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concat_idents! is not very useful #13294

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alexcrichton opened this issue Apr 3, 2014 · 5 comments
Closed

concat_idents! is not very useful #13294

alexcrichton opened this issue Apr 3, 2014 · 5 comments
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@alexcrichton
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It cannot access local variables due to hygiene, it can't be used to create names of a function (not where a macro can appear), and it can basically only be used to access non-hygienic things.

I believe the utility of this macro has been greatly reduced over time, and it may be time to just remove it (or feature gate it)

Nominating (it's a core built-in macro)
@alexcrichton alexcrichton mentioned this issue Apr 3, 2014
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@huonw huonw mentioned this issue Apr 3, 2014
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huonw added a commit to huonw/rust that referenced this issue Apr 4, 2014
@huonw
rustc: feature-gate concat_idents!.
6c5e1d0 
concat_idents! is not as useful as it could be, due to macros only being
allowed in limited places, and hygiene, so lets feature gate it until we
make a decision about it.

cc rust-lang#13294
bors added a commit that referenced this issue Apr 4, 2014
@bors
auto merge of #13295 : huonw/rust/gate-concat-idents, r=alexcrichton
286b62e 
rustc: feature-gate `concat_idents!`.

concat_idents! is not as useful as it could be, due to macros only being
allowed in limited places, and hygiene, so lets feature gate it until we
make a decision about it.

cc #13294
@huonw
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huonw commented Apr 4, 2014

(Feature gated in #13295.)

@pnkfelix
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not accepted for 1.0 milestone as this is now feature gated.

Assigning P-low (rather than closing) so that we can determine what else, if anything, to do here.

@huonw huonw mentioned this issue Apr 11, 2014
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@kmcallister
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I think a good concat_idents! is important, although not urgent. Otherwise it's a big regression from C.

@aturon aturon mentioned this issue Apr 23, 2014
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@Manishearth Manishearth mentioned this issue Aug 28, 2014
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@emberian
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I agree with @kmcallister, it's a quite useful feature in some cases.

@kylewlacy kylewlacy mentioned this issue Sep 1, 2015
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@ghost ghost mentioned this issue Nov 5, 2015
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@steveklabnik
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Closing in favor of #29599

@c410-f3r c410-f3r mentioned this issue May 25, 2023
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flip1995 pushed a commit to flip1995/rust that referenced this issue Sep 5, 2024
@bors
Auto merge of rust-lang#13294 - WeiTheShinobi:new_lint_used_underscor…
603d5a1 
…e_items, r=llogiq

Add new lint: `used_underscore_items`

Closes rust-lang#13260

---

changelog: new [`used_underscore_items`] lint against using items with a single leading underscore
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@steveklabnik @alexcrichton @pnkfelix @kmcallister @emberian @huonw