[Yaml] ~ is not interpreted as null when used as array key

[ivoba]

Q	A
Bug report?	yes
Feature request?	no
BC Break report?	no
RFC?	no
Symfony version	3.3.5

When using ~ as array key its interpreted as string "~" since i upgraded to symfony 3.3.
Before it was interpreted as null resp. "".

As it is in Yaml spec it should be interpreted as null even as key, i suppose:
http://www.yaml.org/type/null.html

Example:

my_service:
  class: SomeClass
  arguments:
    -
     ~: 'default'
     key: 'value'

Arguments results in:

array:2 [▼
"~" => "default"
"key" => "value"
]

Expected would have been:

array:2 [▼
"" => "default"
"key" => "value"
]

Is this intended behaviour?

[javiereguiluz]

I'd say this is a bug, but our main Yaml maintainer @xabbuh will confirm. Thanks for reporting!

[xabbuh]

Well, inside the YamlFileLoader of the DependencyInjection component we use the PARSE_KEYS_AS_STRING flag which evaluates ~ as '~'. So IMO that's expected.

[xabbuh]

In 3.4 you will additionally see a deprecation message that advices you to quote evaluable keys (see #22948).

[ivoba]

Ok, thanks for clarification.

[ivoba]

@xabbuh shouldnt then the quoted tilde be interpreted as null? Or will this come in 3.4?

my_service:
  class: SomeClass
  arguments:
    -
     "~": 'default'
     key: 'value'

Currently its not.

[javiereguiluz]

@ivoba I'd say that quoted '~' is just a string, so the current behavior is OK. However, unquoted ~ is always null in Yaml, so I still think this is a bug. (Not very important because it's strange to use null as the key value).

[GuilhemN]

This will be fixed in 4.0: keys will always be evaluated and ~ will be forbidden as key (as it's forbidden in php).

[javiereguiluz]

@GuilhemN but null keys work in PHP, right? See https://3v4l.org/mLn6T

[xabbuh]

The actual key is the empty string (PHP casts null to a string).

[GuilhemN]

This can be closed imo, it is already fixed in 4.0.