Implement RFC 1560 behind `#![feature(item_like_imports)]` #35894

jseyfried · 2016-08-22T06:59:34Z

This implements rust-lang/rfcs#1560 (cc #35120) behind the item_like_imports feature gate.

The RFC text describes the changes to name resolution enabled by #![feature(item_like_imports) in detail. To summarize,

Items and named imports shadow glob imports.
Multiple globs can import the same name if the name is unused or the imports are shadowed.
Multiple globs can import the same name if the imports are of the same item (following re-exports).
- The visibility of such a name is the maximum visibility of the imports.
- Equivalently, adding a glob import will never reduce the visibility of a name, nor will removing one increase it.
Non-prelude private imports can be used wherever we currently allow private items to be used.
- Prelude-imported names are unaffected, i.e. they continue to be usable only in lexical scopes.
Globs import all visible names, not just public names.
- Equivalently, glob importing from an ancestor module imports all of the ancestor's names, and glob importing from other modules is unchanged.

r? @nrc

jseyfried · 2016-08-22T10:29:32Z

cc @petrochenkov

bors · 2016-08-23T03:55:23Z

☔ The latest upstream changes (presumably #35908) made this pull request unmergeable. Please resolve the merge conflicts.

nrc · 2016-08-24T05:28:50Z

src/librustc_resolve/build_reduced_graph.rs

@@ -390,7 +388,7 @@ impl<'b> Resolver<'b> {
                debug!("(building reduced graph for external crate) building module {} {:?}",
                       name, vis);
                let parent_link = ModuleParentLink(parent, name);
-                let module = self.new_module(parent_link, Some(def), true);
+                let module = self.new_module(parent_link, Some(def), DUMMY_NODE_ID);


what does using DUMMY_NODE_ID mean? Seems like it is just ignored when searching, so it would probably be better to use an Option and None here.

DUMMY_NODE_ID means that the module is from an extern crate, so its nearest normal ancestor doesn't have a node id. normal_ancestor_id is never used on modules from extern crates, so the the choice of node id here isn't particularly relevant.

Then I think it would be better to use Option here, rather than DUMMY_NODE_ID, this seems like the moral equivalent of using null. Put another way, it would be nice to enforce "normal_ancestor_id is never used on modules from extern crates" statically.

nrc · 2016-08-28T19:42:55Z

r=me with the last comments addressed.

bors · 2016-08-28T20:18:50Z

☔ The latest upstream changes (presumably #35984) made this pull request unmergeable. Please resolve the merge conflicts.

jseyfried · 2016-08-29T06:08:53Z

@bors r=nrc

bors · 2016-08-29T06:08:54Z

📌 Commit 58616c8 has been approved by nrc

bors · 2016-08-29T08:01:38Z

⌛ Testing commit 58616c8 with merge 614a792...

bors · 2016-08-29T08:08:30Z

💔 Test failed - auto-win-gnu-32-opt-rustbuild

jseyfried · 2016-08-29T09:14:00Z

@bors retry

bors · 2016-08-29T09:17:16Z

⌛ Testing commit 58616c8 with merge 7f96d62...

bors · 2016-08-29T09:23:45Z

💔 Test failed - auto-mac-64-opt-rustbuild

arielb1 · 2016-08-29T17:19:13Z

@bors retry

…id`.

…gle imports.

to reexport some (but not all) namespaces with less visibility.

to reexport some (but not all) names with less visibility.

jseyfried · 2016-09-01T22:33:45Z

@bors r=nrc

bors · 2016-09-01T22:33:46Z

📌 Commit bba8b09 has been approved by nrc

jseyfried · 2016-09-02T00:36:06Z

@bors r=nrc

bors · 2016-09-02T00:36:07Z

📌 Commit 90ce504 has been approved by nrc

bors · 2016-09-02T02:03:28Z

⌛ Testing commit 90ce504 with merge 8aeb15a...

@nrc

Implement RFC 1560 behind `#![feature(item_like_imports)]` This implements rust-lang/rfcs#1560 (cc #35120) behind the `item_like_imports` feature gate. The [RFC text](https://github.com/rust-lang/rfcs/blob/master/text/1560-name-resolution.md#changes-to-name-resolution-rules) describes the changes to name resolution enabled by `#![feature(item_like_imports)` in detail. To summarize, - Items and named imports shadow glob imports. - Multiple globs can import the same name if the name is unused or the imports are shadowed. - Multiple globs can import the same name if the imports are of the same item (following re-exports). - The visibility of such a name is the maximum visibility of the imports. - Equivalently, adding a glob import will never reduce the visibility of a name, nor will removing one increase it. - Non-prelude private imports can be used wherever we currently allow private items to be used. - Prelude-imported names are unaffected, i.e. they continue to be usable only in lexical scopes. - Globs import all visible names, not just public names. - Equivalently, glob importing from an ancestor module imports all of the ancestor's names, and glob importing from other modules is unchanged. r? @nrc

bors · 2016-09-02T05:24:34Z

rust-highfive assigned nrc Aug 22, 2016

jseyfried force-pushed the new_import_semantics branch 2 times, most recently from 540a351 to a1b7904 Compare August 22, 2016 09:24

jseyfried mentioned this pull request Aug 22, 2016

[WIP] Implement RFC 1560. #32213

Closed

jseyfried mentioned this pull request Aug 22, 2016

resolve: More groundwork for item_like_imports (RFC 1560) #35776

Merged

jseyfried mentioned this pull request Aug 24, 2016

use some::Trait as _; rust-lang/rfcs#1311

Closed

nrc reviewed Aug 24, 2016
View reviewed changes

brson mentioned this pull request Aug 25, 2016

glob imports ignore private items #23157

Closed

jseyfried force-pushed the new_import_semantics branch from 4709766 to 6a88bc1 Compare August 26, 2016 21:24

jseyfried force-pushed the new_import_semantics branch from 6a88bc1 to 58616c8 Compare August 29, 2016 06:08

jseyfried added 13 commits September 1, 2016 22:29

Improve diagnostics and remove dead code.

1e4c817

Refactor away resolver.current_vis and add `module.normal_ancestor_…

95528d1

…id`.

Add field dummy_binding to Resolver.

513e955

Add item_like_imports feature.

5ba22c0

item_like_imports: Treat private imports like private items.

efc0bea

item_like_imports: Allow glob imports to be shadowed by items and sin…

aad1f3c

…gle imports.

item_like_imports: Allow single imports with a given visibility

c56a5af

to reexport some (but not all) namespaces with less visibility.

item_like_imports: Allow glob imports with a given visibility

097b6d6

to reexport some (but not all) names with less visibility.

item_like_imports: Make all visible items glob importable.

245a0c5

item_like_imports: Allow multiple glob imports of the same item.

f582fa3

item_like_imports: Allow unused ambiguous glob imports.

681a14f

Avoid reporting multiple ambiguity errors for a single use of a name.

32a0cfe

Avoid cascading name resolution errors caused by an ambiguous module.

4f5616e

jseyfried force-pushed the new_import_semantics branch from 7155c77 to bba8b09 Compare September 1, 2016 22:31

Address comments.

90ce504

jseyfried force-pushed the new_import_semantics branch from bba8b09 to 90ce504 Compare September 2, 2016 00:35

bors merged commit 90ce504 into rust-lang:master Sep 2, 2016

This was referenced Sep 2, 2016

rustc: Implement custom derive (macros 1.1) #35957

Merged

Implement untagged unions (RFC 1444) #36016

Merged

crate-ify compiler-rt into compiler-builtins #35021

Merged

jseyfried deleted the new_import_semantics branch October 11, 2016 06:49

rpjohnst mentioned this pull request Sep 7, 2017

RFC: Clarify and streamline paths and visibility rust-lang/rfcs#2126

Merged

petrochenkov mentioned this pull request Jul 3, 2019

Change "A non-empty glob must import something with the glob's visibility" to be a lint? #62334

Closed

Implement RFC 1560 behind #![feature(item_like_imports)] #35894

Implement RFC 1560 behind #![feature(item_like_imports)] #35894

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Implement RFC 1560 behind `#![feature(item_like_imports)]` #35894

Implement RFC 1560 behind `#![feature(item_like_imports)]` #35894

jseyfried Aug 24, 2016 •

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