Add `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` lint by Aaron1011 · Pull Request #79819 · rust-lang/rust

Aaron1011 · 2020-12-08T02:04:23Z

This PR adds an allow-by-default future-compatibility lint
SEMICOLON_IN_EXPRESSIONS_FROM_MACROS. It fires when a trailing semicolon in a
macro body is ignored due to the macro being used in expression
position:

macro_rules! foo {() => {true;// WARN}}fnmain(){let val = matchtrue{true => false,
_ => foo!()};}

The lint takes its level from the macro call site, and
can be allowed for a particular macro by adding
#[allow(macro_trailing_semicolon)].

The lint is set to warn for all internal rustc crates (when being built
by a stage1 compiler). After the next beta bump, we can enable
the lint for the bootstrap compiler as well.

rust-highfive · 2020-12-08T02:04:26Z

r? @matthewjasper

(rust-highfive has picked a reviewer for you, use r? to override)

Aaron1011 · 2020-12-08T03:39:58Z

This becomes tricky when the macro is defined in a different crate. I think we need to instead take the lint level from the macro call site - otherwise, the warning becomes unsurpressable in downstream code.

Aaron1011 · 2020-12-08T04:00:30Z

Unfortunately, inert attributes on macro invocations (e.g. #[allow(macro_trailing_semicolon)] my_macro!()) is an issue of its own: #63221

Aaron1011 · 2020-12-08T04:08:44Z

Additionally, linting is currently done after HIR lowering, so the macro call doesn't even exist by the time we would be ready to emit the lint.

Implementing this will require some further thought.

petrochenkov · 2020-12-11T12:55:11Z

r? @petrochenkov

petrochenkov · 2020-12-12T22:49:20Z

I agree that the NodeId for linting should be taken from the use site rather than from definition site.

We have a method fn lint_node_id to obtain an ID that is close enough to the given macro invocation.
(#[allow(macro_trailing_semicolon)] my_macro!() still won't work though.)

Dylan-DPC-zz · 2021-01-13T02:16:51Z

@bors try

bors · 2021-01-13T02:17:05Z

⌛ Trying commit 1d8d56e95636056cf085c02decd7a386264310d3 with merge 50473808b4098f3d96d962b3940d38962305e408...

Aaron1011 · 2021-01-27T19:40:01Z

@petrochenkov I've updated the PR to use lint_node_id

petrochenkov · 2021-01-27T22:30:54Z

The comment on macro_rules! declare_lint explains how to fix and test the lint-docs check.

cc rust-lang#79813 This PR adds an allow-by-default future-compatibility lint `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS`. It fires when a trailing semicolon in a macro body is ignored due to the macro being used in expression position: ```rust macro_rules! foo { () => { true; // WARN } } fn main() { let val = match true { true => false, _ => foo!() }; } ``` The lint takes its level from the macro call site, and can be allowed for a particular macro by adding `#[allow(semicolon_in_expressions_from_macros)]`. The lint is set to warn for all internal rustc crates (when being built by a stage1 compiler). After the next beta bump, we can enable the lint for the bootstrap compiler as well.

Aaron1011 · 2021-01-28T13:52:51Z

@bors r=petrochenkov

bors · 2021-01-28T13:52:53Z

📌 Commit f902551 has been approved by petrochenkov

…micolon, r=petrochenkov Add `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` lint cc rust-lang#79813 This PR adds an allow-by-default future-compatibility lint `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS`. It fires when a trailing semicolon in a macro body is ignored due to the macro being used in expression position: ```rust macro_rules! foo { () => { true; // WARN } } fn main() { let val = match true { true => false, _ => foo!() }; } ``` The lint takes its level from the macro call site, and can be allowed for a particular macro by adding `#[allow(macro_trailing_semicolon)]`. The lint is set to warn for all internal rustc crates (when being built by a stage1 compiler). After the next beta bump, we can enable the lint for the bootstrap compiler as well.

Rollup of 10 pull requests Successful merges: - rust-lang#79570 (rustc: Stabilize `-Zrun-dsymutil` as `-Csplit-debuginfo`) - rust-lang#79819 (Add `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` lint) - rust-lang#79991 (rustdoc: Render HRTB correctly for bare functions) - rust-lang#80215 (Use -target when linking binaries for Mac Catalyst) - rust-lang#81158 (Point to span of upvar making closure FnMut) - rust-lang#81176 (Improve safety of `LateContext::qpath_res`) - rust-lang#81287 (Split rustdoc JSON types into separately versioned crate) - rust-lang#81306 (Fuse inner iterator in FlattenCompat and improve related tests) - rust-lang#81333 (clean up some const error reporting around promoteds) - rust-lang#81459 (Fix rustdoc text selection for page titles) Failed merges: r? `@ghost` `@rustbot` modify labels: rollup

Opening to gather data about the impact of changing the lint level of rust-lang#79819

rust-highfive assigned matthewjasper Dec 8, 2020

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Aaron1011 force-pushed the feature/macro-trailing-semicolon branch from f8734e0 to c138cfbCompare December 8, 2020 02:05

Aaron1011 mentioned this pull request Dec 8, 2020
Tracking Issue for denying trailing semicolons in expression macro bodies #79813
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Aaron1011 force-pushed the feature/macro-trailing-semicolon branch from c138cfb to 1d8d56eCompare December 8, 2020 02:51

rust-highfive assigned petrochenkov and unassigned matthewjasper Dec 11, 2020

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Aaron1011 mentioned this pull request Dec 28, 2020
Parse bang macro as a statement when used in trailing expr position #78991
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Aaron1011 force-pushed the feature/macro-trailing-semicolon branch from 1d8d56e to 2603555Compare January 27, 2021 19:39

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petrochenkov reviewed Jan 27, 2021
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Comment threadcompiler/rustc_expand/src/lib.rs Outdated
Comment threadcompiler/rustc_expand/src/base.rs Outdated
Comment threadcompiler/rustc_expand/src/expand.rs Outdated
Comment threadcompiler/rustc_lint_defs/src/builtin.rs Outdated

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petrochenkov added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Jan 28, 2021

Aaron1011 force-pushed the feature/macro-trailing-semicolon branch from 96c5f6b to 4867fadCompare January 28, 2021 13:50

Aaron1011 force-pushed the feature/macro-trailing-semicolon branch from 4867fad to f902551Compare January 28, 2021 13:52

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 28, 2021

Dylan-DPC-zz mentioned this pull request Jan 28, 2021
Rollup of 8 pull requests #81475
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Aaron1011 mentioned this pull request Jan 28, 2021
[EXPERIMENT] Error on trailing semicolons in macro expressions #81477
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JohnTitor mentioned this pull request Jan 29, 2021
Rollup of 10 pull requests #81493
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bors merged commit 4003a73 into rust-lang:masterJan 29, 2021

rustbot added this to the 1.51.0 milestone Jan 29, 2021

Aaron1011 mentioned this pull request Jan 29, 2021
internal compiler error: failed to process buffered lint here #81531
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notheotherben added a commit to SierraSoftworks/rex-rs that referenced this pull request Feb 1, 2021
fix: Address issues with Rust nightly caused byrust-lang/rust#79819
661c355

Aaron1011 mentioned this pull request Feb 2, 2021
Stop ignoring trailing semicolons in a macro body when a macro is invoked in expression position rust-lang/lang-team#70
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jethrogb mentioned this pull request Feb 3, 2021
Revert allow semicolons lint #81695
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Aaron1011 added a commit to Aaron1011/rust that referenced this pull request Jul 4, 2021
[EXPERIMENT] Error on trailing semicolons in macro expressions
fcdc68c
Opening to gather data about the impact of changing the lint level of rust-lang#79819

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