From c1981ffb44b704fce9a69d6ba2fd1ba8feed5c9c Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <as-cii@github.com>
Date: Thu, 7 Sep 2017 17:52:04 +0200
Subject: [PATCH] Correctly remove block decorations whose markers have been
 destroyed

In https://github.com/atom/atom/pull/15503 we mistakenly assumed
`marker.isValid` accounted only for the validity of the marker. However,
that method returns `false` also for markers that are valid but have
been destroyed. As a result, the editor component was mistakenly not
removing block decorations associated with such markers.

With this commit we will rely on the local `wasValid` variable instead.
If its value is `true`, it means that the block decoration has been
accounted for in the `lineTopIndex` and must, as a result, be cleaned up
in case the marker or the decoration gets destroyed.
---
 spec/text-editor-component-spec.js | 21 +++++++++++++++++++++
 src/text-editor-component.js       |  2 +-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/spec/text-editor-component-spec.js b/spec/text-editor-component-spec.js
index e2cd0988b..d1ff883c9 100644
--- a/spec/text-editor-component-spec.js
+++ b/spec/text-editor-component-spec.js
@@ -2299,6 +2299,27 @@ describe('TextEditorComponent', () => {
       ])
     })
 
+    it('removes block decorations whose markers have been destroyed', async () => {
+      const {editor, component, element} = buildComponent({rowsPerTile: 3})
+      const {marker} = createBlockDecorationAtScreenRow(editor, 2, {height: 5, position: 'before'})
+      await component.getNextUpdatePromise()
+      assertLinesAreAlignedWithLineNumbers(component)
+      assertTilesAreSizedAndPositionedCorrectly(component, [
+        {tileStartRow: 0, height: 3 * component.getLineHeight() + 5},
+        {tileStartRow: 3, height: 3 * component.getLineHeight()},
+        {tileStartRow: 6, height: 3 * component.getLineHeight()}
+      ])
+
+      marker.destroy()
+      await component.getNextUpdatePromise()
+      assertLinesAreAlignedWithLineNumbers(component)
+      assertTilesAreSizedAndPositionedCorrectly(component, [
+        {tileStartRow: 0, height: 3 * component.getLineHeight()},
+        {tileStartRow: 3, height: 3 * component.getLineHeight()},
+        {tileStartRow: 6, height: 3 * component.getLineHeight()}
+      ])
+    })
+
     it('removes block decorations whose markers are invalidated, and adds them back when they become valid again', async () => {
       const editor = buildEditor({rowsPerTile: 3, autoHeight: false})
       const {item, decoration, marker} = createBlockDecorationAtScreenRow(editor, 3, {height: 44, position: 'before', invalidate: 'touch'})
diff --git a/src/text-editor-component.js b/src/text-editor-component.js
index 333486df8..c668ea8f6 100644
--- a/src/text-editor-component.js
+++ b/src/text-editor-component.js
@@ -2506,7 +2506,7 @@ class TextEditorComponent {
         didUpdateDisposable.dispose()
         didDestroyDisposable.dispose()
 
-        if (marker.isValid()) {
+        if (wasValid) {
           this.blockDecorationsToMeasure.delete(decoration)
           this.heightsByBlockDecoration.delete(decoration)
           this.blockDecorationsByElement.delete(element)