gccrs: Fix bad handling for recursive type query

When resolving a type like this which is generic it causes the argument
substitution to go through bounds checking which is expected. But this
can call a type bounds probe which again calls a type query which will be
on the Impl Type on an impl block which can result in a recursive type
query which does eventually get caught and errors correctly. But this then
triggers some old error diagnositcs which are not valid error codes but old
error messages we used to catch simple errors very early on which do not
apply for this senario.

Fixes Rust-GCC#2905

gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check-item.cc (TypeCheckItem::resolve_impl_block_substitutions):
	dont check for unconstrained when the self is not resolved
	* typecheck/rust-hir-type-check-type.cc (TypeCheckType::resolve_root_path):
	remove bad debug error diagnostic
	* typecheck/rust-tyty-subst.cc: likewise

gcc/testsuite/ChangeLog:

	* rust/compile/nr2/exclude: nr2 cant handle this
	* rust/compile/issue-2905-1.rs: New test.
	* rust/compile/issue-2905-2.rs: New test.

Signed-off-by: Philip Herron <herron.philip@googlemail.com>

3 files changed, 10 insertions, 8 deletions

diff --git a/gcc/rust/typecheck/rust-hir-type-check-item.cc b/gcc/rust/typecheck/rust-hir-type-check-item.cc
index 51ce827..ce8e759 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-item.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-item.cc
@@ -724,6 +724,14 @@ TypeCheckItem::resolve_impl_block_substitutions (HIR::ImplBlock &impl_block,
     }
 
   TyTy::BaseType *self = TypeCheckType::Resolve (impl_block.get_type ().get ());
+  if (self->is<TyTy::ErrorType> ())
+    {
+      // we cannot check for unconstrained type arguments when the Self type is
+      // not resolved it will just add extra errors that dont help as well as
+      // the case where this could just be a recursive type query that should
+      // fail and will work later on anyway
+      return {substitutions, region_constraints};
+    }
 
   // inherit the bounds
   if (!specified_bound.is_error ())
diff --git a/gcc/rust/typecheck/rust-hir-type-check-type.cc b/gcc/rust/typecheck/rust-hir-type-check-type.cc
index f2e0405..f3aee8a 100644
--- a/gcc/rust/typecheck/rust-hir-type-check-type.cc
+++ b/gcc/rust/typecheck/rust-hir-type-check-type.cc
@@ -426,11 +426,8 @@ TypeCheckType::resolve_root_path (HIR::TypePath &path, size_t *offset,
       if (!query_type (ref, &lookup))
 	{
 	  if (is_root)
-	    {
-	      rust_error_at (seg->get_locus (),
-			     "failed to resolve root segment");
-	      return new TyTy::ErrorType (path.get_mappings ().get_hirid ());
-	    }
+	    return new TyTy::ErrorType (path.get_mappings ().get_hirid ());
+
 	  return root_tyty;
 	}
 
diff --git a/gcc/rust/typecheck/rust-tyty-subst.cc b/gcc/rust/typecheck/rust-tyty-subst.cc
index 48dcd95..83d0e35 100644
--- a/gcc/rust/typecheck/rust-tyty-subst.cc
+++ b/gcc/rust/typecheck/rust-tyty-subst.cc
@@ -634,8 +634,6 @@ SubstitutionRef::get_mappings_from_generic_args (
 	      if (resolved == nullptr
 		  || resolved->get_kind () == TyTy::TypeKind::ERROR)
 		{
-		  rust_error_at (binding.get_locus (),
-				 "failed to resolve type arguments");
 		  return SubstitutionArgumentMappings::error ();
 		}
 
@@ -701,7 +699,6 @@ SubstitutionRef::get_mappings_from_generic_args (
       BaseType *resolved = Resolver::TypeCheckType::Resolve (arg.get ());
       if (resolved == nullptr || resolved->get_kind () == TyTy::TypeKind::ERROR)
 	{
-	  rust_error_at (args.get_locus (), "failed to resolve type arguments");
 	  return SubstitutionArgumentMappings::error ();
 	}