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author | Matthew Dempsky <mdempsky@google.com> | 2022-08-04 10:12:28 -0700 |
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committer | Matthew Dempsky <mdempsky@google.com> | 2022-08-04 10:12:28 -0700 |
commit | d558507db42d600e5ad82748bda0cb91df57b97d (patch) | |
tree | 169457500d42144774eb68c5ab2ef70ad67aa673 /src/cmd/vendor/golang.org/x/tools/internal/typeparams/coretype.go | |
parent | c9f2150cfb3c1db87f6434f727c25403d985a6e4 (diff) | |
parent | 85d87b9c7507628144db51bd1e7e80cc3afed128 (diff) | |
download | go-d558507db42d600e5ad82748bda0cb91df57b97d.tar.gz go-d558507db42d600e5ad82748bda0cb91df57b97d.zip |
[dev.unified] all: merge master (85d87b9) into dev.unifieddev.unified
Merge List:
+ 2022-08-04 85d87b9c75 all: update vendored golang.org/x dependencies for Go 1.20 development
+ 2022-08-04 fb1bfd4d37 all: remove pre-Go 1.17 workarounds
+ 2022-08-04 44ff9bff0c runtime: clean up panic and deadlock lock ranks
+ 2022-08-04 f42dc0de74 runtime: make the lock rank DAG make more sense
+ 2022-08-04 d29a0282e9 runtime: add mayAcquire annotation for finlock
+ 2022-08-04 c5be4ed7df runtime: add missing trace lock edges
+ 2022-08-04 2b8a9a484f runtime: generate the lock ranking from a DAG description
+ 2022-08-04 ddfd639408 runtime: delete unused lock ranks
+ 2022-08-04 426ea5702b internal/dag: add a Graph type and make node order deterministic
+ 2022-08-04 d37cc9a8cd go/build, internal/dag: lift DAG parser into an internal package
+ 2022-08-04 ab0a94c6d3 cmd/dist: require Go 1.17 for building Go
+ 2022-08-04 1e3c19f3fe runtime: support riscv64 SV57 mode
+ 2022-08-03 f28fa952b5 make.bat, make.rc: show bootstrap toolchain version
+ 2022-08-03 87384801dc cmd/asm: update package doc to describe "-p" option
+ 2022-08-03 c6a2dada0d net: disable TestIPv6WriteMsgUDPAddrPortTargetAddrIPVersion [sic] on DragonflyBSD
+ 2022-08-02 29b9a328d2 runtime: trivial replacements of g in remaining files
+ 2022-08-02 c647264619 runtime: trivial replacements of g in signal_unix.go
+ 2022-08-02 399f50c9d7 runtime: tricky replacements of g in traceback.go
+ 2022-08-02 4509e951ec runtime: tricky replacements of g in proc.go
+ 2022-08-02 4400238ec8 runtime: trivial replacements of _g_ in remaining files
+ 2022-08-02 5999a28de8 runtime: trivial replacements of _g_ in os files
+ 2022-08-02 0e18cf6d09 runtime: trivial replacements of _g_ in GC files
+ 2022-08-02 4358a53a97 runtime: trivial replacements of _g_ in proc.go
+ 2022-08-02 b486518964 runtime: tricky replacements of _g_ in os3_solaris.go
+ 2022-08-02 54a0ab3f7b runtime: tricky replacements of _g_ in os3_plan9.go
+ 2022-08-02 4240ff764b runtime: tricky replacements of _g_ in signal_windows.go
+ 2022-08-02 8666d89ca8 runtime: tricky replacements of _g_ in signal_unix.go
+ 2022-08-02 74cee276fe runtime: tricky replacements of _g_ in trace.go
+ 2022-08-02 222799fde6 runtime: tricky replacements of _g_ in mgc.go
+ 2022-08-02 e9d7f54a1a runtime: tricky replacements of _g_ in proc.go
+ 2022-08-02 5e8d261918 runtime: rename _p_ to pp
+ 2022-08-02 0ad2ec6596 runtime: clean up dopanic_m
+ 2022-08-02 7e952962df runtime: clean up canpanic
+ 2022-08-02 9dbc0f3556 runtime: fix outdated g.m comment in traceback.go
+ 2022-08-02 d723df76da internal/goversion: update Version to 1.20
+ 2022-08-02 1b7e71e8ae all: disable tests that fail on Alpine
+ 2022-08-01 f2a9f3e2e0 test: improve generic type assertion test
+ 2022-08-01 27038b70f8 cmd/compile: fix wrong dict pass condition for type assertions
+ 2022-08-01 e99f53fed9 doc: move Go 1.19 release notes to x/website
+ 2022-08-01 8b13a073a1 doc: mention removal of cmd/compile's -importmap and -installsuffix flags
+ 2022-08-01 e95fd4c238 doc/go1.19: fix typo: EM_LONGARCH -> EM_LOONGARCH
+ 2022-08-01 dee3efd9f8 doc/go1.19: fix a few links that were missing trailing slashes
+ 2022-07-30 f32519e5fb runtime: fix typos
+ 2022-07-29 9a2001a8cc cmd/dist: always pass -short=true with -quick
+ 2022-07-28 5c8ec89cb5 doc/go1.19: minor adjustments and links
+ 2022-07-28 417be37048 doc/go1.19: improve the loong64 release notes
+ 2022-07-28 027855e8d8 os/exec: add GODEBUG setting to opt out of ErrDot changes
Change-Id: Idc0fbe93978c0dff7600b90a2c3ecc067fd9f5f2
Diffstat (limited to 'src/cmd/vendor/golang.org/x/tools/internal/typeparams/coretype.go')
-rw-r--r-- | src/cmd/vendor/golang.org/x/tools/internal/typeparams/coretype.go | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/src/cmd/vendor/golang.org/x/tools/internal/typeparams/coretype.go b/src/cmd/vendor/golang.org/x/tools/internal/typeparams/coretype.go new file mode 100644 index 0000000000..993135ec90 --- /dev/null +++ b/src/cmd/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 + } +} |