build -libs /path/to/foo.a /path/to/bar.so

Multiple libraries can be listed separated by spaces.

Indirect linking (library name + search path)

Use -ext_libs together with -dlib/--lib_dir to link by library base-name:

fobis build -ext_libs foo sao -dlib /path/to/my_libraries/

This is equivalent to passing -L/path/to/my_libraries/ -lfoo -lsao to the linker. The library files in lib_dir must follow the lib<name>.[a|so] naming convention.

Libraries that contain Fortran modules

When an external library exposes Fortran modules (.mod files), the compiler needs to find those files during the compile phase. Add the directory containing the .mod files with -i/--include:

fobis build -libs /path/to/libmylib.a -i /path/to/mylib/mod/

fobos options

All library options are available in a fobos file:

[default]
compiler = gnu
cflags   = -c -O2
libs     = /path/to/foo.a /path/to/bar.a
ext_libs = baz qux
lib_dir  = /path/to/libs/
include  = /path/to/libs/mod/

Custom archiver and ranlib

By default FoBiS.py uses the system ar -rcs to create static libraries and ranlib to index them. Alternative toolchains — LLVM (llvm-ar, llvm-ranlib), Intel, AMD AOCC, cross-compilation environments — can be selected with three options:

Option	Default	Description
-ar AR	ar	Archiver executable
-arflags ARFLAGS	-rcs	Archiver flags
-ranlib RANLIB	ranlib	Ranlib executable; set to empty string to skip

LLVM toolchain example

fobis build -t src/mylib.f90 -mklib static -ar llvm-ar -ranlib llvm-ranlib

llvm-ar updates the symbol table internally, so the ranlib step can be skipped entirely:

fobis build -t src/mylib.f90 -mklib static -ar llvm-ar -ranlib ""

fobos example

[llvm-static]
compiler = custom
fc       = flang-new
ar       = llvm-ar
ranlib   = llvm-ranlib
mklib    = static
target   = src/mylib.f90
output   = libmylib.a
build_dir = ./build/
obj_dir   = ./obj/
mod_dir   = ./mod/

Volatile libraries

Libraries that may change between builds (e.g. CI-generated artifacts) can be declared as volatile. FoBiS.py saves an MD5 hash on first use and forces a full recompile whenever the library file changes.

See Volatile Libraries for details.

Summary of library options

Option	Description
-libs PATH…	External libraries — full paths
-vlibs PATH…	Volatile external libraries — full paths
-ext_libs NAME…	External libraries — by name (linker path)
-ext_vlibs NAME…	Volatile external libraries — by name
-dlib DIR…, --lib_dir DIR…	Library search directories
-i DIR…, --include DIR…	Include directories (for .mod and .h files)