[gccrs COMMIT 2/4] Replace indexing with reverse iterator

[gerris.rs@gmail.com]

From: Pierre-Emmanuel Patry <pierre.emmanuel.patry@opensrcsec.com>

This change makes the code a bit simpler, it comes from a series of patch
that got deleted and was iterating backward on the self segments.

gcc/rust/ChangeLog:

	* resolve/rust-early-name-resolver-2.0.cc (Early::finalize_rebind_import):
	Use a reverse iterator instead of an index.

Signed-off-by: Pierre-Emmanuel Patry <pierre.emmanuel.patry@opensrcsec.com>
---
This change was merged into the gccrs repository and is posted here for
upstream visibility and potential drive-by review, as requested by GCC
release managers.
Each commit email contains a link to its details on github from where you can
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Commit on github: https://github.com/Rust-GCC/gccrs/commit/cec82b879625ca04331785ca784ed48bf7af88ff

The commit has NOT been mentioned in any issue.

The commit has been mentioned in the following pull-request(s):
 - https://github.com/Rust-GCC/gccrs/pull/4844

 gcc/rust/resolve/rust-early-name-resolver-2.0.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/gcc/rust/resolve/rust-early-name-resolver-2.0.cc b/gcc/rust/resolve/rust-early-name-resolver-2.0.cc
index 28e1d90a5..cb67af3e9 100644
--- a/gcc/rust/resolve/rust-early-name-resolver-2.0.cc
+++ b/gcc/rust/resolve/rust-early-name-resolver-2.0.cc
@@ -540,8 +540,11 @@ Early::finalize_rebind_import (const Early::ImportPair &mapping)
 	    // Erroneous `self` or `{self}` use declaration
 	    if (segments.size () == 1)
 	      return;
-	    declared_name = segments[segments.size () - 2].as_string ();
-	    import_id = segments[segments.size () - 2].get_node_id ();
+
+	    auto pre_self_segment = segments.rbegin () + 1;
+
+	    declared_name = pre_self_segment->as_string ();
+	    import_id = pre_self_segment->get_node_id ();
 	  }
 	else
 	  {
-- 
2.55.0