summaryrefslogtreecommitdiffstats
path: root/tests/ui/coinduction
diff options
context:
space:
mode:
authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:19:43 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:19:43 +0000
commit3e3e70d529d8c7d7c4d7bc4fefc9f109393b9245 (patch)
treedaf049b282ab10e8c3d03e409b3cd84ff3f7690c /tests/ui/coinduction
parentAdding debian version 1.68.2+dfsg1-1. (diff)
downloadrustc-3e3e70d529d8c7d7c4d7bc4fefc9f109393b9245.tar.xz
rustc-3e3e70d529d8c7d7c4d7bc4fefc9f109393b9245.zip
Merging upstream version 1.69.0+dfsg1.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tests/ui/coinduction')
-rw-r--r--tests/ui/coinduction/canonicalization-rerun.rs54
1 files changed, 54 insertions, 0 deletions
diff --git a/tests/ui/coinduction/canonicalization-rerun.rs b/tests/ui/coinduction/canonicalization-rerun.rs
new file mode 100644
index 000000000..b10ba3a81
--- /dev/null
+++ b/tests/ui/coinduction/canonicalization-rerun.rs
@@ -0,0 +1,54 @@
+// check-pass
+// revisions: old new
+//[new] compile-flags: -Ztrait-solver=next
+
+// If we use canonical goals during trait solving we have to reevaluate
+// the root goal of a cycle until we hit a fixpoint.
+//
+// Here `main` has a goal `(?0, ?1): Trait` which is canonicalized to
+// `exists<^0, ^1> (^0, ^1): Trait`.
+//
+// - `exists<^0, ^1> (^0, ^1): Trait` -instantiate-> `(?0, ?1): Trait`
+// -`(?1, ?0): Trait` -canonicalize-> `exists<^0, ^1> (^0, ^1): Trait`
+// - COINDUCTIVE CYCLE OK (no constraints)
+// - `(): ConstrainToU32<?0>` -canonicalize-> `exists<^0> (): ConstrainToU32<^0>`
+// - OK (^0 = u32 -apply-> ?0 = u32)
+// - OK (?0 = u32 -canonicalize-> ^0 = u32)
+// - coinductive cycle with provisional result != final result, rerun
+//
+// - `exists<^0, ^1> (^0, ^1): Trait` -instantiate-> `(?0, ?1): Trait`
+// -`(?1, ?0): Trait` -canonicalize-> `exists<^0, ^1> (^0, ^1): Trait`
+// - COINDUCTIVE CYCLE OK (^0 = u32 -apply-> ?1 = u32)
+// - `(): ConstrainToU32<?0>` -canonicalize-> `exists<^0> (): ConstrainToU32<^0>`
+// - OK (^0 = u32 -apply-> ?1 = u32)
+// - OK (?0 = u32, ?1 = u32 -canonicalize-> ^0 = u32, ^1 = u32)
+// - coinductive cycle with provisional result != final result, rerun
+//
+// - `exists<^0, ^1> (^0, ^1): Trait` -instantiate-> `(?0, ?1): Trait`
+// -`(?1, ?0): Trait` -canonicalize-> `exists<^0, ^1> (^0, ^1): Trait`
+// - COINDUCTIVE CYCLE OK (^0 = u32, ^1 = u32 -apply-> ?1 = u32, ?0 = u32)
+// - `(): ConstrainToU32<?0>` -canonicalize-> `exists<^0> (): ConstrainToU32<^0>`
+// - OK (^0 = u32 -apply-> ?1 = u32)
+// - OK (?0 = u32, ?1 = u32 -canonicalize-> ^0 = u32, ^1 = u32)
+// - coinductive cycle with provisional result == final result, DONE
+#![feature(rustc_attrs)]
+#[rustc_coinductive]
+trait Trait {}
+
+impl<T, U> Trait for (T, U)
+where
+ (U, T): Trait,
+ (): ConstrainToU32<T>,
+{}
+
+trait ConstrainToU32<T> {}
+impl ConstrainToU32<u32> for () {}
+
+fn impls_trait<T, U>()
+where
+ (T, U): Trait,
+{}
+
+fn main() {
+ impls_trait::<_, _>();
+}