[gcc r13-6157] gccrs: Add catch for recusive type queries

[gcc r13-6157] gccrs: Add catch for recusive type queries

[Arthur Cohen]

https://gcc.gnu.org/g:543ba35905b948a6cd0cf39832a020597068570d

commit r13-6157-g543ba35905b948a6cd0cf39832a020597068570d
Author: Philip Herron <philip.herron@embecosm.com>
Date:   Fri Sep 30 13:41:09 2022 +0100

    gccrs: Add catch for recusive type queries
    
    When we have a type query where by generic substitution occurs we can hit
    the case where we need to Probe the bounds of the substited item to
    determine whether the the bounds are compatible this can cause us to
    end up querying the same type recursively.
    
    Fixes #1550
    
    gcc/rust/ChangeLog:
    
            * typecheck/rust-hir-type-check-base.cc (TypeCheckBase::query_type):
            Check for recursive queries.
            * typecheck/rust-hir-type-check.h: New functions: `query_completed`,
            `query_in_progress`, `insert_query`.
            * typecheck/rust-tyty-bounds.cc (TypeBoundsProbe::scan): Use `query_type` API.

Diff:
---
 gcc/rust/typecheck/rust-hir-type-check-base.cc | 10 ++++++++++
 gcc/rust/typecheck/rust-hir-type-check.h       | 12 ++++++++++++
 gcc/rust/typecheck/rust-tyty-bounds.cc         |  5 +++--
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/gcc/rust/typecheck/rust-hir-type-check-base.cc b/gcc/rust/typecheck/rust-hir-type-check-base.cc
index cf496d3eb19..85826aec8fe 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-base.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-base.cc
@@ -495,14 +495,20 @@ TypeCheckBase::resolve_generic_params (
 bool
 TypeCheckBase::query_type (HirId reference, TyTy::BaseType **result)
 {
+  if (context->query_in_progress (reference))
+    return false;
+
   if (context->lookup_type (reference, result))
     return true;
 
+  context->insert_query (reference);
+
   HIR::Item *item = mappings->lookup_hir_item (reference);
   if (item != nullptr)
     {
       rust_debug_loc (item->get_locus (), "resolved item {%u} to", reference);
       *result = TypeCheckItem::Resolve (*item);
+      context->query_completed (reference);
       return true;
     }
 
@@ -520,6 +526,7 @@ TypeCheckBase::query_type (HirId reference, TyTy::BaseType **result)
 		      reference);
 
       *result = TypeCheckItem::ResolveImplItem (*impl_block, *impl_item);
+      context->query_completed (reference);
       return true;
     }
 
@@ -530,6 +537,7 @@ TypeCheckBase::query_type (HirId reference, TyTy::BaseType **result)
   if (found_impl_block_type)
     {
       *result = TypeCheckItem::ResolveImplBlockSelf (*impl_block_by_type);
+      context->query_completed (reference);
       return true;
     }
 
@@ -544,6 +552,7 @@ TypeCheckBase::query_type (HirId reference, TyTy::BaseType **result)
       rust_assert (block != nullptr);
 
       *result = TypeCheckTopLevelExternItem::Resolve (extern_item, *block);
+      context->query_completed (reference);
       return true;
     }
 
@@ -551,6 +560,7 @@ TypeCheckBase::query_type (HirId reference, TyTy::BaseType **result)
   Location possible_locus = mappings->lookup_location (reference);
   rust_debug_loc (possible_locus, "query system failed to resolve: [%u]",
 		  reference);
+  context->query_completed (reference);
 
   return false;
 }
diff --git a/gcc/rust/typecheck/rust-hir-type-check.h b/gcc/rust/typecheck/rust-hir-type-check.h
index 3e9c9c4d21a..a1dd8052246 100644
--- a/gcc/rust/typecheck/rust-hir-type-check.h
+++ b/gcc/rust/typecheck/rust-hir-type-check.h
@@ -372,6 +372,15 @@ public:
     return true;
   }
 
+  void insert_query (HirId id) { querys_in_progress.insert (id); }
+
+  void query_completed (HirId id) { querys_in_progress.erase (id); }
+
+  bool query_in_progress (HirId id) const
+  {
+    return querys_in_progress.find (id) != querys_in_progress.end ();
+  }
+
 private:
   TypeCheckContext ();
 
@@ -406,6 +415,9 @@ private:
 
   // predicates
   std::map<HirId, TyTy::TypeBoundPredicate> predicates;
+
+  // query context lookups
+  std::set<HirId> querys_in_progress;
 };
 
 class TypeResolution
diff --git a/gcc/rust/typecheck/rust-tyty-bounds.cc b/gcc/rust/typecheck/rust-tyty-bounds.cc
index 5b5ff751e2b..1a2ed3b7422 100644
--- a/gcc/rust/typecheck/rust-tyty-bounds.cc
+++ b/gcc/rust/typecheck/rust-tyty-bounds.cc
@@ -34,8 +34,9 @@ TypeBoundsProbe::scan ()
       if (!impl->has_trait_ref ())
 	return true;
 
-      TyTy::BaseType *impl_type = TypeCheckItem::ResolveImplBlockSelf (*impl);
-      if (impl_type->get_kind () == TyTy::TypeKind::ERROR)
+      HirId impl_ty_id = impl->get_type ()->get_mappings ().get_hirid ();
+      TyTy::BaseType *impl_type = nullptr;
+      if (!query_type (impl_ty_id, &impl_type))
 	return true;
 
       if (!receiver->can_eq (impl_type, false))