111 lines
2.3 KiB
Rust
111 lines
2.3 KiB
Rust
#![warn(clippy::field_reassign_with_default)]
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#[derive(Default)]
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struct A {
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i: i32,
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j: i64,
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}
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struct B {
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i: i32,
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j: i64,
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}
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/// Implements .next() that returns a different number each time.
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struct SideEffect(i32);
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impl SideEffect {
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fn new() -> SideEffect {
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SideEffect(0)
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}
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fn next(&mut self) -> i32 {
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self.0 += 1;
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self.0
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}
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}
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fn main() {
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// wrong, produces first error in stderr
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let mut a: A = Default::default();
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a.i = 42;
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// right
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let mut a: A = Default::default();
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// right
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let a = A {
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i: 42,
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..Default::default()
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};
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// right
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let mut a: A = Default::default();
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if a.i == 0 {
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a.j = 12;
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}
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// right
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let mut a: A = Default::default();
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let b = 5;
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// right
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let mut b = 32;
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let mut a: A = Default::default();
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b = 2;
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// right
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let b: B = B { i: 42, j: 24 };
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// right
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let mut b: B = B { i: 42, j: 24 };
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b.i = 52;
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// right
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let mut b = B { i: 15, j: 16 };
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let mut a: A = Default::default();
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b.i = 2;
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// wrong, produces second error in stderr
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let mut a: A = Default::default();
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a.j = 43;
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a.i = 42;
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// wrong, produces third error in stderr
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let mut a: A = Default::default();
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a.i = 42;
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a.j = 43;
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a.j = 44;
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// wrong, produces fourth error in stderr
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let mut a = A::default();
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a.i = 42;
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// wrong, but does not produce an error in stderr, because we can't produce a correct kind of
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// suggestion with current implementation
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let mut c: (i32, i32) = Default::default();
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c.0 = 42;
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c.1 = 21;
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// wrong, produces the fifth error in stderr
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let mut a: A = Default::default();
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a.i = Default::default();
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// wrong, produces the sixth error in stderr
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let mut a: A = Default::default();
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a.i = Default::default();
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a.j = 45;
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// right, because an assignment refers to another field
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let mut x = A::default();
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x.i = 42;
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x.j = 21 + x.i as i64;
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// right, we bail out if there's a reassignment to the same variable, since there is a risk of
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// side-effects affecting the outcome
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let mut x = A::default();
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let mut side_effect = SideEffect::new();
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x.i = side_effect.next();
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x.j = 2;
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x.i = side_effect.next();
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}
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