[clang-format] Don't remove parentheses of fold expressions (#91045)

Fixes #90966.

Author: owenca

clang/lib/Format/UnwrappedLineParser.cpp

@@ -2511,6 +2511,7 @@ bool UnwrappedLineParser::parseParens(TokenType AmpAmpTokenType) {
   assert(FormatTok->is(tok::l_paren) && "'(' expected.");
   auto *LeftParen = FormatTok;
   bool SeenEqual = false;
+  bool MightBeFoldExpr = false;
   const bool MightBeStmtExpr = Tokens->peekNextToken()->is(tok::l_brace);
   nextToken();
   do {
@@ -2522,7 +2523,7 @@ bool UnwrappedLineParser::parseParens(TokenType AmpAmpTokenType) {
         parseChildBlock();
       break;
     case tok::r_paren:
-      if (!MightBeStmtExpr && !Line->InMacroBody &&
+      if (!MightBeStmtExpr && !MightBeFoldExpr && !Line->InMacroBody &&
           Style.RemoveParentheses > FormatStyle::RPS_Leave) {
         const auto *Prev = LeftParen->Previous;
         const auto *Next = Tokens->peekNextToken();
@@ -2565,6 +2566,10 @@ bool UnwrappedLineParser::parseParens(TokenType AmpAmpTokenType) {
         parseBracedList();
       }
       break;
+    case tok::ellipsis:
+      MightBeFoldExpr = true;
+      nextToken();
+      break;
     case tok::equal:
       SeenEqual = true;
       if (Style.isCSharp() && FormatTok->is(TT_FatArrow))

clang/unittests/Format/FormatTest.cpp

@@ -27204,15 +27204,24 @@ TEST_F(FormatTest, RemoveParentheses) {
                "if ((({ a; })))\n"
                "  b;",
                Style);
+  verifyFormat("static_assert((std::is_constructible_v<T, Args &&> && ...));",
+               "static_assert(((std::is_constructible_v<T, Args &&> && ...)));",
+               Style);
   verifyFormat("return (0);", "return (((0)));", Style);
   verifyFormat("return (({ 0; }));", "return ((({ 0; })));", Style);
+  verifyFormat("return ((... && std::is_convertible_v<TArgsLocal, TArgs>));",
+               "return (((... && std::is_convertible_v<TArgsLocal, TArgs>)));",
+               Style);
 
   Style.RemoveParentheses = FormatStyle::RPS_ReturnStatement;
   verifyFormat("#define Return0 return (0);", Style);
   verifyFormat("return 0;", "return (0);", Style);
   verifyFormat("co_return 0;", "co_return ((0));", Style);
   verifyFormat("return 0;", "return (((0)));", Style);
   verifyFormat("return ({ 0; });", "return ((({ 0; })));", Style);
+  verifyFormat("return (... && std::is_convertible_v<TArgsLocal, TArgs>);",
+               "return (((... && std::is_convertible_v<TArgsLocal, TArgs>)));",
+               Style);
   verifyFormat("inline decltype(auto) f() {\n"
                "  if (a) {\n"
                "    return (a);\n"