cmd/compile/internal/noder: decode generic methods and pipe receivers

Change-Id: I7a66fba400a743f4ef2fb989cd8e74e955e22b0f
Reviewed-on: https://go-review.googlesource.com/c/go/+/762020
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Mark Freeman <markfreeman@google.com>
Reviewed-by: Robert Griesemer <gri@google.com>

2 files changed, 47 insertions, 11 deletions

diff --git a/src/cmd/compile/internal/noder/reader.go b/src/cmd/compile/internal/noder/reader.go
index ebb5043a05..e0545a86db 100644
--- a/src/cmd/compile/internal/noder/reader.go
+++ b/src/cmd/compile/internal/noder/reader.go
@@ -784,14 +784,22 @@ func (pr *pkgReader) objIdxMayFail(idx index, implicits, explicits []*types.Type
 		return name, nil
 
 	case pkgbits.ObjFunc:
-		if sym.Name == "init" {
-			sym = Renameinit()
-		}
-
 		npos := r.pos()
 		setBasePos(npos)
+
+		var sel *types.Sym
+		var recv *types.Field
+		if r.Version().Has(pkgbits.GenericMethods) && r.Bool() {
+			sel = r.selector()
+			r.recvTypeParamNames()
+			recv = r.param()
+		} else {
+			if sym.Name == "init" {
+				sym = Renameinit()
+			}
+		}
 		r.typeParamNames()
-		typ := r.signature(nil)
+		typ := r.signature(recv)
 		fpos := r.pos()
 
 		fn := ir.NewFunc(fpos, npos, sym, typ)
@@ -819,7 +827,7 @@ func (pr *pkgReader) objIdxMayFail(idx index, implicits, explicits []*types.Type
 			}
 		}
 
-		rext.funcExt(name, nil)
+		rext.funcExt(name, sel)
 		return name, nil
 
 	case pkgbits.ObjType:
@@ -1021,7 +1029,11 @@ func (pr *pkgReader) objDictIdx(sym *types.Sym, idx index, implicits, explicits
 	}
 
 	nimplicits := r.Len()
-	nexplicits := r.Len()
+	nreceivers := 0
+	if r.Version().Has(pkgbits.GenericMethods) {
+		nreceivers = r.Len()
+	}
+	nexplicits := r.Len() + nreceivers
 
 	if nimplicits > len(implicits) || nexplicits != len(explicits) {
 		return nil, fmt.Errorf("%v has %v+%v params, but instantiated with %v+%v args", sym, nimplicits, nexplicits, len(implicits), len(explicits))
@@ -1029,6 +1041,7 @@ func (pr *pkgReader) objDictIdx(sym *types.Sym, idx index, implicits, explicits
 
 	dict.targs = append(implicits[:nimplicits:nimplicits], explicits...)
 	dict.implicits = nimplicits
+	dict.receivers = nreceivers
 
 	// Within the compiler, we can just skip over the type parameters.
 	for range dict.targs[dict.implicits:] {
@@ -1095,10 +1108,19 @@ func (pr *pkgReader) objDictIdx(sym *types.Sym, idx index, implicits, explicits
 	return &dict, nil
 }
 
+func (r *reader) recvTypeParamNames() {
+	r.Sync(pkgbits.SyncTypeParamNames)
+
+	for range r.dict.targs[r.dict.implicits : r.dict.implicits+r.dict.receivers] {
+		r.pos()
+		r.localIdent()
+	}
+}
+
 func (r *reader) typeParamNames() {
 	r.Sync(pkgbits.SyncTypeParamNames)
 
-	for range r.dict.targs[r.dict.implicits:] {
+	for range r.dict.targs[r.dict.implicits+r.dict.receivers:] {
 		r.pos()
 		r.localIdent()
 	}
diff --git a/src/cmd/compile/internal/noder/writer.go b/src/cmd/compile/internal/noder/writer.go
index a42b11f6fa..85686a481a 100644
--- a/src/cmd/compile/internal/noder/writer.go
+++ b/src/cmd/compile/internal/noder/writer.go
@@ -203,9 +203,10 @@ type writer struct {
 
 // A writerDict tracks types and objects that are used by a declaration.
 type writerDict struct {
-	// implicits is a slice of type parameters from the enclosing
-	// declarations.
+	// implicits contains type parameters from enclosing declarations.
 	implicits []*types2.TypeParam
+	// receivers contains receiver type parameters of the declaration.
+	receivers []*types2.TypeParam
 
 	// derived is a slice of type indices for computing derived types
 	// (i.e., types that depend on the declaration's type parameters).
@@ -934,11 +935,21 @@ func (w *writer) objDict(obj types2.Object, dict *writerDict) {
 	// doesn't care about referenced functions.
 
 	w.dict = dict // TODO(mdempsky): This is a bit sketchy.
-
 	w.Len(len(dict.implicits))
 
+	rtparams := objRecvTypeParams(obj)
 	tparams := objTypeParams(obj)
+
+	if w.Version().Has(pkgbits.GenericMethods) {
+		w.Len(len(rtparams))
+	} else {
+		assert(len(rtparams) == 0)
+	}
 	w.Len(len(tparams))
+
+	for _, rtparam := range rtparams {
+		w.typ(rtparam.Constraint())
+	}
 	for _, tparam := range tparams {
 		w.typ(tparam.Constraint())
 	}
@@ -970,6 +981,9 @@ func (w *writer) objDict(obj types2.Object, dict *writerDict) {
 	for _, implicit := range dict.implicits {
 		w.Bool(implicit.Underlying().(*types2.Interface).IsMethodSet())
 	}
+	for _, rtparam := range rtparams {
+		w.Bool(rtparam.Underlying().(*types2.Interface).IsMethodSet())
+	}
 	for _, tparam := range tparams {
 		w.Bool(tparam.Underlying().(*types2.Interface).IsMethodSet())
 	}