fix multiline dynamic import comments (#6025)

CHANGELOG.unreleased.md

@@ -42,9 +42,41 @@ Examples:
 
 -->
 
-- JavaScript: Add parentheses for immediately-constructed fn/class ([#5996] by [@bakkot])
+- JavaScript: Fix multiline dynamic import comments ([#6025] by [@noahsug])
+
+  <!-- prettier-ignore -->
+  ```js
+  // Input
+  import(
+    /* Hello */
+    'something'
+    /* Hello */
+  )
+  import(
+    'myreallylongdynamicallyloadedmodulenamemyreallylongdynamicallyloadedmodulename'
+  )
+
+  // Output (Prettier stable)
+  import(/* Hello */
+  "something");
+  /* Hello */
+  import('myreallylongdynamicallyloadedmodulenamemyreallylongdynamicallyloadedmodulename');
 
+  // Output (Prettier master)
+  import(
+    /* Hello */
+    'something'
+    /* Hello */
+  )
+  import(
+    'myreallylongdynamicallyloadedmodulenamemyreallylongdynamicallyloadedmodulename'
+  );
   ```
+
+- JavaScript: Add parentheses for immediately-constructed fn/class ([#5996] by [@bakkot])
+
+  <!-- prettier-ignore -->
+  ```js
   // Input
   new class {};
   new function() {}

src/language-js/printer-estree.js

@@ -1165,7 +1165,6 @@ function printPathNoParens(path, options, print, args) {
         (!isNew &&
           n.callee.type === "Identifier" &&
           (n.callee.name === "require" || n.callee.name === "define")) ||
-        n.callee.type === "Import" ||
         // Template literals as single arguments
         (n.arguments.length === 1 &&
           isTemplateOnItsOwnLine(
@@ -3953,7 +3952,12 @@ function printArgumentsList(path, options, print) {
     return concat(parts);
   }, "arguments");
 
-  const maybeTrailingComma = shouldPrintComma(options, "all") ? "," : "";
+  const maybeTrailingComma =
+    // Dynamic imports cannot have trailing commas
+    !(node.callee && node.callee.type === "Import") &&
+    shouldPrintComma(options, "all")
+      ? ","
+      : "";
 
   function allArgsBrokenOut() {
     return group(
@@ -4051,7 +4055,7 @@ function printArgumentsList(path, options, print) {
     concat([
       "(",
       indent(concat([softline, concat(printedArguments)])),
-      ifBreak(shouldPrintComma(options, "all") ? "," : ""),
+      ifBreak(maybeTrailingComma),
       softline,
       ")"
     ]),
@@ -6435,8 +6439,7 @@ function canAttachComment(node) {
     node.type !== "Block" &&
     node.type !== "EmptyStatement" &&
     node.type !== "TemplateElement" &&
-    node.type !== "Import" &&
-    !(node.callee && node.callee.type === "Import")
+    node.type !== "Import"
   );
 }
 

tests/comments/__snapshots__/jsfmt.spec.js.snap

@@ -530,6 +530,18 @@ import(/* Hello */ 'something' /* Hello */)
 
 import('something' /* Hello */ + 'else')
 
+import(
+  /* Hello */
+  'something'
+  /* Hello */
+)
+
+wrap(
+  import(/* Hello */
+    'something'
+  )
+)
+
 =====================================output=====================================
 import(/* Hello */ "something");
 
@@ -539,6 +551,19 @@ import(/* Hello */ "something" /* Hello */);
 
 import("something" /* Hello */ + "else");
 
+import(
+  /* Hello */
+  "something"
+  /* Hello */
+);
+
+wrap(
+  import(
+    /* Hello */
+    "something"
+  )
+);
+
 ================================================================================
 `;
 

tests/comments/dynamic_imports.js

@@ -5,3 +5,15 @@ import('something' /* Hello */)
 import(/* Hello */ 'something' /* Hello */)
 
 import('something' /* Hello */ + 'else')
+
+import(
+  /* Hello */
+  'something'
+  /* Hello */
+)
+
+wrap(
+  import(/* Hello */
+    'something'
+  )
+)

tests/trailing_comma/__snapshots__/jsfmt.spec.js.snap

@@ -1,5 +1,61 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`dynamic-import.js 1`] = `
+====================================options=====================================
+parsers: ["flow", "typescript"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+import(
+  'myreallylongdynamicallyloadedmodulenamemyreallylongdynamicallyloadedmodulename'
+);
+
+=====================================output=====================================
+import(
+  "myreallylongdynamicallyloadedmodulenamemyreallylongdynamicallyloadedmodulename"
+);
+
+================================================================================
+`;
+
+exports[`dynamic-import.js 2`] = `
+====================================options=====================================
+parsers: ["flow", "typescript"]
+printWidth: 80
+trailingComma: "all"
+                                                                                | printWidth
+=====================================input======================================
+import(
+  'myreallylongdynamicallyloadedmodulenamemyreallylongdynamicallyloadedmodulename'
+);
+
+=====================================output=====================================
+import(
+  "myreallylongdynamicallyloadedmodulenamemyreallylongdynamicallyloadedmodulename"
+);
+
+================================================================================
+`;
+
+exports[`dynamic-import.js 3`] = `
+====================================options=====================================
+parsers: ["flow", "typescript"]
+printWidth: 80
+trailingComma: "es5"
+                                                                                | printWidth
+=====================================input======================================
+import(
+  'myreallylongdynamicallyloadedmodulenamemyreallylongdynamicallyloadedmodulename'
+);
+
+=====================================output=====================================
+import(
+  "myreallylongdynamicallyloadedmodulenamemyreallylongdynamicallyloadedmodulename"
+);
+
+================================================================================
+`;
+
 exports[`es5.js 1`] = `
 ====================================options=====================================
 parsers: ["flow", "typescript"]

tests/trailing_comma/dynamic-import.js

@@ -0,0 +1,3 @@
+import(
+  'myreallylongdynamicallyloadedmodulenamemyreallylongdynamicallyloadedmodulename'
+);