Add autofixable suggestion for unseparated integer literal suffixes

[JJJollyjim]

changelog: Add autofixable suggestion for unseparated integer literal suffixes

Somewhat WIP, since I haven't been able to get this working when adding // run-rustfix to ui/literals.rs. I think the issue is that there are multiple suggestions operating on one numerical literal, and I'm not sure what the best approach is to work around that.

Thanks

[flip1995]

You could split up the test case in tests especially for this lint and the other tests. This would also help with #2038. ;)

[JJJollyjim]

Okay, will do 👍

Was just checking that this is only a test issue and not something end users will notice

[JJJollyjim]

No longer WIP, assuming this CI passes :)

[flip1995]

Thanks!

[tesuji]

@flip1995 Should this lint on constant literals only? I tried to improve this lint too
but this lint triggers on event assert! macro. :D:

[tesuji]

An error message:

---- [ui] ui/filter_map_next.rs stdout ----
normalized stderr:
error: LIT: Lit { token: Lit { kind: Integer, symbol: 7, suffix: Some(u32) }, node: Int(7, Unsigned(u32)), span: Span { lo: BytePos(180), hi: BytePos(209), ctxt: #0 } }
  --> $DIR/filter_map_next.rs:7:5
   |
LL |     assert_eq!(element, Some(1));
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `-D clippy::unseparated-literal-suffix` implied by `-D warnings`
help: SPAN: Span { lo: BytePos(180), hi: BytePos(209), ctxt: #0 }
   |
LL |     assert_eq!(element, Some(1_u32
   |

Edit: Because I removed these 2 lines:

rust-clippy/clippy_lints/src/misc_early.rs

Lines 395 to 396 in 918d609

	if let Some(firstch) = src.chars().next();
	if char::to_digit(firstch, 10).is_some();

[flip1995]

There's probably something weird going with the macro expansion. I can't really tell what exactly, without seeing all of your changes.

Should this lint on constant literals only?

I'm not sure if I understand your question correctly. Literals are always constant, since they're always one of a literal string ("str"), a literal number (42, 3.14) or a literal boolean (true). (docs)

[flip1995]

@bors r+

[bors]

📌 Commit 370433f has been approved by flip1995

[bors]

⌛ Testing commit 370433f with merge 835205b...

[bors]

☀️ Test successful - checks-travis, status-appveyor
Approved by: flip1995
Pushing 835205b to master...