Enable flatten-format-args by default. #109999
Merged
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
m-ou-se
added
T-libs-api
rustbot
added
the
S-waiting-on-review
This comment was marked as outdated.
This comment was marked as outdated.
56 tasks
Noratrieb
reviewed
Apr 6, 2023
m-ou-se
added
S-blocked
m-ou-se
force-pushed
the
flatten-format-args
branch
from
c551788 to
a77d39b
Compare
m-ou-se
added
I-compiler-nominated
I am a bit worried about these two cases because these are not achievable by proc macros, and thus would make
|
This comment was marked as resolved.
This comment was marked as resolved.
Note that I'm not saying that necessarily means that
A proc macro
It's usually okay for a standard library macro to use something that's not yet stable. The Footnotes
|
This is a quite convincing argument, and address my main worry that this would turn |
This comment has been minimized.
This comment has been minimized.
flip1995
reviewed
Apr 14, 2023
m-ou-se
force-pushed
the
flatten-format-args
branch
from
87d942c to
63d8758
Compare
|
r? @oli-obk |
m-ou-se
removed
the
S-waiting-on-team
|
@bors r+ |
bors
added
S-waiting-on-bors
|
⌛ Testing commit 2cd5ce0 with merge 7bcb998f019b911e8852347cce2433683f85e3ee... |
|
The job Click to see the possible cause of the failure (guessed by this bot) |
|
💔 Test failed - checks-actions |
bors
added
S-waiting-on-review
|
@bors retry |
bors
added
S-waiting-on-bors
|
☀️ Test successful - checks-actions |
|
Finished benchmarking commit (d19b64f): comparison URL. Overall result: ✅ improvements - no action needed@rustbot label: -perf-regression Instruction countThis is a highly reliable metric that was used to determine the overall result at the top of this comment.
Max RSS (memory usage)ResultsThis 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.
CyclesResultsThis 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.
|
This was referenced Apr 24, 2023
|
Love this! |
flip1995
pushed a commit
to flip1995/rust
that referenced
this pull request
May 5, 2023
Enable flatten-format-args by default. Part of rust-lang#99012. This enables the `flatten-format-args` feature that was added by rust-lang#106824: > This change inlines string literals, integer literals and nested format_args!() into format_args!() during ast lowering, making all of the following pairs result in equivalent hir: > > ```rust > println!("Hello, {}!", "World"); > println!("Hello, World!"); > ``` > > ```rust > println!("[info] {}", format_args!("error")); > println!("[info] error"); > ``` > > ```rust > println!("[{}] {}", status, format_args!("error: {}", msg)); > println!("[{}] error: {}", status, msg); > ``` > > ```rust > println!("{} + {} = {}", 1, 2, 1 + 2); > println!("1 + 2 = {}", 1 + 2); > ``` > > And so on. > > This is useful for macros. E.g. a `log::info!()` macro could just pass the tokens from the user directly into a `format_args!()` that gets efficiently flattened/inlined into a `format_args!("info: {}")`. > > It also means that `dbg!(x)` will have its file, line, and expression name inlined: > > ```rust > eprintln!("[{}:{}] {} = {:#?}", file!(), line!(), stringify!(x), x); // before > eprintln!("[example.rs:1] x = {:#?}", x); // after > ``` > > Which can be nice in some cases, but also means a lot more unique static strings than before if dbg!() is used a lot. This is mostly an optimization, except that it will be visible through [`fmt::Arguments::as_str()`](https://doc.rust-lang.org/nightly/std/fmt/struct.Arguments.html#method.as_str). In rust-lang#106823, there was already a libs-api FCP about the documentation of `fmt::Arguments::as_str()` to allow it to give `Some` rather than `None` depending on optimizations like this. That was just a documentation update though. This PR is the one that actually makes the user visible change: ```rust assert_eq!(format_args!("abc").as_str(), Some("abc")); // Unchanged. assert_eq!(format_args!("ab{}", "c").as_str(), Some("abc")); // Was `None` before! ```
Mark-Simulacrum
added
the
relnotes
# for free
to join this conversation on GitHub.
Already have an account?
# to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Part of #99012.
This enables the
flatten-format-argsfeature that was added by #106824:This is mostly an optimization, except that it will be visible through
fmt::Arguments::as_str().In #106823, there was already a libs-api FCP about the documentation of
fmt::Arguments::as_str()to allow it to giveSomerather thanNonedepending on optimizations like this. That was just a documentation update though. This PR is the one that actually makes the user visible change: