gccrs: Fix bad recursive operator overload call

When we are typechecking the impl block for DerefMut for &mut T
the implementation follows the usual operator overload check
but this ended up just resolving directly to the Trait definition
which ends up being recursive which we usually handle. The issue
we had is that a dereference call can be for either the DEREF
or DEREF_MUT lang item here it was looking for a recurisve call
to the DEREF lang item but we were in the DEREF_MUT lang item
so this case was not accounted for.

Fixes #3032

gcc/rust/ChangeLog:

	* typecheck/rust-hir-trait-reference.h: new get locus helper
	* typecheck/rust-hir-trait-resolve.cc (AssociatedImplTrait::get_locus): implemention
	* typecheck/rust-hir-type-check-expr.cc (TypeCheckExpr::resolve_operator_overload):
	fix overload

gcc/testsuite/ChangeLog:

	* rust/compile/nr2/exclude: nr2 cant handle this
	* rust/compile/issue-3032-1.rs: New test.
	* rust/compile/issue-3032-2.rs: New test.

Signed-off-by: Philip Herron <[email protected]>

gcc/rust/typecheck/rust-hir-trait-reference.h

@@ -246,6 +246,8 @@ class AssociatedImplTrait
 
   HIR::ImplBlock *get_impl_block ();
 
+  location_t get_locus () const;
+
   TyTy::BaseType *get_self ();
   const TyTy::BaseType *get_self () const;
 

gcc/rust/typecheck/rust-hir-trait-resolve.cc

@@ -669,6 +669,12 @@ AssociatedImplTrait::reset_associated_types ()
   trait->clear_associated_types ();
 }
 
+location_t
+AssociatedImplTrait::get_locus () const
+{
+  return impl->get_locus ();
+}
+
 Analysis::NodeMapping
 TraitItemReference::get_parent_trait_mappings () const
 {

gcc/rust/typecheck/rust-hir-type-check-expr.cc

@@ -1822,10 +1822,20 @@ TypeCheckExpr::resolve_operator_overload (LangItem::Kind lang_item_type,
       HIR::ImplBlock *parent = impl_item.first;
       HIR::Function *fn = impl_item.second;
 
-      if (parent->has_trait_ref ()
-	  && fn->get_function_name ().as_string ().compare (
-	       associated_item_name)
-	       == 0)
+      bool is_deref = lang_item_type == LangItem::Kind::DEREF
+		      || lang_item_type == LangItem::Kind::DEREF_MUT;
+      bool is_deref_match = fn->get_function_name ().as_string ().compare (
+			      LangItem::ToString (LangItem::Kind::DEREF))
+			      == 0
+			    || fn->get_function_name ().as_string ().compare (
+				 LangItem::ToString (LangItem::Kind::DEREF_MUT))
+				 == 0;
+
+      bool is_recursive_op
+	= fn->get_function_name ().as_string ().compare (associated_item_name)
+	    == 0
+	  || (is_deref && is_deref_match);
+      if (parent->has_trait_ref () && is_recursive_op)
 	{
 	  TraitReference *trait_reference
 	    = TraitResolver::Lookup (*parent->get_trait_ref ().get ());
@@ -1842,7 +1852,8 @@ TypeCheckExpr::resolve_operator_overload (LangItem::Kind lang_item_type,
 
 	      bool is_lang_item_impl
 		= trait_reference->get_mappings ().get_defid ()
-		  == respective_lang_item_id;
+		    == respective_lang_item_id
+		  || (is_deref && is_deref_match);
 	      bool self_is_lang_item_self
 		= fntype->get_self_type ()->is_equal (*adjusted_self);
 	      bool recursive_operator_overload

gcc/testsuite/rust/compile/issue-3032-1.rs

@@ -0,0 +1,58 @@
+#![feature(negative_impls)]
+
+#[lang = "sized"]
+trait Sized {}
+
+#[lang = "deref"]
+pub trait Deref {
+    /// The resulting type after dereferencing.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    // #[rustc_diagnostic_item = "deref_target"]
+    type Target: ?Sized;
+
+    /// Dereferences the value.
+    #[must_use]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    // #[rustc_diagnostic_item = "deref_method"]
+    fn deref(&self) -> &Self::Target;
+}
+
+impl<T: ?Sized> Deref for &T {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        *self
+    }
+}
+
+// this is added because of #3030
+extern "C" {
+    fn never() -> !;
+}
+
+impl<T: ?Sized> !DerefMut for &T {
+    fn deref_mut(&mut self) -> &mut T {
+        unsafe { never() }
+    }
+}
+
+impl<T: ?Sized> Deref for &mut T {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        *self
+    }
+}
+
+#[lang = "deref_mut"]
+pub trait DerefMut: Deref {
+    /// Mutably dereferences the value.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    fn deref_mut(&mut self) -> &mut Self::Target;
+}
+
+impl<T: ?Sized> DerefMut for &mut T {
+    fn deref_mut(&mut self) -> &mut T {
+        *self
+    }
+}

gcc/testsuite/rust/compile/issue-3032-2.rs

@@ -0,0 +1,49 @@
+#![feature(negative_impls)]
+
+#[lang = "sized"]
+trait Sized {}
+
+#[lang = "deref"]
+pub trait Deref {
+    /// The resulting type after dereferencing.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    // #[rustc_diagnostic_item = "deref_target"]
+    type Target: ?Sized;
+
+    /// Dereferences the value.
+    #[must_use]
+    #[stable(feature = "rust1", since = "1.0.0")]
+    // #[rustc_diagnostic_item = "deref_method"]
+    fn deref(&self) -> &Self::Target;
+}
+
+impl<T: ?Sized> Deref for &T {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        *self
+    }
+}
+
+impl<T: ?Sized> !DerefMut for &T {}
+
+impl<T: ?Sized> Deref for &mut T {
+    type Target = T;
+
+    fn deref(&self) -> &T {
+        *self
+    }
+}
+
+#[lang = "deref_mut"]
+pub trait DerefMut: Deref {
+    /// Mutably dereferences the value.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    fn deref_mut(&mut self) -> &mut Self::Target;
+}
+
+impl<T: ?Sized> DerefMut for &mut T {
+    fn deref_mut(&mut self) -> &mut T {
+        *self
+    }
+}

gcc/testsuite/rust/compile/nr2/exclude

@@ -234,4 +234,6 @@ issue-3139-3.rs
 issue-3036.rs
 issue-2951.rs
 issue-2203.rs
-issue-2499.rs
+issue-2499.rs
+issue-3032-1.rs
+issue-3032-2.rs