Context works strange in 16.6.3 in renderToStaticMarkup

[konstantin24121]

Do you want to request a feature or report a bug?

bug or unexpected behavior

What is the current behavior?

In version react-dom@16.6.1 I used Context.Consumer in renderToStaticMarkup and it works fine if a call it, but in react-dom@16.6.3 Context.Consumer lose Context.Provider. To be precise Consumer loses only new values passed to Provider, default values work fine in all cases.

Example below:

with react-dom@16.6.1 - https://codesandbox.io/s/0movl04pyw
with react-dom@16.6.3 - https://codesandbox.io/s/6j39m60j9n

What is the expected behavior?

Context.Consumer don't lose a context passed with Context.Provider.
Maybe the example is wrong and there is another way to render Context.Consumer's components into a string?

Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?
In react-dom@16.6.1 - works fine
In react-dom@16.6.3 - context losed

[aweary]

Seems related to #14182 (comment)

[gaearon]

Context shouldn't propagate through renderToStaticMarkup / renderToString calls. Unfortunately that was a bug in the original release which got fixed in 16.6.3. While I understand in your case you might have expected it to work, but it's just as likely that it could cause product bugs (in case you're rendering <Something /> that's meant to be isolated and it picks up the wrong context from above).

The use case itself is interesting and potentially legit. I'll create a separate issue to track it.

[gaearon]

Filed #14292 to track it.