[dev.regabi] cmd/compile: simplify function/interface/struct typechecking

After the previous CL, the only callers to NewFuncType, tointerface,
or NewStructType are the functions for type-checking the type literal
ASTs. So just inline the code there.

While here, refactor the Field type-checking logic a little bit, to
reduce some duplication.

Passes toolstash -cmp.

Change-Id: Ie12d14b87ef8b6e528ac9dccd609604bd09b98ec
Reviewed-on: https://go-review.googlesource.com/c/go/+/279956
Trust: Matthew Dempsky <mdempsky@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>

src/cmd/compile/internal/typecheck/dcl.go

@@ -281,72 +281,6 @@ func CheckFuncStack() {
 	}
 }
 
-// turn a parsed function declaration into a type
-func NewFuncType(nrecv *ir.Field, nparams, nresults []*ir.Field) *types.Type {
-	funarg := func(n *ir.Field) *types.Field {
-		lno := base.Pos
-		base.Pos = n.Pos
-
-		if n.Ntype != nil {
-			n.Type = typecheckNtype(n.Ntype).Type()
-			n.Ntype = nil
-		}
-
-		f := types.NewField(n.Pos, n.Sym, n.Type)
-		f.SetIsDDD(n.IsDDD)
-		if n.Decl != nil {
-			n.Decl.SetType(f.Type)
-			f.Nname = n.Decl
-		}
-
-		base.Pos = lno
-		return f
-	}
-	funargs := func(nn []*ir.Field) []*types.Field {
-		res := make([]*types.Field, len(nn))
-		for i, n := range nn {
-			res[i] = funarg(n)
-		}
-		return res
-	}
-
-	var recv *types.Field
-	if nrecv != nil {
-		recv = funarg(nrecv)
-	}
-
-	t := types.NewSignature(types.LocalPkg, recv, funargs(nparams), funargs(nresults))
-	checkdupfields("argument", t.Recvs().FieldSlice(), t.Params().FieldSlice(), t.Results().FieldSlice())
-	return t
-}
-
-// convert a parsed id/type list into
-// a type for struct/interface/arglist
-func NewStructType(l []*ir.Field) *types.Type {
-	lno := base.Pos
-
-	fields := make([]*types.Field, len(l))
-	for i, n := range l {
-		base.Pos = n.Pos
-
-		if n.Ntype != nil {
-			n.Type = typecheckNtype(n.Ntype).Type()
-			n.Ntype = nil
-		}
-		f := types.NewField(n.Pos, n.Sym, n.Type)
-		if n.Embedded {
-			checkembeddedtype(n.Type)
-			f.Embedded = 1
-		}
-		f.Note = n.Note
-		fields[i] = f
-	}
-	checkdupfields("field", fields)
-
-	base.Pos = lno
-	return types.NewStruct(types.LocalPkg, fields)
-}
-
 // Add a method, declared as a function.
 // - msym is the method symbol
 // - t is function type (with receiver)
@@ -604,27 +538,6 @@ func initname(s string) bool {
 	return s == "init"
 }
 
-func tointerface(nmethods []*ir.Field) *types.Type {
-	if len(nmethods) == 0 {
-		return types.Types[types.TINTER]
-	}
-
-	lno := base.Pos
-
-	methods := make([]*types.Field, len(nmethods))
-	for i, n := range nmethods {
-		base.Pos = n.Pos
-		if n.Ntype != nil {
-			n.Type = typecheckNtype(n.Ntype).Type()
-			n.Ntype = nil
-		}
-		methods[i] = types.NewField(n.Pos, n.Sym, n.Type)
-	}
-
-	base.Pos = lno
-	return types.NewInterface(types.LocalPkg, methods)
-}
-
 var vargen int
 
 func Temp(t *types.Type) *ir.Name {

src/cmd/compile/internal/typecheck/type.go

@@ -73,13 +73,42 @@ func tcChanType(n *ir.ChanType) ir.Node {
 
 // tcFuncType typechecks an OTFUNC node.
 func tcFuncType(n *ir.FuncType) ir.Node {
-	n.SetOTYPE(NewFuncType(n.Recv, n.Params, n.Results))
+	misc := func(f *types.Field, nf *ir.Field) {
+		f.SetIsDDD(nf.IsDDD)
+		if nf.Decl != nil {
+			nf.Decl.SetType(f.Type)
+			f.Nname = nf.Decl
+		}
+	}
+
+	lno := base.Pos
+
+	var recv *types.Field
+	if n.Recv != nil {
+		recv = tcField(n.Recv, misc)
+	}
+
+	t := types.NewSignature(types.LocalPkg, recv, tcFields(n.Params, misc), tcFields(n.Results, misc))
+	checkdupfields("argument", t.Recvs().FieldSlice(), t.Params().FieldSlice(), t.Results().FieldSlice())
+
+	base.Pos = lno
+
+	n.SetOTYPE(t)
 	return n
 }
 
 // tcInterfaceType typechecks an OTINTER node.
 func tcInterfaceType(n *ir.InterfaceType) ir.Node {
-	n.SetOTYPE(tointerface(n.Methods))
+	if len(n.Methods) == 0 {
+		n.SetOTYPE(types.Types[types.TINTER])
+		return n
+	}
+	
+	lno := base.Pos
+	methods := tcFields(n.Methods, nil)
+	base.Pos = lno
+
+	n.SetOTYPE(types.NewInterface(types.LocalPkg, methods))
 	return n
 }
 
@@ -117,6 +146,43 @@ func tcSliceType(n *ir.SliceType) ir.Node {
 
 // tcStructType typechecks an OTSTRUCT node.
 func tcStructType(n *ir.StructType) ir.Node {
-	n.SetOTYPE(NewStructType(n.Fields))
+	lno := base.Pos
+
+	fields := tcFields(n.Fields, func(f *types.Field, nf *ir.Field) {
+		if nf.Embedded {
+			checkembeddedtype(f.Type)
+			f.Embedded = 1
+		}
+		f.Note = nf.Note
+	})
+	checkdupfields("field", fields)
+
+	base.Pos = lno
+	n.SetOTYPE(types.NewStruct(types.LocalPkg, fields))
 	return n
 }
+
+// tcField typechecks a generic Field.
+// misc can be provided to handle specialized typechecking.
+func tcField(n *ir.Field, misc func(*types.Field, *ir.Field)) *types.Field {
+	base.Pos = n.Pos
+	if n.Ntype != nil {
+		n.Type = typecheckNtype(n.Ntype).Type()
+		n.Ntype = nil
+	}
+	f := types.NewField(n.Pos, n.Sym, n.Type)
+	if misc != nil {
+		misc(f, n)
+	}
+	return f
+}
+
+// tcFields typechecks a slice of generic Fields.
+// misc can be provided to handle specialized typechecking.
+func tcFields(l []*ir.Field, misc func(*types.Field, *ir.Field)) []*types.Field {
+	fields := make([]*types.Field, len(l))
+	for i, n := range l {
+		fields[i] = tcField(n, misc)
+	}
+	return fields
+}