4 files changed, 74 insertions, 14 deletions

diff --git a/src/pkg/text/template/exec.go b/src/pkg/text/template/exec.go
index b9c03d8f0..8ec8174a1 100644
--- a/src/pkg/text/template/exec.go
+++ b/src/pkg/text/template/exec.go
@@ -5,6 +5,7 @@
 package template
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"reflect"
@@ -125,8 +126,23 @@ func (t *Template) Execute(wr io.Writer, data interface{}) (err error) {
 		wr:   wr,
 		vars: []variable{{"$", value}},
 	}
+	t.init()
 	if t.Tree == nil || t.Root == nil {
-		state.errorf("%q is an incomplete or empty template", t.name)
+		var b bytes.Buffer
+		for name, tmpl := range t.tmpl {
+			if tmpl.Tree == nil || tmpl.Root == nil {
+				continue
+			}
+			if b.Len() > 0 {
+				b.WriteString(", ")
+			}
+			fmt.Fprintf(&b, "%q", name)
+		}
+		var s string
+		if b.Len() > 0 {
+			s = "; defined templates are: " + b.String()
+		}
+		state.errorf("%q is an incomplete or empty template%s", t.Name(), s)
 	}
 	state.walk(value, t.Root)
 	return
@@ -603,6 +619,8 @@ func (s *state) evalArg(dot reflect.Value, typ reflect.Type, n parse.Node) refle
 		return s.validateType(s.evalVariableNode(dot, arg, nil, zero), typ)
 	case *parse.PipeNode:
 		return s.validateType(s.evalPipeline(dot, arg), typ)
+	case *parse.IdentifierNode:
+		return s.evalFunction(dot, arg, arg, nil, zero)
 	}
 	switch typ.Kind() {
 	case reflect.Bool:
diff --git a/src/pkg/text/template/exec_test.go b/src/pkg/text/template/exec_test.go
index 683e9ac76..0ab20acc9 100644
--- a/src/pkg/text/template/exec_test.go
+++ b/src/pkg/text/template/exec_test.go
@@ -499,6 +499,8 @@ var execTests = []execTest{
 	{"bug8b", "{{4|dddArg 3}}", "", tVal, false},
 	// A bug was introduced that broke map lookups for lower-case names.
 	{"bug9", "{{.cause}}", "neglect", map[string]string{"cause": "neglect"}, true},
+	// Field chain starting with function did not work.
+	{"bug10", "{{mapOfThree.three}}-{{(mapOfThree).three}}", "3-3", 0, true},
 }
 
 func zeroArgs() string {
@@ -560,19 +562,24 @@ func stringer(s fmt.Stringer) string {
 	return s.String()
 }
 
+func mapOfThree() interface{} {
+	return map[string]int{"three": 3}
+}
+
 func testExecute(execTests []execTest, template *Template, t *testing.T) {
 	b := new(bytes.Buffer)
 	funcs := FuncMap{
-		"add":      add,
-		"count":    count,
-		"dddArg":   dddArg,
-		"echo":     echo,
-		"makemap":  makemap,
-		"oneArg":   oneArg,
-		"typeOf":   typeOf,
-		"vfunc":    vfunc,
-		"zeroArgs": zeroArgs,
-		"stringer": stringer,
+		"add":        add,
+		"count":      count,
+		"dddArg":     dddArg,
+		"echo":       echo,
+		"makemap":    makemap,
+		"mapOfThree": mapOfThree,
+		"oneArg":     oneArg,
+		"stringer":   stringer,
+		"typeOf":     typeOf,
+		"vfunc":      vfunc,
+		"zeroArgs":   zeroArgs,
 	}
 	for _, test := range execTests {
 		var tmpl *Template
@@ -816,3 +823,40 @@ func TestExecuteOnNewTemplate(t *testing.T) {
 	// This is issue 3872.
 	_ = New("Name").Templates()
 }
+
+const testTemplates = `{{define "one"}}one{{end}}{{define "two"}}two{{end}}`
+
+func TestMessageForExecuteEmpty(t *testing.T) {
+	// Test a truly empty template.
+	tmpl := New("empty")
+	var b bytes.Buffer
+	err := tmpl.Execute(&b, 0)
+	if err == nil {
+		t.Fatal("expected initial error")
+	}
+	got := err.Error()
+	want := `template: empty: "empty" is an incomplete or empty template`
+	if got != want {
+		t.Errorf("expected error %s got %s", want, got)
+	}
+	// Add a non-empty template to check that the error is helpful.
+	tests, err := New("").Parse(testTemplates)
+	if err != nil {
+		t.Fatal(err)
+	}
+	tmpl.AddParseTree("secondary", tests.Tree)
+	err = tmpl.Execute(&b, 0)
+	if err == nil {
+		t.Fatal("expected second error")
+	}
+	got = err.Error()
+	want = `template: empty: "empty" is an incomplete or empty template; defined templates are: "secondary"`
+	if got != want {
+		t.Errorf("expected error %s got %s", want, got)
+	}
+	// Make sure we can execute the secondary.
+	err = tmpl.ExecuteTemplate(&b, "secondary", 0)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/src/pkg/text/template/funcs.go b/src/pkg/text/template/funcs.go
index 31549dc45..818766364 100644
--- a/src/pkg/text/template/funcs.go
+++ b/src/pkg/text/template/funcs.go
@@ -18,7 +18,7 @@ import (
 // FuncMap is the type of the map defining the mapping from names to functions.
 // Each function must have either a single return value, or two return values of
 // which the second has type error. In that case, if the second (error)
-// argument evaluates to non-nil during execution, execution terminates and
+// return value evaluates to non-nil during execution, execution terminates and
 // Execute returns that error.
 type FuncMap map[string]interface{}
 
diff --git a/src/pkg/text/template/parse/parse.go b/src/pkg/text/template/parse/parse.go
index c0fb9274a..802e298c2 100644
--- a/src/pkg/text/template/parse/parse.go
+++ b/src/pkg/text/template/parse/parse.go
@@ -429,7 +429,6 @@ func (t *Tree) pipeline(context string) (pipe *PipeNode) {
 			t.unexpected(token, context)
 		}
 	}
-	return
 }
 
 func (t *Tree) parseControl(context string) (pos Pos, line int, pipe *PipeNode, list, elseList *ListNode) {
@@ -445,7 +444,6 @@ func (t *Tree) parseControl(context string) (pos Pos, line int, pipe *PipeNode,
 		if next.Type() != nodeEnd {
 			t.errorf("expected end; found %s", next)
 		}
-		elseList = elseList
 	}
 	return pipe.Position(), line, pipe, list, elseList
 }