55 lines
2.0 KiB
Rust
55 lines
2.0 KiB
Rust
// check-pass
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#![allow(unused)]
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use std::borrow::Borrow;
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use std::ops::Deref;
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struct PlainType<T>(T);
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#[derive(Clone)]
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struct CloneType<T>(T);
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fn main() {
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let non_clone_type_ref = &PlainType(1u32);
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let non_clone_type_ref_clone: &PlainType<u32> = non_clone_type_ref.clone();
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//~^ WARNING call to `.clone()` on a reference in this situation does nothing
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let clone_type_ref = &CloneType(1u32);
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let clone_type_ref_clone: CloneType<u32> = clone_type_ref.clone();
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let clone_type_ref = &&CloneType(1u32);
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let clone_type_ref_clone: &CloneType<u32> = clone_type_ref.clone();
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//~^ WARNING using `.clone()` on a double reference, which returns `&CloneType<u32>`
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let non_deref_type = &PlainType(1u32);
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let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
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//~^ WARNING call to `.deref()` on a reference in this situation does nothing
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let non_deref_type = &&PlainType(1u32);
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let non_deref_type_deref: &PlainType<u32> = non_deref_type.deref();
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//~^ WARNING using `.deref()` on a double reference, which returns `&PlainType<u32>`
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let non_borrow_type = &PlainType(1u32);
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let non_borrow_type_borrow: &PlainType<u32> = non_borrow_type.borrow();
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//~^ WARNING call to `.borrow()` on a reference in this situation does nothing
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// Borrowing a &&T does not warn since it has collapsed the double reference
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let non_borrow_type = &&PlainType(1u32);
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let non_borrow_type_borrow: &PlainType<u32> = non_borrow_type.borrow();
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let xs = ["a", "b", "c"];
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let _v: Vec<&str> = xs.iter().map(|x| x.clone()).collect(); // could use `*x` instead
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//~^ WARNING using `.clone()` on a double reference, which returns `&str`
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}
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fn generic<T>(non_clone_type: &PlainType<T>) {
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non_clone_type.clone();
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//~^ WARNING call to `.clone()` on a reference in this situation does nothing
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}
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fn non_generic(non_clone_type: &PlainType<u32>) {
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non_clone_type.clone();
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//~^ WARNING call to `.clone()` on a reference in this situation does nothing
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}
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