Enum Error 

pub enum Error {
    Parse(Error),
    NamesDontMatch(String, String),
    MultipleSingularValues(String),
    MultipleLiteralValues(String),
    UnsupportedLiteral(String),
    SingularAttrRequired(String),
    ParametrizedAttrRequired(String),
    AttributeUnknownArgument {
        attr: String,
        arg: String,
    },
    ArgTypeProhibited {
        attr: String,
        arg: String,
    },
    ArgNumberExceedsMax {
        attr: String,
        type_name: String,
        no: usize,
        max_no: u8,
    },
    ArgMustNotHaveValue {
        attr: String,
        arg: String,
    },
    ArgRequired {
        attr: String,
        arg: String,
    },
    ArgNameMustBeIdent,
    ArgNameMustBeUnique {
        attr: String,
        arg: String,
    },
    ArgValueRequired {
        attr: String,
        arg: String,
    },
    ArgValueTypeMismatch {
        attr: String,
        arg: String,
    },
    ArgValueMustBeLiteral,
    ArgValueMustBeType,
    ArgValueMustBeExpr,
    ParametrizedAttrHasNoValue(String),
    NestedListsNotSupported(String),
}

Errors representing inconsistency in proc macro attribute structure

Variants

Parse(Error)

Parse error from a syn crate

NamesDontMatch(String, String)

Names of two merged attributes must match each other

MultipleSingularValues(String)

Singular argument (of form #[attr = ...]) has multiple occurrences each assigned value. This is meaningless.

MultipleLiteralValues(String)

Multiple literal non-string values are given for a parametrized attribute in form of #[attr(literal1, literal2)]. This is meaningless.

UnsupportedLiteral(String)

Attribute contains unsupported literal argument

SingularAttrRequired(String)

Attribute must be in a singular form (#[attr] or #[attr = ...])

ParametrizedAttrRequired(String)

Attribute must be in a parametrized form (#[attr(...)])

AttributeUnknownArgument

Attribute has an unknown argument

Fields

attr: String

Attribute name

arg: String

Argument name

ArgTypeProhibited

Attribute is not allowed to have argument of type arg

Fields

attr: String

Attribute name

arg: String

Argument name

ArgNumberExceedsMax

Number of arg arguments in attribute attr exceeds maximum

Fields

attr: String

Attribute name

type_name: String

Argument type name

no: usize

Number of arguments

max_no: u8

Maximum allowed number of arguments

ArgMustNotHaveValue

Attribute argument arg must not have a value

Fields

attr: String

Attribute name

arg: String

Argument name

ArgRequired

Attribute must has an arg argument

Fields

attr: String

Attribute name

arg: String

Argument name

ArgNameMustBeIdent

Attribute or attribute argument name (in form of #[attr(arg = ...)]) must be an identifier (like arg) and not a path (like std::io)

ArgNameMustBeUnique

The same argument name is used multiple times within parametrized attribute (like in #[attr(name1 = value1, name1 = value2)])

Fields

attr: String

Attribute name

arg: String

Argument name

ArgValueRequired

Attribute or attribute argument must has a value: #[attr(arg = value)]

Fields

attr: String

Attribute name

arg: String

Argument name

ArgValueTypeMismatch

Attribute value type mismatch

Fields

attr: String

Attribute name

arg: String

Argument name

ArgValueMustBeLiteral

Parametrized attribute argument must have a literal value (string, integer etc): #[attr(arg = "value")] or #[arg = 4]

ArgValueMustBeType

Parametrized attribute argument must be a valid type name: #[attr(arg = u8)] or #[arg = String]

ArgValueMustBeExpr

Parametrized attribute argument must be a valid rust expression: #[attr(arg = 2 + 2)] or #[arg = { u16::MAX as usize }]

ParametrizedAttrHasNoValue(String)

Parametrized attribute (in form of #[attr(...)]) does not have a single value

NestedListsNotSupported(String)

👎Deprecated since 1.1.0: This error variant is not used anymore after the introduction of custom attribute parser

Lists nested within attribute arguments, like #[attr(arg(...))] are not supported

Trait Implementations

impl Clone for Error

fn clone(&self) -> Error

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Error

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

Formats the value using the given formatter.

impl Display for Error

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

Formats the value using the given formatter.

impl Error for Error

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0: use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0: replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

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

Provides type-based access to context intended for error reports.

impl From<Error> for Error

fn from(err: Error) -> Self

Converts to this type from the input type.

impl From<Error> for Error

fn from(err: Error) -> Self

Converts to this type from the input type.

impl From<Infallible> for Error

fn from(_: Infallible) -> Self

Converts to this type from the 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: 64 bytes

Size for each variant:

• Parse: 32 bytes
• NamesDontMatch: 56 bytes
• MultipleSingularValues: 32 bytes
• MultipleLiteralValues: 32 bytes
• UnsupportedLiteral: 32 bytes
• SingularAttrRequired: 32 bytes
• ParametrizedAttrRequired: 32 bytes
• AttributeUnknownArgument: 56 bytes
• ArgTypeProhibited: 56 bytes
• ArgNumberExceedsMax: 64 bytes
• ArgMustNotHaveValue: 56 bytes
• ArgRequired: 56 bytes
• ArgNameMustBeIdent: 0 bytes
• ArgNameMustBeUnique: 56 bytes
• ArgValueRequired: 56 bytes
• ArgValueTypeMismatch: 56 bytes
• ArgValueMustBeLiteral: 0 bytes
• ArgValueMustBeType: 0 bytes
• ArgValueMustBeExpr: 0 bytes
• ParametrizedAttrHasNoValue: 32 bytes
• NestedListsNotSupported: 32 bytes