[dev.typeparams] cmd/compile: move MethodValueWrapper to walk

walk is the only pass that use the function, so un-export it, too.

Change-Id: I32ec64d1c15fda7bb54bd8efa528ed32c102876d
Reviewed-on: https://go-review.googlesource.com/c/go/+/330841
Trust: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Run-TryBot: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

1 files changed, 79 insertions, 1 deletions

diff --git a/src/cmd/compile/internal/walk/closure.go b/src/cmd/compile/internal/walk/closure.go
index f399a26689..a86ed2ab80 100644
--- a/src/cmd/compile/internal/walk/closure.go
+++ b/src/cmd/compile/internal/walk/closure.go
@@ -179,7 +179,7 @@ func walkMethodValue(n *ir.SelectorExpr, init *ir.Nodes) ir.Node {
 
 	clos := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(typ), nil)
 	clos.SetEsc(n.Esc())
-	clos.List = []ir.Node{ir.NewUnaryExpr(base.Pos, ir.OCFUNC, typecheck.MethodValueWrapper(n).Nname), n.X}
+	clos.List = []ir.Node{ir.NewUnaryExpr(base.Pos, ir.OCFUNC, methodValueWrapper(n).Nname), n.X}
 
 	addr := typecheck.NodAddr(clos)
 	addr.SetEsc(n.Esc())
@@ -198,3 +198,81 @@ func walkMethodValue(n *ir.SelectorExpr, init *ir.Nodes) ir.Node {
 
 	return walkExpr(cfn, init)
 }
+
+// methodValueWrapper returns the DCLFUNC node representing the
+// wrapper function (*-fm) needed for the given method value. If the
+// wrapper function hasn't already been created yet, it's created and
+// added to typecheck.Target.Decls.
+func methodValueWrapper(dot *ir.SelectorExpr) *ir.Func {
+	if dot.Op() != ir.OMETHVALUE {
+		base.Fatalf("methodValueWrapper: unexpected %v (%v)", dot, dot.Op())
+	}
+
+	t0 := dot.Type()
+	meth := dot.Sel
+	rcvrtype := dot.X.Type()
+	sym := ir.MethodSymSuffix(rcvrtype, meth, "-fm")
+
+	if sym.Uniq() {
+		return sym.Def.(*ir.Func)
+	}
+	sym.SetUniq(true)
+
+	savecurfn := ir.CurFunc
+	saveLineNo := base.Pos
+	ir.CurFunc = nil
+
+	// Set line number equal to the line number where the method is declared.
+	if pos := dot.Selection.Pos; pos.IsKnown() {
+		base.Pos = pos
+	}
+	// Note: !dot.Selection.Pos.IsKnown() happens for method expressions where
+	// the method is implicitly declared. The Error method of the
+	// built-in error type is one such method.  We leave the line
+	// number at the use of the method expression in this
+	// case. See issue 29389.
+
+	tfn := ir.NewFuncType(base.Pos, nil,
+		typecheck.NewFuncParams(t0.Params(), true),
+		typecheck.NewFuncParams(t0.Results(), false))
+
+	fn := typecheck.DeclFunc(sym, tfn)
+	fn.SetDupok(true)
+	fn.SetNeedctxt(true)
+	fn.SetWrapper(true)
+
+	// Declare and initialize variable holding receiver.
+	ptr := ir.NewNameAt(base.Pos, typecheck.Lookup(".this"))
+	ptr.Class = ir.PAUTOHEAP
+	ptr.SetType(rcvrtype)
+	ptr.Curfn = fn
+	ptr.SetIsClosureVar(true)
+	ptr.SetByval(true)
+	fn.ClosureVars = append(fn.ClosureVars, ptr)
+
+	call := ir.NewCallExpr(base.Pos, ir.OCALL, ir.NewSelectorExpr(base.Pos, ir.OXDOT, ptr, meth), nil)
+	call.Args = ir.ParamNames(tfn.Type())
+	call.IsDDD = tfn.Type().IsVariadic()
+
+	var body ir.Node = call
+	if t0.NumResults() != 0 {
+		ret := ir.NewReturnStmt(base.Pos, nil)
+		ret.Results = []ir.Node{call}
+		body = ret
+	}
+
+	fn.Body = []ir.Node{body}
+	typecheck.FinishFuncBody()
+
+	typecheck.Func(fn)
+	// Need to typecheck the body of the just-generated wrapper.
+	// typecheckslice() requires that Curfn is set when processing an ORETURN.
+	ir.CurFunc = fn
+	typecheck.Stmts(fn.Body)
+	sym.Def = fn
+	typecheck.Target.Decls = append(typecheck.Target.Decls, fn)
+	ir.CurFunc = savecurfn
+	base.Pos = saveLineNo
+
+	return fn
+}