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go/types, types2: remove unused code in lookupFieldOrMethod
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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>
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@griesemer
griesemer committed Jan 6, 2022
1 parent c5540e5 commit 2bfa6ef
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Showing 3 changed files with 9 additions and 61 deletions.
32 changes: 4 additions & 28 deletions src/cmd/compile/internal/types2/lookup.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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

Expand Down Expand Up @@ -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 {
Expand Down Expand Up @@ -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)
Expand All @@ -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?
}
}
}

Expand All @@ -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
}
}
Expand Down
26 changes: 4 additions & 22 deletions src/go/types/lookup.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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

Expand Down Expand Up @@ -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 {
Expand Down Expand Up @@ -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)
Expand All @@ -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
}
}
}

Expand All @@ -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
}
}
Expand Down
12 changes: 1 addition & 11 deletions src/go/types/methodset.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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 {
Expand All @@ -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)
}
}

Expand Down

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