Fix rust-lang/rust#79255 - Incorrect try suggestion for float cast

[nico-abram]

changelog: Fix rust-lang/rust#79255 - Incorrect try suggestion for float literal cast ending in dot

[rust-highfive]

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[ebroto]

I think it would be simpler if we just remove the dot instead. What do you think?

[nico-abram]

Sounds good to me, simpler implementation and will keep the suggestions more uniform
I was just going off the issue saying The correct suggestion is 3.0_f32, will probably change it tomorrow

@iago-lito thoughts?

[iago-lito]

@nico Hm, the truth is that I didn't even think that 3_f32 was also valid ^ ^"

So IIUC now the question is which formatting to suggest among:

• 3.0_f32
• 3_f32
• 3.0f32
• 3f32
  right?

Well, I'm not sure whether there are official recommendations regarding this.
My personal feeling is that Rust likes to favor explicitness and readability, so I think the first option, 3.0_f32, is the most consistent suggestion.

---

Alternately, picking the option that yields the formatting maybe-closest from what the user had in mind is also interesting, like:

• 3. as f32 would suggest 3_f32
• 3 as f32 would suggest 3f32
• 3.0 as f32 would suggest 3.0_f32 or 3.0f32

but that feels messy. I'd rather expect Rust not to try to accomodate my thoughs and just spit out the most explicit + readable option.

---

Even more alternately, defer the question to rustfmt options. Once the user has defined the one they like best in their rustfmt.toml, either they apply the fix then run a fmt pass, or the fix is super-sophisticated and goes read these options to directly decide which formatting to suggest.

---

To be clear, I also think most of this is overkill. My preferred solution is to just
suggest 3.0_f32 and call it a day ;)

[ebroto]

@iago-lito I think this solution is good because it doesn't need to change a lot the current implementation, note that _ is always added.

Also, .0 is kind of redundant given that we are specifying the type explicitly.

[ebroto]

@bors r+

Thanks!

[bors]

📌 Commit 3b53de6 has been approved by ebroto

[bors]

⌛ Testing commit 3b53de6 with merge 403816f...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: ebroto
Pushing 403816f to master...