From 080690b3ad2515c8a9c4ba8f3fb2aea09e969c79 Mon Sep 17 00:00:00 2001
From: Michael Mauderer <michael.mauderer@enso.org>
Date: Wed, 17 Jan 2024 10:18:40 +0000
Subject: [PATCH] Fix for code enabling/disabling output context on single node
 (#8776)

---
 .../src/components/GraphEditor/GraphNode.vue  | 33 +++++++++----------
 app/gui2/src/util/ast/__tests__/match.test.ts |  7 ++++
 app/gui2/src/util/ast/match.ts                | 10 +++++-
 3 files changed, 32 insertions(+), 18 deletions(-)

diff --git a/app/gui2/src/components/GraphEditor/GraphNode.vue b/app/gui2/src/components/GraphEditor/GraphNode.vue
index 77aa4132f8b..9b0b9acec1f 100644
--- a/app/gui2/src/components/GraphEditor/GraphNode.vue
+++ b/app/gui2/src/components/GraphEditor/GraphNode.vue
@@ -179,24 +179,23 @@ const isOutputContextOverridden = computed({
   set(shouldOverride) {
     const module = projectStore.module
     if (!module) return
-    const replacements = shouldOverride
-      ? [Ast.TextLiteral.new(projectStore.executionMode)]
-      : undefined
     const edit = props.node.rootSpan.module.edit()
-    const newAst = prefixes.modify(
-      edit,
-      props.node.rootSpan,
-      projectStore.isOutputContextEnabled
-        ? {
-            enableOutputContext: undefined,
-            disableOutputContext: replacements,
-          }
-        : {
-            enableOutputContext: replacements,
-            disableOutputContext: undefined,
-          },
-    )
-    graph.setNodeContent(props.node.rootSpan.exprId, newAst.code())
+    const replacementText = shouldOverride
+      ? [Ast.TextLiteral.new(projectStore.executionMode, edit)]
+      : undefined
+    const replacements = projectStore.isOutputContextEnabled
+      ? {
+          enableOutputContext: undefined,
+          disableOutputContext: replacementText,
+        }
+      : {
+          enableOutputContext: replacementText,
+          disableOutputContext: undefined,
+        }
+    const expression = props.node.rootSpan
+    const newAst = prefixes.modify(edit, expression, replacements)
+    const code = newAst.code()
+    graph.setNodeContent(props.node.rootSpan.exprId, code)
   },
 })
 
diff --git a/app/gui2/src/util/ast/__tests__/match.test.ts b/app/gui2/src/util/ast/__tests__/match.test.ts
index a7f1fc8b93c..9c8a8eb3ca6 100644
--- a/app/gui2/src/util/ast/__tests__/match.test.ts
+++ b/app/gui2/src/util/ast/__tests__/match.test.ts
@@ -106,4 +106,11 @@ test.each([
   const intron = Ast.parse(source, edit)
   const instantiated = pattern.instantiate(edit, [intron.exprId])
   expect(instantiated.code(edit)).toBe(result)
+
+  // Check that `instantiate` has not affected the base module.
+  const intron2 = Ast.parse(source, edit)
+  const originalParent = intron2.parent
+  const edit2 = edit.edit()
+  pattern.instantiate(edit2, [intron2.exprId])
+  expect(edit.get(intron2.exprId)!.parent).toBe(originalParent)
 })
diff --git a/app/gui2/src/util/ast/match.ts b/app/gui2/src/util/ast/match.ts
index 85621cc40f3..5baccf09a46 100644
--- a/app/gui2/src/util/ast/match.ts
+++ b/app/gui2/src/util/ast/match.ts
@@ -1,3 +1,4 @@
+import { assert } from '@/util/assert'
 import { Ast } from '@/util/ast'
 import { MutableModule } from '@/util/ast/abstract'
 
@@ -44,7 +45,14 @@ export class Pattern {
     for (const matched of placeholders(ast, this.placeholder)) {
       const replacement = subtrees.shift()
       if (replacement === undefined) break
-      edit.get(replacement)!.parent = matched.parent
+      const replacementAst = edit.splice(edit.get(replacement))
+      if (replacementAst === null) {
+        console.error(
+          'Subtree ID provided to `instantiate` is not accessible in the `edit` module.',
+        )
+        continue
+      }
+      replacementAst.parent = matched.parent
       matched.ref.node = replacement
     }
     return ast