Add `crate::` to trait suggestions in Rust 2018. #54603

davidtwco · 2018-09-26T23:19:39Z

In the 2018 edition, when suggesting traits to import that implement a
given method that is being invoked, suggestions will now include the
crate:: prefix if the suggested trait is local to the current crate.

r? @nikomatsakis

src/librustc/ty/item_path.rs

nikomatsakis · 2018-09-27T18:13:28Z

src/librustc/ty/item_path.rs

+                    // In particular, don't recurse to print the crate root if we
+                    // just printed `std`. In doing this, we are able to add
+                    // `crate::` to trait import suggestions.
+                    DefPathData::CrateRoot if data.as_interned_str() == "std" => {},


I am not happy about special-casing std, but I guess it .. maybe makes sense?

In particular, is this only necessary because we stick the extern crate std in the prelude?

More generally, we could convert this into a check to see if this crate is in the list of "prelude crates".

@eddyb points to this code, which constructs the set of prelude crates:

rust/src/librustc_resolve/lib.rs

Lines 1666 to 1675 in c9865b1

let mut extern_prelude: FxHashSet<Name> =

session.opts.externs.iter().map(|kv| Symbol::intern(kv.0)).collect();

// HACK(eddyb) this ignore the `no_{core,std}` attributes.

// FIXME(eddyb) warn (elsewhere) if core/std is used with `no_{core,std}`.

// if !attr::contains_name(&krate.attrs, "no_core") {

// if !attr::contains_name(&krate.attrs, "no_std") {

extern_prelude.insert(Symbol::intern("core"));

extern_prelude.insert(Symbol::intern("std"));

extern_prelude.insert(Symbol::intern("meta"));

But we'd have to store it somewhere more accessible, I imagine.

Fixed this with the most recent commit.

src/test/ui/rust-2018/trait-import-suggestions.stderr

src/librustc/session/mod.rs

src/librustc/ty/item_path.rs

eddyb · 2018-09-28T20:47:22Z

src/librustc/session/mod.rs

@@ -981,6 +980,23 @@ impl Session {
    pub fn edition(&self) -> Edition {
        self.opts.edition
    }
+
+    /// Get set of prelude crate names.
+    pub fn prelude_crate_names(&self) -> FxHashSet<Name> {


Should probably use the approach from #54650 - especially as that is r+'d.

(feel free to rebase on top of that PR)

davidtwco · 2018-09-29T06:22:09Z

I've rebased this atop @eddyb's #54650 and marked it as WIP so that it isn't merged until after that.

In the 2018 edition, when suggesting traits to import that implement a given method that is being invoked, suggestions will now include the `crate::` prefix if the suggested trait is local to the current crate.

Avoid hardcoding and special-casing the `std` crate name in the item path logic by moving the prelude crate name logic into the `Session` type so it can be reused in the item path logic and resolve module.

This commit takes a different approach to add the `crate::` prefix to item paths than previous commits. Previously, recursion was stopped after a prelude crate name was pushed to the path. It is theorized that this was the cause of the linking issues since the same path logic is used for symbol names and that not recursing meant that details were being missed that affect symbol names. As of this commit, instead of ceasing recursion, a flag is passed through to any subsequent recursive calls so that the same effect can be achieved by checking that flag.

davidtwco · 2018-10-01T23:42:20Z

I've rebased this atop master now that @eddyb's #54650 has landed.

nikomatsakis · 2018-10-02T19:44:33Z

@bors r+

bors · 2018-10-02T19:44:34Z

📌 Commit 02357e4 has been approved by nikomatsakis

@nikomatsakis

Add `crate::` to trait suggestions in Rust 2018. Fixes rust-lang#54559. In the 2018 edition, when suggesting traits to import that implement a given method that is being invoked, suggestions will now include the `crate::` prefix if the suggested trait is local to the current crate. r? @nikomatsakis

@nikomatsakis

Add `crate::` to trait suggestions in Rust 2018. Fixes rust-lang#54559. In the 2018 edition, when suggesting traits to import that implement a given method that is being invoked, suggestions will now include the `crate::` prefix if the suggested trait is local to the current crate. r? @nikomatsakis

@ghost

Rollup of 10 pull requests Successful merges: - #54269 (#53840: Consolidate pattern check errors) - #54458 (Allow both explicit and elided lifetimes in the same impl header) - #54603 (Add `crate::` to trait suggestions in Rust 2018.) - #54648 (Update Cargo's submodule) - #54680 (make run-pass tests with empty main just compile-pass tests) - #54687 (Use impl_header_lifetime_elision in libcore) - #54699 (Re-export `getopts` so custom drivers can reference it.) - #54702 (do not promote comparing function pointers) - #54728 (Renumber `proc_macro` tracking issues) - #54745 (make `CStr::from_bytes_with_nul_unchecked()` a const fn) Failed merges: r? @ghost

rust-highfive assigned nikomatsakis Sep 26, 2018

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Sep 26, 2018

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davidtwco force-pushed the issue-54559 branch from 757b756 to 819d3df Compare September 27, 2018 08:57

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suggesting for traits do not search the "prelude crates" #54618

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davidtwco force-pushed the issue-54559 branch from f2c1d62 to e59c7ba Compare September 27, 2018 23:31

nikomatsakis approved these changes Sep 28, 2018

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davidtwco force-pushed the issue-54559 branch from e59c7ba to df172fa Compare September 28, 2018 19:52

eddyb reviewed Sep 28, 2018

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davidtwco force-pushed the issue-54559 branch from df172fa to 27ab241 Compare September 29, 2018 06:20

davidtwco changed the title ~~Add crate:: to trait suggestions in Rust 2018.~~ WIP: Add crate:: to trait suggestions in Rust 2018. Sep 29, 2018

davidtwco added 3 commits October 2, 2018 01:16

Add crate:: to trait suggestions in Rust 2018.

9e2d6e1

In the 2018 edition, when suggesting traits to import that implement a given method that is being invoked, suggestions will now include the `crate::` prefix if the suggested trait is local to the current crate.

Move prelude crate names into Session.

4cbd397

Avoid hardcoding and special-casing the `std` crate name in the item path logic by moving the prelude crate name logic into the `Session` type so it can be reused in the item path logic and resolve module.

davidtwco force-pushed the issue-54559 branch from 27ab241 to 02357e4 Compare October 1, 2018 23:41

davidtwco changed the title ~~WIP: Add crate:: to trait suggestions in Rust 2018.~~ Add crate:: to trait suggestions in Rust 2018. Oct 1, 2018

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Oct 2, 2018

pietroalbini mentioned this pull request Oct 2, 2018

Rollup of 10 pull requests #54763

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pietroalbini mentioned this pull request Oct 2, 2018

Rollup of 10 pull requests #54767

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bors merged commit 02357e4 into rust-lang:master Oct 3, 2018

davidtwco deleted the issue-54559 branch October 3, 2018 07:25

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Add `crate::` to trait suggestions in Rust 2018. #54603

Add `crate::` to trait suggestions in Rust 2018. #54603

davidtwco commented Sep 26, 2018 •

edited

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davidtwco commented Sep 29, 2018

davidtwco commented Oct 1, 2018

nikomatsakis commented Oct 2, 2018

bors commented Oct 2, 2018

	let mut extern_prelude: FxHashSet<Name> =
	session.opts.externs.iter().map(\|kv\| Symbol::intern(kv.0)).collect();

	// HACK(eddyb) this ignore the `no_{core,std}` attributes.
	// FIXME(eddyb) warn (elsewhere) if core/std is used with `no_{core,std}`.
	// if !attr::contains_name(&krate.attrs, "no_core") {
	// if !attr::contains_name(&krate.attrs, "no_std") {
	extern_prelude.insert(Symbol::intern("core"));
	extern_prelude.insert(Symbol::intern("std"));
	extern_prelude.insert(Symbol::intern("meta"));

Add crate:: to trait suggestions in Rust 2018. #54603

Add crate:: to trait suggestions in Rust 2018. #54603

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davidtwco commented Sep 29, 2018

davidtwco commented Oct 1, 2018

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bors commented Oct 2, 2018

Add `crate::` to trait suggestions in Rust 2018. #54603

Add `crate::` to trait suggestions in Rust 2018. #54603

davidtwco commented Sep 26, 2018 •

edited