clang-format: [JS] do not merge side-effect imports.

The if condition was testing the current element, but
forgot to check the previous element (doh), so it
would fail depending on sort order of the imports.

Differential Revision: https://reviews.llvm.org/D101020

clang/lib/Format/SortJavaScriptImports.cpp

@@ -271,6 +271,7 @@ private:
       //   import Default from 'foo'; on either previous or this.
       //   mismatching
       if (Reference->Category == JsModuleReference::SIDE_EFFECT ||
+          PreviousReference->Category == JsModuleReference::SIDE_EFFECT ||
           Reference->IsExport != PreviousReference->IsExport ||
           !PreviousReference->Prefix.empty() || !Reference->Prefix.empty() ||
           !PreviousReference->DefaultImport.empty() ||

clang/unittests/Format/SortImportsTestJS.cpp

@@ -364,6 +364,13 @@ TEST_F(SortImportsTestJS, MergeImports) {
   // do merge exports
   verifySort("export {A, B} from 'foo';\n", "export {A} from 'foo';\n"
                                             "export   {B} from 'foo';");
+
+  // do not merge side effect imports with named ones
+  verifySort("import './a';\n"
+             "\n"
+             "import {bar} from './a';\n",
+             "import {bar} from './a';\n"
+             "import './a';\n");
 }
 
 } // end namespace