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>

diff --git a/src/go/types/context.go b/src/go/types/context.go
index 0c2b0958c109f2d1e79258c0146a38935a45610c..1f102f0b8b78267f5ffdfcf45321e7bd01368e8d 100644 (file)
--- a/src/go/types/context.go
+++ b/src/go/types/context.go
@@ -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()
 

diff --git a/src/go/types/instantiate.go b/src/go/types/instantiate.go
index 814d457de3dfe08ec789e200589c51200cfba6a6..62d9e1840184f936951eb2cfd7b00a4e4f1071ba 100644 (file)
--- a/src/go/types/instantiate.go
+++ b/src/go/types/instantiate.go
@@ -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)