cmd/vet: Doesn't complain when the field tags are not parsable by the reflect: StructTag.Get() call

[szank]

Hi, I have noticed a problem with go vet that have stung me recently.
Go vet doesn't report an error in the field tag formatting.

Let's take an example struct :

// TestStruct comment
type TestStruct struct {
    A string `json:"jsona",xml:"xmla"`
}

As you can see I have set the field tags, and while the tags looks OK, the tag format is incorrect. To illustrate, the example code:

package main

import (
    "fmt"
    "reflect"
)

// TestStruct comment
type TestStruct struct {
    A string `json:"jsona",xml:"xmla"`
}

func main() {

    var theStruct = TestStruct{"A"}

    fmt.Println("First field tag: ", reflect.TypeOf(theStruct).Field(0).Tag)
    fmt.Println("Json tag value:  ", reflect.TypeOf(theStruct).Field(0).Tag.Get("json"))
    fmt.Println("XML tag value:   ", reflect.TypeOf(theStruct).Field(0).Tag.Get("xml"))
}

Did return

First field tag:  json:"jsona",xml:"xmla"
Json tag value:   jsona
XML tag value:  

The problem here is the coma character between json and xml tags.
The go vet tool doesn't complain about this type of error and I would like to fix it if it is OK.

I will raise a pull request if the maintainers agree that this is a bug in the go vet tool indeed.

[minux]

Yes, i think go vet should detect this case. But note that we don't use pull request, please send a CL instead. See https://golang.org/doc/contribute.html.

[rsc]

Actually the tags are parseable in this case. The tag json:"jsona",xml:"xmla" is the same as json:"jsona" ,xml:"xmla". That is, there is an entry with key json and an entry with key ,xml. If you did tag.Get(",xml") you could retrieve the second one.

That said, it's obviously a mistake and probably one vet should catch even though it's not technically illegal. Will send a CL.

[gopherbot]

CL https://golang.org/cl/32031 mentions this issue.