cmd/compile: do not declare func nodes

The primary responsibility of declare() to associate a symbol (Sym) with
a declaration (Node), so "oldname" will work. Function literals are
anonymous, so their symbols does not need to be declared.

Passes toolstash-check.

Change-Id: I739b1054e3953e85fbd74a99148b9cfd7e5a57eb
Reviewed-on: https://go-review.googlesource.com/c/go/+/249078
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/gc/alg.go

@@ -429,8 +429,7 @@ func hashfor(t *types.Type) *Node {
 	}
 
 	n := newname(sym)
-	n.SetClass(PFUNC)
-	n.Sym.SetFunc(true)
+	setNodeNameFunc(n)
 	n.Type = functype(nil, []*Node{
 		anonfield(types.NewPtr(t)),
 		anonfield(types.Types[TUINTPTR]),

src/cmd/compile/internal/gc/closure.go

@@ -107,18 +107,7 @@ func typecheckclosure(clo *Node, top int) {
 	}
 
 	xfunc.Func.Nname.Sym = closurename(Curfn)
-	disableExport(xfunc.Func.Nname.Sym)
-	if xfunc.Func.Nname.Sym.Def != nil {
-		// The only case we can reach here is when the outer function was redeclared.
-		// In that case, don't bother to redeclare the closure. Otherwise, we will get
-		// a spurious error message, see #17758. While we are here, double check that
-		// we already reported other error.
-		if nsavederrors+nerrors == 0 {
-			Fatalf("unexpected symbol collision %v", xfunc.Func.Nname.Sym)
-		}
-	} else {
-		declare(xfunc.Func.Nname, PFUNC)
-	}
+	setNodeNameFunc(xfunc.Func.Nname)
 	xfunc = typecheck(xfunc, ctxStmt)
 
 	// Type check the body now, but only if we're inside a function.
@@ -473,7 +462,6 @@ func makepartialcall(fn *Node, t0 *types.Type, meth *types.Sym) *Node {
 	tfn.List.Set(structargs(t0.Params(), true))
 	tfn.Rlist.Set(structargs(t0.Results(), false))
 
-	disableExport(sym)
 	xfunc := dclfunc(sym, tfn)
 	xfunc.Func.SetDupok(true)
 	xfunc.Func.SetNeedctxt(true)

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

@@ -985,10 +985,14 @@ func makefuncsym(s *types.Sym) {
 	}
 }
 
-// disableExport prevents sym from being included in package export
-// data. To be effectual, it must be called before declare.
-func disableExport(sym *types.Sym) {
-	sym.SetOnExportList(true)
+// setNodeNameFunc marks a node as a function.
+func setNodeNameFunc(n *Node) {
+	if n.Op != ONAME || n.Class() != Pxxx {
+		Fatalf("expected ONAME/Pxxx node, got %v", n)
+	}
+
+	n.SetClass(PFUNC)
+	n.Sym.SetFunc(true)
 }
 
 func dclfunc(sym *types.Sym, tfn *Node) *Node {
@@ -1000,7 +1004,7 @@ func dclfunc(sym *types.Sym, tfn *Node) *Node {
 	fn.Func.Nname = newfuncnamel(lineno, sym)
 	fn.Func.Nname.Name.Defn = fn
 	fn.Func.Nname.Name.Param.Ntype = tfn
-	declare(fn.Func.Nname, PFUNC)
+	setNodeNameFunc(fn.Func.Nname)
 	funchdr(fn)
 	fn.Func.Nname.Name.Param.Ntype = typecheck(fn.Func.Nname.Name.Param.Ntype, ctxType)
 	return fn

src/cmd/compile/internal/gc/init.go

@@ -45,7 +45,6 @@ func fninit(n []*Node) {
 	if len(nf) > 0 {
 		lineno = nf[0].Pos // prolog/epilog gets line number of first init stmt
 		initializers := lookup("init")
-		disableExport(initializers)
 		fn := dclfunc(initializers, nod(OTFUNC, nil, nil))
 		for _, dcl := range dummyInitFn.Func.Dcl {
 			dcl.Name.Curfn = fn

src/cmd/compile/internal/gc/subr.go

@@ -1543,7 +1543,6 @@ func genwrapper(rcvr *types.Type, method *types.Field, newnam *types.Sym) {
 	tfn.List.Set(structargs(method.Type.Params(), true))
 	tfn.Rlist.Set(structargs(method.Type.Results(), false))
 
-	disableExport(newnam)
 	fn := dclfunc(newnam, tfn)
 	fn.Func.SetDupok(true)
 
@@ -1631,8 +1630,7 @@ func hashmem(t *types.Type) *Node {
 	sym := Runtimepkg.Lookup("memhash")
 
 	n := newname(sym)
-	n.SetClass(PFUNC)
-	n.Sym.SetFunc(true)
+	setNodeNameFunc(n)
 	n.Type = functype(nil, []*Node{
 		anonfield(types.NewPtr(t)),
 		anonfield(types.Types[TUINTPTR]),

src/cmd/compile/internal/gc/walk.go

@@ -3166,8 +3166,7 @@ func eqfor(t *types.Type) (n *Node, needsize bool) {
 	case ASPECIAL:
 		sym := typesymprefix(".eq", t)
 		n := newname(sym)
-		n.SetClass(PFUNC)
-		n.Sym.SetFunc(true)
+		setNodeNameFunc(n)
 		n.Type = functype(nil, []*Node{
 			anonfield(types.NewPtr(t)),
 			anonfield(types.NewPtr(t)),