Struct autocfg::AutoCfg

pub struct AutoCfg { /* private fields */ }

Helper to detect compiler features for cfg output in build scripts.

Implementations

impl AutoCfg

pub fn new() -> Result<Self, Error>

Create a new AutoCfg instance.

Common errors

• rustc can’t be executed, from RUSTC or in the PATH.
• The version output from rustc can’t be parsed.
• OUT_DIR is not set in the environment, or is not a writable directory.

pub fn with_dir<T: Into<PathBuf>>(dir: T) -> Result<Self, Error>

Create a new AutoCfg instance with the specified output directory.

Common errors

• rustc can’t be executed, from RUSTC or in the PATH.
• The version output from rustc can’t be parsed.
• dir is not a writable directory.

pub fn probe_rustc_version(&self, major: usize, minor: usize) -> bool

Test whether the current rustc reports a version greater than or equal to “major.minor”.

pub fn emit_rustc_version(&self, major: usize, minor: usize)

Sets a cfg value of the form rustc_major_minor, like rustc_1_29, if the current rustc is at least that version.

pub fn probe_sysroot_crate(&self, name: &str) -> bool

Tests whether the given sysroot crate can be used.

The test code is subject to change, but currently looks like:

extern crate CRATE as probe;

pub fn emit_sysroot_crate(&self, name: &str)

Emits a config value has_CRATE if probe_sysroot_crate returns true.

pub fn probe_path(&self, path: &str) -> bool

Tests whether the given path can be used.

The test code is subject to change, but currently looks like:

pub use PATH;

pub fn emit_has_path(&self, path: &str)

Emits a config value has_PATH if probe_path returns true.

Any non-identifier characters in the path will be replaced with _ in the generated config value.

pub fn emit_path_cfg(&self, path: &str, cfg: &str)

Emits the given cfg value if probe_path returns true.

pub fn probe_trait(&self, name: &str) -> bool

Tests whether the given trait can be used.

The test code is subject to change, but currently looks like:

pub trait Probe: TRAIT + Sized {}

pub fn emit_has_trait(&self, name: &str)

Emits a config value has_TRAIT if probe_trait returns true.

Any non-identifier characters in the trait name will be replaced with _ in the generated config value.

pub fn emit_trait_cfg(&self, name: &str, cfg: &str)

Emits the given cfg value if probe_trait returns true.

pub fn probe_type(&self, name: &str) -> bool

Tests whether the given type can be used.

The test code is subject to change, but currently looks like:

pub type Probe = TYPE;

pub fn emit_has_type(&self, name: &str)

Emits a config value has_TYPE if probe_type returns true.

Any non-identifier characters in the type name will be replaced with _ in the generated config value.

pub fn emit_type_cfg(&self, name: &str, cfg: &str)

Emits the given cfg value if probe_type returns true.

pub fn probe_expression(&self, expr: &str) -> bool

Tests whether the given expression can be used.

The test code is subject to change, but currently looks like:

pub fn probe() { let _ = EXPR; }

pub fn emit_expression_cfg(&self, expr: &str, cfg: &str)

Emits the given cfg value if probe_expression returns true.

pub fn probe_constant(&self, expr: &str) -> bool

Tests whether the given constant expression can be used.

The test code is subject to change, but currently looks like:

pub const PROBE: () = ((), EXPR).0;

pub fn emit_constant_cfg(&self, expr: &str, cfg: &str)

Emits the given cfg value if probe_constant returns true.

Trait Implementations

impl Clone for AutoCfg

fn clone(&self) -> AutoCfg

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for AutoCfg

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.