xmake-fortran

name	xmake-fortran
description	Use when building Fortran projects with xmake — binary/library targets with `.f`/`.f90`/`.for` sources, gfortran or Intel Fortran (`ifort`) toolchain selection, and mixing Fortran with C interoperability.

Building Fortran with Xmake

Xmake supports Fortran since v2.3.6 via gfortran, and Intel Fortran (ifort) since v2.3.8.

1. Minimal project

xmake create -l fortran -t console hello
cd hello
xmake run

add_rules("mode.debug", "mode.release")

target("hello")
    set_kind("binary")
    add_files("src/*.f90")

Recognized extensions: .f, .F, .f90, .F90, .f95, .F95, .f03, .F03, .f08, .F08, .for, .FOR. The uppercase variants get preprocessed.

2. Target kinds

target("app")       set_kind("binary")
target("mylib")     set_kind("static")
target("mydyn")     set_kind("shared")

3. Compiler selection

xmake f --toolchain=gfortran              # default gfortran
xmake f --toolchain=ifort                 # Intel Fortran
xmake f --toolchain=ifx                   # Intel oneAPI LLVM-based Fortran

Pin a specific install with --sdk=/opt/intel/oneapi.

4. Flags

target("app")
    add_files("src/*.f90")
    add_fcflags("-O3", "-ffree-form")           -- gfortran flags
    add_ldflags("-lm")

add_fcflags = Fortran compiler flags.

5. Mixing Fortran with C

target("solver")
    set_kind("static")
    add_files("src/*.f90", "src/*.c")
    add_includedirs("include", {public = true})

target("app")
    set_kind("binary")
    add_files("src/main.cpp")
    add_deps("solver")
    set_languages("c++17")

Use iso_c_binding on the Fortran side and extern "C" on the C++ side. Xmake handles the link step — gfortran's runtime is added automatically when Fortran objects are present.

6. Modules (Fortran modules, not C++ modules)

Fortran module/end module produces .mod files. Xmake tracks them automatically for dependency ordering — list source files in add_files in any order; xmake scans USE statements.

Pitfalls

• Fixed-form vs free-form. .f/.for default to fixed form (columns matter); .f90+ default to free form. Flag overrides work per-file if needed.
• .mod leaking across targets. Each target has its own module cache. Share modules by linking the static/shared library and letting xmake propagate the -I path.
• Intel compiler flag dialect. ifort and ifx differ from gfortran in many flag names. Gate with is_toolchain.
• Mixing Fortran and C++ without a C intermediate. Fortran↔C++ name mangling is messy; always bridge through a C layer.

When to branch out

• Target basics → xmake-targets
• Cross-compile → xmake-cross-compilation
• Mixing with C/C++ → xmake-targets