Rewrite and refactor format_args!() builtin macro. #100996

m-ou-se · 2022-08-25T10:57:29Z

This is a near complete rewrite of compiler/rustc_builtin_macros/src/format.rs.

This gets rid of the massive unmaintanable Context struct, and splits the macro expansion into three parts:

First, parse_args will parse the (literal, arg, arg, name=arg, name=arg) syntax, but doesn't parse the template (the literal) itself.
Second, make_format_args will parse the template, the format options, resolve argument references, produce diagnostics, and turn the whole thing into a FormatArgs structure.
Finally, expand_parsed_format_args will turn that FormatArgs structure into the expression that the macro expands to.

In other words, the format_args builtin macro used to be a hard-to-maintain 'single pass compiler', which I've split into a three phase compiler with a parser/tokenizer (step 1), semantic analysis (step 2), and backend (step 3). (It's compilers all the way down. ^^)

This can serve as a great starting point for #99012, which will only need to change the implementation of 3, while leaving step 1 and 2 unchanged.

It also makes rust-lang/compiler-team#541 easier, which could then upgrade the new FormatArgs struct to an ast node and remove step 3, moving that step to later in the compilation process.

It also fixes a few diagnostics bugs.

This also significantly reduces the amount of generated code for cases with arguments in non-default order without formatting options, like "{1} {0}" or "{a} {}", etc.

m-ou-se · 2022-08-25T12:47:00Z

@Alexendoo I saw you've sent a few PRs touching this code recently. In case you were planning to send more of those, be aware I'm refactoring the entire thing. ^^

Alexendoo · 2022-08-25T13:02:06Z

Thanks for the heads up! The main one I was planning to do was #101000 so that is handy 😄

m-ou-se · 2022-08-26T19:44:20Z

@bors try @rust-timer queue

rust-timer · 2022-08-26T19:44:22Z

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

bors · 2022-08-26T19:44:29Z

⌛ Trying commit 46505b5ee3d606a643d19a2322bff8cb52dce760 with merge f0b6903fbee6a3632b1b3059d24324e030e0430b...

bors · 2022-08-26T20:55:26Z

💔 Test failed - checks-actions

m-ou-se · 2022-08-26T20:56:52Z

@bors try

bors · 2022-08-26T20:57:00Z

⌛ Trying commit fe3eb3dcf6547820441af4c4f8fcb4bbc22b1b4e with merge 83ba636722d8a682cc06767b5b8577368ad42ed9...

With efficient lookup through a hash map.

m-ou-se · 2022-09-27T11:46:45Z

@bors r=estebank

bors · 2022-09-27T11:46:47Z

📌 Commit 20bb600 has been approved by estebank

It is now in the queue for this repository.

bors · 2022-09-27T13:27:20Z

⌛ Testing commit 20bb600 with merge 87338df73726f7517d94a980dd56de09bf6cc975...

bors · 2022-09-27T14:49:54Z

💔 Test failed - checks-actions

m-ou-se · 2022-09-27T15:05:42Z

Weird, the relevant logs seem to be empty.

@bors retry

bors · 2022-09-28T01:36:32Z

⌛ Testing commit 20bb600 with merge d6734be...

bors · 2022-09-28T04:18:13Z

☀️ Test successful - checks-actions
Approved by: estebank
Pushing d6734be to master...

rust-timer · 2022-09-28T06:02:27Z

Finished benchmarking commit (d6734be): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean¹	range	count²
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	1.5%	[1.1%, 2.0%]	6
Improvements ✅ (primary)	-0.3%	[-0.7%, -0.2%]	7
Improvements ✅ (secondary)	-1.2%	[-1.5%, -0.6%]	7
All ❌✅ (primary)	-0.3%	[-0.7%, -0.2%]	7

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean¹	range	count²
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	2.7%	[1.8%, 5.7%]	5
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.2%	[-3.9%, -1.0%]	8
All ❌✅ (primary)	-	-	0

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean¹	range	count²
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	3.5%	[2.8%, 4.2%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.3%	[-3.9%, -2.8%]	2
All ❌✅ (primary)	-	-	0

the arithmetic mean of the percent change ↩ ↩² ↩³
number of relevant changes ↩ ↩² ↩³

nnethercote · 2022-09-28T06:16:52Z

keccak is noisy at the moment. The other changes are likely real, but the wins and losses balance out.

@rustbot label: +perf-regression-triaged

…-ou-se Fix `format_args` capture for macro expanded format strings Since rust-lang#100996 `format_args` capture for macro expanded strings aren't prevented when the span of the expansion points to a string literal, e.g. ```rust // not a terribly realistic example, but also happens for proc_macros that set // the span of the output to an input str literal, such as indoc macro_rules! x { ($e:expr) => { $e } } fn main() { let a = 1; println!(x!("{a}")); } ``` The tests didn't catch it as the span of `concat!()` points to the macro invocation r? `@m-ou-se`

m-ou-se added A-macros Area: All kinds of macros (custom derive, macro_rules!, proc macros, ..) T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Aug 25, 2022

m-ou-se self-assigned this Aug 25, 2022

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 25, 2022

m-ou-se mentioned this pull request Aug 25, 2022

Separate CountIsStar from CountIsParam in rustc_parse_format. #101000

Merged

m-ou-se force-pushed the format-args-2 branch 2 times, most recently from c8de89a to 9a62d8d Compare August 25, 2022 13:00

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m-ou-se force-pushed the format-args-2 branch 4 times, most recently from 746295f to 46505b5 Compare August 26, 2022 18:40

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Aug 26, 2022

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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-review Status: Awaiting review from the assignee but also interested parties. labels Aug 26, 2022

m-ou-se added 3 commits September 27, 2022 13:31

Turn format arguments Vec into its own struct.

cf53fef

With efficient lookup through a hash map.

Update doc comments.

ba7bf1d

Remove confusing drop.

20bb600

m-ou-se force-pushed the format-args-2 branch from 13d187a to 20bb600 Compare September 27, 2022 11:46

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 Sep 27, 2022

bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Sep 27, 2022

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 Sep 27, 2022

bors added the merged-by-bors This PR was explicitly merged by bors. label Sep 28, 2022

bors merged commit d6734be into rust-lang:master Sep 28, 2022

rustbot added this to the 1.66.0 milestone Sep 28, 2022

bors mentioned this pull request Sep 28, 2022

builtin_macros: Migrate diagnostic #101935

Closed

rustbot added the perf-regression Performance regression. label Sep 28, 2022

rustbot added the perf-regression-triaged The performance regression has been triaged. label Sep 28, 2022

m-ou-se deleted the format-args-2 branch September 28, 2022 10:41

Alexendoo mentioned this pull request Sep 30, 2022

Fix format_args capture for macro expanded format strings #102519

Merged

Rewrite and refactor format_args!() builtin macro. #100996

Rewrite and refactor format_args!() builtin macro. #100996

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rust-timer commented Sep 28, 2022

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Instruction count

Max RSS (memory usage)

Cycles

Footnotes

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nnethercote commented Sep 28, 2022

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m-ou-se commented Aug 25, 2022 •

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