[clang-format] Handle parenthesized list in RemoveParentheses (#100852)

Also, reformat clang-format source to remove redundant parentheses
enclosing single list items.

Fixes #100768.

Author: owenca

clang/lib/Format/UnwrappedLineParser.cpp

@@ -2534,6 +2534,7 @@ bool UnwrappedLineParser::parseBracedList(bool IsAngleBracket, bool IsEnum) {
 bool UnwrappedLineParser::parseParens(TokenType AmpAmpTokenType) {
   assert(FormatTok->is(tok::l_paren) && "'(' expected.");
   auto *LeftParen = FormatTok;
+  bool SeenComma = false;
   bool SeenEqual = false;
   bool MightBeFoldExpr = false;
   const bool MightBeStmtExpr = Tokens->peekNextToken()->is(tok::l_brace);
@@ -2553,10 +2554,14 @@ bool UnwrappedLineParser::parseParens(TokenType AmpAmpTokenType) {
         const auto *Next = Tokens->peekNextToken();
         const bool DoubleParens =
             Prev && Prev->is(tok::l_paren) && Next && Next->is(tok::r_paren);
+        const bool CommaSeparated =
+            !DoubleParens && Prev && Prev->isOneOf(tok::l_paren, tok::comma) &&
+            Next && Next->isOneOf(tok::comma, tok::r_paren);
         const auto *PrevPrev = Prev ? Prev->getPreviousNonComment() : nullptr;
-        const bool Disallowed =
+        const bool Excluded =
             PrevPrev &&
             (PrevPrev->isOneOf(tok::kw___attribute, tok::kw_decltype) ||
+             SeenComma ||
              (SeenEqual &&
               (PrevPrev->isOneOf(tok::kw_if, tok::kw_while) ||
                PrevPrev->endsSequence(tok::kw_constexpr, tok::kw_if))));
@@ -2566,7 +2571,8 @@ bool UnwrappedLineParser::parseParens(TokenType AmpAmpTokenType) {
              (!NestedLambdas.empty() && !NestedLambdas.back())) &&
             Prev && Prev->isOneOf(tok::kw_return, tok::kw_co_return) && Next &&
             Next->is(tok::semi);
-        if ((DoubleParens && !Disallowed) || ReturnParens) {
+        if ((DoubleParens && !Excluded) || (CommaSeparated && !SeenComma) ||
+            ReturnParens) {
           LeftParen->Optional = true;
           FormatTok->Optional = true;
         }
@@ -2595,6 +2601,10 @@ bool UnwrappedLineParser::parseParens(TokenType AmpAmpTokenType) {
         parseBracedList();
       }
       break;
+    case tok::comma:
+      SeenComma = true;
+      nextToken();
+      break;
     case tok::ellipsis:
       MightBeFoldExpr = true;
       nextToken();

clang/tools/clang-format/ClangFormat.cpp

@@ -364,7 +364,7 @@ emitReplacementWarnings(const Replacements &Replaces, StringRef AssumedFileName,
                            : SourceMgr::DiagKind::DK_Warning,
           "code should be clang-formatted [-Wclang-format-violations]");
 
-      Diag.print(nullptr, llvm::errs(), (ShowColors && !NoShowColors));
+      Diag.print(nullptr, llvm::errs(), ShowColors && !NoShowColors);
       if (ErrorLimit && ++Errors >= ErrorLimit)
         break;
     }

clang/unittests/Format/FormatTest.cpp

@@ -27445,6 +27445,10 @@ TEST_F(FormatTest, RemoveParentheses) {
   verifyFormat("static_assert((std::is_constructible_v<T, Args &&> && ...));",
                "static_assert(((std::is_constructible_v<T, Args &&> && ...)));",
                Style);
+  verifyFormat("foo((a, b));", "foo(((a, b)));", Style);
+  verifyFormat("foo((a, b));", "foo(((a), b));", Style);
+  verifyFormat("foo((a, b));", "foo((a, (b)));", Style);
+  verifyFormat("foo((a, b, c));", "foo((a, ((b)), c));", Style);
   verifyFormat("return (0);", "return (((0)));", Style);
   verifyFormat("return (({ 0; }));", "return ((({ 0; })));", Style);
   verifyFormat("return ((... && std::is_convertible_v<TArgsLocal, TArgs>));",

clang/unittests/Format/MatchFilePathTest.cpp

@@ -53,7 +53,7 @@ TEST_F(MatchFilePathTest, Newline) {
 
 TEST_F(MatchFilePathTest, Star) {
   EXPECT_TRUE(match(std::string(50, 'a'), "*a*a*a*a*a*a*a*a*a*a"));
-  EXPECT_FALSE(match((std::string(50, 'a') + 'b'), "*a*a*a*a*a*a*a*a*a*a"));
+  EXPECT_FALSE(match(std::string(50, 'a') + 'b', "*a*a*a*a*a*a*a*a*a*a"));
 }
 
 TEST_F(MatchFilePathTest, CaseSensitive) {