Enum rustc_error_messages::SubdiagnosticMessage

pub enum SubdiagnosticMessage {
    Str(Cow<'static, str>),
    Eager(Cow<'static, str>),
    FluentIdentifier(Cow<'static, str>),
    FluentAttr(Cow<'static, str>),
}

Abstraction over a message in a subdiagnostic (i.e. label, note, help, etc) to support both translatable and non-translatable diagnostic messages.

Translatable messages for subdiagnostics are typically attributes attached to a larger Fluent message so messages of this type must be combined with a DiagnosticMessage (using DiagnosticMessage::with_subdiagnostic_message) before rendering. However, subdiagnostics from the Subdiagnostic derive refer to Fluent identifiers directly.

Variants

Str(Cow<'static, str>)

Non-translatable diagnostic message.

Eager(Cow<'static, str>)

Translatable message which has already been translated eagerly.

Some diagnostics have repeated subdiagnostics where the same interpolated variables would be instantiated multiple times with different values. As translation normally happens immediately prior to emission, after the diagnostic and subdiagnostic derive logic has run, the setting of diagnostic arguments in the derived code will overwrite previous variable values and only the final value will be set when translation occurs - resulting in incorrect diagnostics. Eager translation results in translation for a subdiagnostic happening immediately after the subdiagnostic derive’s logic has been run. This variant stores messages which have been translated eagerly.

FluentIdentifier(Cow<'static, str>)

Identifier of a Fluent message. Instances of this variant are generated by the Subdiagnostic derive.

FluentAttr(Cow<'static, str>)

Attribute of a Fluent message. Needs to be combined with a Fluent identifier to produce an actual translated message. Instances of this variant are generated by the fluent_messages macro.

https://projectfluent.org/fluent/guide/attributes.html

Trait Implementations

impl From<&'static str> for SubdiagnosticMessage

fn from(s: &'static str) -> Self

Converts to this type from the input type.

impl From<Cow<'static, str>> for SubdiagnosticMessage

fn from(s: Cow<'static, str>) -> Self

Converts to this type from the input type.

impl From<String> for SubdiagnosticMessage

fn from(s: String) -> Self

Converts to this type from the input type.

impl Into<SubdiagnosticMessage> for DiagnosticMessage

Translating into a subdiagnostic message from a diagnostic message is a little strange - but the subdiagnostic functions (e.g. span_label) take a SubdiagnosticMessage and the subdiagnostic derive refers to typed identifiers that are DiagnosticMessages, so need to be able to convert between these, as much as they’ll be converted back into DiagnosticMessage using with_subdiagnostic_message eventually. Don’t use this other than for the derive.

fn into(self) -> SubdiagnosticMessage

Converts this type into the (usually inferred) input type.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 32 bytes

Size for each variant:

• Str: 24 bytes
• Eager: 24 bytes
• FluentIdentifier: 24 bytes
• FluentAttr: 24 bytes