Allow `use` macro imports to shadow global macros by jseyfried · Pull Request #40501 · rust-lang/rust (original) (raw)

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Terminology:

global scope: builtin macros, macros from the prelude, #[macro_use], or #![plugin(..)].
legacy scope: crate-local macro_rules!.
modern scope: use macro imports, macro (once implemented).

Today, the legacy scope can shadow the global scope (modulo RFC 1560 expanded shadowing restrictions). However, the modern scope cannot shadow or be shadowed by either the global or legacy scopes, leading to ambiguity errors.

This PR allows the modern scope to shadow the global scope (subject to some restrictions).
More specifically, a name in the global scope is as shadowable as a glob import in the module self. In other words, we imagine a special, implicit glob import in each module item:

mod foo { #[lexical_only] // Not accessible via foo::<name>, like pre-RFC 1560 use imports. #[shadowable_by_legacy_scope] // for back-compat use ::*; }

r? @nrc

jseyfried changed the title~~Allow use macro imports to shadow built macors~~ Allow use macro imports to shadow builtin macors

Mar 14, 2017

jseyfried changed the title~~Allow use macro imports to shadow builtin macors~~ Allow use macro imports to shadow builtin macros

Mar 14, 2017

I think the terminology could be improved - built-in suggests that it is part of the compiler, but only a small subset of macros are and they are (iirc) in the prelude too. If I understand correctly, the distinction is more between legacy-imported and legacy-local?

LGTM, I'd like to fix (or better understand) the naming issue, but r+ with that.

jseyfried changed the title~~Allow use macro imports to shadow builtin macros~~ Allow use macro imports to shadow global macros

Mar 16, 2017

Agreed -- I renamed "builtin scope" to "global scope".
@bors r=nrc

📌 Commit a0707df has been approved by nrc

bors added a commit that referenced this pull request

Mar 18, 2017

Rollup of 22 pull requests

Successful merges: #40241, #40346, #40348, #40377, #40398, #40409, #40441, #40445, #40509, #40521, #40523, #40532, #40538, #40564, #40581, #40583, #40588, #40589, #40590, #40603, #40611, #40621
Failed merges: #40501, #40541

☔ The latest upstream changes (presumably #40346) made this pull request unmergeable. Please resolve the merge conflicts.

📌 Commit d123e76 has been approved by nrc

frewsxcv added a commit to frewsxcv/rust that referenced this pull request

Mar 24, 2017

Allow use macro imports to shadow global macros

Terminology:

global scope: builtin macros, macros from the prelude, #[macro_use], or #![plugin(..)].
legacy scope: crate-local macro_rules!.
modern scope: use macro imports, macro (once implemented).

This PR allows the modern scope to shadow the global scope (subject to some restrictions). More specifically, a name in the global scope is as shadowable as a glob import in the module self. In other words, we imagine a special, implicit glob import in each module item:

mod foo {
    #[lexical_only] // Not accessible via `foo::<name>`, like pre-RFC 1560 `use` imports.
    #[shadowable_by_legacy_scope] // for back-compat
    use <global_macros>::*;
}

r? @nrc

bors added a commit that referenced this pull request

Mar 24, 2017

📌 Commit d64d381 has been approved by nrc

alexcrichton added a commit to alexcrichton/rust that referenced this pull request

Mar 25, 2017

Allow use macro imports to shadow global macros

Terminology:

global scope: builtin macros, macros from the prelude, #[macro_use], or #![plugin(..)].
legacy scope: crate-local macro_rules!.
modern scope: use macro imports, macro (once implemented).

This PR allows the modern scope to shadow the global scope (subject to some restrictions). More specifically, a name in the global scope is as shadowable as a glob import in the module self. In other words, we imagine a special, implicit glob import in each module item:

mod foo {
    #[lexical_only] // Not accessible via `foo::<name>`, like pre-RFC 1560 `use` imports.
    #[shadowable_by_legacy_scope] // for back-compat
    use <global_macros>::*;
}

r? @nrc

bors added a commit that referenced this pull request

Mar 25, 2017

Rollup of 11 pull requests

Successful merges: #40347, #40501, #40516, #40524, #40540, #40642, #40683, #40764, #40778, #40807, #40809
Failed merges: #40771

bors added a commit that referenced this pull request

Mar 25, 2017

Rollup of 11 pull requests

Successful merges: #40347, #40501, #40516, #40524, #40540, #40642, #40683, #40764, #40778, #40807, #40809
Failed merges: #40771

⌛ Testing commit d64d381 with merge 7022e44...

try to fix the build on emscripten #40821
@bors retry

⌛ Testing commit d64d381 with merge 1a95c82...

try to fix the build on emscripten #40821
@bors retry

⌛ Testing commit d64d381 with merge 20ae752...

try to fix the build on emscripten #40821
@bors retry

⌛ Testing commit d64d381 with merge ae3186d...

Debuginfo tests spurious failures on MinGW #40835
@bors retry

bors added a commit that referenced this pull request

Mar 26, 2017

Allow use macro imports to shadow global macros

Terminology:

global scope: builtin macros, macros from the prelude, #[macro_use], or #![plugin(..)].
legacy scope: crate-local macro_rules!.
modern scope: use macro imports, macro (once implemented).

This PR allows the modern scope to shadow the global scope (subject to some restrictions). More specifically, a name in the global scope is as shadowable as a glob import in the module self. In other words, we imagine a special, implicit glob import in each module item:

mod foo {
    #[lexical_only] // Not accessible via `foo::<name>`, like pre-RFC 1560 `use` imports.
    #[shadowable_by_legacy_scope] // for back-compat
    use <global_macros>::*;
}

r? @nrc

Allow use macro imports to shadow global macros by jseyfried · Pull Request #40501 · rust-lang/rust (original) (raw)

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Allow `use` macro imports to shadow global macros by jseyfried · Pull Request #40501 · rust-lang/rust (original) (raw)