go/types: make ptrRecv a method hasPtrRecv of Func

This is a clean port of CL 351310 from types2 to go/types
with the necessary changes to methodset.go which doesn't
exist in types2.

Change-Id: Ifdac820d3be14c7bfa778b7bca3f6ba58d220b2e
Reviewed-on: https://go-review.googlesource.com/c/go/+/351311
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

src/go/types/lookup.go

@@ -212,7 +212,7 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 			//        is shorthand for (&x).m()".
 			if f, _ := obj.(*Func); f != nil {
 				// determine if method has a pointer receiver
-				hasPtrRecv := tpar == nil && ptrRecv(f)
+				hasPtrRecv := tpar == nil && f.hasPtrRecv()
 				if hasPtrRecv && !indirect && !addressable {
 					return nil, nil, true // pointer/addressable receiver required
 				}

src/go/types/methodset.go

@@ -232,10 +232,10 @@ func (s methodSet) add(list []*Func, index []int, indirect bool, multiples bool)
 		// if f is not in the set, add it
 		if !multiples {
 			// TODO(gri) A found method may not be added because it's not in the method set
-			// (!indirect && ptrRecv(f)). A 2nd method on the same level may be in the method
+			// (!indirect && f.hasPtrRecv()). A 2nd method on the same level may be in the method
 			// set and may not collide with the first one, thus leading to a false positive.
 			// Is that possible? Investigate.
-			if _, found := s[key]; !found && (indirect || !ptrRecv(f)) {
+			if _, found := s[key]; !found && (indirect || !f.hasPtrRecv()) {
 				s[key] = &Selection{MethodVal, nil, f, concat(index, i), indirect}
 				continue
 			}
@@ -244,22 +244,3 @@ func (s methodSet) add(list []*Func, index []int, indirect bool, multiples bool)
 	}
 	return s
 }
-
-// ptrRecv reports whether the receiver is of the form *T.
-func ptrRecv(f *Func) bool {
-	// If a method's receiver type is set, use that as the source of truth for the receiver.
-	// Caution: Checker.funcDecl (decl.go) marks a function by setting its type to an empty
-	// signature. We may reach here before the signature is fully set up: we must explicitly
-	// check if the receiver is set (we cannot just look for non-nil f.typ).
-	if sig, _ := f.typ.(*Signature); sig != nil && sig.recv != nil {
-		_, isPtr := deref(sig.recv.typ)
-		return isPtr
-	}
-
-	// If a method's type is not set it may be a method/function that is:
-	// 1) client-supplied (via NewFunc with no signature), or
-	// 2) internally created but not yet type-checked.
-	// For case 1) we can't do anything; the client must know what they are doing.
-	// For case 2) we can use the information gathered by the resolver.
-	return f.hasPtrRecv
-}

src/go/types/named.go

@@ -257,7 +257,7 @@ func expandNamed(env *Environment, n *Named, instPos token.Pos) (tparams *TypePa
 			// During type checking origm may not have a fully set up type, so defer
 			// instantiation of its signature until later.
 			m := NewFunc(origm.pos, origm.pkg, origm.name, nil)
-			m.hasPtrRecv = ptrRecv(origm)
+			m.hasPtrRecv_ = origm.hasPtrRecv()
 			// Setting instRecv here allows us to complete later (we need the
 			// instRecv to get targs and the original method).
 			m.instRecv = n
@@ -316,7 +316,7 @@ func (check *Checker) completeMethod(env *Environment, m *Func) {
 		sig = &copy
 	}
 	var rtyp Type
-	if ptrRecv(m) {
+	if m.hasPtrRecv() {
 		rtyp = NewPointer(rbase)
 	} else {
 		rtyp = rbase

src/go/types/object.go

@@ -317,8 +317,8 @@ func (*Var) isDependency() {} // a variable may be a dependency of an initializa
 // An abstract method may belong to many interfaces due to embedding.
 type Func struct {
 	object
-	instRecv   *Named // if non-nil, the receiver type for an incomplete instance method
-	hasPtrRecv bool   // only valid for methods that don't have a type yet
+	instRecv    *Named // if non-nil, the receiver type for an incomplete instance method
+	hasPtrRecv_ bool   // only valid for methods that don't have a type yet; use hasPtrRecv() to read
 }
 
 // NewFunc returns a new function with the given signature, representing
@@ -343,6 +343,25 @@ func (obj *Func) FullName() string {
 // Scope returns the scope of the function's body block.
 func (obj *Func) Scope() *Scope { return obj.typ.(*Signature).scope }
 
+// hasPtrRecv reports whether the receiver is of the form *T for the given method obj.
+func (obj *Func) hasPtrRecv() bool {
+	// If a method's receiver type is set, use that as the source of truth for the receiver.
+	// Caution: Checker.funcDecl (decl.go) marks a function by setting its type to an empty
+	// signature. We may reach here before the signature is fully set up: we must explicitly
+	// check if the receiver is set (we cannot just look for non-nil obj.typ).
+	if sig, _ := obj.typ.(*Signature); sig != nil && sig.recv != nil {
+		_, isPtr := deref(sig.recv.typ)
+		return isPtr
+	}
+
+	// If a method's type is not set it may be a method/function that is:
+	// 1) client-supplied (via NewFunc with no signature), or
+	// 2) internally created but not yet type-checked.
+	// For case 1) we can't do anything; the client must know what they are doing.
+	// For case 2) we can use the information gathered by the resolver.
+	return obj.hasPtrRecv_
+}
+
 func (*Func) isDependency() {} // a function may be a dependency of an initialization expression
 
 // A Label represents a declared label.

src/go/types/resolver.go

@@ -483,7 +483,7 @@ func (check *Checker) collectObjects() {
 		// Determine the receiver base type and associate m with it.
 		ptr, base := check.resolveBaseTypeName(m.ptr, m.recv)
 		if base != nil {
-			m.obj.hasPtrRecv = ptr
+			m.obj.hasPtrRecv_ = ptr
 			check.methods[base] = append(check.methods[base], m.obj)
 		}
 	}