encoding/json: allow semicolon in field key / struct tag

Allow ';' as a valid character for json field keys and struct tags.

Fixes #39189

Change-Id: I4b602a1b0674ff028db07623682f0d1e8e9fd6c9
Reviewed-on: https://go-review.googlesource.com/c/go/+/234818
Run-TryBot: Daniel Martí <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Trust: Giovanni Bajo <[email protected]>
Trust: Daniel Martí <[email protected]>
Reviewed-by: Daniel Martí <[email protected]>

Author: seankhliao

json/encode.go

@@ -946,7 +946,7 @@ func isValidTag(s string) bool {
 	}
 	for _, c := range s {
 		switch {
-		case strings.ContainsRune("!#$%&()*+-./:<=>?@[]^_{|}~ ", c):
+		case strings.ContainsRune("!#$%&()*+-./:;<=>?@[]^_{|}~ ", c):
 			// Backslash and quote chars are reserved, but
 			// otherwise any punctuation chars are allowed
 			// in a tag name.

json/tagkey_test.go

@@ -41,7 +41,7 @@ type percentSlashTag struct {
 }
 
 type punctuationTag struct {
-	V string `json:"!#$%&()*+-./:<=>?@[]^_{|}~"` // https://golang.org/issue/3546
+	V string `json:"!#$%&()*+-./:;<=>?@[]^_{|}~ "` // https://golang.org/issue/3546
 }
 
 type dashTag struct {
@@ -90,7 +90,7 @@ var structTagObjectKeyTests = []struct {
 	{badFormatTag{"Orfevre"}, "Orfevre", "Y"},
 	{badCodeTag{"Reliable Man"}, "Reliable Man", "Z"},
 	{percentSlashTag{"brut"}, "brut", "text/html%"},
-	{punctuationTag{"Union Rags"}, "Union Rags", "!#$%&()*+-./:<=>?@[]^_{|}~"},
+	{punctuationTag{"Union Rags"}, "Union Rags", "!#$%&()*+-./:;<=>?@[]^_{|}~ "},
 	{spaceTag{"Perreddu"}, "Perreddu", "With space"},
 	{unicodeTag{"Loukanikos"}, "Loukanikos", "Ελλάδα"},
 }