cmd/compile: remove typechecker calls in varDecl()

We can now use transformAssign.

The only remaining typechecker calls in the noder2 pass are for
CompLitExpr nodes (OCOMPLIT).

Change-Id: I25671c79cc30749767bb16f84e9f151b943eccd1
Reviewed-on: https://go-review.googlesource.com/c/go/+/305509
Run-TryBot: Dan Scales <danscales@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Robert Griesemer <gri@golang.org>
Trust: Dan Scales <danscales@google.com>

src/cmd/compile/internal/noder/decl.go

@@ -211,11 +211,24 @@ func (g *irgen) varDecl(out *ir.Nodes, decl *syntax.VarDecl) {
 			} else if ir.CurFunc == nil {
 				name.Defn = as
 			}
-			out.Append(typecheck.Stmt(as))
+			lhs := []ir.Node{as.X}
+			rhs := []ir.Node{}
+			if as.Y != nil {
+				rhs = []ir.Node{as.Y}
+			}
+			transformAssign(as, lhs, rhs)
+			as.X = lhs[0]
+			if as.Y != nil {
+				as.Y = rhs[0]
+			}
+			as.SetTypecheck(1)
+			out.Append(as)
 		}
 	}
 	if as2 != nil {
-		out.Append(typecheck.Stmt(as2))
+		transformAssign(as2, as2.Lhs, as2.Rhs)
+		as2.SetTypecheck(1)
+		out.Append(as2)
 	}
 }
 

src/cmd/compile/internal/noder/expr.go

@@ -15,7 +15,6 @@ import (
 )
 
 func (g *irgen) expr(expr syntax.Expr) ir.Node {
-	// TODO(mdempsky): Change callers to not call on nil?
 	if expr == nil {
 		return nil
 	}

src/cmd/compile/internal/noder/helpers.go

@@ -18,10 +18,6 @@ import (
 //
 // TODO(mdempsky): Move into their own package so they can be easily
 // reused by iimport and frontend optimizations.
-//
-// TODO(mdempsky): Update to consistently return already typechecked
-// results, rather than leaving the caller responsible for using
-// typecheck.Expr or typecheck.Stmt.
 
 type ImplicitNode interface {
 	ir.Node