diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:19:13 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:19:13 +0000 |
commit | 218caa410aa38c29984be31a5229b9fa717560ee (patch) | |
tree | c54bd55eeb6e4c508940a30e94c0032fbd45d677 /tests/ui/regions/regions-relate-bound-regions-on-closures-to-inference-variables.rs | |
parent | Releasing progress-linux version 1.67.1+dfsg1-1~progress7.99u1. (diff) | |
download | rustc-218caa410aa38c29984be31a5229b9fa717560ee.tar.xz rustc-218caa410aa38c29984be31a5229b9fa717560ee.zip |
Merging upstream version 1.68.2+dfsg1.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tests/ui/regions/regions-relate-bound-regions-on-closures-to-inference-variables.rs')
-rw-r--r-- | tests/ui/regions/regions-relate-bound-regions-on-closures-to-inference-variables.rs | 57 |
1 files changed, 57 insertions, 0 deletions
diff --git a/tests/ui/regions/regions-relate-bound-regions-on-closures-to-inference-variables.rs b/tests/ui/regions/regions-relate-bound-regions-on-closures-to-inference-variables.rs new file mode 100644 index 000000000..b1bdb813a --- /dev/null +++ b/tests/ui/regions/regions-relate-bound-regions-on-closures-to-inference-variables.rs @@ -0,0 +1,57 @@ +// run-pass +#![allow(dead_code)] +// Test that this fairly specialized, but also reasonable, pattern +// typechecks. The pattern involves regions bound in closures that +// wind up related to inference variables. +// +// NB. Changes to the region implementations have broken this pattern +// a few times, but it happens to be used in the compiler so those +// changes were caught. However, those uses in the compiler could +// easily get changed or refactored away in the future. + +struct Ctxt<'tcx> { + x: &'tcx Vec<isize> +} + +struct Foo<'a,'tcx:'a> { + cx: &'a Ctxt<'tcx>, +} + +impl<'a,'tcx> Foo<'a,'tcx> { + fn bother(&mut self) -> isize { + self.elaborate_bounds(Box::new(|this| { + // (*) Here: type of `this` is `&'f0 Foo<&'f1, '_2>`, + // where `'f0` and `'f1` are fresh, free regions that + // result from the bound regions on the closure, and `'2` + // is a region inference variable created by the call. Due + // to the constraints on the type, we find that `'_2 : 'f1 + // + 'f2` must hold (and can be assumed by the callee). + // Region inference has to do some clever stuff to avoid + // inferring `'_2` to be `'static` in this case, because + // it is created outside the closure but then related to + // regions bound by the closure itself. See the + // `region_constraints.rs` file (and the `givens` field, in + // particular) for more details. + this.foo() + })) + } + + fn foo(&mut self) -> isize { + 22 + } + + fn elaborate_bounds( + &mut self, + mut mk_cand: Box<dyn for<'b> FnMut(&mut Foo<'b, 'tcx>) -> isize>) + -> isize + { + mk_cand(self) + } +} + +fn main() { + let v = vec![]; + let cx = Ctxt { x: &v }; + let mut foo = Foo { cx: &cx }; + assert_eq!(foo.bother(), 22); // just so the code is not dead, basically +} |