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author | Paul Holzinger <pholzing@redhat.com> | 2022-09-08 15:32:44 +0200 |
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committer | Paul Holzinger <pholzing@redhat.com> | 2022-09-09 11:58:20 +0200 |
commit | eb28a1c08469d56494006d0f2c64933ab7078d01 (patch) | |
tree | dbacf86cf194955f34f09ec56d2df284321e2ae7 /vendor/golang.org/x/tools/internal/typeparams/coretype.go | |
parent | 7e2f002b0751c2c24e9c243495cbc313d0c3c103 (diff) | |
download | podman-eb28a1c08469d56494006d0f2c64933ab7078d01.tar.gz podman-eb28a1c08469d56494006d0f2c64933ab7078d01.tar.bz2 podman-eb28a1c08469d56494006d0f2c64933ab7078d01.zip |
update buildah and c/common to latest
also includes bumps for c/storage and c/image
Signed-off-by: Paul Holzinger <pholzing@redhat.com>
Diffstat (limited to 'vendor/golang.org/x/tools/internal/typeparams/coretype.go')
-rw-r--r-- | vendor/golang.org/x/tools/internal/typeparams/coretype.go | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/vendor/golang.org/x/tools/internal/typeparams/coretype.go b/vendor/golang.org/x/tools/internal/typeparams/coretype.go new file mode 100644 index 000000000..993135ec9 --- /dev/null +++ b/vendor/golang.org/x/tools/internal/typeparams/coretype.go @@ -0,0 +1,122 @@ +// 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 typeparams + +import ( + "go/types" +) + +// CoreType returns the core type of T or nil if T does not have a core type. +// +// See https://go.dev/ref/spec#Core_types for the definition of a core type. +func CoreType(T types.Type) types.Type { + U := T.Underlying() + if _, ok := U.(*types.Interface); !ok { + return U // for non-interface types, + } + + terms, err := _NormalTerms(U) + if len(terms) == 0 || err != nil { + // len(terms) -> empty type set of interface. + // err != nil => U is invalid, exceeds complexity bounds, or has an empty type set. + return nil // no core type. + } + + U = terms[0].Type().Underlying() + var identical int // i in [0,identical) => Identical(U, terms[i].Type().Underlying()) + for identical = 1; identical < len(terms); identical++ { + if !types.Identical(U, terms[identical].Type().Underlying()) { + break + } + } + + if identical == len(terms) { + // https://go.dev/ref/spec#Core_types + // "There is a single type U which is the underlying type of all types in the type set of T" + return U + } + ch, ok := U.(*types.Chan) + if !ok { + return nil // no core type as identical < len(terms) and U is not a channel. + } + // https://go.dev/ref/spec#Core_types + // "the type chan E if T contains only bidirectional channels, or the type chan<- E or + // <-chan E depending on the direction of the directional channels present." + for chans := identical; chans < len(terms); chans++ { + curr, ok := terms[chans].Type().Underlying().(*types.Chan) + if !ok { + return nil + } + if !types.Identical(ch.Elem(), curr.Elem()) { + return nil // channel elements are not identical. + } + if ch.Dir() == types.SendRecv { + // ch is bidirectional. We can safely always use curr's direction. + ch = curr + } else if curr.Dir() != types.SendRecv && ch.Dir() != curr.Dir() { + // ch and curr are not bidirectional and not the same direction. + return nil + } + } + return ch +} + +// _NormalTerms returns a slice of terms representing the normalized structural +// type restrictions of a type, if any. +// +// For all types other than *types.TypeParam, *types.Interface, and +// *types.Union, this is just a single term with Tilde() == false and +// Type() == typ. For *types.TypeParam, *types.Interface, and *types.Union, see +// below. +// +// Structural type restrictions of a type parameter are created via +// non-interface types embedded in its constraint interface (directly, or via a +// chain of interface embeddings). For example, in the declaration type +// T[P interface{~int; m()}] int the structural restriction of the type +// parameter P is ~int. +// +// With interface embedding and unions, the specification of structural type +// restrictions may be arbitrarily complex. For example, consider the +// following: +// +// type A interface{ ~string|~[]byte } +// +// type B interface{ int|string } +// +// type C interface { ~string|~int } +// +// type T[P interface{ A|B; C }] int +// +// In this example, the structural type restriction of P is ~string|int: A|B +// expands to ~string|~[]byte|int|string, which reduces to ~string|~[]byte|int, +// which when intersected with C (~string|~int) yields ~string|int. +// +// _NormalTerms computes these expansions and reductions, producing a +// "normalized" form of the embeddings. A structural restriction is normalized +// if it is a single union containing no interface terms, and is minimal in the +// sense that removing any term changes the set of types satisfying the +// constraint. It is left as a proof for the reader that, modulo sorting, there +// is exactly one such normalized form. +// +// Because the minimal representation always takes this form, _NormalTerms +// returns a slice of tilde terms corresponding to the terms of the union in +// the normalized structural restriction. An error is returned if the type is +// invalid, exceeds complexity bounds, or has an empty type set. In the latter +// case, _NormalTerms returns ErrEmptyTypeSet. +// +// _NormalTerms makes no guarantees about the order of terms, except that it +// is deterministic. +func _NormalTerms(typ types.Type) ([]*Term, error) { + switch typ := typ.(type) { + case *TypeParam: + return StructuralTerms(typ) + case *Union: + return UnionTermSet(typ) + case *types.Interface: + return InterfaceTermSet(typ) + default: + return []*Term{NewTerm(false, typ)}, nil + } +} |