TypeAlias

Is this type a subtype of that type?

Is this type the same as that type? This is the case iff this <:< that and that <:< this.

The set of abstract term members of this type.

The set of abstract type members of this type.

All members of this type. Warning: this can be expensive to compute!

This type seen as if it were the type of a member of prefix type pre declared in class cls.

The singleton types that must or may be in this type. @see Atoms. Overridden and cached in OrType.

The base classes of this type as determined by ClassDenotation in linearization order, with the class itself as first element. Inherited by all type proxies. Overridden for And and Or types. Nil for all other types.

The basetype of this type with given class symbol, NoType if base is not a class.

This type seen as a TypeBounds

The least class or trait of which this type is a subtype or parameterized instance, or NoSymbol if none exists (either because this type is not a value type, or because superclasses are ambiguous).

The least (wrt <:<) set of class symbols of which this type is a subtype

Does this type contain wildcard types?

The set of distinct symbols referred to by this type, after all aliases are expanded

Follow aliases and dereferences LazyRefs, annotated types and instantiated TypeVars until type is no longer alias type, annotated type, LazyRef, or instantiated type variable.

Follow aliases and dereferences LazyRefs and instantiated TypeVars until type is no longer alias type, LazyRef, or instantiated type variable. Goes through annotated types and rewraps annotations on the result.

Like dealiasKeepAnnots, but keeps only refining annotations

A denotation containing the declaration(s) in this type with the given name. The result is either a SymDenotation or a MultiDenotation of SymDenotations. The info(s) are the original symbol infos, no translation takes place.

The scope of all declarations of this type. Defined by ClassInfo, inherited by type proxies. Empty scope for all other types.

Widen from constant type to its underlying non-constant base type.

If this is a prototype with some ignored component, reveal one more layer of it. Otherwise the type itself.

If this is a prototype with some ignored component, reveal it, and deepen the result transitively. Otherwise the type itself.

The non-alias type bounds type with given bounds

Does this type have a supertype with an annotation satisfying given predicate p?

True if this type is an instance of the given cls or an instance of a non-bottom subclass of cls.

Drop annotation of given cls from this type

Dealias, and if result is a dependent function type, drop the apply refinement.

If this is a proto type, WildcardType, otherwise the type itself

Compare this == that, assuming corresponding binders in bs are equal. The normal equals should be equivalent to equals(that, null). We usually overrideequalswhen we overrideisoexcept if theequals` comes from a case class, so it already has the right definition anyway.

Is this type different from NoType?

Returns true if there is a part of this type that satisfies predicate p.

A fallback text representation, if the pattern matching in Printers does not have a case for this showable element

The final result type of a PolyType, MethodType, or ExprType, after skipping all parameter sections, the type itself for all others.

A denotation containing the declaration(s) in this type with the given name, as seen from prefix type pre. Declarations that have a flag in excluded are omitted.

Find member of this type with given name, all required flags and no excluded flag and produce a denotation that contains the type of the member as seen from given prefix pre.

The parameter names in the first parameter section of a generic type or MethodType, Empty list for others

The parameter types in the first parameter section of a generic type or MethodType, Empty list for others

The first parent of this type, AnyRef if list of parents is empty

Returns true if all parts of this type satisfy predicate p.

Performs operation on all parts of this type

Is this type a subtype of that type?

Does the type carry an annotation that is an instance of cls?

Is this type of kind AnyKind?

Same as this.classSymbols.contains(cls) but more efficient

The upper bound of a TypeBounds type, the type itself otherwise

The set of implicit term members of this type

True iff symd is a denotation of a class type parameter and the reference `

 . ` is an actual argument reference, i.e. `pre` is not the
ThisType of `symd`'s owner, or a reference to `symd`'s owner.'

Is this a Method or PolyType which has contextual parameters as first value parameter list?

Is this a higher-kinded type lambda with given parameter variances?

Is this type a (neither aliased nor applied nor annotated) reference to class sym?

Is this a MethodType for which the parameters will not be used?

Is some part of the widened version of this type produced as a repair for an error?

Is this type produced as a repair for an error?

Is this type exactly Any (no vars, aliases, refinements etc allowed)?

Is this type exactly Nothing (no vars, aliases, refinements etc allowed)?

Is this type exactly Null (no vars, aliases, refinements etc allowed)?

Does this type not refer to TypeParamRefs or uninstantiated TypeVars?

Is this a Method or PolyType which has implicit or contextual parameters?

Is this a match type or a higher-kinded abstraction of one?

Same as hasClassSmbol(MatchableClass), except that we also follow the constraint bounds of type variables in the constraint.

Is this type guaranteed not to have null as a value?

Is this (an alias of) the scala.Nothing type?

Is this (an alias of) the scala.Null type?

Is this the type of a method with a leading empty parameter list?

Is this either not a method at all, or a parameterless method?

Is this type still provisional? This is the case if the type contains, or depends on, uninstantiated type variables or type symbols that have the Provisional flag set. This is an antimonotonic property - once a type is not provisional, it stays so forever.

Is this type a (possibly refined or applied or aliased) type reference to the given type symbol?

Is this a type of a repeated parameter?

Is this type a (possibly aliased) singleton type?

Does this type denote a stable reference (i.e. singleton type)?

Like in isStableMember, "stability" means idempotence. Rationale: If an expression has a stable type, the expression must be idempotent, so stable types must be singleton types of stable expressions.

Is this an alias TypeBounds?

Is this type a primitive value type which can be widened to the primitive value type that?

Is this type a value type?

Is this a value type or a type lambda?

Is this a value type or a wildcard?

Is this the type of a method that has a repeated parameter type as last parameter type?

The lower bound of a TypeBounds type, the type itself otherwise

If this normalizes* to a refinement type that has a refinement for name (which might be followed by other refinements), and the refined info is a type alias, return the alias, otherwise return NoType. Used to reduce types of the form

P { ... type T = / += / -= U ... } # T

to just U. Does not perform the reduction if the resulting type would contain a reference to the "this" of the current refined type, except in the following situation

(1) The "this" reference can be avoided by following an alias. Example:

P { type T = String, type R = P{...}.T } # R  -->  String

(*) normalizes means: follow instantiated typevars and aliases.

Map function f over elements of an AndType, rebuilding with function g

Map function f over elements of an OrType, rebuilding with function g

Is this type close enough to that type so that members with the two types would override each other? This means:

• Either both types are polytypes with the same number of type parameters and their result types match after renaming corresponding type parameters
• Or both types are method types with =:=-equivalent(*) parameter types and matching result types after renaming corresponding parameter types if the method types are dependent.
• Or both types are =:=-equivalent
• Or phase.erasedTypes is false, and neither type takes term or type parameters.

(*) when matching with a Java method, we also regard Any and Object as equivalent parameter types.

Under explicit nulls, this function will always use unsafe-nulls semamtics to check the types. This is because we are using a relaxed rule (ignoring Null types) to check overriding Java methods.

This is the same as matches except that it also matches => T with T and vice versa.

The member of this type with the given name

The member with given name and required and/or excluded flags

The set of member classes of this type

The info of sym, seen as a member of this type.

The set of names of members of this type that pass the given name filter when seen as members of pre. More precisely, these are all of members name such that keepOnly(pre, name) is true.

The set of members of this type that have all of required flags but none of excluded flags set.

The parts of this type which are type or term refs and which satisfy predicate p.

A prefix-less refined this or a termRef to a new skolem symbol that has the given type as info.

The set of abstract type members of this type.

A denotation containing the non-private declaration(s) in this type with the given name

The non-private member of this type with the given name.

The result of normalization using tryNormalize, or the type itself if tryNormlize yields NoType

The normalized prefix of this type is: For an alias type, the normalized prefix of its alias For all other named type and class infos: the prefix. Inherited by all other type proxies. NoType for all other types.

Does this type occur as a part of type that?

This type, if it exists, otherwise that type

Is this type a legal type for member sym1 that overrides another member sym2 of type that? This is the same as <:<, except that

The parameter types of a PolyType or MethodType, Empty list for others

The parameter names of a PolyType or MethodType, Empty list for others

The least (wrt <:<) set of symbols satisfying the include predicate of which this type is a subtype

The full parent types, including all type arguments

Returns the set of methods that are abstract and do not overlap with any of java.lang.Object methods.

Conceptually, a SAM (functional interface) has exactly one abstract method. If an interface declares an abstract method overriding one of the public methods of java.lang.Object, that also does not count toward the interface's abstract method count.

this & that, but handle CyclicReferences by falling back to safe_&.

If this is a repeated type, its element type, otherwise the type itself

The resultType of a LambdaType, or ExprType, the type itself for others

If this is an ignored proto type, its underlying type, otherwise the type itself

Safer version of &.

This version does not simplify the bounds of the intersection of two TypeBounds. The simplification done by & requires subtyping checks which may end up calling & again, in most cases this should be safe but because of F-bounded types, this can result in an infinite loop (which will be masked unless -Yno-deep-subtypes is enabled). pos/i536 demonstrates that the infinite loop can also involve lower bounds.

The type <this . sym>, reduced if possible

The type <this . name> with given denotation, reduced if possible.

The type <this . name> , reduced if possible

The string representation of this showable element.

The string representation with each line after the first one indented by the given given margin (in spaces).

The summarized string representation of this showable element. Recursion depth is limited to some smallish value. Default is Config.summarizeDepth.

Utility method to show the underlying type of a TypeProxy chain together with the proxy type itself.

The signature of this type. This is by default NotAMethod, but is overridden for PolyTypes, MethodTypes, and TermRef types. (the reason why we deviate from the "final-method-with-pattern-match-in-base-class" pattern is that method signatures use caching, so encapsulation is improved using an OO scheme).

A simplified version of this type which is equivalent wrt =:= to this type. This applies a typemap to the type which (as all typemaps) follows type variable instances and reduces typerefs over refined types. It also

• re-evaluates all occurrences of And/OrType with &/| because what was a union or intersection of type variables might be a simpler type after the type variables are instantiated.
• maps poly params in the current constraint set back to their type vars.
• forces match types to be fully defined and tries to normalize them.

NOTE: Simplifying an intersection type might change its erasure (for example, the Java erasure of Object & Serializable is Object, but its simplification is Serializable). This means that simplification should never be used in a MethodicType, because that could lead to a different signature. Since this isn't very useful anyway, this method handles this by never simplifying inside a MethodicType.

Remove all AnnotatedTypes wrapping this type.

Strip LazyRef wrappers

Strip PolyType prefixes

Map a TypeVar to either its instance if it is instantiated, or its origin, if not, until the result is no longer a TypeVar. Identity on all other types.

Strip TypeVars and Annotation wrappers

Substitute all types of the form TypeParamRef(from, N) by TypeParamRef(to, N).

Substitute all types that refer in their symbol attribute to one of the symbols in from by the corresponding types in to.

Substitute all occurrences of symbols in from by corresponding types in to. Unlike for subst, the to types can be type bounds. A TypeBounds target will be replaced by range that gets absorbed in an approximating type map.

Substitute a bound type by some other type

Substitute bound types by some other types

Substitute all occurrences of RecThis(binder) by tp

Substitute all occurrences of symbols in from by references to corresponding symbols in to

Substitute all occurrences of This(cls) by tp

As substThis, but only is class is a static owner (i.e. a globally accessible object)

The closest supertype of this type. This is the same as underlying, except that

• instead of a TyperBounds type it returns its upper bound, and
• for applied types it returns the upper bound of the constructor re-applied to the arguments.

The term symbol associated with the type

Turn type into a function type.

Convert to text

Same as superType, except for two differences:

• opaque types are treated as transparent aliases
• applied type are matchtype-reduced if possible

Note: the reason to reduce match type aliases here and not in superType is that superType is context-independent and cached, whereas matchtype reduction depends on context and should not be cached (at least not without the very specific cache invalidation condition for matchtypes).

If this type can be normalized at the top-level by rewriting match types of S[n] types, the result after applying all toplevel normalizations, otherwise NoType

The set of type alias members of this type

The type constructor of an applied type, otherwise the type itself

The set of type members of this type

The type parameter with given name. This tries first decls in order not to provoke a cycle by forcing the info. If that yields no symbol it tries member as an alternative.

The number of applications and refinements in this type, after all aliases are expanded

The type symbol associated with the type

If this is a (possibly aliased, annotated, and/or parameterized) reference to a class, the class type ref, otherwise NoType.

Useful for diagnostics: The underlying type if this type is a type proxy, otherwise NoType

The iterator of underlying types as long as type is a TypeProxy. Useful for diagnostics

Is this type unusable for implicit search or overloading resolution since it has embedded errors that can match anything? This is weaker and more ad-hoc than isErroneous. The main differences are that we always consider aliases (since these are relevant for inference or resolution) but never consider prefixes (since these often do not constrain the search space anyway).

Widen from singleton type to its underlying non-singleton base type by applying one or more underlying dereferences, Also go from => T to T. Identity for all other types. Example:

class Outer { class C ; val x: C } def o: Outer <o.x.type>.widen = o.C

Perform successive widenings and dealiasings until none can be applied anymore

Perform successive widenings and dealiasings while rewrapping annotations, until none can be applied anymore

Perform successive widenings and dealiasings while rewrapping refining annotations, until none can be applied anymore

Widen from ExprType type to its result type. (Note: no stripTypeVar needed because TypeVar's can't refer to ExprTypes.)

Widen type if it is unstable (i.e. an ExprType, or TermRef to unstable symbol

Widen from singleton type to its underlying non-singleton base type by applying one or more underlying dereferences.

Widen all top-level singletons reachable by dealiasing and going to the operands of & and |. Overridden and cached in OrType.

If this is a skolem, its underlying type, otherwise the type itself

Widen from TermRef to its underlying non-termref base type, while also skipping Expr types.

Widen this type and if the result contains embedded soft union types, replace them by their joins. "Embedded" means: inside type lambdas, intersections or recursive types, in prefixes of refined types, or in hard union types. If an embedded soft union is found, we first try to simplify or eliminate it by re-lubbing it while allowing type parameters to be constrained further. Any remaining union types are replaced by their joins.

For instance, if A is an unconstrained type variable, then

  ArrayBuffer[Int] | ArrayBuffer[A]

is approximated by constraining A to be =:= to Int and returning ArrayBuffer[Int] instead of ArrayBuffer[? >: Int | A <: Int & A]

Exception (if -YexplicitNulls is set): if this type is a nullable union (i.e. of the form T | Null), then the top-level union isn't widened. This is needed so that type inference can infer nullable types.