[dev.unified] cmd/compile/internal/typecheck: replace unreachable cod…

…e with assert

Since the removal of -G=0 mode, IR is always well-typed. And in
well-typed IR, convlit will always returns expressions having real
types (i.e., not untyped).

Change-Id: I1ac99a88c94777829852519347a716d19af7948c
Reviewed-on: https://go-review.googlesource.com/c/go/+/413363
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

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

@@ -301,24 +301,14 @@ func assignconvfn(n ir.Node, t *types.Type, context func() string) ir.Node {
 
 	n = convlit1(n, t, false, context)
 	if n.Type() == nil {
-		return n
+		base.Fatalf("cannot assign %v to %v", n, t)
+	}
+	if n.Type().IsUntyped() {
+		base.Fatalf("%L has untyped type", n)
 	}
 	if t.Kind() == types.TBLANK {
 		return n
 	}
-
-	// Convert ideal bool from comparison to plain bool
-	// if the next step is non-bool (like interface{}).
-	if n.Type() == types.UntypedBool && !t.IsBoolean() {
-		if n.Op() == ir.ONAME || n.Op() == ir.OLITERAL {
-			r := ir.NewConvExpr(base.Pos, ir.OCONVNOP, nil, n)
-			r.SetType(types.Types[types.TBOOL])
-			r.SetTypecheck(1)
-			r.SetImplicit(true)
-			n = r
-		}
-	}
-
 	if types.Identical(n.Type(), t) {
 		return n
 	}