lint when calling the blanket Into impl from a From impl

[y21]

Closes #11150

warning: function cannot return without recursing
  --> x.rs:9:9
   |
9  | /         fn from(value: f32) -> Self {
10 | |             value.into()
11 | |         }
   | |_________^
   |
note: recursive call site
  --> x.rs:10:13
   |
10 |             value.into()
   |             ^^^^^^^^^^^^

I'm also thinking that we can probably generalize this lint to #11032 at some point (instead of hardcoding a bunch of impls), like how rustc's unconditional_recursion works, at least up to one indirect call, but this still seems useful for now :)

I've also noticed that we use fn_def_id in a bunch of lints and then try to get the node args of the call in a separate step, so I made a helper function that does both in one. I intend to refactor a bunch of uses of fn_def_id to use this later

I can add more test cases, but this is already using much of the same logic that exists for the other impls that this lint looks for (e.g. making sure that there are no conditional returns).

changelog: [unconditional_recursion]: emit a warning inside of From::from when unconditionally calling the blanket .into() impl

[rustbot]

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[Jarcho]

This should have some negative tests. Otherwise Looks good.

[y21]

added a few more tests I could think of in the last commit, if you have some more concrete ones I can add them. Also removed an unnecessary get_trait_def_id which could be using diagnostic items

[Jarcho]

@bors delegate

All looks good. r=me after squashing.

[y21]

squashed
@bors r=Jarcho

[bors]

📌 Commit 65defdb has been approved by Jarcho

It is now in the queue for this repository.

[bors]

⌛ Testing commit 65defdb with merge 73be486...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: Jarcho
Pushing 73be486 to master...