Change lookup_node_to_hir return type to optional

Previous API was using a boolean and a pointer, this was not practical
and could be replaced with an optional.

gcc/rust/ChangeLog:

	* backend/rust-compile-expr.cc (CompileExpr::visit): Change call to use
	the returned optional.
	(CompileExpr::generate_closure_function): Likewise.
	* backend/rust-compile-resolve-path.cc (ResolvePathRef::resolve):
	Likewise.
	* backend/rust-compile-type.cc (TyTyResolveCompile::visit): Likewise.
	* backend/rust-mangle-v0.cc (v0_path): Likewise.
	* checks/errors/privacy/rust-visibility-resolver.cc:
	Likewise.
	* checks/errors/rust-const-checker.cc (ConstChecker::visit): Likewise.
	* checks/errors/rust-unsafe-checker.cc (UnsafeChecker::visit):
	Likewise.
	* checks/lints/rust-lint-marklive.cc (MarkLive::visit): Likewise.
	(MarkLive::visit_path_segment): Likewise.
	* typecheck/rust-hir-trait-resolve.cc (TraitResolver::resolve_path_to_trait):
	Likewise.
	* typecheck/rust-hir-type-check-path.cc (TypeCheckExpr::resolve_root_path):
	Likewise.
	* typecheck/rust-hir-type-check-type.cc (TypeCheckType::resolve_root_path):
	Likewise.
	(ResolveWhereClauseItem::visit): Likewise.
	* util/rust-hir-map.cc (Mappings::lookup_node_to_hir): Return an
	optional instead of a boolean.
	* util/rust-hir-map.h: Change function prototype to match the new
	return type.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

1 files changed, 4 insertions, 3 deletions

diff --git a/gcc/rust/backend/rust-mangle-v0.cc b/gcc/rust/backend/rust-mangle-v0.cc
index f62c51e..bb2b0d4 100644
--- a/gcc/rust/backend/rust-mangle-v0.cc
+++ b/gcc/rust/backend/rust-mangle-v0.cc
@@ -374,14 +374,15 @@ v0_path (Rust::Compile::Context *ctx, const TyTy::BaseType *ty,
   V0Path v0path = {};
 
   cpath.iterate_segs ([&] (const Resolver::CanonicalPath &seg) {
-    HirId hir_id;
-    bool ok = mappings.lookup_node_to_hir (seg.get_node_id (), &hir_id);
-    if (!ok)
+    tl::optional<HirId> hid = mappings.lookup_node_to_hir (seg.get_node_id ());
+    if (!hid.has_value ())
       {
 	// FIXME: generic arg in canonical path? (e.g. <i32> in crate::S<i32>)
 	rust_unreachable ();
       }
 
+    auto hir_id = hid.value ();
+
     HirId parent_impl_id = UNKNOWN_HIRID;
     HIR::ImplItem *impl_item
       = mappings.lookup_hir_implitem (hir_id, &parent_impl_id);