Change appendIfUnique for overwriting

Author: Armando Aguirre Sepulveda

.vscode/tasks.json

@@ -25,7 +25,12 @@
             "label": "tsc: watch ./src",
             "type": "shell",
             "command": "node",
-            "args": ["${workspaceFolder}/node_modules/typescript/lib/tsc.js", "--build", "${workspaceFolder}/src", "--watch"],
+            "args": [
+                "${workspaceFolder}/node_modules/typescript/lib/tsc.js",
+                "--build",
+                "${workspaceFolder}/src",
+                "--watch"
+            ],
             "group": "build",
             "isBackground": true,
             "problemMatcher": [
@@ -36,7 +41,10 @@
             "label": "npm: build:compiler",
             "type": "npm",
             "script": "build:compiler",
-            "group": "build",
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
             "problemMatcher": [
                 "$tsc"
             ]

src/compiler/factory/nodeFactory.ts

@@ -7445,20 +7445,16 @@ function mergeEmitNode(sourceEmitNode: EmitNode, destEmitNode: EmitNode | undefi
 
     // `annotatedNodes` are not merged as they should only present on the parse tree node of a `SourceFile`.
 
-    // `leadingComments` are concatenated with any existing leading comments on the destination
+    // `leadingComments` overwrites the destination
     if (leadingComments) {
         // We use `.slice()` in case `destEmitNode.leadingComments` is pushed to later
-        for (const comment of leadingComments.slice()) {
-            destEmitNode.leadingComments = appendIfUnique(destEmitNode.leadingComments, comment);
-        }
+        destEmitNode.leadingComments = leadingComments.slice();
     }
 
-    // `trailingComments` are concatenated with any existing trailing comments on the destination
+    // `trailingComments` overwrites the destination
     if (trailingComments) {
         // We use `.slice()` in case `destEmitNode.trailingComments` is pushed to later
-        for (const comment of trailingComments) {
-            destEmitNode.trailingComments = appendIfUnique(destEmitNode.trailingComments, comment);
-        }
+        destEmitNode.trailingComments = trailingComments.slice();
     }
 
     // `commentRange` overwrites the destination