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// Code generated by "go test -run=Generate -write=all"; DO NOT EDIT.

// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package types

// validType verifies that the given type does not "expand" indefinitely
// producing a cycle in the type graph.
// (Cycles involving alias types, as in "type A = [10]A" are detected
// earlier, via the objDecl cycle detection mechanism.)
func (check *Checker) validType(typ *Named) {
	check.validType0(typ, nil, nil)
}

// validType0 checks if the given type is valid. If typ is a type parameter
// its value is looked up in the type argument list of the instantiated
// (enclosing) type, if it exists. Otherwise the type parameter must be from
// an enclosing function and can be ignored.
// The nest list describes the stack (the "nest in memory") of types which
// contain (or embed in the case of interfaces) other types. For instance, a
// struct named S which contains a field of named type F contains (the memory
// of) F in S, leading to the nest S->F. If a type appears in its own nest
// (say S->F->S) we have an invalid recursive type. The path list is the full
// path of named types in a cycle, it is only needed for error reporting.
func (check *Checker) validType0(typ Type, nest, path []*Named) bool {
	switch t := Unalias(typ).(type) {
	case nil:
		// We should never see a nil type but be conservative and panic
		// only in debug mode.
		if debug {
			panic("validType0(nil)")
		}

case *Array:
		return check.validType0(t.elem, nest, path)

case *Struct:
		for _, f := range t.fields {
			if !check.validType0(f.typ, nest, path) {
				return false
			}
		}

case *Union:
		for _, t := range t.terms {
			if !check.validType0(t.typ, nest, path) {
				return false
			}
		}

case *Interface:
		for _, etyp := range t.embeddeds {
			if !check.validType0(etyp, nest, path) {
				return false
			}
		}

case *Named:
		// Exit early if we already know t is valid.
		// This is purely an optimization but it prevents excessive computation
		// times in pathological cases such as testdata/fixedbugs/issue6977.go.
		// (Note: The valids map could also be allocated locally, once for each
		// validType call.)
		if check.valids.lookup(t) != nil {
			break
		}

// Don't report a 2nd error if we already know the type is invalid
		// (e.g., if a cycle was detected earlier, via under).
		// Note: ensure that t.orig is fully resolved by calling Underlying().
		if !isValid(t.Underlying()) {
			return false
		}

// If the current type t is also found in nest, (the memory of) t is
		// embedded in itself, indicating an invalid recursive type.
		for _, e := range nest {
			if Identical(e, t) {
				// We have a cycle. If t != t.Origin() then t is an instance of
				// the generic type t.Origin(). Because t is in the nest, t must
				// occur within the definition (RHS) of the generic type t.Origin(),
				// directly or indirectly, after expansion of the RHS.
				// Therefore t.Origin() must be invalid, no matter how it is
				// instantiated since the instantiation t of t.Origin() happens
				// inside t.Origin()'s RHS and thus is always the same and always
				// present.
				// Therefore we can mark the underlying of both t and t.Origin()
				// as invalid. If t is not an instance of a generic type, t and
				// t.Origin() are the same.
				// Furthermore, because we check all types in a package for validity
				// before type checking is complete, any exported type that is invalid
				// will have an invalid underlying type and we can't reach here with
				// such a type (invalid types are excluded above).
				// Thus, if we reach here with a type t, both t and t.Origin() (if
				// different in the first place) must be from the current package;
				// they cannot have been imported.
				// Therefore it is safe to change their underlying types; there is
				// no chance for a race condition (the types of the current package
				// are not yet available to other goroutines).
				assert(t.obj.pkg == check.pkg)
				assert(t.Origin().obj.pkg == check.pkg)
				t.underlying = Typ[Invalid]
				t.Origin().underlying = Typ[Invalid]

// Find the starting point of the cycle and report it.
				// Because each type in nest must also appear in path (see invariant below),
				// type t must be in path since it was found in nest. But not every type in path
				// is in nest. Specifically t may appear in path with an earlier index than the
				// index of t in nest. Search again.
				for start, p := range path {
					if Identical(p, t) {
						check.cycleError(makeObjList(path[start:]))
						return false
					}
				}
				panic("cycle start not found")
			}
		}

// No cycle was found. Check the RHS of t.
		// Every type added to nest is also added to path; thus every type that is in nest
		// must also be in path (invariant). But not every type in path is in nest, since
		// nest may be pruned (see below, *TypeParam case).
		if !check.validType0(t.Origin().fromRHS, append(nest, t), append(path, t)) {
			return false
		}

check.valids.add(t) // t is valid

case *TypeParam:
		// A type parameter stands for the type (argument) it was instantiated with.
		// Check the corresponding type argument for validity if we are in an
		// instantiated type.
		if len(nest) > 0 {
			inst := nest[len(nest)-1] // the type instance
			// Find the corresponding type argument for the type parameter
			// and proceed with checking that type argument.
			for i, tparam := range inst.TypeParams().list() {
				// The type parameter and type argument lists should
				// match in length but be careful in case of errors.
				if t == tparam && i < inst.TypeArgs().Len() {
					targ := inst.TypeArgs().At(i)
					// The type argument must be valid in the enclosing
					// type (where inst was instantiated), hence we must
					// check targ's validity in the type nest excluding
					// the current (instantiated) type (see the example
					// at the end of this file).
					// For error reporting we keep the full path.
					return check.validType0(targ, nest[:len(nest)-1], path)
				}
			}
		}
	}

return true
}

// makeObjList returns the list of type name objects for the given
// list of named types.
func makeObjList(tlist []*Named) []Object {
	olist := make([]Object, len(tlist))
	for i, t := range tlist {
		olist[i] = t.obj
	}
	return olist
}

// Here is an example illustrating why we need to exclude the
// instantiated type from nest when evaluating the validity of
// a type parameter. Given the declarations
//
//   var _ A[A[string]]
//
//   type A[P any] struct { _ B[P] }
//   type B[P any] struct { _ P }
//
// we want to determine if the type A[A[string]] is valid.
// We start evaluating A[A[string]] outside any type nest:
//
//   A[A[string]]
//         nest =
//         path =
//
// The RHS of A is now evaluated in the A[A[string]] nest:
//
//   struct{_ B[P₁]}
//         nest = A[A[string]]
//         path = A[A[string]]
//
// The struct has a single field of type B[P₁] with which
// we continue:
//
//   B[P₁]
//         nest = A[A[string]]
//         path = A[A[string]]
//
//   struct{_ P₂}
//         nest = A[A[string]]->B[P]
//         path = A[A[string]]->B[P]
//
// Eventually we reach the type parameter P of type B (P₂):
//
//   P₂
//         nest = A[A[string]]->B[P]
//         path = A[A[string]]->B[P]
//
// The type argument for P of B is the type parameter P of A (P₁).
// It must be evaluated in the type nest that existed when B was
// instantiated:
//
//   P₁
//         nest = A[A[string]]        <== type nest at B's instantiation time
//         path = A[A[string]]->B[P]
//
// If we'd use the current nest it would correspond to the path
// which will be wrong as we will see shortly. P's type argument
// is A[string], which again must be evaluated in the type nest
// that existed when A was instantiated with A[string]. That type
// nest is empty:
//
//   A[string]
//         nest =                     <== type nest at A's instantiation time
//         path = A[A[string]]->B[P]
//
// Evaluation then proceeds as before for A[string]:
//
//   struct{_ B[P₁]}
//         nest = A[string]
//         path = A[A[string]]->B[P]->A[string]
//
// Now we reach B[P] again. If we had not adjusted nest, it would
// correspond to path, and we would find B[P] in nest, indicating
// a cycle, which would clearly be wrong since there's no cycle in
// A[string]:
//
//   B[P₁]
//         nest = A[string]
//         path = A[A[string]]->B[P]->A[string]  <== path contains B[P]!
//
// But because we use the correct type nest, evaluation proceeds without
// errors and we get the evaluation sequence:
//
//   struct{_ P₂}
//         nest = A[string]->B[P]
//         path = A[A[string]]->B[P]->A[string]->B[P]
//   P₂
//         nest = A[string]->B[P]
//         path = A[A[string]]->B[P]->A[string]->B[P]
//   P₁
//         nest = A[string]
//         path = A[A[string]]->B[P]->A[string]->B[P]
//   string
//         nest =
//         path = A[A[string]]->B[P]->A[string]->B[P]
//
// At this point we're done and A[A[string]] and is valid.

Batal

⬅ go 97 item

Nama	Tipe	Ukuran	Diubah	Aksi
📁testdata	dir	—	2024-02-02 18:09	📂 Buka
🔵alias.go	go	2.2 KB	2024-02-02 18:09	✏️ 👁️
🔵api.go	go	16.5 KB	2024-02-02 18:09	✏️ 👁️
🔵api_predicates.go	go	2.8 KB	2024-02-02 18:09	✏️ 👁️
🔵api_test.go	go	90.4 KB	2024-02-02 18:09	✏️ 👁️
🔵array.go	go	873 B	2024-02-02 18:09	✏️ 👁️
🔵assignments.go	go	16 KB	2024-02-02 18:09	✏️ 👁️
🔵basic.go	go	1.6 KB	2024-02-02 18:09	✏️ 👁️
🔵builtins.go	go	27.1 KB	2024-02-02 18:09	✏️ 👁️
🔵builtins_test.go	go	10.8 KB	2024-02-02 18:09	✏️ 👁️
🔵call.go	go	34.1 KB	2024-02-02 18:09	✏️ 👁️
🔵chan.go	go	980 B	2024-02-02 18:09	✏️ 👁️
🔵check.go	go	20.6 KB	2024-02-02 18:09	✏️ 👁️
🔵check_test.go	go	14.1 KB	2024-02-02 18:09	✏️ 👁️
🔵commentMap_test.go	go	3 KB	2024-02-02 18:09	✏️ 👁️
🔵const.go	go	7.5 KB	2024-02-02 18:09	✏️ 👁️
🔵context.go	go	4.4 KB	2024-02-02 18:09	✏️ 👁️
🔵context_test.go	go	2.4 KB	2024-02-02 18:09	✏️ 👁️
🔵conversions.go	go	8.8 KB	2024-02-02 18:09	✏️ 👁️
🔵decl.go	go	30 KB	2024-02-02 18:09	✏️ 👁️
🔵errorcalls_test.go	go	2.2 KB	2024-02-02 18:09	✏️ 👁️
🔵errors.go	go	9.8 KB	2024-02-02 18:09	✏️ 👁️
🔵errors_test.go	go	1002 B	2024-02-02 18:09	✏️ 👁️
🔵eval.go	go	3.1 KB	2024-02-02 18:09	✏️ 👁️
🔵eval_test.go	go	7.1 KB	2024-02-02 18:09	✏️ 👁️
🔵example_test.go	go	8.9 KB	2024-02-02 18:09	✏️ 👁️
🔵expr.go	go	48.7 KB	2024-02-02 18:09	✏️ 👁️
🔵exprstring.go	go	4.8 KB	2024-02-02 18:09	✏️ 👁️
🔵exprstring_test.go	go	2.5 KB	2024-02-02 18:09	✏️ 👁️
🔵gccgosizes.go	go	1.1 KB	2024-02-02 18:09	✏️ 👁️
🔵gcsizes.go	go	4.3 KB	2024-02-02 18:09	✏️ 👁️
🔵generate.go	go	269 B	2024-02-02 18:09	✏️ 👁️
🔵generate_test.go	go	11.8 KB	2024-02-02 18:09	✏️ 👁️
🔵gotype.go	go	8.3 KB	2024-02-02 18:09	✏️ 👁️
🔵hilbert_test.go	go	3.4 KB	2024-02-02 18:09	✏️ 👁️
🔵index.go	go	11.2 KB	2024-02-02 18:09	✏️ 👁️
🔵infer.go	go	26.2 KB	2024-02-02 18:09	✏️ 👁️
🔵initorder.go	go	9.7 KB	2024-02-02 18:09	✏️ 👁️
🔵instantiate.go	go	12 KB	2024-02-02 18:09	✏️ 👁️
🔵instantiate_test.go	go	5.9 KB	2024-02-02 18:09	✏️ 👁️
🔵interface.go	go	8.1 KB	2024-02-02 18:09	✏️ 👁️
🔵issues_test.go	go	28.1 KB	2024-02-02 18:09	✏️ 👁️
🔵labels.go	go	7.2 KB	2024-02-02 18:09	✏️ 👁️
🔵lookup.go	go	19.7 KB	2024-02-02 18:09	✏️ 👁️
🔵lookup_test.go	go	1.2 KB	2024-02-02 18:09	✏️ 👁️
🔵main_test.go	go	406 B	2024-02-02 18:09	✏️ 👁️
🔵map.go	go	729 B	2024-02-02 18:09	✏️ 👁️
🔵methodset.go	go	7.1 KB	2024-02-02 18:09	✏️ 👁️
🔵methodset_test.go	go	6.7 KB	2024-02-02 18:09	✏️ 👁️
🔵mono.go	go	9.1 KB	2024-02-02 18:09	✏️ 👁️
🔵mono_test.go	go	2.5 KB	2024-02-02 18:09	✏️ 👁️
🔵named.go	go	22.7 KB	2024-02-02 18:09	✏️ 👁️
🔵named_test.go	go	2.6 KB	2024-02-02 18:09	✏️ 👁️
🔵object.go	go	19 KB	2024-02-02 18:09	✏️ 👁️
🔵object_test.go	go	5 KB	2024-02-02 18:09	✏️ 👁️
🔵objset.go	go	998 B	2024-02-02 18:09	✏️ 👁️
🔵operand.go	go	10.3 KB	2024-02-02 18:09	✏️ 👁️
🔵package.go	go	3 KB	2024-02-02 18:09	✏️ 👁️
🔵pointer.go	go	705 B	2024-02-02 18:09	✏️ 👁️
🔵predicates.go	go	16.8 KB	2024-02-02 18:09	✏️ 👁️
🔵resolver.go	go	25.6 KB	2024-02-02 18:09	✏️ 👁️
🔵resolver_test.go	go	4.5 KB	2024-02-02 18:09	✏️ 👁️
🔵return.go	go	4.2 KB	2024-02-02 18:09	✏️ 👁️
🔵scope.go	go	9.4 KB	2024-02-02 18:09	✏️ 👁️
🔵selection.go	go	5.8 KB	2024-02-02 18:09	✏️ 👁️
🔵self_test.go	go	2.8 KB	2024-02-02 18:09	✏️ 👁️
🔵signature.go	go	13 KB	2024-02-02 18:09	✏️ 👁️
🔵sizeof_test.go	go	1.3 KB	2024-02-02 18:09	✏️ 👁️
🔵sizes.go	go	8.9 KB	2024-02-02 18:09	✏️ 👁️
🔵sizes_test.go	go	4 KB	2024-02-02 18:09	✏️ 👁️
🔵slice.go	go	647 B	2024-02-02 18:09	✏️ 👁️
🔵stdlib_test.go	go	13.7 KB	2024-02-02 18:09	✏️ 👁️
🔵stmt.go	go	29.8 KB	2024-02-02 18:09	✏️ 👁️
🔵struct.go	go	6.2 KB	2024-02-02 18:09	✏️ 👁️
🔵subst.go	go	11.1 KB	2024-02-02 18:09	✏️ 👁️
🔵termlist.go	go	3.8 KB	2024-02-02 18:09	✏️ 👁️
🔵termlist_test.go	go	7.3 KB	2024-02-02 18:09	✏️ 👁️
🔵token_test.go	go	1.2 KB	2024-02-02 18:09	✏️ 👁️
🔵tuple.go	go	999 B	2024-02-02 18:09	✏️ 👁️
🔵type.go	go	422 B	2024-02-02 18:09	✏️ 👁️
🔵typelists.go	go	1.9 KB	2024-02-02 18:09	✏️ 👁️
🔵typeparam.go	go	4.8 KB	2024-02-02 18:09	✏️ 👁️
🔵typeset.go	go	13.6 KB	2024-02-02 18:09	✏️ 👁️
🔵typeset_test.go	go	2.3 KB	2024-02-02 18:09	✏️ 👁️
🔵typestring.go	go	12 KB	2024-02-02 18:09	✏️ 👁️
🔵typestring_test.go	go	3.9 KB	2024-02-02 18:09	✏️ 👁️
🔵typeterm.go	go	3.6 KB	2024-02-02 18:09	✏️ 👁️
🔵typeterm_test.go	go	5.1 KB	2024-02-02 18:09	✏️ 👁️
🔵typexpr.go	go	15.5 KB	2024-02-02 18:09	✏️ 👁️
🔵under.go	go	2.7 KB	2024-02-02 18:09	✏️ 👁️
🔵unify.go	go	27.6 KB	2024-02-02 18:09	✏️ 👁️
🔵union.go	go	6.2 KB	2024-02-02 18:09	✏️ 👁️
🔵universe.go	go	8 KB	2024-02-02 18:09	✏️ 👁️
🔵util.go	go	748 B	2024-02-02 18:09	✏️ 👁️
🔵util_test.go	go	568 B	2024-02-02 18:09	✏️ 👁️
🔵validtype.go	go	9 KB	2024-02-02 18:09	✏️ 👁️
🔵version.go	go	4 KB	2024-02-02 18:09	✏️ 👁️

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