text/template: template.New("").ParseFiles("path/to/file") fails with "is an incomplete or empty template" #61139
Description
What version of Go are you using (go version)?
go version go1.19.5 linux/amd64
Does this issue reproduce with the latest release?
Unknown
What operating system and processor architecture are you using (go env)?
linux/amd64
What did you do?
If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
example.tpl
<html>
<body>
<p>{{helloWorld}}</p>
</body>
</html>
issue.go
package main
import (
"os"
"text/template"
)
func main() {
tplFuncs := map[string]any{
"helloWorld": func() string { return "Hello, World." },
}
t := template.Must(template.New("").Funcs(tplFuncs).ParseFiles("example.tpl"))
checkErr(t.Execute(os.Stdout, nil))
}
func checkErr(err error) {
if err != nil {
panic(err)
}
}
What did you expect to see?
<html>
<body>
<p>Hello, World.</p>
</body>
</html>
What did you see instead?
panic: template: : "" is an incomplete or empty template
goroutine 1 [running]:
main.checkErr(...)
/tmp/text-template-issue/issue.go:17
main.main()
/tmp/text-template-issue/issue.go:13 +0x205
goroutine 6 [runnable]:
text/template/parse.(*lexer).emit(...)
/go/src/text/template/parse/lex.go:165
text/template/parse.lexText(0xc000084000)
/go/src/text/template/parse/lex.go:278 +0x4c5
text/template/parse.(*lexer).run(0xc000084000)
/go/src/text/template/parse/lex.go:240 +0x2a
created by text/template/parse.lex
/go/src/text/template/parse/lex.go:233 +0x1dd
exit status 2
Please note that the following program works as expected and produces the correct output:
issue.go, revised:
package main
import (
"os"
"text/template"
)
func main() {
tplFuncs := map[string]any{
"helloWorld": func() string { return "Hello, World." },
}
t := template.Must(template.New("").Funcs(tplFuncs).Parse(fileGetContents("example.tpl")))
checkErr(t.Execute(os.Stdout, nil))
}
func checkErr(err error) {
if err != nil {
panic(err)
}
}
func fileGetContents(filename string) string {
contents := new(bytes.Buffer)
f, err := os.Open(filename)
checkErr(err)
_, err = io.Copy(contents, f)
if err != io.EOF {
checkErr(err)
}
checkErr(f.Close())
return contents.String()
}
output:
<html>
<body>
<p>Hello, World.</p>
</body>
</html>
tl;dr
.ParseFiles() doesn't work but passing the file contents to .Parse() does.
-day