[TextField] Migrate FilledInput to emotion

[duganbrett]

This PR migrates the FilledInput component to the new emotion format as a part of #24405.

• I have followed (at least) the PR section of the contributing guide.

[mui-pr-bot]

@material-ui/core: parsed: +0.14% , gzip: +0.17%

Details of bundle changes

Generated by 🚫 dangerJS against 7003e0c

[duganbrett]

Very open to guidance on this one. Some of the way classes need to be applied on the input variants is not that obvious to me.

[mnajdova]

Very open to guidance on this one. Some of the way classes need to be applied on the input variants is not that obvious to me.

This was a bit trickier than what I anticipated :) I tried to fix all issues with a73218b (let's see if everything is resolved) We need to be careful when styling existing component regarding which things are coming from state (for example hiddenLabel, which things come from context etc). For these we must use the classes selector coming from that component, for the rest we can safely use the styleProps.

Regarding the overrides & classes, I belive we should add only the things which are new to this component, in this case the new names for the slots (MuiFilledInput-root & MuiFilledInput-input + the classes for the new underlined class key) Cc @oliviertassinari

[oliviertassinari]

This one does look tricky. I'm not sure about the increase of specificity. Should we implement the components prop in the InputBase and wrap the nested InputBaseInput with styled instead?

[mnajdova]

This one does look tricky. I'm not sure about the increase of specificity. Should we implement the components prop in the InputBase and wrap the nested InputBaseInput with styled instead?

That is the other option, yeah. Let me prepare a different PR for it and see which one will work better 👍

[mnajdova]

@oliviertassinari prepared #24634 I think it's better if we use components & componentsProps, we are able to avoid any increasing of specificity

[duganbrett]

@mnajdova @oliviertassinari Thank you, both! Learning a lot. I hope this helps others with the remaining TextField variants. Feel free to close.

[mnajdova]

@mnajdova @oliviertassinari Thank you, both! Learning a lot. I hope this helps others with the remaining TextField variants. Feel free to close.

Thanks for exploring 🙏 , this was a tricky one. Hopefully now #24634 can serve as a template for the other input components. Closing this one.