exp/template: fix implementation of printValue.

R=r
CC=golang-dev
https://golang.org/cl/4878042

diff --git a/src/pkg/exp/template/exec.go b/src/pkg/exp/template/exec.go
index 2f3235303a2f6dc5ec6ff5a17192fdf490831ffd..ff4e3876afc1387a235e82ad4073207c608c0263 100644 (file)
--- a/src/pkg/exp/template/exec.go
+++ b/src/pkg/exp/template/exec.go
@@ -620,19 +620,23 @@ func indirect(v reflect.Value) (rv reflect.Value, isNil bool) {
 // printValue writes the textual representation of the value to the output of
 // the template.
 func (s *state) printValue(n parse.Node, v reflect.Value) {
+       if v.Kind() == reflect.Ptr {
+               v, _ = indirect(v) // fmt.Fprint handles nil.
+       }
        if !v.IsValid() {
                fmt.Fprint(s.wr, "<no value>")
                return
        }
-       switch v.Kind() {
-       case reflect.Ptr:
-               v, _ = indirect(v) // fmt.Fprint handles nil.
-       case reflect.Chan, reflect.Func, reflect.Interface:
-               s.errorf("can't print %s of type %s", n, v.Type())
-       }
-       // If it's a value but the pointer implements Stringer, use the pointer.
-       if v.Kind() != reflect.Ptr && v.CanAddr() && reflect.PtrTo(v.Type()).Implements(fmtStringerType) {
-               v = v.Addr()
+
+       if !v.Type().Implements(fmtStringerType) {
+               if v.CanAddr() && reflect.PtrTo(v.Type()).Implements(fmtStringerType) {
+                       v = v.Addr()
+               } else {
+                       switch v.Kind() {
+                       case reflect.Chan, reflect.Func:
+                               s.errorf("can't print %s of type %s", n, v.Type())
+                       }
+               }
        }
        fmt.Fprint(s.wr, v.Interface())
 }

diff --git a/src/pkg/exp/template/exec_test.go b/src/pkg/exp/template/exec_test.go
index 50f159190681b5f4545f29ff79cc74b246619820..58e95263036d1f7d627ac44b6357eaf7b95a1bb4 100644 (file)
--- a/src/pkg/exp/template/exec_test.go
+++ b/src/pkg/exp/template/exec_test.go
@@ -48,6 +48,8 @@ type T struct {
        Empty4 interface{}
        // Non-empty interface.
        NonEmptyInterface I
+       // Stringer.
+       Str fmt.Stringer
        // Pointers
        PI  *int
        PSI *[]int
@@ -92,6 +94,7 @@ var tVal = &T{
        Empty3:            []int{7, 8},
        Empty4:            &U{"UinEmpty"},
        NonEmptyInterface: new(T),
+       Str:               os.NewError("foozle"),
        PI:                newInt(23),
        PSI:               newIntSlice(21, 22, 23),
        Tmpl:              Must(New("x").Parse("test template")), // "x" is the value of .X
@@ -396,6 +399,8 @@ var execTests = []execTest{
        {"bug3", "{{with $}}{{.Method0}}{{end}}", "M0", tVal, true},
        // Nil interface values in if.
        {"bug4", "{{if .Empty0}}non-nil{{else}}nil{{end}}", "nil", tVal, true},
+       // Stringer.
+       {"bug5", "{{.Str}}", "foozle", tVal, true},
 }
 
 func zeroArgs() string {