Optimize performance for string literals in Display::fmt#286
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dtolnay merged 2 commits intodtolnay:masterfrom Feb 11, 2024
Merged
Optimize performance for string literals in Display::fmt#286dtolnay merged 2 commits intodtolnay:masterfrom
dtolnay merged 2 commits intodtolnay:masterfrom
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Compiler is unable to generate as efficient code for `write!(f, "text")` as it does for `f.write_str("text")`. This PR checks if the `#[error("text")]` uses a simple string literal without the `{` and `}` characters, and without arguments, and uses `write_str` if so.
Owner
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Published in 1.0.57. |
Contributor
Author
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thanks for merging and releasing it so fast! Do you know if it would be possible to detect a more advanced case when the formatting string is by itself, and the only argument is a fn fmt(...) {
let s = "string";
write!("{0}", s)
}P.S. Obviously all these things should be eventually done in the compiler... 🤞 |
Owner
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I do not know of a way to optimize that. |
asomers
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May 27, 2024
It would probably be worthwhile to create some new custom errors, but this commit doesn't do it yet. Also, update thiserror to take advantage of dtolnay/thiserror#286
asomers
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It would probably be worthwhile to create some new custom errors, but this commit doesn't do it yet. Also, update thiserror to take advantage of dtolnay/thiserror#286
takumi-earth
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Jan 27, 2026
Optimize performance for string literals in Display::fmt
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Compiler is unable to generate as efficient code for
write!(f, "text")as it does forf.write_str("text"). This PR checks if the#[error("text")]uses a simple string literal without the{and}characters, and without arguments, and useswrite_strif so.Fixes #285