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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:06:37 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-17 12:06:37 +0000
commit246f239d9f40f633160f0c18f87a20922d4e77bb (patch)
tree5a88572663584b3d4d28e5a20e10abab1be40884 /src/test/ui/coherence/const-generics-orphan-check-ok.rs
parentReleasing progress-linux version 1.64.0+dfsg1-1~progress7.99u1. (diff)
downloadrustc-246f239d9f40f633160f0c18f87a20922d4e77bb.tar.xz
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Merging debian version 1.65.0+dfsg1-2.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/test/ui/coherence/const-generics-orphan-check-ok.rs')
-rw-r--r--src/test/ui/coherence/const-generics-orphan-check-ok.rs28
1 files changed, 28 insertions, 0 deletions
diff --git a/src/test/ui/coherence/const-generics-orphan-check-ok.rs b/src/test/ui/coherence/const-generics-orphan-check-ok.rs
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+++ b/src/test/ui/coherence/const-generics-orphan-check-ok.rs
@@ -0,0 +1,28 @@
+// check-pass
+// aux-build:trait-with-const-param.rs
+extern crate trait_with_const_param;
+use trait_with_const_param::*;
+
+// Trivial case, const param after local type.
+struct Local1;
+impl<const N: usize, T> Trait<N, T> for Local1 {}
+
+// Concrete consts behave the same as foreign types,
+// so this also trivially works.
+impl Trait<3, Local1> for i32 {}
+
+// This case isn't as trivial as we would forbid type
+// parameters here, we do allow const parameters though.
+//
+// The reason that type parameters are forbidden for
+// `impl<T> Trait<T, LocalInA> for i32 {}` is that another
+// downstream crate can add `impl<T> Trait<LocalInB, T> for i32`.
+// As these two impls would overlap we forbid any impls which
+// have a type parameter in front of a local type.
+//
+// With const parameters this issue does not exist as there are no
+// constants local to another downstream crate.
+struct Local2;
+impl<const N: usize> Trait<N, Local2> for i32 {}
+
+fn main() {}