refactor: handle the return type of regions_from_generic_args

Handle return value of `regions_from_generic_args` properly everywhere
gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check-path.cc (TypeCheckExpr::visit):
	return error for unresolved lifetimes
	(TypeCheckExpr::resolve_root_path): same as above
	(TypeCheckExpr::resolve_segments): return without explicit error
	* typecheck/rust-hir-type-check-type.cc (TypeCheckType::visit):
	return error for unresolved lifetimes
	(TypeCheckType::resolve_root_path): same as above
	* typecheck/rust-tyty-bounds.cc (TypeBoundPredicate::apply_generic_arguments):
	set error_flag to true for unresolved lifetimes

Signed-off-by: vibhatsu <maulikbarot2915@gmail.com>

Author: v1bh475u

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

@@ -145,12 +145,17 @@ TypeCheckExpr::visit (HIR::QualifiedPathInExpression &expr)
 	  infered = new TyTy::ErrorType (expr.get_mappings ().get_hirid ());
 	  return;
 	}
-      std::vector<TyTy::Region> regions;
+      auto regions
+	= context->regions_from_generic_args (item_seg.get_generic_args ());
+      if (!regions.has_value ())
+	{
+	  infered = new TyTy::ErrorType (expr.get_mappings ().get_hirid ());
+	  return;
+	}
 
       infered = SubstMapper::Resolve (infered, expr.get_locus (),
 				      &item_seg.get_generic_args (),
-				      context->regions_from_generic_args (
-					item_seg.get_generic_args ()));
+				      regions.value ());
     }
 
   // continue on as a path-in-expression
@@ -366,10 +371,14 @@ TypeCheckExpr::resolve_root_path (HIR::PathInExpression &expr, size_t *offset,
       // turbo-fish segment path::<ty>
       if (seg.has_generic_args ())
 	{
-	  lookup = SubstMapper::Resolve (lookup, expr.get_locus (),
-					 &seg.get_generic_args (),
-					 context->regions_from_generic_args (
-					   seg.get_generic_args ()));
+	  auto regions
+	    = context->regions_from_generic_args (seg.get_generic_args ());
+	  if (!regions.has_value ())
+	    return new TyTy::ErrorType (expr.get_mappings ().get_hirid ());
+
+	  lookup
+	    = SubstMapper::Resolve (lookup, expr.get_locus (),
+				    &seg.get_generic_args (), regions.value ());
 	  if (lookup->get_kind () == TyTy::TypeKind::ERROR)
 	    return new TyTy::ErrorType (expr.get_mappings ().get_hirid ());
 	}
@@ -526,10 +535,14 @@ TypeCheckExpr::resolve_segments (NodeId root_resolved_node_id,
 	{
 	  rust_debug_loc (seg.get_locus (), "applying segment generics: %s",
 			  tyseg->as_string ().c_str ());
+	  auto regions
+	    = context->regions_from_generic_args (seg.get_generic_args ());
+	  if (!regions.has_value ())
+	    return;
+
 	  tyseg
 	    = SubstMapper::Resolve (tyseg, expr_locus, &seg.get_generic_args (),
-				    context->regions_from_generic_args (
-				      seg.get_generic_args ()));
+				    regions.value ());
 	  if (tyseg->get_kind () == TyTy::TypeKind::ERROR)
 	    return;
 	}

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

@@ -301,11 +301,17 @@ TypeCheckType::visit (HIR::QualifiedPathInType &path)
 		= new TyTy::ErrorType (path.get_mappings ().get_hirid ());
 	      return;
 	    }
-	  translated
-	    = SubstMapper::Resolve (translated, path.get_locus (),
-				    &generic_seg.get_generic_args (),
-				    context->regions_from_generic_args (
-				      generic_seg.get_generic_args ()));
+	  auto regions = context->regions_from_generic_args (
+	    generic_seg.get_generic_args ());
+	  if (!regions.has_value ())
+	    {
+	      translated
+		= new TyTy::ErrorType (path.get_mappings ().get_hirid ());
+	      return;
+	    }
+	  translated = SubstMapper::Resolve (translated, path.get_locus (),
+					     &generic_seg.get_generic_args (),
+					     regions.value ());
 	}
     }
 
@@ -458,19 +464,22 @@ TypeCheckType::resolve_root_path (HIR::TypePath &path, size_t *offset,
 
 	  auto regions = context->regions_from_generic_args (
 	    generic_segment.get_generic_args ());
+	  if (!regions.has_value ())
+	    return new TyTy::ErrorType (seg->get_mappings ().get_hirid ());
+
 	  lookup = SubstMapper::Resolve (lookup, path.get_locus (),
 					 &generic_segment.get_generic_args (),
-					 regions);
+					 regions.value ());
 	  if (lookup->get_kind () == TyTy::TypeKind::ERROR)
 	    return new TyTy::ErrorType (seg->get_mappings ().get_hirid ());
 	}
       else if (lookup->needs_generic_substitutions ())
 	{
 	  HIR::GenericArgs empty
 	    = HIR::GenericArgs::create_empty (path.get_locus ());
-	  lookup
-	    = SubstMapper::Resolve (lookup, path.get_locus (), &empty,
-				    context->regions_from_generic_args (empty));
+	  lookup = SubstMapper::Resolve (
+	    lookup, path.get_locus (), &empty,
+	    context->regions_from_generic_args (empty).value ());
 	}
 
       *offset = *offset + 1;

gcc/rust/typecheck/rust-tyty-bounds.cc

@@ -538,10 +538,14 @@ TypeBoundPredicate::apply_generic_arguments (HIR::GenericArgs *generic_args,
     }
 
   // now actually perform a substitution
-  auto args = get_mappings_from_generic_args (
-    *generic_args,
-    Resolver::TypeCheckContext::get ()->regions_from_generic_args (
-      *generic_args));
+  auto regions = Resolver::TypeCheckContext::get ()->regions_from_generic_args (
+    *generic_args);
+  if (!regions.has_value ())
+    {
+      error_flag = true;
+      return;
+    }
+  auto args = get_mappings_from_generic_args (*generic_args, regions.value ());
 
   apply_argument_mappings (args, is_super_trait);
 }