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58459abd0c
Currently this code will trigger `trivally_copy_pass_by_ref`:
```
struct OuterStruct {
field: [u8; 8],
}
fn return_inner(outer: &OuterStruct) -> &[u8] {
&outer.field
}
```
If we change the `outer` to be pass-by-value it will not live long
enough for us to return the reference. The above example is trivial but
I've hit this in real code that either returns a reference to either the
argument or in to `self`.
This suppresses the `trivally_copy_pass_by_ref` lint if we return a
reference and it has the same lifetime as the argument. This will likely
miss complex cases with multiple lifetimes bounded by each other but it
should cover the majority of cases with little effort.
69 lines
1.2 KiB
Rust
69 lines
1.2 KiB
Rust
#![allow(many_single_char_names, blacklisted_name)]
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#[derive(Copy, Clone)]
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struct Foo(u32);
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#[derive(Copy, Clone)]
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struct Bar([u8; 24]);
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type Baz = u32;
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fn good(a: &mut u32, b: u32, c: &Bar) {
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}
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fn good_return_implicit_lt_ref(foo: &Foo) -> &u32 {
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&foo.0
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}
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#[allow(needless_lifetimes)]
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fn good_return_explicit_lt_ref<'a>(foo: &'a Foo) -> &'a u32 {
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&foo.0
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}
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fn bad(x: &u32, y: &Foo, z: &Baz) {
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}
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impl Foo {
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fn good(self, a: &mut u32, b: u32, c: &Bar) {
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}
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fn good2(&mut self) {
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}
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fn bad(&self, x: &u32, y: &Foo, z: &Baz) {
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}
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fn bad2(x: &u32, y: &Foo, z: &Baz) {
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}
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}
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impl AsRef<u32> for Foo {
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fn as_ref(&self) -> &u32 {
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&self.0
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}
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}
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impl Bar {
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fn good(&self, a: &mut u32, b: u32, c: &Bar) {
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}
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fn bad2(x: &u32, y: &Foo, z: &Baz) {
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}
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}
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fn main() {
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let (mut foo, bar) = (Foo(0), Bar([0; 24]));
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let (mut a, b, c, x, y, z) = (0, 0, Bar([0; 24]), 0, Foo(0), 0);
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good(&mut a, b, &c);
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good_return_implicit_lt_ref(&y);
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good_return_explicit_lt_ref(&y);
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bad(&x, &y, &z);
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foo.good(&mut a, b, &c);
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foo.good2();
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foo.bad(&x, &y, &z);
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Foo::bad2(&x, &y, &z);
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bar.good(&mut a, b, &c);
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Bar::bad2(&x, &y, &z);
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foo.as_ref();
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}
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