PHP Extension - Field mask element may not have upper-case letter

[FabioBatSilva]

The PHP C extension implementation of Google\Protobuf\FieldMask has some validations that are not present in the native PHP implementation.

C Extension Validations:

protobuf/php/ext/google/protobuf/php-upb.c

Lines 2529 to 2536 in e3ac4c9

	if (ch >= 'A' && ch <= 'Z') {
	jsonenc_err(e, "Field mask element may not have upper-case letter.");
	} else if (ch == '_') {
	if (ptr == end - 1 || *(ptr + 1) < 'a' || *(ptr + 1) > 'z') {
	jsonenc_err(e, "Underscore must be followed by a lowercase letter.");
	}
	ch = *++ptr - 32;
	}

protobuf/php/ext/google/protobuf/php-upb.c

Line 1879 in e3ac4c9

jsondec_err(d, "field mask may not contain '_'");

---

What version of protobuf and what language are you using?
Version: main
Language: php
OS: Linux

What did you do?

<?php

require_once (dirname(__DIR__) . '/vendor/autoload.php');
require_once (__DIR__ . '/test_util.php');

use Google\Protobuf\FieldMask;

$m1 = new FieldMask();
$m2 = new FieldMask();

$m1->setPaths(['phoneNumber', 'email_address']);

$m2->mergeFromJsonString($m1->serializeToJsonString());

var_dump($m2->getPaths());
var_dump($m2->serializeToJsonString());

# Compile the extension 
./php/tests/compile_extension.sh

# Run script
php -d display_errors=on -dextension=../ext/google/protobuf/modules/protobuf.so field_mask_test.php

What did you expect to see

object(Google\Protobuf\Internal\RepeatedField)#640 (2) {
  [0]=>
  string(12) "phone_number"
  [1]=>
  string(13) "email_address"
}
string(26) ""phoneNumber,emailAddress""

Important

Not entirely sure if this behavior is correct.
This is the output I get in the PHP implementation
But the JSON serialization string(26) ""phoneNumber,emailAddress"" seems weird to me.

What did you see instead?

PHP Fatal error:  Uncaught Exception: Error occurred during JSON serialization: Field mask element may not have upper-case letter.