fobis

name

fobis

description

Expert knowledge of FoBiS.py (Fortran Building System for poor men) — an automatic Fortran build tool that resolves module dependency hierarchies without manual makefiles. Use this skill whenever the user asks about: writing or editing a fobos file; running any fobis subcommand (build, clean, fetch, install, rule, doctests, scaffold, check, test, coverage, tree, introspect, run, cache, commit); Fortran project build configuration; diagnosing FoBiS build errors; adding GitHub dependencies to a Fortran project; the --json output flag; multi-mode builds; templates; variables and varsets; library builds (static/shared); MPI/OpenMP/coarray/OpenMP-offload builds; feature flags and conditional compilation; build profiles; the build cache; external-library auto-detection and pkg-config (.pc) generation; multi-target builds; convention-based source auto-discovery; the lock file and semver dependency constraints; the first-class test runner and coverage reports; LLM-assisted commit messages; the cflags-heritage feature; parallel compilation; or any question that mentions "fobos", "FoBiS", or building Fortran projects. When in doubt, trigger this skill — it is better to consult it unnecessarily than to miss it.

FoBiS.py Expert Knowledge

FoBiS.py is a CLI tool that auto-builds modern Fortran projects by parsing source files and resolving inter-module dependency hierarchies. It eliminates manual makefile dependency tracking.

Currency: This reflects FoBiS.py 3.8.x (15-subcommand Typer CLI). The canonical CLI binary is fobis; FoBiS.py remains a legacy alias. Flags use double-dash long form (--mode, --ex, --ls, --lmodes). Legacy single-dash multi-char forms (-mode, -ex) are auto-normalized but should not be written in new scripts/docs.

Core Concept

FoBiS.py scans your source directories, parses every .f90 (and related) file for module, use, and include statements, builds a dependency graph, and compiles in the correct order. The only file you need is fobos — the project configuration file (INI format, auto-loaded from the current directory).

---

CLI Commands

15 subcommands, grouped by purpose. Every command except commit and the cache/scaffold sub-apps accepts --fobos/-f <path> (non-default fobos file) and --mode <name> (select a build mode).

Build & run

fobis build              # compile and link (the default workhorse)
fobis run [TARGET] [-- ARGS...]   # build if needed, then execute (passthrough args after --)
fobis test [-- ARGS...]  # discover, build, run Fortran test programs (passthrough)
fobis coverage           # generate coverage reports from instrumented runs
fobis check              # validate the dependency graph without building

• build: every compiler/dir/file/preproc option plus profiles, features, varsets, cache, multi-target, hooks, externals — see the fobos option table below. Supports --json.
• run: positional TARGET optional (defaults to the mode's output). --no-build, --dry-run, --example NAME. Args after -- are forwarded to the executed binary.
• test: --suite NAME, --filter GLOB, --timeout SEC (default 60), --no-build, --list, --coverage. Args after -- forwarded to test binaries.
• coverage: --format html|xml|text|all (repeatable, default html), --output-dir, --source-dir, --exclude GLOB, --fail-under N, --tool gcovr|lcov.
• check: --strict (warnings → errors, exit 1), --varset, --src.

Project

fobis fetch              # clone + build GitHub deps from the [dependencies] section
fobis install [REPO]     # install built local files, or clone+build+install a GitHub repo
fobis introspect         # emit machine-readable project metadata (JSON/TOML)
fobis tree               # print the resolved inter-project dependency tree
fobis cache <list|clean|show>   # manage the build-artifact cache

• fetch: --deps-dir, --update, --no-build, --frozen (enforce lockfile), --no-cache. Supports --json.
• install: positional REPO (user/repo or full URL) optional. Local mode (no REPO) installs previously built artifacts to --prefix/-p (default ./) under --bin/--lib/--include. GitHub mode: --branch, --tag, --rev, --update, --no-build, --deps-dir (default ~/.fobis/).
• introspect: --sources, --compiler, --dependencies, --targets, --include-dirs, --buildoptions, --projectinfo, --varsets, --all, --write (to .fobis-info/), --format json|toml, --varset.
• tree: --depth/-d N, --no-dedupe.
• cache list (--cache-dir); cache clean --older-than N (--cache-dir); cache show DEP_NAME (positional required, --cache-dir).

Utilities

fobis clean              # remove compiled objects/mods (use carefully)
fobis rule --ex <name>   # run a custom shell rule from fobos (and intrinsic rules)
fobis doctests           # build & run inline Fortran doctests
fobis scaffold <status|sync|init|list>   # manage project boilerplate from bundled templates
fobis commit             # generate a Conventional-Commits message via a local LLM

• clean: --only-obj and --only-target (mutually exclusive). Supports --json.
• rule: --ex/--execute NAME, --ls/--list, plus intrinsic rules: --get KEY, --get-output-name, --ford project.md, --gcov-analyzer DIR [SUMMARY], --is-ascii-kind-supported, --is-ucs4-kind-supported, --is-float128-kind-supported.
• doctests: --keep-volatile-doctests, --exclude-from-doctests, --doctests-preprocessor cpp|fpp.
• scaffold: subcommands status (--strict for CI), sync (--dry-run, --yes/-y), init (--yes/-y), list. All take --fobos/-f; status/sync take --files GLOB. Manages four artifact categories — verbatim (SHA-256 synced), templated ({{VAR}}-rendered; reads the optional fobos [scaffold] section, e.g. apt_packages), init-only (created once, project-owned, e.g. docs/guide/contributing.md), and symlink (CONTRIBUTING.md → the canonical contributing page; never written through).
• commit: --backend/-b ollama|openai, --url/-u, --model/-m, --max-diff, --refine-passes, --apply (runs git commit), --config/-c, --show-config, --init-config. No --fobos/--mode.

Cross-cutting facts

• --json exists on exactly three commands: build, clean, fetch. (introspect/coverage use --format instead.)
• Passthrough (forward extra args after --): run, test only.
• Global: --version/-v.

---

fobos File Format

INI-format, auto-loaded from the current directory.

Single-mode (simplest)

[default]
compiler  = gnu
cflags    = -c -O2
src       = ./src/
build_dir = ./build/
obj_dir   = ./obj/
mod_dir   = ./mod/
target    = src/main.f90
output    = myapp

The section must be named [default].

Multi-mode

[modes]
modes = debug release

[debug]
compiler  = gnu
cflags    = -c -O0 -g -Wall
build_dir = ./build/debug/
src       = ./src/
target    = src/main.f90
output    = myapp

[release]
compiler  = gnu
cflags    = -c -O3 -march=native
build_dir = ./build/release/
src       = ./src/
target    = src/main.f90
output    = myapp

Select a mode: fobis build --mode release. List modes: fobis build --lmodes. The first listed mode is used when --mode is omitted.

Templates (DRY across modes)

[modes]
modes = debug release

[template-common]
compiler  = gnu
src       = ./src/
target    = src/main.f90
output    = myapp

[debug]
template  = template-common
cflags    = -c -O0 -g -Wall
build_dir = ./build/debug/

[release]
template  = template-common
cflags    = -c -O3
build_dir = ./build/release/

• Mode options override template options.
• Multiple templates: template = template-gnu template-mpi (left wins).
• Templates can chain; circular references are an error.

Variables ($) and varsets

Any $NAME = value in any section (except [varset:*]) joins a global pool and is substituted into the active mode's values. No recursion. A [vars] section is just a conventional home — it is not special-cased; the $-prefix rule is what matters.

[vars]
$SRC    = ./src/
$HDF5   = /opt/hdf5

[debug]
src    = $SRC
cflags = -c -I$HDF5/include

Varsets are named, selectable bundles. Unlike plain $vars, a [varset:NAME] block is applied only when chosen — via --varset name1,name2 (last write wins) or a [varsets] default = ... fallback. Introspect with fobis introspect --varsets.

[varset:local]
$HDF5 = /usr/local/hdf5
[varset:cluster]
$HDF5 = /apps/hdf5/1.14

fobis build --varset cluster

Rules (custom tasks)

[rule-makedoc]
help  = Build documentation
quiet = True
rule  = ford doc/ford.md

[rule-maketar]
help    = Create archive
rule_rm = rm -f project.tar
rule_mk = tar cf project.tar src/ fobos

Run: fobis rule --ex makedoc. List: fobis rule --ls. Use unique keys starting with rule (e.g. rule, rule_rm, rule1) for multiple commands in one rule.

---

Key fobos Options Reference

These are mode keys (valid in [default] or any [mode-X]). A mode recognizes any key whose name matches a build-command option (underscored form).

Option	Description
compiler	gnu, intel, intel_nextgen, g95, opencoarrays-gnu, pgi, ibm, nag, nvfortran, amd, lfortran, custom
fc	Fortran compiler executable (for compiler = custom)
modsw	Module-path compiler switch (for compiler = custom, e.g. -J, -module)
cflags / lflags	Compile / link flags (fobos + CLI are concatenated)
preproc	Preprocessor macro flags (e.g. -DDEBUG)
src	Source root directory/directories (space-separated)
build_dir / obj_dir / mod_dir	Output / object / .mod directories
lib_dir / include	Library / include search directories
target / output	Build target source file / output name
exclude / exclude_dirs	Files / directories to exclude from the build
libs / vlibs	Local library files (full paths) / volatile (md5-tracked, rebuild on change)
ext_libs / ext_vlibs	External libs by name (-l) / volatile by name
dependon	Interdependent fobos projects (path/fobos[:mode])
mklib	Build a library: static or shared
ar / arflags / ranlib	Archiver / flags (-rcs) / ranlib (empty string = skip)
mpi / openmp / openmp_offload / coarray	Enable MPI wrapper / OpenMP / OpenMP offload / coarrays
coverage / profile	Coverage instrumentation / profiling instrumentation
jobs	Parallel compile jobs
cflags_heritage	Persist cflags; force full rebuild when they change
track_build	Record built artifacts for install
build_profile	Named flag preset: debug, release, asan, coverage
features / no_default_features	Activate feature flags / suppress [features] default
varset	Apply named [varset:NAME] bindings
externals	Space-separated external library names to auto-resolve (from [externals])
pkgconfig, pkgconfig_name, pkgconfig_desc, pkgconfig_url, pkgconfig_req, pkgconfig_req_priv	Generate a .pc file
target_filter / examples	Multi-target build controls
pre_build / post_build	Rule names to run before / after the build
no_auto_discover	Disable convention-based source-dir discovery
no_cache / cache_dir	Disable the build cache / override its directory

---

Feature Areas

Build profiles

Built-in compiler-flag presets, selected with build_profile = NAME (fobos) or --build-profile NAME (CLI). Profiles: debug, release, asan, coverage. Tuned per compiler (gnu, intel, intel_nextgen, nvfortran, nag, amd, lfortran); unknown compiler falls back to the gnu preset with a warning. Profile flags are prepended so your explicit cflags win. fobis build --list-profiles prints the full table.

Feature flags (conditional compilation)

[features]
default = prod                 ; reserved key: the default feature set
hdf5    = -DUSE_HDF5            ; leaf feature → flags
prod    = -DNDEBUG @hdf5        ; @hdf5 composes another feature (recursive, cycle-safe)

[feature:gpu]                  ; Tier-2 block with constraints
flags     = -DUSE_GPU
requires  = openmp_offload     ; auto-pulls prerequisites
conflicts = debug              ; hard error if both active

[feature-group:precision]      ; mutual exclusivity
members = single double
default = double               ; with default → exactly-one; without → at-most-one

Resolution order: [features] default (unless --no-default-features) → mode features = ... → CLI --features 'prod,-coverage' (a -name token deactivates). Well-known implicit features need no [features] section and just flip the matching bool: openmp/omp, mpi, coarray, coverage, profile, openmp_offload/omp_offload. Active set is reported in introspect.

External libraries & pkg-config

Declare in [externals] (name = auto | /prefix); activate per mode with externals = name1 name2. auto probes via pkg-config / wrapper scripts for mpi, hdf5, netcdf, blas, openblas, lapack, fftw/fftw3; a prefix probes <prefix>/include and <prefix>/lib. Resolved flags are appended to cflags/lflags. There is no --pkg-config/--with-mpi-auto CLI flag — it is fobos-only.

[externals]
mpi  = auto
hdf5 = /opt/hdf5-1.14

[default]
cflags    = -c
externals = mpi hdf5

To publish a .pc file for your own library, set pkgconfig = true (+ optional pkgconfig_name, pkgconfig_desc, pkgconfig_url, pkgconfig_req, pkgconfig_req_priv; defaults from [project]).

Multi-target builds

[target.solver]
source = src/solver.f90
output = solver

[example.demo]
source = examples/demo.f90
output = demo

[target.NAME] and [example.NAME] define independently-built artifacts. A mode-level target and [target.*] are mutually exclusive. CLI: --target-filter solver,foo restricts which targets build; --examples also builds [example.*]. (fobos help writes the section as [[target.*]]; configparser strips the outer brackets, so both forms produce target.NAME.)

Auto-discovery

When src is unset (fobos and CLI) and --no-auto-discover is off, FoBiS scans src/, source/, app/ for Fortran sources and uses the directories it finds as scan roots.

Build cache

BuildCache content-addresses built use=fobos dependency artifacts; key = SHA-256 of source_commit | compiler | cflags_hash | fobis_version. Default dir $FOBIS_CACHE_DIR or ~/.fobis/cache. Manage with fobis cache list|clean --older-than N|show DEP. Disable per build with --no-cache; relocate with --cache-dir.

Includes ([include])

[include]
paths = base.fobos ?optional.fobos

Pulls sibling fobos files (relative to the including file; ${ENV}/~ expanded). A leading ? marks an include optional (missing → skipped); otherwise a missing file aborts. Merge is parent-wins, except list-typed keys ([modes] modes, [features] default, [varsets] default) which are token-merged. Cycle-detected, depth-capped.

---

Fetch Dependencies & Lock File

The fetch command pulls GitHub-hosted Fortran libraries declared in [dependencies].

[dependencies]
deps_dir = .fobis_deps     ; optional clone dir (default .fobis_deps)

penf     = https://github.com/szaghi/PENF :: tag=v1.5.0
stdlib   = fortran-lang/stdlib :: semver=^0.5 :: use=fobos :: mode=gnu   ; user/repo shorthand
jsonfort = https://github.com/jacobwilliams/json-fortran :: branch=main :: use=fobos

Spec: name = URL [:: branch=X | tag=X | rev=X | semver=EXPR] [:: mode=X] [:: use=sources|fobos]. semver is mutually exclusive with branch/tag/rev and resolves the highest matching git tag (Cargo-style ^, ~, =, >=/<=/>/<, *, comma-AND).

use=	fetch behaviour	build behaviour
sources (default)	clone only	dep dir added to source scan inline
fobos	clone + fobis build in dep	dep fobos added to dependon; dep dir excluded from scan

Workflow:

fobis fetch              # initial clone; pre-build use=fobos deps
fobis fetch --update     # re-pull and re-build
fobis fetch --no-build   # clone only
fobis fetch --frozen     # enforce exact fobos.lock state; abort on drift or missing lock
fobis build              # auto-reads .fobis_deps/.deps_config.ini — no extra flags

---

Test Runner & Coverage

fobis test discovers, builds, and runs Fortran test programs; fobis coverage turns instrumented runs into HTML/XML/text reports. Both read optional fobos sections:

[test]
test_dir = tests          ; directory scanned for test programs (default test)
suite    = unit           ; only run tests tagged ! fobis: suite=unit
timeout  = 120            ; seconds before a test is killed (default 60)
compiler = gnu            ; override compiler for test builds
cflags   = -c -O0 -g

[coverage]
format     = html         ; html xml text (list; default html)
output_dir = coverage     ; report directory (default coverage)
fail_under = 75           ; exit 1 if line coverage < N%
exclude    = tests/*      ; glob(s) to exclude

fobis test --coverage runs the suite then generates the report. fobis test --list shows discovered tests; --suite, --filter, --timeout, --no-build refine the run.

---

LLM Commit Messages

fobis commit drafts a Conventional-Commits message from your staged diff via a local LLM. Backends: ollama (default, http://localhost:11434) and openai (any OpenAI-compatible endpoint). Config: ~/.config/fobis/config.ini ($XDG_CONFIG_HOME honoured), [llm] section keys backend, url, model (default qwen3-coder:30b-a3b-q4_K_M), max_diff_chars (12000), refine_passes (0).

fobis commit --init-config            # write a commented config template
fobis commit --show-config            # print effective config
fobis commit --refine-passes 2        # critique-and-rewrite iterations
fobis commit --apply                  # run `git commit` with the generated message

---

JSON Output (scripting / CI)

Add --json to build, clean, or fetch for structured stdout. Exit codes are unchanged (0 ok / 1 fail); JSON is always printed, even on failure.

fobis build --mode release --json

{ "status": "ok", "target": "all", "objects_compiled": 3, "errors": [] }

result=$(fobis build --mode release --json)
[ "$(echo "$result" | jq -r '.status')" != "ok" ] && { echo "$result" | jq -r '.errors[]'; exit 1; }

For richer machine-readable project metadata (sources, compiler, targets, varsets), use fobis introspect --all --format json instead.

---

Library Builds

Static library

[default]
compiler  = gnu
cflags    = -c -O3
src       = ./src/
obj_dir   = ./obj/
mod_dir   = ./mod/
mklib     = static
output    = libmylib.a

Shared library

[default]
compiler  = gnu
cflags    = -c -fPIC -O3
src       = ./src/
mklib     = shared
output    = libmylib.so

Static-library tooling is configurable: ar, arflags (default -rcs), ranlib (set to empty to skip — e.g. with llvm-ar, which updates the symbol table itself).

---

Interdependent Projects (dependon)

[default]
# project B's fobos
dependon = ../projectA/fobos
src      = ./src/

FoBiS rebuilds project A if needed, then adds its mod_dir and built library to B's build. Spec form: path/fobos[:mode].

---

Diagnosing Common Errors

"Module 'xyz' not found"

1. Missing source path — the file defining module xyz is not in any src directory. Add it to src.
2. Wrong mod_dir — .mod written one place, compiler looking elsewhere. Keep mod_dir consistent.
3. Dependency not fetched — run fobis fetch if the module comes from a GitHub dep.
4. Name-case / filename mismatch — most compilers lowercase the .mod filename; verify on disk.
5. Unresolvable graph — run fobis tree to see the resolved dependency tree, or fobis check (--strict) to validate the graph without building.
6. Wrong dependon path — must point at the dep's fobos file, not its directory.

Build produces no output / does nothing

• Sources may be up-to-date — fobis build --force-compile forces a full rebuild.
• Confirm target points to a file with a program statement, and src actually has .f90 files.
• Check auto-discovery: with no src, FoBiS only scans src/, source/, app/ (disable via --no-auto-discover).

Flags not taking effect after change

Set cflags_heritage = True to auto-detect cflag changes and trigger a full rebuild; otherwise only changed sources recompile.

"The mode X is not defined into the fobos file"

--mode must exactly match a name in [modes] modes = .... Run fobis build --lmodes.

Library build not linking

• Static: mklib = static (output ends .a). Shared: mklib = shared + -fPIC in cflags.
• System libraries: prefer the [externals] section (auto-resolves flags) over hand-written -L/-l.

---

Parsed File Extensions

• Modern Fortran: .f90 .F90 .f95 .F95 .f03 .F03 .f08 .F08 .f2k .F2K
• Legacy: .f .F .for .FOR .fpp .FPP .fortran .f77 .F77
• Include: .inc .INC .h .H

Add custom include extensions: fobis build --inc .cmn.

---

Special Sections Summary

Section	Purpose
[default]	Single-mode build configuration
[modes]	modes = a b c — lists named modes (first = default)
[mode-name]	One section per named mode
[template-*] (any name)	Template for mode inheritance (template = ...)
[vars] (any name)	Conventional home for $NAME = value globals
[varset:NAME] / [varsets]	Named $variable bundles / default = ... selection
[features] / [feature:NAME] / [feature-group:NAME]	Feature flags, per-feature constraints, mutual-exclusion groups
[include]	paths = ... — pull in sibling fobos files
[externals]	External library map (name = auto | /prefix)
[target.NAME] / [example.NAME]	Multi-target / example build sections
[test] / [coverage]	fobis test / fobis coverage defaults
[rule-NAME]	Custom shell rule for fobis rule --ex NAME
[dependencies]	GitHub-hosted build dependencies (used by fetch)
[project]	Metadata: name, authors, version, summary, repository, website, email, year
[scaffold]	Optional fobis scaffold knobs: apt_packages = … (extra CI system packages, space-separated)

---

Further Reading

Full documentation at https://szaghi.github.io/FoBiS/:

• fobos reference · Complete example
• Command reference (all 15 subcommands)
• Feature flags · Build profiles · Varsets
• External libraries · Build cache · Auto-discovery
• Fetch dependencies · Lock file & semver · Interdependent builds
• Test runner · Coverage · JSON output
• Source code