go/analysis/passes/structtag: ignore findings for "encoding/json/v2"

The v2 "json" effort will eventually live in "encoding/json/v2".
Ignore structtag findings there as we assume that the package
is testing its own behavior with invalid struct tags.

Change-Id: I0ac0e7bf1f11d02dfcd1fabc17bde3c7ff59312f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/639295
LUCI-TryBot-Result: Go LUCI <[email protected]>
Run-TryBot: Joseph Tsai <[email protected]>
Auto-Submit: Joseph Tsai <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>

Author: dsnet

go/analysis/passes/structtag/structtag.go

@@ -89,7 +89,7 @@ var checkTagSpaces = map[string]bool{"json": true, "xml": true, "asn1": true}
 // checkCanonicalFieldTag checks a single struct field tag.
 func checkCanonicalFieldTag(pass *analysis.Pass, field *types.Var, tag string, seen *namesSeen) {
 	switch pass.Pkg.Path() {
-	case "encoding/json", "encoding/xml":
+	case "encoding/json", "encoding/json/v2", "encoding/xml":
 		// These packages know how to use their own APIs.
 		// Sometimes they are testing what happens to incorrect programs.
 		return