Enum rustc_trait_selection::traits::ObligationCauseCode

pub enum ObligationCauseCode<'tcx> {
    MiscObligation,
    SliceOrArrayElem,
    TupleElem,
    ItemObligation(DefId),
    BindingObligation(DefId, Span),
    ExprItemObligation(DefId, HirId, usize),
    ExprBindingObligation(DefId, Span, HirId, usize),
    ReferenceOutlivesReferent(Ty<'tcx>),
    ObjectTypeBound(Ty<'tcx>, Region<'tcx>),
    Coercion {
        source: Ty<'tcx>,
        target: Ty<'tcx>,
    },
    AssignmentLhsSized,
    TupleInitializerSized,
    StructInitializerSized,
    VariableType(HirId),
    SizedArgumentType(Option<Span>),
    SizedReturnType,
    SizedYieldType,
    InlineAsmSized,
    SizedClosureCapture(LocalDefId),
    SizedCoroutineInterior(LocalDefId),
    RepeatElementCopy {
        is_constable: IsConstable,
        elt_type: Ty<'tcx>,
        elt_span: Span,
        elt_stmt_span: Span,
    },
    FieldSized {
        adt_kind: AdtKind,
        span: Span,
        last: bool,
    },
    ConstSized,
    SharedStatic,
    BuiltinDerivedObligation(DerivedObligationCause<'tcx>),
    ImplDerivedObligation(Box<ImplDerivedObligationCause<'tcx>>),
    DerivedObligation(DerivedObligationCause<'tcx>),
    FunctionArgumentObligation {
        arg_hir_id: HirId,
        call_hir_id: HirId,
        parent_code: InternedObligationCauseCode<'tcx>,
    },
    CompareImplItemObligation {
        impl_item_def_id: LocalDefId,
        trait_item_def_id: DefId,
        kind: AssocKind,
    },
    CheckAssociatedTypeBounds {
        impl_item_def_id: LocalDefId,
        trait_item_def_id: DefId,
    },
    ExprAssignable,
    MatchExpressionArm(Box<MatchExpressionArmCause<'tcx>>),
    Pattern {
        span: Option<Span>,
        root_ty: Ty<'tcx>,
        origin_expr: bool,
    },
    IfExpression(Box<IfExpressionCause<'tcx>>),
    IfExpressionWithNoElse,
    MainFunctionType,
    StartFunctionType,
    LangFunctionType(Symbol),
    IntrinsicType,
    LetElse,
    MethodReceiver,
    UnifyReceiver(Box<UnifyReceiverContext<'tcx>>),
    ReturnNoExpression,
    ReturnValue(HirId),
    OpaqueReturnType(Option<(Ty<'tcx>, Span)>),
    BlockTailExpression(HirId, MatchSource),
    TrivialBound,
    AwaitableExpr(HirId),
    ForLoopIterator,
    QuestionMark,
    WellFormed(Option<WellFormedLoc>),
    MatchImpl(ObligationCause<'tcx>, DefId),
    BinOp {
        rhs_span: Option<Span>,
        is_lit: bool,
        output_ty: Option<Ty<'tcx>>,
    },
    AscribeUserTypeProvePredicate(Span),
    RustCall,
    DropImpl,
    ConstParam(Ty<'tcx>),
    TypeAlias(InternedObligationCauseCode<'tcx>, Span, DefId),
}

Variants

MiscObligation

Not well classified or should be obvious from the span.

SliceOrArrayElem

A slice or array is WF only if T: Sized.

TupleElem

A tuple is WF only if its middle elements are Sized.

ItemObligation(DefId)

Must satisfy all of the where-clause predicates of the given item.

BindingObligation(DefId, Span)

Like ItemObligation, but carries the span of the predicate when it can be identified.

ExprItemObligation(DefId, HirId, usize)

Like ItemObligation, but carries the HirId of the expression that caused the obligation, and the usize indicates exactly which predicate it is in the list of instantiated predicates.

ExprBindingObligation(DefId, Span, HirId, usize)

Combines ExprItemObligation and BindingObligation.

ReferenceOutlivesReferent(Ty<'tcx>)

A type like &'a T is WF only if T: 'a.

ObjectTypeBound(Ty<'tcx>, Region<'tcx>)

A type like Box<Foo<'a> + 'b> is WF only if 'b: 'a.

Coercion

Fields

source: Ty<'tcx>

target: Ty<'tcx>

Obligation incurred due to a coercion.

AssignmentLhsSized

Various cases where expressions must be Sized / Copy / etc. L = X implies that L is Sized.

TupleInitializerSized

(x1, .., xn) must be Sized.

StructInitializerSized

S { ... } must be Sized.

VariableType(HirId)

Type of each variable must be Sized.

SizedArgumentType(Option<Span>)

Argument type must be Sized.

SizedReturnType

Return type must be Sized.

SizedYieldType

Yield type must be Sized.

InlineAsmSized

Inline asm operand type must be Sized.

SizedClosureCapture(LocalDefId)

Captured closure type must be Sized.

SizedCoroutineInterior(LocalDefId)

Types live across coroutine yields must be Sized.

RepeatElementCopy

Fields

is_constable: IsConstable

If element is a const fn or const ctor we display a help message suggesting to move it to a new const item while saying that T doesn’t implement Copy.

elt_type: Ty<'tcx>

elt_span: Span

elt_stmt_span: Span

Span of the statement/item in which the repeat expression occurs. We can use this to place a const declaration before it

[expr; N] requires type_of(expr): Copy.

FieldSized

Fields

adt_kind: AdtKind

span: Span

last: bool

Types of fields (other than the last, except for packed structs) in a struct must be sized.

ConstSized

Constant expressions must be sized.

SharedStatic

static items must have Sync type.

BuiltinDerivedObligation(DerivedObligationCause<'tcx>)

ImplDerivedObligation(Box<ImplDerivedObligationCause<'tcx>>)

DerivedObligation(DerivedObligationCause<'tcx>)

FunctionArgumentObligation

Fields

arg_hir_id: HirId

The node of the relevant argument in the function call.

call_hir_id: HirId

The node of the function call.

parent_code: InternedObligationCauseCode<'tcx>

The obligation introduced by this argument.

CompareImplItemObligation

Fields

impl_item_def_id: LocalDefId

trait_item_def_id: DefId

kind: AssocKind

Error derived when checking an impl item is compatible with its corresponding trait item’s definition

CheckAssociatedTypeBounds

Fields

impl_item_def_id: LocalDefId

trait_item_def_id: DefId

Checking that the bounds of a trait’s associated type hold for a given impl

ExprAssignable

Checking that this expression can be assigned to its target.

MatchExpressionArm(Box<MatchExpressionArmCause<'tcx>>)

Computing common supertype in the arms of a match expression

Pattern

Fields

span: Option<Span>

The span of the scrutinee or type expression which caused the root_ty type.

root_ty: Ty<'tcx>

The root expected type induced by a scrutinee or type expression.

origin_expr: bool

Whether the Span came from an expression or a type expression.

Type error arising from type checking a pattern against an expected type.

IfExpression(Box<IfExpressionCause<'tcx>>)

Computing common supertype in an if expression

IfExpressionWithNoElse

Computing common supertype of an if expression with no else counter-part

MainFunctionType

main has wrong type

StartFunctionType

start has wrong type

LangFunctionType(Symbol)

language function has wrong type

IntrinsicType

Intrinsic has wrong type

LetElse

A let else block does not diverge

MethodReceiver

Method receiver

UnifyReceiver(Box<UnifyReceiverContext<'tcx>>)

ReturnNoExpression

return with no expression

ReturnValue(HirId)

return with an expression

OpaqueReturnType(Option<(Ty<'tcx>, Span)>)

Opaque return type of this function

BlockTailExpression(HirId, MatchSource)

Block implicit return

TrivialBound

#[feature(trivial_bounds)] is not enabled

AwaitableExpr(HirId)

ForLoopIterator

QuestionMark

WellFormed(Option<WellFormedLoc>)

Well-formed checking. If a WellFormedLoc is provided, then it will be used to perform HIR-based wf checking after an error occurs, in order to generate a more precise error span. This is purely for diagnostic purposes - it is always correct to use MiscObligation instead, or to specify WellFormed(None)

MatchImpl(ObligationCause<'tcx>, DefId)

From match_impl. The cause for us having to match an impl, and the DefId we are matching against.

BinOp

Fields

rhs_span: Option<Span>

is_lit: bool

output_ty: Option<Ty<'tcx>>

AscribeUserTypeProvePredicate(Span)

RustCall

DropImpl

Obligations to prove that a std::ops::Drop impl is not stronger than the ADT it’s being implemented for.

ConstParam(Ty<'tcx>)

Requirement for a const N: Ty to implement Ty: ConstParamTy

TypeAlias(InternedObligationCauseCode<'tcx>, Span, DefId)

Obligations emitted during the normalization of a weak type alias.

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: 48 bytes

Size for each variant:

• MiscObligation: 0 bytes
• SliceOrArrayElem: 0 bytes
• TupleElem: 0 bytes
• ItemObligation: 11 bytes
• BindingObligation: 19 bytes
• ExprItemObligation: 31 bytes
• ExprBindingObligation: 39 bytes
• ReferenceOutlivesReferent: 15 bytes
• ObjectTypeBound: 23 bytes
• Coercion: 23 bytes
• AssignmentLhsSized: 0 bytes
• TupleInitializerSized: 0 bytes
• StructInitializerSized: 0 bytes
• VariableType: 11 bytes
• SizedArgumentType: 15 bytes
• SizedReturnType: 0 bytes
• SizedYieldType: 0 bytes
• InlineAsmSized: 0 bytes
• SizedClosureCapture: 7 bytes
• SizedCoroutineInterior: 7 bytes
• RepeatElementCopy: 31 bytes
• FieldSized: 11 bytes
• ConstSized: 0 bytes
• SharedStatic: 0 bytes
• BuiltinDerivedObligation: 47 bytes
• ImplDerivedObligation: 15 bytes
• DerivedObligation: 47 bytes
• FunctionArgumentObligation: 31 bytes
• CompareImplItemObligation: 15 bytes
• CheckAssociatedTypeBounds: 15 bytes
• ExprAssignable: 0 bytes
• MatchExpressionArm: 15 bytes
• Pattern: 23 bytes
• IfExpression: 15 bytes
• IfExpressionWithNoElse: 0 bytes
• MainFunctionType: 0 bytes
• StartFunctionType: 0 bytes
• LangFunctionType: 7 bytes
• IntrinsicType: 0 bytes
• LetElse: 0 bytes
• MethodReceiver: 0 bytes
• UnifyReceiver: 15 bytes
• ReturnNoExpression: 0 bytes
• ReturnValue: 11 bytes
• OpaqueReturnType: 23 bytes
• BlockTailExpression: 19 bytes
• TrivialBound: 0 bytes
• AwaitableExpr: 11 bytes
• ForLoopIterator: 0 bytes
• QuestionMark: 0 bytes
• WellFormed: 11 bytes
• MatchImpl: 39 bytes
• BinOp: 23 bytes
• AscribeUserTypeProvePredicate: 11 bytes
• RustCall: 0 bytes
• DropImpl: 0 bytes
• ConstParam: 15 bytes
• TypeAlias: 31 bytes