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go/types: re-use type hashing logic in Context.typeHash 

The special handling for *Named types is not necessary. The hash of an
instance is simply the hash of its type followed by its type argument
list.

Change-Id: I7aa58e73b81731c3cad3a2fd14124f63cfb685a7
Reviewed-on: https://go-review.googlesource.com/c/go/+/362800
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
This commit is contained in:
Robert Findley 2021-11-09 22:28:18 -05:00
parent 2dbf37045c
commit ede97290ed
2 changed files with 12 additions and 18 deletions
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26
src/go/types/context.go
View File

@ -37,28 +37,22 @@ func NewContext() *Context {
}
}
// typeHash returns a string representation of typ, which can be used as an exact
// type hash: types that are identical produce identical string representations.
// If typ is a *Named type and targs is not empty, typ is printed as if it were
// instantiated with targs. The result is guaranteed to not contain blanks (" ").
// typeHash returns a string representation of typ instantiated with targs,
// which can be used as an exact type hash: types that are identical produce
// identical string representations. If targs is not empty, typ is printed as
// if it were instantiated with targs. The result is guaranteed to not contain
// blanks (" ").
func (ctxt *Context) typeHash(typ Type, targs []Type) string {
assert(ctxt != nil)
assert(typ != nil)
var buf bytes.Buffer
h := newTypeHasher(&buf, ctxt)
// Caution: don't use asNamed here. TypeHash may be called for unexpanded
// types. We don't need anything other than name and type arguments below,
// which do not require expansion.
if named, _ := typ.(*Named); named != nil && len(targs) > 0 {
// Don't use WriteType because we need to use the provided targs
// and not any targs that might already be with the *Named type.
h.typePrefix(named)
h.typeName(named.obj)
h.typ(typ)
if len(targs) > 0 {
// TODO(rfindley): consider asserting on isGeneric(typ) here, if and when
// isGeneric handles *Signature types.
h.typeList(targs)
} else {
assert(targs == nil)
h.typ(typ)
}
return strings.Replace(buf.String(), " ", "#", -1) // ReplaceAll is not available in Go1.4
@ -66,7 +60,7 @@ func (ctxt *Context) typeHash(typ Type, targs []Type) string {
// lookup returns an existing instantiation of orig with targs, if it exists.
// Otherwise, it returns nil.
func (ctxt *Context) lookup(h string, orig *Named, targs []Type) Type {
func (ctxt *Context) lookup(h string, orig Type, targs []Type) Type {
ctxt.mu.Lock()
defer ctxt.mu.Unlock()

4
src/go/types/instantiate.go
View File

@ -60,8 +60,8 @@ func (check *Checker) instance(pos token.Pos, orig Type, targs []Type, ctxt *Con
h = ctxt.typeHash(orig, targs)
// typ may already have been instantiated with identical type arguments. In
// that case, re-use the existing instance.
if named := ctxt.lookup(h, orig, targs); named != nil {
return named
if inst := ctxt.lookup(h, orig, targs); inst != nil {
return inst
}
}
tname := NewTypeName(pos, orig.obj.pkg, orig.obj.name, nil)