The manifest reference

axle.toml sits at a project’s root. Every table is optional except [package], and an absent key falls back to a default rather than an error. Projects and dependencies is the guided version; this page is the lookup table.

[package]
name = "smalt"
version = "0.1.0"
targets = ["x86_64-pc-windows-msvc", "x86_64-unknown-linux-gnu"]

[workspace]
members = ["app", "core"]

[dependencies]
mathx = { path = "../mathx", features = ["wayland"] }

[features]
wayland = false

[port.win32]
when = { os = "windows" }
dirs = ["win32"]

[link]
libs  = ["SDL2"]
paths = ["C:/SDL2/lib"]

[fmt]
max_line_width = 100

`[package]`

Key	Type	Default	Meaning
`name`	string	required	the package name, and the artefact’s name in `target/`
`version`	string	`""`	free-form; nothing derives from it yet
`kind`	`"bin"` or `"lib"`	inferred	what the crate builds to
`entry`	path, relative to the project	inferred	the crate’s entry source
`targets`	list of triples	`[]`	the targets this project promises to serve

kind and entry are inferred from the source layout when omitted:

Layout	`kind`	`entry`
`src/main.axle` present	`bin`	`src/main.axle`
only `src/lib.axle`	`lib`	`src/lib.axle`

If both files exist, the crate is a bin. A lib exports pub items for dependents to import and is never a build’s entry point.

targets is a promise, not a build setting: listing a triple is what makes the port checks enforce it. List none and you have promised nothing, which is what lets a port be written one module at a time. A triple the compiler does not recognise is refused rather than skipped.

`[workspace]`

Key	Type	Default	Meaning
`members`	list of directories	`[]`	crates compiled alongside this one

A manifest carrying [workspace] is both a crate and the root of a workspace: members are extra graph roots, compiled whether or not the root depends on them. Cross-crate use edges still come from each crate’s own [dependencies] — [workspace] members decides what is built, never what is visible.

`[dependencies]`

[dependencies]
mathx = { path = "../mathx", features = ["wayland"] }

Key	Type	Default	Meaning
`path`	path, relative to this manifest	required	the dependency’s directory
`features`	list of names	`[]`	features to turn on in that dependency

Only path dependencies exist: no registry, no git source, no lockfile.

features only ever enables. That is what makes the request safe to union — two crates asking for different features of one library both get theirs, in any order, and neither takes anything away from the other. A feature the dependency defaults to on is that crate’s own decision about itself.

`[features]`

[features]
wayland = false

A name and its default state. Two things turn a feature on: the default here, or a request — --features from the command line for the root crate, a [dependencies] edge for everything else. Nothing turns one off. A name a [port]’s when asks for but this table never declared is refused: it could never be on, so the port could never apply.

--features reaches the root crate and stops there, because two crates may spell the same name while meaning different things.

`[port.<name>]`

A port is one backend of a piece of code: a condition, and the directories that carry it. Nothing is reserved — a crate with no [port] table has no port directories, so a probes/linux/ is an ordinary directory.

Key	Type	Default	Meaning
`when`	table	`{}` (applies everywhere)	the condition under which this port is the active one
`dirs`	list of directory names	required, non-empty	this port’s code, at any depth under `src/`

A port with no directory is refused: nothing could ever select it.

The `when` axes

Axis	Values
`os`	`windows`, `linux`, `macos`
`arch`	`x86_64`, `aarch64`
`feature`	any name declared in `[features]`

Every axis takes one value or a list:

when = { os = "linux" }
when = { os = ["linux", "macos"] }
when = { os = "linux", feature = "wayland" }

Several axes in one when must all hold. A value no axis has is refused with the list of valid ones, and a feature no [features] table declares is refused too — the alternative is a port that is silently never active.

{ os = "linux", feature = "wayland" } is narrower than { os = "linux" }, so it wins when the feature is on and the plain Linux port serves when it is off. Exactly one port is active for any target: a target left uncovered, or two ports applying with neither narrower, is refused rather than resolved by declaration order.

`[link]`

Key	Type	Default	Meaning
`libs`	list of names	`[]`	native libraries to link
`paths`	list of directories	`[]`	where to find them

On Windows these become /DEFAULTLIB:<name>.lib and /LIBPATH:<dir>; on Unix, -l<name> and -L<dir>. The flags patch the same list ad hoc: axle build --link-lib SDL2 --lib-path C:/SDL2/lib.

`[fmt]`

Overrides for axle fmt and the language server’s formatter. Every key is optional; an absent one uses the formatter’s default.

Key	Type	Meaning
`max_line_width`	integer	width before a breakable construct wraps
`indent_width`	integer	columns of indentation per nesting level
`use_tabs`	bool	indent with hard tabs instead of spaces
`brace_on_same_line`	bool	keep `{` on the construct’s line, or move it down
`trailing_comma`	bool	trailing comma on a broken brace-delimited list
`max_blank_lines`	integer	blank lines preserved between items
`single_line_if_max_width`	integer	column ceiling under which a single-statement `if` with no `else` stays on one line; `0` disables the rule

A key the parser does not know

Unrecognised keys are ignored, not reported, so a misspelled one is a setting that silently does nothing. When a table seems to have no effect, check the spelling first.

The manifest reference

[package]

[workspace]

[dependencies]

[features]

[port.<name>]

The when axes

[link]

[fmt]