handler: drop the special case for "jrpc" tags

This code path was inadequately tested and not visibly used.  The idea was to
give a hook for custom unmarshalers, but for that purpose the library does not
need to do anything special -- the implementation can look up tags if it wants
to, or do something else.

handler/handler.go

@@ -261,11 +261,6 @@ func (fi *FuncInfo) Wrap() Func {
 // Otherwise, if the field has a `json:"name"` tag and the name is not empty,
 // "name" is used.
 //
-// Otherwise, if the field nas a `jrpc:"name"` tag, "name" is used.  Note: This
-// case is meant to support types with custom implementations of UnmarshalJSON.
-// Assigning a name that does not match the field name can cause json.Unmarshal
-// to report an error.
-//
 // Otherwise, if the field is anonymous (embedded) it is skipped. To include an
 // anonymous field, ensure it is tagged for one of the previous rules.
 //

handler/handler_test.go

@@ -167,11 +167,11 @@ func TestCheck_structArg(t *testing.T) {
 		B    int    `json:"-"`
 		C    bool   `json:",omitempty"`
 		D    byte   // unspecified, use default name
-		Evil int    `jrpc:"evil"`
+		Evil int    `json:"eee"`
 	}
 
 	const base = `{"jsonrpc":"2.0","id":1,"method":"M","params":%s}`
-	const inputObj = `{"apple":"1","c":true,"d":25,"evil":666}`
+	const inputObj = `{"apple":"1","c":true,"d":25,"eee":666}`
 	const inputArray = `["1", true, 25, 666]`
 	fail := errors.New("fail")
 

handler/positional.go

@@ -56,10 +56,6 @@ func structFieldNames(atype reflect.Type) (bool, []string) {
 			}
 			// fall through to other cases
 		}
-		if tag, ok := fi.Tag.Lookup("jrpc"); ok {
-			names = append(names, tag)
-			continue
-		}
 		if fi.Anonymous {
 			// This is an untagged anonymous field. Tagged anonymous fields are
 			// handled by the cases above.