Improve suggestion for missing fmt str in println #52394
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Improve suggestion for missing fmt str in println Avoid using `concat!(fmt, "\n")` to improve the diagnostics being emitted when the first `println!()` argument isn't a formatting string literal. Fix #52347.
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cc @ollie27 |
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☀️ Test successful - status-travis |
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@rust-timer build effb34d |
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Insufficient permissions to issue commands to rust-timer. |
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cc @kennytm |
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Note to self: Need to fix |
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@rust-timer build effb34d |
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Success: Queued effb34d with parent 49f1e5d, comparison URL. |
src/libstd/macros.rs
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| ($fmt:expr, $($arg:tt)*) => (print!(concat!($fmt, "\n"), $($arg)*)); | ||
| ($fmt:expr) => ({ | ||
| print!($fmt); | ||
| print!("\n"); |
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Using two print!s will mean stdout will be unlocked before printing the \n. Replacing these two rules with
($($arg:tt)*) => (print!("{}\n", format_args!($($arg)*)));will avoid that issue.
src/libsyntax_ext/concat.rs
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| } | ||
| } | ||
| } | ||
| if missing_literal.len() > 0 { | ||
| let mut err = cx.struct_span_err(missing_literal, "expected a literal"); | ||
| err.note("only `&str` literals can be passed to `concat!()`"); |
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Most literals can be passed to concat!, not just &str.
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True, but the wording "only literals..." could be harder to understand to newcomers... What do you think of
only literals (like `"foo"`, `42` and `3.14`) can be passed to `concat!()`
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@kennytm can we get another perf run? After the last change I doubt this will introduce any regression. |
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@bors try |
Improve suggestion for missing fmt str in println Avoid using `concat!(fmt, "\n")` to improve the diagnostics being emitted when the first `println!()` argument isn't a formatting string literal. Fix #52347.
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☀️ Test successful - status-travis |
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@rust-timer build ac3b07a |
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Success: Queued ac3b07a with parent fb8bde0, comparison URL. |
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Perf is ready. Looks even worse than the previous one. |
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In that case I guess I'll have to come up with something more involved if we want this :-/ |
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Cc @dtolnay after the talk in Rust Meetup. Note to self, see if marching quote literals is possible. |
Address rust-lang#30143 as well. `writeln!()` hasn't been changed.
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I'm not entirely sure why (or if) this is needed.
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@bors r=oli-obk |
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📌 Commit dc563d9 has been approved by |
Improve suggestion for missing fmt str in println Avoid using `concat!(fmt, "\n")` to improve the diagnostics being emitted when the first `println!()` argument isn't a formatting string literal. Fix #52347.
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☀️ Test successful - status-appveyor, status-travis |
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📣 Toolstate changed by #52394! Tested on commit 3d51086. 💔 clippy-driver on windows: test-pass → test-fail (cc @Manishearth @llogiq @mcarton @oli-obk, @rust-lang/infra). |
Tested on commit rust-lang/rust@3d51086. Direct link to PR: <rust-lang/rust#52394> 💔 clippy-driver on windows: test-pass → test-fail (cc @Manishearth @llogiq @mcarton @oli-obk, @rust-lang/infra). 💔 clippy-driver on linux: test-pass → test-fail (cc @Manishearth @llogiq @mcarton @oli-obk, @rust-lang/infra).
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Avoid using
concat!(fmt, "\n")to improve the diagnostics beingemitted when the first
println!()argument isn't a formatting stringliteral.
Fix #52347.