go/types, types2: remove unused code in lookupFieldOrMethod

The underlying type of a type parameter is an interface,
so we don't need a special case for type parameters anymore.
Simply share the (identical) code for interfaces.

Adjust code in types.NewMethodSet accordingly.

No functional difference.
Preparation for fix of issues below.

For #50233.
For #50417.

Change-Id: Ib2deadd12f89e6918dec224b4ce35583001c3101
Reviewed-on: https://go-review.googlesource.com/c/go/+/375514
Trust: Robert Griesemer <gri@golang.org>
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

diff --git a/src/cmd/compile/internal/types2/lookup.go b/src/cmd/compile/internal/types2/lookup.go
index ee764c7d1407ef2fdc1a9c2da41fb00ef461e82e..7bdf13b4b7a9b9f700cd2f6fb3f801706680fe3f 100644 (file)
--- a/src/cmd/compile/internal/types2/lookup.go
+++ b/src/cmd/compile/internal/types2/lookup.go
@@ -82,7 +82,7 @@ func lookupFieldOrMethod(T Type, addressable, checkFold bool, pkg *Package, name
 
        typ, isPtr := deref(T)
 
-       // *typ where typ is an interface has no methods.
+       // *typ where typ is an interface (incl. a type parameter) has no methods.
        if isPtr {
                if _, ok := under(typ).(*Interface); ok {
                        return
@@ -106,7 +106,6 @@ func lookupFieldOrMethod(T Type, addressable, checkFold bool, pkg *Package, name
                var next []embeddedType // embedded types found at current depth
 
                // look for (pkg, name) in all types at current depth
-               var tpar *TypeParam // set if obj receiver is a type parameter
                for _, e := range current {
                        typ := e.typ
 
@@ -139,13 +138,9 @@ func lookupFieldOrMethod(T Type, addressable, checkFold bool, pkg *Package, name
                                        indirect = e.indirect
                                        continue // we can't have a matching field or interface method
                                }
-
-                               // continue with underlying type
-                               typ = named.under()
                        }
 
-                       tpar = nil
-                       switch t := typ.(type) {
+                       switch t := under(typ).(type) {
                        case *Struct:
                                // look for a matching field and collect embedded types
                                for i, f := range t.fields {
@@ -178,7 +173,7 @@ func lookupFieldOrMethod(T Type, addressable, checkFold bool, pkg *Package, name
                                }
 
                        case *Interface:
-                               // look for a matching method
+                               // look for a matching method (interface may be a type parameter)
                                if i, m := lookupMethodFold(t.typeSet().methods, pkg, name, checkFold); m != nil {
                                        assert(m.typ != nil)
                                        index = concat(e.index, i)
@@ -188,24 +183,6 @@ func lookupFieldOrMethod(T Type, addressable, checkFold bool, pkg *Package, name
                                        obj = m
                                        indirect = e.indirect
                                }
-
-                       case *TypeParam:
-                               if i, m := lookupMethodFold(t.iface().typeSet().methods, pkg, name, checkFold); m != nil {
-                                       assert(m.typ != nil)
-                                       index = concat(e.index, i)
-                                       if obj != nil || e.multiples {
-                                               return nil, index, false // collision
-                                       }
-                                       tpar = t
-                                       obj = m
-                                       indirect = e.indirect
-                               }
-                               if obj == nil {
-                                       // At this point we're not (yet) looking into methods
-                                       // that any underlying type of the types in the type list
-                                       // might have.
-                                       // TODO(gri) Do we want to specify the language that way?
-                               }
                        }
                }
 
@@ -217,8 +194,7 @@ func lookupFieldOrMethod(T Type, addressable, checkFold bool, pkg *Package, name
                        //        is shorthand for (&x).m()".
                        if f, _ := obj.(*Func); f != nil {
                                // determine if method has a pointer receiver
-                               hasPtrRecv := tpar == nil && f.hasPtrRecv()
-                               if hasPtrRecv && !indirect && !addressable {
+                               if f.hasPtrRecv() && !indirect && !addressable {
                                        return nil, nil, true // pointer/addressable receiver required
                                }
                        }

diff --git a/src/go/types/lookup.go b/src/go/types/lookup.go
index c787601a06512ae0644f1c4651a8625e26417126..7f3fbd69290198503df7a06f0c9ad8e010a1f8f9 100644 (file)
--- a/src/go/types/lookup.go
+++ b/src/go/types/lookup.go
@@ -80,7 +80,7 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
 
        typ, isPtr := deref(T)
 
-       // *typ where typ is an interface has no methods.
+       // *typ where typ is an interface (incl. a type parameter) has no methods.
        if isPtr {
                if _, ok := under(typ).(*Interface); ok {
                        return
@@ -104,7 +104,6 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
                var next []embeddedType // embedded types found at current depth
 
                // look for (pkg, name) in all types at current depth
-               var tpar *TypeParam // set if obj receiver is a type parameter
                for _, e := range current {
                        typ := e.typ
 
@@ -137,13 +136,9 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
                                        indirect = e.indirect
                                        continue // we can't have a matching field or interface method
                                }
-
-                               // continue with underlying type
-                               typ = named.under()
                        }
 
-                       tpar = nil
-                       switch t := typ.(type) {
+                       switch t := under(typ).(type) {
                        case *Struct:
                                // look for a matching field and collect embedded types
                                for i, f := range t.fields {
@@ -176,7 +171,7 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
                                }
 
                        case *Interface:
-                               // look for a matching method
+                               // look for a matching method (interface may be a type parameter)
                                if i, m := t.typeSet().LookupMethod(pkg, name); m != nil {
                                        assert(m.typ != nil)
                                        index = concat(e.index, i)
@@ -186,18 +181,6 @@ func lookupFieldOrMethod(T Type, addressable bool, pkg *Package, name string) (o
                                        obj = m
                                        indirect = e.indirect
                                }
-
-                       case *TypeParam:
-                               if i, m := t.iface().typeSet().LookupMethod(pkg, name); m != nil {
-                                       assert(m.typ != nil)
-                                       index = concat(e.index, i)
-                                       if obj != nil || e.multiples {
-                                               return nil, index, false // collision
-                                       }
-                                       tpar = t
-                                       obj = m
-                                       indirect = e.indirect
-                               }
                        }
                }
 
@@ -209,8 +192,7 @@ 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 && f.hasPtrRecv()
-                               if hasPtrRecv && !indirect && !addressable {
+                               if f.hasPtrRecv() && !indirect && !addressable {
                                        return nil, nil, true // pointer/addressable receiver required
                                }
                        }

diff --git a/src/go/types/methodset.go b/src/go/types/methodset.go
index e17be7c41af748b53e9fac3cb7bbd0e18422a4f5..5c3bc392714fb5f4e2da918696ad3245dcbb5008 100644 (file)
--- a/src/go/types/methodset.go
+++ b/src/go/types/methodset.go
@@ -126,16 +126,9 @@ func NewMethodSet(T Type) *MethodSet {
                                seen[named] = true
 
                                mset = mset.add(named.methods, e.index, e.indirect, e.multiples)
-
-                               // continue with underlying type, but only if it's not a type parameter
-                               // TODO(rFindley): should this use named.under()? Can there be a difference?
-                               typ = named.underlying
-                               if _, ok := typ.(*TypeParam); ok {
-                                       continue
-                               }
                        }
 
-                       switch t := typ.(type) {
+                       switch t := under(typ).(type) {
                        case *Struct:
                                for i, f := range t.fields {
                                        if fset == nil {
@@ -158,9 +151,6 @@ func NewMethodSet(T Type) *MethodSet {
 
                        case *Interface:
                                mset = mset.add(t.typeSet().methods, e.index, true, e.multiples)
-
-                       case *TypeParam:
-                               mset = mset.add(t.iface().typeSet().methods, e.index, true, e.multiples)
                        }
                }