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* [gcc/devel/rust/master] gccrs: Fix bad type inference
@ 2023-03-30 6:45 Thomas Schwinge
0 siblings, 0 replies; only message in thread
From: Thomas Schwinge @ 2023-03-30 6:45 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:c6c02b9135e54e181ea6bdd8892a243c50cb6c7a
commit c6c02b9135e54e181ea6bdd8892a243c50cb6c7a
Author: Philip Herron <herron.philip@googlemail.com>
Date: Thu Mar 23 21:18:18 2023 +0000
gccrs: Fix bad type inference
gcc/rust/ChangeLog:
* typecheck/rust-hir-trait-resolve.cc: don't inject extra inference variables
gcc/testsuite/ChangeLog:
* rust/compile/issue-1893.rs: New test.
Signed-off-by: Philip Herron <herron.philip@googlemail.com>
Diff:
---
gcc/rust/typecheck/rust-hir-trait-resolve.cc | 37 ++++++++++++------------
gcc/testsuite/rust/compile/issue-1893.rs | 42 ++++++++++++++++++++++++++++
2 files changed, 60 insertions(+), 19 deletions(-)
diff --git a/gcc/rust/typecheck/rust-hir-trait-resolve.cc b/gcc/rust/typecheck/rust-hir-trait-resolve.cc
index a5303b18cf6..2d5917a59f4 100644
--- a/gcc/rust/typecheck/rust-hir-trait-resolve.cc
+++ b/gcc/rust/typecheck/rust-hir-trait-resolve.cc
@@ -472,7 +472,7 @@ AssociatedImplTrait::setup_associated_types (
TyTy::SubstitutionArgumentMappings infer_arguments (std::move (args), {},
locus, param_subst_cb);
TyTy::BaseType *impl_self_infer
- = (associated_self->needs_generic_substitutions ())
+ = (!associated_self->is_concrete ())
? SubstMapperInternal::Resolve (associated_self, infer_arguments)
: associated_self;
@@ -495,19 +495,6 @@ AssociatedImplTrait::setup_associated_types (
impl_trait_predicate_args.push_back (r);
}
- // we need to unify the receiver with the impl-block Self so that we compute
- // the type correctly as our receiver may be generic and we are inferring its
- // generic arguments and this Self might be the concrete version or vice
- // versa.
- auto result = unify_site_and (get_impl_block ()->get_mappings ().get_hirid (),
- TyTy::TyWithLocation (receiver),
- TyTy::TyWithLocation (impl_self_infer),
- impl_predicate.get_locus (),
- true /*emit-errors*/, true /*commit-if-ok*/,
- true /*infer*/, true /*cleanup-on-fail*/);
- rust_assert (result->get_kind () != TyTy::TypeKind::ERROR);
- TyTy::BaseType *self_result = result;
-
// unify the bounds arguments
std::vector<TyTy::BaseType *> hrtb_bound_arguments;
for (const auto &arg : bound.get_substs ())
@@ -520,22 +507,34 @@ AssociatedImplTrait::setup_associated_types (
hrtb_bound_arguments.push_back (r);
}
- if (impl_trait_predicate_args.size () != hrtb_bound_arguments.size ())
- return self_result;
-
+ rust_assert (impl_trait_predicate_args.size ()
+ == hrtb_bound_arguments.size ());
for (size_t i = 0; i < impl_trait_predicate_args.size (); i++)
{
TyTy::BaseType *a = impl_trait_predicate_args.at (i);
TyTy::BaseType *b = hrtb_bound_arguments.at (i);
- result
+ TyTy::BaseType *result
= unify_site_and (a->get_ref (), TyTy::TyWithLocation (a),
TyTy::TyWithLocation (b), impl_predicate.get_locus (),
true /*emit-errors*/, true /*commit-if-ok*/,
- true /*infer*/, true /*cleanup-on-fail*/);
+ false /*infer*/, true /*cleanup-on-fail*/);
rust_assert (result->get_kind () != TyTy::TypeKind::ERROR);
}
+ // we need to unify the receiver with the impl-block Self so that we compute
+ // the type correctly as our receiver may be generic and we are inferring its
+ // generic arguments and this Self might be the concrete version or vice
+ // versa.
+ auto result = unify_site_and (get_impl_block ()->get_mappings ().get_hirid (),
+ TyTy::TyWithLocation (receiver),
+ TyTy::TyWithLocation (impl_self_infer),
+ impl_predicate.get_locus (),
+ true /*emit-errors*/, true /*commit-if-ok*/,
+ false /*infer*/, true /*cleanup-on-fail*/);
+ rust_assert (result->get_kind () != TyTy::TypeKind::ERROR);
+ TyTy::BaseType *self_result = result;
+
// create the argument list
std::vector<TyTy::SubstitutionArg> associated_arguments;
for (auto &p : substitutions)
diff --git a/gcc/testsuite/rust/compile/issue-1893.rs b/gcc/testsuite/rust/compile/issue-1893.rs
new file mode 100644
index 00000000000..ff8bef79bbc
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-1893.rs
@@ -0,0 +1,42 @@
+pub enum Option<T> {
+ None,
+ Some(T),
+}
+
+pub enum Result<T, E> {
+ Ok(T),
+ Err(E),
+}
+
+pub trait TryFrom<T> {
+ /// The type returned in the event of a conversion error.
+ type Error;
+
+ /// Performs the conversion.
+ fn try_from(value: T) -> Result<Self, Self::Error>;
+}
+
+pub trait From<T> {
+ fn from(_: T) -> Self;
+}
+
+impl<T> From<T> for T {
+ fn from(t: T) -> T {
+ t
+ }
+}
+
+impl<T, U> TryFrom<U> for T
+where
+ T: From<U>,
+{
+ type Error = !;
+
+ fn try_from(value: U) -> Result<Self, Self::Error> {
+ Result::Ok(T::from(value))
+ }
+}
+
+pub fn test(n: usize) {
+ let _a = <usize>::try_from(n);
+}
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