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Calling macros with full paths doesn't work with implicit crates #52576

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Manishearth opened this issue Jul 20, 2018 · 1 comment · Fixed by #52841
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Calling macros with full paths doesn't work with implicit crates #52576

Manishearth opened this issue Jul 20, 2018 · 1 comment · Fixed by #52841
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@Manishearth
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Manishearth commented Jul 20, 2018 •
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// edition = "2018"
// [dependencies] lazy_static = "1.0.1"

#![feature(rustc_2018_preview)]
#![feature(use_extern_macros)]
lazy_static::lazy_static! {static ref FOO: u8 = 1;}

This fails to compile (even with extern crate lazy_static). It does compile if I add a use lazy_static.

AIUI this is a bug, you should be able to import directly from crates in macros as well.

cc @dtolnay @alexcrichton
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This is a sub-issue of #52512 (fix is in progress).

@Manishearth Manishearth mentioned this issue Jul 20, 2018
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@petrochenkov petrochenkov self-assigned this Jul 21, 2018
@petrochenkov petrochenkov mentioned this issue Jul 30, 2018
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Mark-Simulacrum added a commit to Mark-Simulacrum/rust that referenced this issue Aug 1, 2018
@Mark-Simulacrum
Rollup merge of rust-lang#52841 - petrochenkov:premacro, r=alexcrichton
1f0d8c6 
resolve: Implement prelude search for macro paths, implement tool attributes

When identifier is macro path is resolved in scopes (i.e. the first path segment - `foo` in `foo::mac!()` or `foo!()`), scopes are searched in the same order as for non-macro paths - items in modules, extern prelude, tool prelude (see later), standard library prelude, language prelude, but with some extra shadowing restrictions (names from globs and macro expansions cannot shadow names from outer scopes). See the comment in `fn resolve_lexical_macro_path_segment` for more details.

"Tool prelude" currently contains two "tool modules" `rustfmt` and `clippy`, and is searched immediately after extern prelude.
This makes the [possible long-term solution](https://github.com/rust-lang/rfcs/blob/master/text/2103-tool-attributes.md#long-term-solution) for tool attributes exactly equivalent to the existing extern prelude scheme, except that `--extern=my_crate` making crate names available in scope is replaced with something like `--tool=my_tool` making tool names available in scope.

The `tool_attributes` feature is still unstable and `#![feature(tool_attributes)]` now implicitly enables `#![feature(use_extern_macros)]`. `use_extern_macros` is a prerequisite for `tool_attributes`, so their stabilization will happen in the same order.
If `use_extern_macros` is not enabled, then tool attributes are treated as custom attributes (this is temporary, anyway).

Fixes rust-lang#52576
Fixes rust-lang#52512
Fixes rust-lang#51277
cc rust-lang#52269
bors added a commit that referenced this issue Aug 2, 2018
@bors
Auto merge of #52841 - petrochenkov:premacro, r=alexcrichton
40e4b6e 
resolve: Implement prelude search for macro paths, implement tool attributes

When identifier is macro path is resolved in scopes (i.e. the first path segment - `foo` in `foo::mac!()` or `foo!()`), scopes are searched in the same order as for non-macro paths - items in modules, extern prelude, tool prelude (see later), standard library prelude, language prelude, but with some extra shadowing restrictions (names from globs and macro expansions cannot shadow names from outer scopes). See the comment in `fn resolve_lexical_macro_path_segment` for more details.

"Tool prelude" currently contains two "tool modules" `rustfmt` and `clippy`, and is searched immediately after extern prelude.
This makes the [possible long-term solution](https://github.com/rust-lang/rfcs/blob/master/text/2103-tool-attributes.md#long-term-solution) for tool attributes exactly equivalent to the existing extern prelude scheme, except that `--extern=my_crate` making crate names available in scope is replaced with something like `--tool=my_tool` making tool names available in scope.

The `tool_attributes` feature is still unstable and `#![feature(tool_attributes)]` now implicitly enables `#![feature(use_extern_macros)]`. `use_extern_macros` is a prerequisite for `tool_attributes`, so their stabilization will happen in the same order.
If `use_extern_macros` is not enabled, then tool attributes are treated as custom attributes (this is temporary, anyway).

Fixes #52576
Fixes #52512
Fixes #51277
cc #52269
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resolve: Implement prelude search for macro paths, implement tool attributes petrochenkov/rust
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