Enable ELIDED_LIFETIMES_IN_PATHS lint in doctests for the compiler/libstd

[jyn514]

We should enable https://doc.rust-lang.org/beta/nightly-rustc/rustc_lint/builtin/static.ELIDED_LIFETIMES_IN_PATHS.html globally in rustc, I would be a fan of that change to make sure we enforce LabelText<'_> over LabelText.

rust/src/bootstrap/builder.rs

Lines 1662 to 1667 in f94c926

	// When extending this list, add the new lints to the RUSTFLAGS of the
	// build_bootstrap function of src/bootstrap/bootstrap.py as well as
	// some code doesn't go through this `rustc` wrapper.
	lint_flags.push("-Wrust_2018_idioms");
	lint_flags.push("-Wunused_lifetimes");
	lint_flags.push("-Wsemicolon_in_expressions_from_macros");

would be the place to add that.

Originally posted by @compiler-errors in #105975 (comment)

[atamakahere-git]

I'll try to do it, It'll take some time to understand, though a little more explanation would be helpful.

[jyn514]

@tanveerraza789 what sort of explanation are you looking for? There's an overview of bootstrap and what it does on https://rustc-dev-guide.rust-lang.org/building/bootstrapping.html, but you don't need to know everything to start working on this issue :)

The important context for this issue is that bootstrap is a build system that wraps cargo and builds the compiler and standard library; I think we should set this lint for both, which happens automatically if you put it next to the other lints I linked. I expect the hardest part to be actually fixing the lints, there will be a lot of different places to update.

[atamakahere-git]

Okay I understood, Thanks.

[dmezh]

@tanveerraza789 I was wondering if you'd like to claim this issue or if it's free to work on. Thanks 😄

[atamakahere-git]

@dmezh Sure, you can claim.
I've been experimenting with the lints but I'm not able to get desired results right now. Maybe you can get a lead.

[dmezh]

@rustbot claim

[compiler-errors]

Actually, this lint is already enabled because we have -Wrust_2018_idioms, and it's a member of that lint group. The only reason the code in the issue that @jyn514 had linked didn't trigger was because it was in a doc block.

I don't think this issue is actionable.

[dmezh]

@compiler-errors I did enable it and there were no new warnings at all, so that makes sense.

[atamakahere-git]

Same happened with me, so ya.

[jyn514]

Hmm, ok - there's another attribute you can pass to enable warnings in doctests:
https://doc.rust-lang.org/nightly/rustdoc/write-documentation/documentation-tests.html#showing-warnings-in-doctests

but yeah this is less important if it's only in doctests and not the compiler proper.

[onur-ozkan]

@rustbot claim