text/template: 0xef is an integer, not a floating-point value.

The discriminator in the execution engine was stupid.
Add a test to the parse package too. The problem wasn't there
but the particular case ('e' in a hex integer) was not covered.

Fixes golang#8622.

LGTM=ruiu
R=golang-codereviews, ruiu
CC=golang-codereviews
https://golang.org/cl/133530043

src/pkg/text/template/exec.go

@@ -393,7 +393,7 @@ func (s *state) idealConstant(constant *parse.NumberNode) reflect.Value {
 	switch {
 	case constant.IsComplex:
 		return reflect.ValueOf(constant.Complex128) // incontrovertible.
-	case constant.IsFloat && strings.IndexAny(constant.Text, ".eE") >= 0:
+	case constant.IsFloat && !isHexConstant(constant.Text) && strings.IndexAny(constant.Text, ".eE") >= 0:
 		return reflect.ValueOf(constant.Float64)
 	case constant.IsInt:
 		n := int(constant.Int64)
@@ -407,6 +407,10 @@ func (s *state) idealConstant(constant *parse.NumberNode) reflect.Value {
 	return zero
 }
 
+func isHexConstant(s string) bool {
+	return len(s) > 2 && s[0] == '0' && (s[1] == 'x' || s[1] == 'X')
+}
+
 func (s *state) evalFieldNode(dot reflect.Value, field *parse.FieldNode, args []parse.Node, final reflect.Value) reflect.Value {
 	s.at(field)
 	return s.evalFieldChain(dot, dot, field, field.Ident, args, final)

src/pkg/text/template/exec_test.go

@@ -514,6 +514,11 @@ var execTests = []execTest{
 	{"bug10", "{{mapOfThree.three}}-{{(mapOfThree).three}}", "3-3", 0, true},
 	// Dereferencing nil pointer while evaluating function arguments should not panic. Issue 7333.
 	{"bug11", "{{valueString .PS}}", "", T{}, false},
+	// 0xef gave constant type float64. Issue 8622.
+	{"bug12xe", "{{printf `%T` 0xef}}", "int", T{}, true},
+	{"bug12xE", "{{printf `%T` 0xEE}}", "int", T{}, true},
+	{"bug12Xe", "{{printf `%T` 0Xef}}", "int", T{}, true},
+	{"bug12XE", "{{printf `%T` 0XEE}}", "int", T{}, true},
 }
 
 func zeroArgs() string {

src/pkg/text/template/parse/parse_test.go

@@ -69,6 +69,8 @@ var numberTests = []numberTest{
 	{text: "1+2."},
 	{text: "'x"},
 	{text: "'xx'"},
+	// Issue 8622 - 0xe parsed as floating point. Very embarrassing.
+	{"0xef", true, true, true, false, 0xef, 0xef, 0xef, 0},
 }
 
 func TestNumberParse(t *testing.T) {