clang-format: [JS] handle object types in extends positions.

[mprobst]

Summary

clang-format would previously drop the whitespace after extends in code such as:

class Foo extends {} {}

Where the first set of curly braces is an inline object literal type.

[mprobst]

• revert bogus change

[djasper]

Looks good.

lib/Format/TokenAnnotator.cpp

if (Style.isCpp()) {
     // that the identifier is not a pseudo keyword like `yield`, either.
     if (Left.is(tok::identifier) && Keywords.IsJavaScriptIdentifier(Left) &&
         Right.is(TT_TemplateString))
       return false;
     if (Right.is(tok::star) &&
         Left.isOneOf(Keywords.kw_function, Keywords.kw_yield))
       return false;
     if (Right.isOneOf(tok::l_brace, tok::l_square) &&
-        Left.isOneOf(Keywords.kw_function, Keywords.kw_yield))
+        Left.isOneOf(Keywords.kw_function, Keywords.kw_yield,
+                     Keywords.kw_extends, Keywords.kw_implements))
       return true;
     // JS methods can use some keywords as names (e.g. `delete()`).
     if (Right.is(tok::l_paren) && Line.MustBeDeclaration &&
         Left.Tok.getIdentifierInfo())
       return false;
     if ((Left.isOneOf(Keywords.kw_let, Keywords.kw_var, Keywords.kw_in,
                       tok::kw_const) ||
          // "of" is only a keyword if it appears after another identifier

lib/Format/UnwrappedLineParser.cpp

void UnwrappedLineParser::parseRecord(bool ParseAsExpr) {
   // The actual identifier can be a nested name specifier, and in macros
   // it is often token-pasted.
   while (FormatTok->isOneOf(tok::identifier, tok::coloncolon, tok::hashhash,
                             tok::kw___attribute, tok::kw___declspec,
                             tok::kw_alignas) ||
          ((Style.Language == FormatStyle::LK_Java ||
            Style.Language == FormatStyle::LK_JavaScript) &&
           FormatTok->isOneOf(tok::period, tok::comma))) {
+    if (Style.Language == FormatStyle::LK_JavaScript &&
+        FormatTok->isOneOf(Keywords.kw_extends, Keywords.kw_implements)) {
+      // JavaScript/TypeScript supports inline object types in
+      // extends/implements positions:
+      //     class Foo implements {bar: number} { }
+      nextToken();
+      if (FormatTok->is(tok::l_brace)) {
+        tryToParseBracedList();
+        continue;
+      }
+    }
     bool IsNonMacroIdentifier =
         FormatTok->is(tok::identifier) &&
         FormatTok->TokenText != FormatTok->TokenText.upper();
     nextToken();
     // We can have macros or attributes in between 'class' and the class name.
     if (!IsNonMacroIdentifier && FormatTok->Tok.is(tok::l_paren))
       parseParens();
   }

unittests/Format/FormatTestJS.cpp

verifyFormat("interface a {}\n"
                "var x;");
 
   // Arrays of object type literals.
   verifyFormat("interface I {\n"
                "  o: {}[];\n"
                "}");
 }
 
+TEST_F(FormatTestJS, ObjectTypesInExtendsImplements) {
+  verifyFormat("class C extends {} {}");
+  verifyFormat("class C implements {bar: number} {}");
+  // Somewhat odd, but probably closest to reasonable formatting?
+  verifyFormat("class C implements {\n"
+               "  bar: number,\n"
+               "  baz: string,\n"
+               "} {}");
+  verifyFormat("class C<P extends {}> {}");
+}
+
 TEST_F(FormatTestJS, EnumDeclarations) {
   verifyFormat("enum Foo {\n"
                "  A = 1,\n"
                "  B\n"
                "}");
   verifyFormat("export /* somecomment*/ enum Foo {\n"
                "  A = 1,\n"
                "  B\n"