From 5f4f171b73232e5ec5e4b7153084a93033ab5cf0 Mon Sep 17 00:00:00 2001
From: Michael Davis
Date: Sun, 16 Oct 2022 14:52:04 -0500
Subject: Fix debug assertion for diagnostic sort order (#4319)

The debug assertion that document diagnostics are sorted incorrectly
panics for cases like `[161..164, 162..162]`. The merging behavior
in the following lines that relies on the assertion only needs the
input ranges to be sorted by `range.start`, so this change simplifies
the assertion to only catch violations of that assumption.---
 helix-term/src/ui/editor.rs | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/helix-term/src/ui/editor.rs b/helix-term/src/ui/editor.rs
index fb70fa0f..8e9d8631 100644
--- a/helix-term/src/ui/editor.rs
+++ b/helix-term/src/ui/editor.rs
@@ -302,16 +302,7 @@ impl EditorView {
         let mut warning_vec = Vec::new();
         let mut error_vec = Vec::new();
 
-        let diagnostics = doc.diagnostics();
-
-        // Diagnostics must be sorted by range. Otherwise, the merge strategy
-        // below would not be accurate.
-        debug_assert!(diagnostics
-            .windows(2)
-            .all(|window| window[0].range.start <= window[1].range.start
-                && window[0].range.end <= window[1].range.end));
-
-        for diagnostic in diagnostics {
+        for diagnostic in doc.diagnostics() {
             // Separate diagnostics into different Vecs by severity.
             let (vec, scope) = match diagnostic.severity {
                 Some(Severity::Info) => (&mut info_vec, info),
@@ -325,6 +316,11 @@ impl EditorView {
             // merge the two together. Otherwise push a new span.
             match vec.last_mut() {
                 Some((_, range)) if diagnostic.range.start <= range.end => {
+                    // This branch merges overlapping diagnostics, assuming that the current
+                    // diagnostic starts on range.start or later. If this assertion fails,
+                    // we will discard some part of `diagnostic`. This implies that
+                    // `doc.diagnostics()` is not sorted by `diagnostic.range`.
+                    debug_assert!(range.start <= diagnostic.range.start);
                     range.end = diagnostic.range.end.max(range.end)
                 }
                 _ => vec.push((scope, diagnostic.range.start..diagnostic.range.end)),
-- 
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