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* [gcc/devel/rust/master] Fix type inference on unit-structs
@ 2022-08-09 20:39 Thomas Schwinge
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From: Thomas Schwinge @ 2022-08-09 20:39 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:92eef6c33d49137707e5b3962822c6dded1f3c79
commit 92eef6c33d49137707e5b3962822c6dded1f3c79
Author: Philip Herron <philip.herron@embecosm.com>
Date: Mon Aug 8 17:05:54 2022 +0100
Fix type inference on unit-structs
When we initilize a structure that contains an identifier for the value
which resolves to a generic unit-struct. The unit struct has no fields
but it also contains a reference to a generic parameter which needs to be
infered this updates the code for identifiers to act like a
PathInExpression to infer the generic parameters when its unit struct only.
Fixes #1447
Diff:
---
gcc/rust/typecheck/rust-hir-type-check-expr.h | 11 +++++++++++
gcc/testsuite/rust/compile/issue-1447.rs | 28 +++++++++++++++++++++++++++
2 files changed, 39 insertions(+)
diff --git a/gcc/rust/typecheck/rust-hir-type-check-expr.h b/gcc/rust/typecheck/rust-hir-type-check-expr.h
index de542ca70e8..0c44f28e4ac 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-expr.h
+++ b/gcc/rust/typecheck/rust-hir-type-check-expr.h
@@ -310,6 +310,17 @@ public:
}
infered = lookup->clone ();
+
+ // Generic unit structs look like an identifier but they actually need be
+ // handled as a path-in-expression so this gives us a chance to infer the
+ // generic parameters.
+ // see https://github.com/Rust-GCC/gccrs/issues/1447
+ bool is_unit_struct
+ = infered->get_kind () == TyTy::TypeKind::ADT && infered->is_unit ();
+ if (is_unit_struct && infered->needs_generic_substitutions ())
+ {
+ infered = SubstMapper::InferSubst (infered, expr.get_locus ());
+ }
}
void visit (HIR::LiteralExpr &expr) override
diff --git a/gcc/testsuite/rust/compile/issue-1447.rs b/gcc/testsuite/rust/compile/issue-1447.rs
new file mode 100644
index 00000000000..e0543e6247c
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-1447.rs
@@ -0,0 +1,28 @@
+// { dg-options "-w" }
+struct PhantomData<T>;
+
+struct Hasher<S> {
+ _marker: PhantomData<S>,
+}
+
+struct Sip24Rounds;
+
+struct SipHasher24 {
+ hasher: Hasher<Sip24Rounds>,
+}
+
+impl SipHasher24 {
+ pub fn new_with_keys(key0: u64, key1: u64) -> SipHasher24 {
+ SipHasher24 {
+ hasher: Hasher::new_with_keys(),
+ }
+ }
+}
+
+impl<S> Hasher<S> {
+ fn new_with_keys() -> Hasher<S> {
+ Hasher {
+ _marker: PhantomData,
+ }
+ }
+}
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