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Auto merge of #125610 - oli-obk:define_opaque_types14, r=compiler-errors

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Allow constraining opaque types during various unsizing casts

allows unsizing of tuples, arrays and Adts to constraint opaque types in their generic parameters to concrete types on either side of the unsizing cast.

Also allows constraining opaque types during trait object casts that only differ in auto traits or lifetimes.

cc #116652
This commit is contained in:
bors
2024-06-25 05:09:30 +00:00
parent fc555cd832 45da03541c
commit 164e1297e1
21 changed files with 330 additions and 61 deletions
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8
compiler/rustc_trait_selection/src/traits/select/confirmation.rs
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@@ -1162,7 +1162,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let InferOk { mut obligations, .. } = self
.infcx
.at(&obligation.cause, obligation.param_env)
.sup(DefineOpaqueTypes::No, target, source_trait)
.sup(DefineOpaqueTypes::Yes, target, source_trait)
.map_err(|_| Unimplemented)?;
// Register one obligation for 'a: 'b.
@@ -1229,7 +1229,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let InferOk { obligations, .. } = self
.infcx
.at(&obligation.cause, obligation.param_env)
.eq(DefineOpaqueTypes::No, b, a)
.eq(DefineOpaqueTypes::Yes, b, a)
.map_err(|_| Unimplemented)?;
ImplSource::Builtin(BuiltinImplSource::Misc, obligations)
@@ -1277,7 +1277,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let InferOk { obligations, .. } = self
.infcx
.at(&obligation.cause, obligation.param_env)
.eq(DefineOpaqueTypes::No, target, new_struct)
.eq(DefineOpaqueTypes::Yes, target, new_struct)
.map_err(|_| Unimplemented)?;
nested.extend(obligations);
@@ -1310,7 +1310,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
let InferOk { mut obligations, .. } = self
.infcx
.at(&obligation.cause, obligation.param_env)
.eq(DefineOpaqueTypes::No, target, new_tuple)
.eq(DefineOpaqueTypes::Yes, target, new_tuple)
.map_err(|_| Unimplemented)?;
// Add a nested `T: Unsize<U>` predicate.