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Rollup merge of #140593 - m-ou-se:some-temp, r=Nadrieril
Temporary lifetime extension through tuple struct and tuple variant constructors This makes temporary lifetime extension work for tuple struct and tuple variant constructors, such as `Some()`. Before: ```rust let a = &temp(); // Extended let a = Some(&temp()); // Not extended :( let a = Some { 0: &temp() }; // Extended ``` After: ```rust let a = &temp(); // Extended let a = Some(&temp()); // Extended let a = Some { 0: &temp() }; // Extended ``` So, with this change, this works: ```rust let a = Some(&String::from("hello")); // New: String lifetime now extended! println!("{a:?}"); ``` Until now, we did not extend through tuple struct/variant constructors (like `Some`), because they are function calls syntactically, and we do not want to extend the String lifetime in: ```rust let a = some_function(&String::from("hello")); // String not extended! ``` However, it turns out to be very easy to distinguish between regular functions and constructors at the point where we do lifetime extension. In practice, constructors nearly always use UpperCamelCase while regular functions use lower_snake_case, so it should still be easy to for a human programmer at the call site to see whether something qualifies for lifetime extension or not. This needs a lang fcp. --- More examples of what will work after this change: ```rust let x = Person { name: "Ferris", job: Some(&Job { // `Job` now extended! title: "Chief Rustacean", organisation: "Acme Ltd.", }), }; dbg!(x); ``` ```rust let file = if use_stdout { None } else { Some(&File::create("asdf")?) // `File` now extended! }; set_logger(file); ``` ```rust use std::path::Component; let c = Component::Normal(&OsString::from(format!("test-{num}"))); // OsString now extended! assert_eq!(path.components.first().unwrap(), c); ```
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