Keep curly braces and from keyword in empty import statements (pr…

…ettier#15756)

changelog_unreleased/javascript/15756.md

@@ -0,0 +1,16 @@
+#### Keep curly braces and `from` keyword in empty `import` statements (#15756 by @fisker)
+
+<!-- prettier-ignore -->
+```js
+// Input
+import { } from 'foo';
+import { /* comment */ } from 'bar';
+
+// Prettier stable
+import {} from "foo";
+import /* comment */ "bar";
+
+// Prettier main
+import {} from "foo";
+import {} from /* comment */ "bar";
+```

src/language-js/print/module.js

@@ -148,7 +148,7 @@ function printModuleSource(path, options, print) {
 
   /** @type{Doc[]} */
   const parts = [];
-  if (!shouldNotPrintSpecifiers(node, options)) {
+  if (shouldPrintSpecifiers(node, options)) {
     parts.push(" from");
   }
   parts.push(" ", print("source"));
@@ -159,7 +159,7 @@ function printModuleSource(path, options, print) {
 function printModuleSpecifiers(path, options, print) {
   const { node } = path;
 
-  if (shouldNotPrintSpecifiers(node, options)) {
+  if (!shouldPrintSpecifiers(node, options)) {
     return "";
   }
 
@@ -231,21 +231,22 @@ function printModuleSpecifiers(path, options, print) {
   return parts;
 }
 
-function shouldNotPrintSpecifiers(node, options) {
-  const { type, importKind, source, specifiers } = node;
-
+function shouldPrintSpecifiers(node, options) {
   if (
-    type !== "ImportDeclaration" ||
-    isNonEmptyArray(specifiers) ||
-    importKind === "type"
+    node.type !== "ImportDeclaration" ||
+    isNonEmptyArray(node.specifiers) ||
+    node.importKind === "type"
   ) {
-    return false;
+    return true;
   }
 
-  // TODO: check tokens
-  return !/{\s*}/.test(
-    options.originalText.slice(locStart(node), locStart(source)),
+  const text = getTextWithoutComments(
+    options,
+    locStart(node),
+    locStart(node.source),
   );
+
+  return text.trimEnd().endsWith("from");
 }
 
 function getTextWithoutComments(options, start, end) {
@@ -288,8 +289,8 @@ function getImportAttributesOrAssertionsKeyword(node, options) {
 
   const textBetweenSourceAndAttributes = getTextWithoutComments(
     options,
-    node.source.range[1],
-    node.attributes[0].range[0],
+    locEnd(node.source),
+    locStart(node.attributes[0]),
   );
 
   if (textBetweenSourceAndAttributes.trimStart().startsWith("assert")) {

tests/format/js/import/__snapshots__/jsfmt.spec.js.snap

@@ -286,9 +286,92 @@ printWidth: 80
                                                                                 | printWidth
 =====================================input======================================
 import { } from '@types/googlemaps';
+import 'a';
+import /* comment */ 'a';
+import // comment
+'a';
+import { /* comment */ } from 'a';
+import /* comment */ {} from 'a';
+import {} /* comment */ from 'a';
+import {} from /* comment */ 'a';
+import /* comment */ {/* comment */} /* comment */ from /* comment */ 'a';
+import {
+  // comment
+} from 'a';
+import // comment
+{} from 'a';
+import {}
+// comment
+from 'a';
+import {} from
+// comment
+'a';
+import
+// comment
+{
+// comment
+}
+// comment
+from
+// comment
+'a';
+
+import // {} from
+'a';
+import {} from // comment ends with from
+'a';
+import {} from /* comment ends with from */ 'a';
+import {} from // comment not ends with from ___
+'a';
+import {} from /* comment not ends with from ___ */ 'a';
+
+import // comment ends with from
+'a';
+import /* comment ends with from */ 'a';
+import // comment not ends with from ___
+'a';
+import /* comment not ends with from ___ */ 'a';
 
 =====================================output=====================================
 import {} from "@types/googlemaps";
+import "a";
+import /* comment */ "a";
+import // comment
+"a";
+import {} from /* comment */ "a";
+import {} from /* comment */ "a";
+import {} from /* comment */ "a";
+import {} from /* comment */ "a";
+import {} from /* comment */ /* comment */ /* comment */ /* comment */ "a";
+import {} from // comment
+"a";
+import {} from // comment
+"a";
+import {} from // comment
+"a";
+import {} from // comment
+"a";
+import {} from // comment
+// comment
+// comment
+// comment
+"a";
+
+import // {} from
+"a";
+import {} from // comment ends with from
+"a";
+import {} from /* comment ends with from */ "a";
+import {} from // comment not ends with from ___
+"a";
+import {} from /* comment not ends with from ___ */ "a";
+
+import // comment ends with from
+"a";
+import /* comment ends with from */ "a";
+import // comment not ends with from ___
+"a";
+import /* comment not ends with from ___ */ "a";
 
 ================================================================================
 `;
@@ -300,9 +383,92 @@ printWidth: 80
                                                                                 | printWidth
 =====================================input======================================
 import { } from '@types/googlemaps';
+import 'a';
+import /* comment */ 'a';
+import // comment
+'a';
+import { /* comment */ } from 'a';
+import /* comment */ {} from 'a';
+import {} /* comment */ from 'a';
+import {} from /* comment */ 'a';
+import /* comment */ {/* comment */} /* comment */ from /* comment */ 'a';
+import {
+  // comment
+} from 'a';
+import // comment
+{} from 'a';
+import {}
+// comment
+from 'a';
+import {} from
+// comment
+'a';
+import
+// comment
+{
+// comment
+}
+// comment
+from
+// comment
+'a';
+
+import // {} from
+'a';
+import {} from // comment ends with from
+'a';
+import {} from /* comment ends with from */ 'a';
+import {} from // comment not ends with from ___
+'a';
+import {} from /* comment not ends with from ___ */ 'a';
+
+import // comment ends with from
+'a';
+import /* comment ends with from */ 'a';
+import // comment not ends with from ___
+'a';
+import /* comment not ends with from ___ */ 'a';
 
 =====================================output=====================================
 import {} from "@types/googlemaps";
+import "a";
+import /* comment */ "a";
+import // comment
+"a";
+import {} from /* comment */ "a";
+import {} from /* comment */ "a";
+import {} from /* comment */ "a";
+import {} from /* comment */ "a";
+import {} from /* comment */ /* comment */ /* comment */ /* comment */ "a";
+import {} from // comment
+"a";
+import {} from // comment
+"a";
+import {} from // comment
+"a";
+import {} from // comment
+"a";
+import {} from // comment
+// comment
+// comment
+// comment
+"a";
+
+import // {} from
+"a";
+import {} from // comment ends with from
+"a";
+import {} from /* comment ends with from */ "a";
+import {} from // comment not ends with from ___
+"a";
+import {} from /* comment not ends with from ___ */ "a";
+
+import // comment ends with from
+"a";
+import /* comment ends with from */ "a";
+import // comment not ends with from ___
+"a";
+import /* comment not ends with from ___ */ "a";
 
 ================================================================================
 `;

tests/format/js/import/empty-import.js

@@ -1 +1,46 @@
 import { } from '@types/googlemaps';
+import 'a';
+import /* comment */ 'a';
+import // comment
+'a';
+import { /* comment */ } from 'a';
+import /* comment */ {} from 'a';
+import {} /* comment */ from 'a';
+import {} from /* comment */ 'a';
+import /* comment */ {/* comment */} /* comment */ from /* comment */ 'a';
+import {
+  // comment
+} from 'a';
+import // comment
+{} from 'a';
+import {}
+// comment
+from 'a';
+import {} from
+// comment
+'a';
+import
+// comment
+{
+// comment
+}
+// comment
+from
+// comment
+'a';
+
+import // {} from
+'a';
+import {} from // comment ends with from
+'a';
+import {} from /* comment ends with from */ 'a';
+import {} from // comment not ends with from ___
+'a';
+import {} from /* comment not ends with from ___ */ 'a';
+
+import // comment ends with from
+'a';
+import /* comment ends with from */ 'a';
+import // comment not ends with from ___
+'a';
+import /* comment not ends with from ___ */ 'a';