go.tools: remove dead code

LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/90320043

go/loader/util.go

@@ -71,29 +71,9 @@ func parseFiles(fset *token.FileSet, ctxt *build.Context, displayPath func(strin
 
 // ---------- Internal helpers ----------
 
-// unparen returns e with any enclosing parentheses stripped.
-func unparen(e ast.Expr) ast.Expr {
-	for {
-		p, ok := e.(*ast.ParenExpr)
-		if !ok {
-			break
-		}
-		e = p.X
-	}
-	return e
-}
-
-func unreachable() {
-	panic("unreachable")
-}
-
 // TODO(adonovan): make this a method: func (*token.File) Contains(token.Pos)
 func tokenFileContainsPos(f *token.File, pos token.Pos) bool {
 	p := int(pos)
 	base := f.Base()
 	return base <= p && p < base+f.Size()
 }
-
-func filename(file *ast.File, fset *token.FileSet) string {
-	return fset.File(file.Pos()).Name()
-}

go/pointer/pointer_test.go

@@ -423,17 +423,6 @@ func checkPointsToExpectation(e *expectation, pts pointer.PointsToSet, lineMappi
 	return ok
 }
 
-// underlying returns the underlying type of typ.  Copied from go/types.
-func underlyingType(typ types.Type) types.Type {
-	if typ, ok := typ.(*types.Named); ok {
-		return typ.Underlying() // underlying types are never NamedTypes
-	}
-	if typ == nil {
-		panic("underlying(nil)")
-	}
-	return typ
-}
-
 func checkTypesExpectation(e *expectation, pts pointer.PointsToSet, typ types.Type) bool {
 	var expected typeutil.Map
 	var surplus typeutil.Map