[Serializer] Fix: Report Xml warning/error instead of silently returning a wrong xml

[VincentLanglet]

Q	A
Branch?	7.1
Bug fix?	yes
New feature?	no
Deprecations?	no
Issues	Fix #...
License	MIT

When DomDocument::saveXML encounter an error/warning, for example

DOMDocument::saveXML(): xmlEscapeEntities : char out of range

the method will return false or an empty/incomplete XML.

In case of false, since symfony doesn't use strict type, it will be cast into string (for 6.4+ version with native typehint) so the encode method will return an empty string.
In case of empty/incomplete XML, symfony returns it as if, without any notice about the error/warning.

I think Symfony should not silently ignore such XML error when decoding.

Or should it be an option ?

[VincentLanglet]

Others failure (especially lint) are unrelated.
I don't touch them to minize the conflict with up-merge.

[nicolas-grekas]

Don't we get an exception from ErrorHandler in debug mode at the moment?
Let's do this on 7.1 so that we're confident we won't break any existing apps?

[VincentLanglet]

Don't we get an exception from ErrorHandler in debug mode at the moment?

Yes, but not in production. So it silently return a wrong xml in prod.

Let's do this on 7.1 so that we're confident we won't break any existing apps?

Ok for 7.1. Should I do the PR like this or with an option to passe to the encoder @nicolas-grekas ?

[nicolas-grekas]

No options on my side.

[VincentLanglet]

Let's do this on 7.1 so that we're confident we won't break any existing apps?

Done @nicolas-grekas :)

[nicolas-grekas]

that doesn't work: php won't fallback on the previous handler for deprecation
instead, I suggest using the @ operator and using error_get_last to compute the exception message when needed

[VincentLanglet]

$result = @$data->saveXML($ignorePiNode ? $data->documentElement : null);

if (false === $result) {
    throw Exception();
}

doesn't cover all the case.

For instance

$dom = new DOMDocument();

$root = $dom->createElement('root');
$dom->appendChild($root);
$text = $dom->createTextNode("Invalid character: " . chr(7));
$root->appendChild($text);
$saved = $dom->saveXML();

// Check if saving was successful
if ($saved === false) {
    echo "Error saving XML\n";
} else {
    echo "XML saved successfully\n";
    echo $saved;
}

gives

Warning: DOMDocument::saveXML(): xmlEscapeEntities : char out of range in /home/user/scripts/code.php on line 9
XML saved successfully
<?xml version="1.0"?>
<root></root>

[VincentLanglet]

It should be better with 41c83a3 @nicolas-grekas

[fabpot]

Thank you @VincentLanglet.