coverage: Don't instrument `#[automatically_derived]` functions #120185

Zalathar · 2024-01-21T04:43:52Z

This PR makes the coverage instrumentor detect and skip functions that have #[automatically_derived] on their enclosing impl block.

Most notably, this means that methods generated by built-in derives (e.g. Clone, Debug, PartialEq) are now ignored by coverage instrumentation, and won't appear as executed or not-executed in coverage reports.

This is a noticeable change in user-visible behaviour, but overall I think it's a net improvement. For example, we've had a few user requests for this sort of change (e.g. #105055, #84605 (comment)), and I believe it's the behaviour that most users will expect/prefer by default.

It's possible to imagine situations where users would want to instrument these derived implementations, but I think it's OK to treat that as an opportunity to consider adding more fine-grained option flags to control the details of coverage instrumentation, while leaving this new behaviour as the default.

(Also note that while -Cinstrument-coverage is a stable feature, the exact details of coverage instrumentation are allowed to change. So we can make this change; the main question is whether we should.)

Fixes #105055.

rustbot · 2024-01-21T04:44:00Z

r? @b-naber

(rustbot has picked a reviewer for you, use r? to override)

rustbot · 2024-01-21T04:44:02Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

Swatinem

I agree that skipping these is a much better default behavior.

If users want these derives to be instrumented, they can implement them manually. Which btw is trivial as rust-analyzer will auto-generate all of the inner derive code automatically.

oli-obk · 2024-01-21T11:04:42Z

@bors r+ rollup

If it becomes an issue we can make it configurable

bors · 2024-01-21T11:04:45Z

📌 Commit 7263a76 has been approved by oli-obk

It is now in the queue for this repository.

coverage: Don't instrument `#[automatically_derived]` functions This PR makes the coverage instrumentor detect and skip functions that have [`#[automatically_derived]`](https://doc.rust-lang.org/reference/attributes/derive.html#the-automatically_derived-attribute) on their enclosing impl block. Most notably, this means that methods generated by built-in derives (e.g. `Clone`, `Debug`, `PartialEq`) are now ignored by coverage instrumentation, and won't appear as executed or not-executed in coverage reports. This is a noticeable change in user-visible behaviour, but overall I think it's a net improvement. For example, we've had a few user requests for this sort of change (e.g. rust-lang#105055, rust-lang#84605 (comment)), and I believe it's the behaviour that most users will expect/prefer by default. It's possible to imagine situations where users would want to instrument these derived implementations, but I think it's OK to treat that as an opportunity to consider adding more fine-grained option flags to control the details of coverage instrumentation, while leaving this new behaviour as the default. (Also note that while `-Cinstrument-coverage` is a stable feature, the exact details of coverage instrumentation are allowed to change. So we *can* make this change; the main question is whether we *should*.) Fixes rust-lang#105055.

Rollup of 12 pull requests Successful merges: - rust-lang#118639 (Undeprecate lint `unstable_features` and make use of it in the compiler) - rust-lang#118714 ( Explanation that fields are being used when deriving `(Partial)Ord` on enums) - rust-lang#119801 (Fix deallocation with wrong allocator in (A)Rc::from_box_in) - rust-lang#119948 (Make `unsafe_op_in_unsafe_fn` migrated in edition 2024) - rust-lang#119999 (remote-test: use u64 to represent file size) - rust-lang#120058 (bootstrap: improvements for compiler builds) - rust-lang#120160 (Manually implement derived `NonZero` traits.) - rust-lang#120177 (Remove duplicate dependencies for rustc) - rust-lang#120185 (coverage: Don't instrument `#[automatically_derived]` functions) - rust-lang#120194 (Shorten `#[must_use]` Diagnostic Message for `Option::is_none`) - rust-lang#120200 (Correct the anchor of an URL in an error message) - rust-lang#120203 (Replace `#!/bin/bash` with `#!/usr/bin/env bash` in rust-installer tests) r? `@ghost` `@rustbot` modify labels: rollup

Zalathar · 2024-01-22T01:12:43Z

Ugh, failed in rollup because I forgot to bless the separate coverage-run-rustdoc suite (again).

Zalathar · 2024-01-22T01:21:45Z

Rebased and re-blessed (diff); no functional changes since last review.

@rustbot ready

saethlin · 2024-01-22T03:01:29Z

@bors r=oli-obk

bors · 2024-01-22T03:01:31Z

📌 Commit 41dcba8 has been approved by oli-obk

It is now in the queue for this repository.

matthiaskrgr · 2024-01-22T06:53:54Z

@bors r-
may have failed in #120209 (comment) ?

Zalathar · 2024-01-22T07:08:26Z

@matthiaskrgr Yes, I noticed this earlier today and have already pushed a fix, so this PR is ready to merge again in its current state.

Rollup of 10 pull requests Successful merges: - rust-lang#114764 ([style edition 2024] Combine all delimited exprs as last argument) - rust-lang#118326 (Add `NonZero*::count_ones`) - rust-lang#118636 (Add the unstable option to reduce the binary size of dynamic library…) - rust-lang#119460 (coverage: Never emit improperly-ordered coverage regions) - rust-lang#119616 (Add a new `wasm32-wasi-preview2` target) - rust-lang#120185 (coverage: Don't instrument `#[automatically_derived]` functions) - rust-lang#120265 (Remove no-system-llvm) - rust-lang#120284 (privacy: Refactor top-level visiting in `TypePrivacyVisitor`) - rust-lang#120285 (Remove extra # from url in suggestion) - rust-lang#120299 (Add mw to review rotation and add some owner assignments) Failed merges: - rust-lang#120124 (Split assembly tests for ELF and MachO) r? `@ghost` `@rustbot` modify labels: rollup

Rollup of 9 pull requests Successful merges: - rust-lang#114764 ([style edition 2024] Combine all delimited exprs as last argument) - rust-lang#118326 (Add `NonZero*::count_ones`) - rust-lang#119460 (coverage: Never emit improperly-ordered coverage regions) - rust-lang#119616 (Add a new `wasm32-wasi-preview2` target) - rust-lang#120185 (coverage: Don't instrument `#[automatically_derived]` functions) - rust-lang#120265 (Remove no-system-llvm) - rust-lang#120284 (privacy: Refactor top-level visiting in `TypePrivacyVisitor`) - rust-lang#120285 (Remove extra # from url in suggestion) - rust-lang#120299 (Add mw to review rotation and add some owner assignments) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#120185 - Zalathar:auto-derived, r=wesleywiser coverage: Don't instrument `#[automatically_derived]` functions This PR makes the coverage instrumentor detect and skip functions that have [`#[automatically_derived]`](https://doc.rust-lang.org/reference/attributes/derive.html#the-automatically_derived-attribute) on their enclosing impl block. Most notably, this means that methods generated by built-in derives (e.g. `Clone`, `Debug`, `PartialEq`) are now ignored by coverage instrumentation, and won't appear as executed or not-executed in coverage reports. This is a noticeable change in user-visible behaviour, but overall I think it's a net improvement. For example, we've had a few user requests for this sort of change (e.g. rust-lang#105055, rust-lang#84605 (comment)), and I believe it's the behaviour that most users will expect/prefer by default. It's possible to imagine situations where users would want to instrument these derived implementations, but I think it's OK to treat that as an opportunity to consider adding more fine-grained option flags to control the details of coverage instrumentation, while leaving this new behaviour as the default. (Also note that while `-Cinstrument-coverage` is a stable feature, the exact details of coverage instrumentation are allowed to change. So we *can* make this change; the main question is whether we *should*.) Fixes rust-lang#105055.

* Add automatically_derived to all impl functions in deku-derive * Motivation: rust-lang/rust#120185

As per rust-lang/rust#120185, functions with their enclosing impl body marked as `#[automatically_derived]` won't be featured in coverage reports.

* chore: mark TypeInfo derived impl as automatically_derived As per rust-lang/rust#120185, functions with their enclosing impl body marked as `#[automatically_derived]` won't be featured in coverage reports. * chore: elide lifetimes * Update tests.rs paritytech/parity-scale-codec/pull/653 disallowed duplicate indexes for variants. * fix: ui tests were outdated

…ust-lang/rust#120185))

coverage: Treat `#[automatically_derived]` as `#[coverage(off)]` One of the contributing factors behind #141577 (comment) was the presence of derive-macro-generated code containing nested closures. Coverage instrumentation already has a heuristic for skipping code marked with `#[automatically_derived]` (#120185), because derived code is usually not worth instrumenting, and also has a tendency to trigger vexing edge-case bugs in coverage instrumentation or coverage codegen. However, the existing heuristic only applied to the associated items directly within an auto-derived impl block, and had no effect on closures or nested items within those associated items. This PR therefore extends the search for `#[coverage(..)]` attributes to also treat `#[automatically_derived]` as an implied `#[coverage(off)]` for the purposes of coverage instrumentation. --- This change doesn’t rule out an entire category of bugs, because it only affects code that actually uses the auto-derived attribute. But it should reduce the overall chance of edge-case macro span bugs being observed in the wild.

…errors coverage: Treat `#[automatically_derived]` as `#[coverage(off)]` One of the contributing factors behind rust-lang#141577 (comment) was the presence of derive-macro-generated code containing nested closures. Coverage instrumentation already has a heuristic for skipping code marked with `#[automatically_derived]` (rust-lang#120185), because derived code is usually not worth instrumenting, and also has a tendency to trigger vexing edge-case bugs in coverage instrumentation or coverage codegen. However, the existing heuristic only applied to the associated items directly within an auto-derived impl block, and had no effect on closures or nested items within those associated items. This PR therefore extends the search for `#[coverage(..)]` attributes to also treat `#[automatically_derived]` as an implied `#[coverage(off)]` for the purposes of coverage instrumentation. --- This change doesn’t rule out an entire category of bugs, because it only affects code that actually uses the auto-derived attribute. But it should reduce the overall chance of edge-case macro span bugs being observed in the wild.

Rollup merge of #144560 - Zalathar:auto-derived, r=compiler-errors coverage: Treat `#[automatically_derived]` as `#[coverage(off)]` One of the contributing factors behind #141577 (comment) was the presence of derive-macro-generated code containing nested closures. Coverage instrumentation already has a heuristic for skipping code marked with `#[automatically_derived]` (#120185), because derived code is usually not worth instrumenting, and also has a tendency to trigger vexing edge-case bugs in coverage instrumentation or coverage codegen. However, the existing heuristic only applied to the associated items directly within an auto-derived impl block, and had no effect on closures or nested items within those associated items. This PR therefore extends the search for `#[coverage(..)]` attributes to also treat `#[automatically_derived]` as an implied `#[coverage(off)]` for the purposes of coverage instrumentation. --- This change doesn’t rule out an entire category of bugs, because it only affects code that actually uses the auto-derived attribute. But it should reduce the overall chance of edge-case macro span bugs being observed in the wild.

rustbot assigned b-naber Jan 21, 2024

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jan 21, 2024

rustbot added the A-code-coverage Area: Source-based code coverage (-Cinstrument-coverage) label Jan 21, 2024

Zalathar mentioned this pull request Jan 21, 2024

Tracking issue for function attribute #[coverage] #84605

Open

Swatinem approved these changes Jan 21, 2024

View reviewed changes

This was referenced Jan 21, 2024

Clone is required in a bound by Copy, however Clone is marked as uncovered taiki-e/cargo-llvm-cov#193

Closed

Disable coverage for derived traits taiki-e/cargo-llvm-cov#222

Closed

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-review Status: Awaiting review from the assignee but also interested parties. labels Jan 21, 2024

TaKO8Ki mentioned this pull request Jan 21, 2024

Rollup of 12 pull requests #120209

Closed

Zalathar force-pushed the auto-derived branch from 7263a76 to 5dda729 Compare January 22, 2024 01:17

coverage: Don't instrument #[automatically_derived] functions

41dcba8

Zalathar force-pushed the auto-derived branch from 5dda729 to 41dcba8 Compare January 22, 2024 01:21

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jan 22, 2024

bors removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jan 22, 2024

bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jan 22, 2024

fmease mentioned this pull request Jan 24, 2024

Rollup of 10 pull requests #120303

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fmease mentioned this pull request Jan 24, 2024

Rollup of 9 pull requests #120309

Merged

bors merged commit 8bd126c into rust-lang:master Jan 24, 2024

rustbot added this to the 1.77.0 milestone Jan 24, 2024

Zalathar deleted the auto-derived branch January 24, 2024 23:04

davidhewitt mentioned this pull request Mar 23, 2024

PyO3 v0.21 beta pyfunction annotation coverage PyO3/pyo3#3989

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daxpedda mentioned this pull request Aug 18, 2024

Use #[automatically_derived] instead of #[coverage(off)] wasm-bindgen/wasm-bindgen#4078

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BlueGreenMagick mentioned this pull request Aug 30, 2024

Put #[automatically_derived] on impls siefkenj/tsify#44

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oxalica mentioned this pull request Sep 22, 2024

Mark #[automatically_derived] for generated impls dtolnay/thiserror#322

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wcampbell0x2a added a commit to sharksforarms/deku that referenced this pull request Oct 27, 2024

Mark auto derived functions

affa54c

* Add automatically_derived to all impl functions in deku-derive * Motivation: rust-lang/rust#120185

wcampbell0x2a mentioned this pull request Oct 27, 2024

Mark auto derived functions sharksforarms/deku#495

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wcampbell0x2a added a commit to sharksforarms/deku that referenced this pull request Oct 29, 2024

Mark auto derived functions (#495)

b3be1e3

* Add automatically_derived to all impl functions in deku-derive * Motivation: rust-lang/rust#120185

tdittr mentioned this pull request Dec 9, 2024

Mark generated impl de::Visitor blocks as #[automatically_derived] serde-rs/serde#2866

Merged

This was referenced Dec 21, 2024

derive: Use #[automatically_derived] on generated impls tokio-rs/valuable#136

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Exclude instantiations from statistics? taiki-e/cargo-llvm-cov#397

Closed

Invalid line coverage for multiple partially covered derive macros taiki-e/cargo-llvm-cov#404

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saiintbrisson mentioned this pull request Feb 14, 2025

chore: mark TypeInfo derived impl as automatically_derived paritytech/scale-info#218

Merged

taiki-e mentioned this pull request Mar 18, 2025

Coverage not detected when deserializing with custom derserializers (serde-json) taiki-e/cargo-llvm-cov#427

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guzman-raphael added a commit to guzman-raphael/getset that referenced this pull request Apr 16, 2025

Skip coverage on generated impl blocks (See [rust-lang/rust#120185](r…

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…ust-lang/rust#120185))

guzman-raphael mentioned this pull request Apr 22, 2025

Add UniFFI client with Python bindings walkerlab/orcapod#71

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Zalathar mentioned this pull request Jul 28, 2025

coverage: Treat #[automatically_derived] as #[coverage(off)] #144560

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