Struct Label 

pub struct Label(/* private fields */);

One GitHub runner label, normalised.

Normalisation is lower-casing, and it is not cosmetic. The v1 spike registered a runner with ["rm-d18-spike","Windows","X64","self-hosted-rm"] and GitHub returned windows and x64 (docs/spikes/d18-org-jit-verification.md, Point 3, finding 3). A label read back from the API therefore never matches a mixed-case label held locally unless both sides are folded first. Folding on construction makes every comparison in this crate — Eq, Ord, Hash, set membership — case insensitive for free, so no call site can forget.

The fold is ASCII, matching HostLabel and the target [Name] types. The only case folding this crate has evidence for is GitHub’s, and the only evidence is the spike above, which is entirely ASCII. Unicode to_lowercase() would also make folding length-changing — İ (U+0130) lowercases to two chars — which is how a 256-character label could exceed Self::MAX_LEN after construction. ASCII folding is length-preserving, so that class of bug cannot occur, and the length check below is applied to the folded value regardless so the stored string is what was measured.

What the character rules are for. They are round-trippability rules, not injection defences, and reading them as the latter is how a rule that defends nothing gets added. A Label is never interpolated into a shell: it travels as one element of the runner’s comma-separated --labels argument and as a JSON string. So exactly two characters break the round trip — the comma, which is the separator itself, and control characters, which break both the argument and the JSON framing. Nothing else does, and a quote rule in particular is neither necessary (no shell is involved) nor sufficient (<, >, $, `, ;, |, & and whitespace would all still pass).

An explicit allow-list was considered and rejected: real GitHub labels include c#, .net, x86_64 and similar, so any allow-list narrow enough to be worth having would reject legitimate runs-on values and turn a cosmetic concern into a demand-matching failure in crate::policy::RunsOn::required_labels.

Implementations

impl Label

pub const MAX_LEN: usize = 256

GitHub’s documented maximum label length.

pub fn new(raw: impl AsRef<str>) -> Result<Self, ValidationError>

Errors

Empty, over-long, comma-bearing, or control-character-bearing input. A comma is rejected because it separates labels in the runner’s own configuration, so a label containing one is not round-trippable; control characters break the same argument and the JSON encoding around it. See the type documentation for why the list stops there.

pub fn as_str(&self) -> &str

Trait Implementations

impl Clone for Label

fn clone(&self) -> Label

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Label

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Label

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Display for Label

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

Formats the value using the given formatter.

impl Eq for Label

impl From<Label> for String

fn from(value: Label) -> Self

Converts to this type from the input type.

impl FromStr for Label

type Err = ValidationError

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Self, Self::Err>

Parses a string s to return a value of this type.

impl Hash for Label

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 Label

fn cmp(&self, other: &Label) -> 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.

fn clamp_to<R>(self, range: R) -> Self

where Self: Sized, R: ClampBounds<Self>,

🔬This is a nightly-only experimental API. (clamp_to)

Restrict a value to a certain range.

impl PartialEq for Label

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

Equality operator ==.

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

Inequality operator !=.

impl PartialOrd for Label

fn partial_cmp(&self, other: &Label) -> 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 Label

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Label

impl TryFrom<&str> for Label

type Error = ValidationError

The type returned in the event of a conversion error.

fn try_from(value: &str) -> Result<Self, Self::Error>

Performs the conversion.

impl TryFrom<String> for Label

type Error = ValidationError

The type returned in the event of a conversion error.

fn try_from(value: String) -> Result<Self, Self::Error>

Performs the conversion.