GraphQL: Fix dangling comments in empty "listValue" (#19422)

changelog_unreleased/graphql/18581.md

@@ -1,4 +1,4 @@
-#### Fix comment print (#18581 by @fisker)
+#### Fix crash with comment only object value (#18581 by @fisker)
 
 <!-- prettier-ignore -->
 ```gql

changelog_unreleased/graphql/19422.md

@@ -0,0 +1,23 @@
+#### Fix crash with comment only list value (#19422 by @fisker)
+
+<!-- prettier-ignore -->
+```gql
+# Input
+query {
+  a(x: [
+    # only comment
+  ])
+}
+
+# Prettier stable
+Error: Comment "only comment" was not printed. Please report this error!
+
+# Prettier main
+query {
+  a(
+    x: [
+      # only comment
+    ]
+  )
+}
+```

src/language-graphql/printer-graphql.js

@@ -133,16 +133,21 @@ function genericPrint(path, options, print) {
     case "Variable":
       return ["$", print("name")];
 
-    case "ListValue":
+    case "ListValue": {
+      const isEmpty = !isNonEmptyArray(node.values);
       return group([
         "[",
-        indent([
-          softline,
-          join([ifBreak("", ", "), softline], path.map(print, "values")),
-        ]),
+        printDanglingComments(path, options, { indent: true }),
+        isEmpty
+          ? ""
+          : indent([
+              softline,
+              join([ifBreak("", ", "), softline], path.map(print, "values")),
+            ]),
         softline,
         "]",
       ]);
+    }
 
     case "ObjectValue": {
       const isEmpty = !isNonEmptyArray(node.fields);

tests/format/graphql/comments/__snapshots__/format.test.js.snap

@@ -37,6 +37,12 @@ query {
   }
 }
 
+query {
+  a(x: [
+    # only comment
+  ])
+}
+
 =====================================output=====================================
 query {
   search(
@@ -48,6 +54,14 @@ query {
   }
 }
 
+query {
+  a(
+    x: [
+      # only comment
+    ]
+  )
+}
+
 ================================================================================
 `;
 

tests/format/graphql/comments/dangling.graphql

@@ -5,3 +5,9 @@ query {
       id
   }
 }
+
+query {
+  a(x: [
+    # only comment
+  ])
+}