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33 lines
674 B
Rust
33 lines
674 B
Rust
//! Test that Debug::fmt is called exactly once during formatting.
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//!
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//! This is a regression test for PR https://github.com/rust-lang/rust/pull/10715
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//@ run-pass
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//@ needs-threads
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use std::cell::Cell;
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use std::{fmt, thread};
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struct Foo(Cell<isize>);
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impl fmt::Debug for Foo {
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fn fmt(&self, _fmt: &mut fmt::Formatter) -> fmt::Result {
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let Foo(ref f) = *self;
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assert_eq!(f.get(), 0);
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f.set(1);
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Ok(())
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}
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}
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pub fn main() {
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thread::spawn(move || {
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let mut f = Foo(Cell::new(0));
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println!("{:?}", f);
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let Foo(ref mut f) = f;
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assert_eq!(f.get(), 1);
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})
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.join()
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.ok()
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.unwrap();
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}
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