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This repository was archived by the owner on May 28, 2025. It is now read-only.

Commit 4b1efa2

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Unrolled build for rust-lang#135304
Rollup merge of rust-lang#135304 - steffahn:tests_from_132289, r=compiler-errors Add tests cases from review of rust-lang#132289 Adding my comments as test-cases as suggested by ``@jackh726`` in rust-lang#132289 (comment) 
2 parents 88ab2d8 + 5e50518 commit 4b1efa2

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pub type A = &'static [usize; 1];
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pub type B = &'static [usize; 100];
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pub trait Trait<P> {
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type Assoc;
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}
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pub type Dyn<P> = dyn Trait<P, Assoc = A>;
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pub trait LocallyUnimplemented<P> {}
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impl<P, T: ?Sized> Trait<P> for T
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where
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T: LocallyUnimplemented<P>,
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{
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type Assoc = B;
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}
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trait MakeArray<Arr> {
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fn make() -> &'static Arr;
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}
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impl<const N: usize> MakeArray<[usize; N]> for () {
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fn make() -> &'static [usize; N] {
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&[1337; N]
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}
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}
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// it would be sound for this return type to be interpreted as being
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// either of A or B, if that's what a soundness fix for overlap of
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// dyn Trait's impls would entail
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// In this test, we check at the call-site that the interpretation
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// is consistent across crates in this specific scenario.
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pub fn function<P>() -> (<Dyn<P> as Trait<P>>::Assoc, usize) {
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let val = <() as MakeArray<_>>::make();
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(val, val.len())
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}
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use std::ops::Index;
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pub trait Trait {
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fn f(&self)
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where
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dyn Index<(), Output = ()>: Index<()>;
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// rustc (correctly) determines ^^^^^^^^ this bound to be true
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}
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pub fn call(x: &dyn Trait) {
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x.f(); // so we can call `f`
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}
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// This is a regression test for issues that came up during review of the (closed)
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// PR #132289; this single-crate test case is
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// the first example from @steffahn during review.
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// https://github.com/rust-lang/rust/pull/132289#issuecomment-2564492153
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//@ check-pass
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type A = &'static [usize; 1];
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type B = &'static [usize; 100];
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type DynSomething = dyn Something<Assoc = A>;
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trait Super {
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type Assoc;
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}
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impl Super for Foo {
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type Assoc = A;
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}
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trait IsDynSomething {}
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impl IsDynSomething for DynSomething {}
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impl<T: ?Sized> Super for T
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where
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T: IsDynSomething,
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{
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type Assoc = B;
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}
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trait Something: Super {
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fn method(&self) -> Self::Assoc;
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}
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struct Foo;
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impl Something for Foo {
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fn method(&self) -> Self::Assoc {
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&[1337]
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}
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}
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fn main() {
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let x = &Foo;
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let y: &DynSomething = x;
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// no surprises here
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let _arr1: A = x.method();
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// this (`_arr2`) can't ever become B either, soundly
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let _arr2: A = y.method();
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// there aren't any other arrays being defined anywhere in this
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// test case, besides the length-1 one containing [1337]
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}
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// This is a regression test for issues that came up during review of the (closed)
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// PR #132289; this 2-crate test case is adapted from
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// the second example from @steffahn during review.
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// https://github.com/rust-lang/rust/pull/132289#issuecomment-2564587796
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//@ run-pass
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//@ aux-build: pr_review_132289_2_lib.rs
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extern crate pr_review_132289_2_lib;
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use pr_review_132289_2_lib::{function, Dyn, LocallyUnimplemented};
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struct Param;
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impl LocallyUnimplemented<Param> for Dyn<Param> {}
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// it would be sound for `function::<Param>`'s return type to be
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// either of A or B, if that's what a soundness fix for overlap of
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// dyn Trait's impls would entail
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// In this test, we check at this call-site that the interpretation
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// is consistent with the function definition's body.
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fn main() {
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let (arr, len) = function::<Param>();
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assert_eq!(arr.len(), len);
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}
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// This is a regression test for issues that came up during review of the (closed)
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// PR #132289; this 3-ish-crate (including std) test case is adapted from
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// the third example from @steffahn during review.
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// https://github.com/rust-lang/rust/pull/132289#issuecomment-2564599221
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//@ run-pass
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//@ check-run-results
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//@ aux-build: pr_review_132289_3_lib.rs
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extern crate pr_review_132289_3_lib;
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use std::ops::Index;
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use pr_review_132289_3_lib::{call, Trait};
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trait SubIndex<I>: Index<I> {}
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struct Param;
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trait Project {
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type Ty: ?Sized;
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}
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impl Project for () {
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type Ty = dyn SubIndex<Param, Output = ()>;
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}
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impl Index<Param> for <() as Project>::Ty {
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type Output = ();
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fn index(&self, _: Param) -> &() {
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&()
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}
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}
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struct Struct;
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impl Trait for Struct {
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fn f(&self)
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where
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// higher-ranked to allow potentially-false bounds
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for<'a> dyn Index<(), Output = ()>: Index<()>,
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// after #132289 rustc used to believe this bound false
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{
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println!("hello!");
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}
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}
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fn main() {
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call(&Struct); // <- would segfault if the method `f` wasn't part of the vtable
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}
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hello!

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