Enum Condition 

pub enum Condition {
    KeyValue {
        key: ConditionKey,
        value: String,
    },
    Feature(String),
    CompilerFamily {
        slot: CompilerSlot,
        family: CompilerKind,
    },
    CompilerVersionReq {
        slot: CompilerSlot,
        req: String,
    },
    All(Vec<Condition>),
    Any(Vec<Condition>),
    Not(Box<Condition>),
}

Typed AST for a cfg(...) target condition.

The wire format matches the manifest text: a key/value (key = "value") leaf, or one of the all / any / not combinators. Equality and ordering are structural, so identical expressions always compare equal regardless of whitespace or quote style in the original source.

Variants

KeyValue

key = "value". The key is restricted to the ConditionKey set; the value is a free-form ASCII string interpreted by evaluate.

Fields

key: ConditionKey

value: String

Feature(String)

feature = "name". Evaluates against the enabled-feature set of the package the condition belongs to, not the platform. Feature conditions are only meaningful - and only accepted - in flag tables ([target.'cfg(...)'.profile]); the manifest layer rejects a feature-referencing cfg that gates a dependency table, because feature resolution itself runs over the dependency graph and a feature→dependency edge would be circular.

CompilerFamily

cc = "<family>" / cxx = "<family>". Matches when the detected compiler in that slot is the named family (crate::compiler::CompilerKind ids). When detection has not run (fail-soft commands) or the slot is unresolved, the detected family counts as unknown, which is matchable. Compiler conditions are accepted on profile flag tables only; the manifest layer rejects them on dependency / toolchain / cache tables, where detection is unavailable.

Fields

slot: CompilerSlot

family: CompilerKind

CompilerVersionReq

cc_version = "<req>" / cxx_version = "<req>". The value is a SemVer requirement (the same grammar as dependency versions, parsed leniently) matched against the detected version zero-padded to major.minor.patch. No detected version ⇒ false. The raw requirement string is preserved verbatim so Display round-trips byte-identically.

Fields

slot: CompilerSlot

req: String

All(Vec<Condition>)

all(<conditions>). Empty all() is rejected at parse time.

Any(Vec<Condition>)

any(<conditions>). Empty any() is rejected at parse time.

Not(Box<Condition>)

not(<single condition>).

Implementations

impl Condition

pub fn parse_cfg(input: &str) -> Result<Self, ConditionParseError>

Parse a full cfg(...) expression. The wrapping cfg(...) is required so the parser is symmetric with the manifest text users write.

Errors

Returns ConditionParseError::ExpectedCfgPrefix when the input is not wrapped in cfg(, ConditionParseError::UnbalancedParens when the trailing ) is missing, and propagates any ConditionParseError from parsing the inner expression.

pub fn parse_inner(input: &str) -> Result<Self, ConditionParseError>

Parse the inner expression of a cfg(...) form (no cfg( prefix or trailing )). Useful for the metadata round-trip path, where we store the inner form.

Errors

Returns a ConditionParseError when the expression is malformed - e.g. an unsupported key, a missing = or quoted value, an empty all()/any(), a not() of wrong arity, unbalanced parentheses, or trailing input after the expression.

pub fn evaluate(&self, ctx: &ConditionContext<'_>) -> bool

Evaluate this condition against the typed ConditionContext - the host platform, the set of features enabled on the owning package, and the detected compiler identities. The result is fully determined by those inputs and the condition’s AST - no global state, no environment lookup, no I/O.

Contexts that carry no feature information (every dependency-gating call) use ConditionContext::platform_only; this is correct-by-construction because a feature-referencing cfg is rejected on dependency tables at manifest-load time, so a Feature leaf can only be reached here through a flag table that threaded the real enabled-feature set in.

pub fn references_feature(&self) -> bool

Whether this condition references any feature = "..." leaf. Used by the manifest layer to reject feature conditions on dependency tables (where they would be circular) while allowing them on flag tables.

pub fn references_compiler(&self) -> bool

Whether this condition references any compiler leaf (cc / cxx / cc_version / cxx_version). Used by the manifest layer to reject compiler conditions on tables evaluated before toolchain detection runs (dependencies, toolchain or compiler-wrapper selection).

Trait Implementations

impl Clone for Condition

fn clone(&self) -> Condition

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Condition

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Condition

fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error>

Deserialize this value from the given Serde deserializer.

impl Display for Condition

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

Canonical string form. Round-trips through Condition::parse_inner.

impl Eq for Condition

impl Hash for Condition

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Ord for Condition

fn cmp(&self, other: &Condition) -> Ordering

This method returns an Ordering between self and other.

fn max(self, other: Self) -> Self

where Self: Sized,

Compares and returns the maximum of two values.

fn min(self, other: Self) -> Self

where Self: Sized,

Compares and returns the minimum of two values.

fn clamp(self, min: Self, max: Self) -> Self

where Self: Sized,

Restrict a value to a certain interval.

impl PartialEq for Condition

fn eq(&self, other: &Condition) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialOrd for Condition

fn partial_cmp(&self, other: &Condition) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &Rhs) -> bool

Tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &Rhs) -> bool

Tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &Rhs) -> bool

Tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &Rhs) -> bool

Tests greater than or equal to (for self and other) and is used by the >= operator.

impl Serialize for Condition

fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error>

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Condition