[clang-format] Break on AfterColon only if not followed by comment

[owenpan]

Summary

Break after a constructor initializer colon only if it's not followed by a
comment on the same line.

Fixes https://github.com/llvm/llvm-project/issues/41128.
Fixes https://github.com/llvm/llvm-project/issues/43246.

[curdeius]

clang/unittests/Format/FormatTest.cpp

7103

You should add a test without modifying an existing one.

[curdeius]

clang/unittests/Format/FormatTest.cpp

7144

How about very long comments? They don't get split now? Please add a test case

[owenpan]

Handle PackContructorInitializers: NextLine and address review comments.

[curdeius]

LGTM. Thanks for addressing my comments.

[MyDeveloperDay]

LGTM

[owenpan]

In D129057#3627748, @curdeius wrote:

LGTM. Thanks for addressing my comments.

Thank you for your quick review and good comments as always!

clang/unittests/Format/FormatTest.cpp

7144

Now trailing comments don't wrap after the colon, but long ones still get split and aligned as usual.

clang/lib/Format/ContinuationIndenter.cpp

bool ContinuationIndenter::mustBreak(const LineState &State) {
   const FormatToken &BreakConstructorInitializersToken =
       Style.BreakConstructorInitializers == FormatStyle::BCIS_AfterColon
           ? Previous
           : Current;
   if (BreakConstructorInitializersToken.is(TT_CtorInitializerColon) &&
       (State.Column + State.Line->Last->TotalLength - Previous.TotalLength >
            getColumnLimit(State) ||
        CurrentState.BreakBeforeParameter) &&
+      (!Current.isTrailingComment() || Current.NewlinesBefore > 0) &&
       (Style.AllowShortFunctionsOnASingleLine != FormatStyle::SFS_All ||
        Style.BreakConstructorInitializers != FormatStyle::BCIS_BeforeColon ||
        Style.ColumnLimit != 0)) {
     return true;
   }
 
   if (Current.is(TT_ObjCMethodExpr) && !Previous.is(TT_SelectorName) &&
       State.Line->startsWith(TT_ObjCMethodSpecifier)) {
if (Current.isNot(tok::comment) && Previous.is(tok::l_paren) &&
     CurrentState.LastSpace = State.Column;
     CurrentState.NestedBlockIndent = State.Column;
   } else if (!Current.isOneOf(tok::comment, tok::caret) &&
              ((Previous.is(tok::comma) &&
                !Previous.is(TT_OverloadedOperator)) ||
               (Previous.is(tok::colon) && Previous.is(TT_ObjCMethodExpr)))) {
     CurrentState.LastSpace = State.Column;
   } else if (Previous.is(TT_CtorInitializerColon) &&
+             (!Current.isTrailingComment() || Current.NewlinesBefore > 0) &&
              Style.BreakConstructorInitializers ==
                  FormatStyle::BCIS_AfterColon) {
     CurrentState.Indent = State.Column;
     CurrentState.LastSpace = State.Column;
   } else if ((Previous.isOneOf(TT_BinaryOperator, TT_ConditionalExpr,
                                TT_CtorInitializerColon)) &&
              ((Previous.getPrecedence() != prec::Assignment &&
                (Previous.isNot(tok::lessless) || Previous.OperatorIndex != 0 ||
unsigned ContinuationIndenter::addTokenOnNewLine(LineState &State,
   }
 
   if (CurrentState.AvoidBinPacking) {
     // If we are breaking after '(', '{', '<', or this is the break after a ':'
     // to start a member initializater list in a constructor, this should not
     // be considered bin packing unless the relevant AllowAll option is false or
     // this is a dict/object literal.
     bool PreviousIsBreakingCtorInitializerColon =
-        Previous.is(TT_CtorInitializerColon) &&
+        PreviousNonComment && PreviousNonComment->is(TT_CtorInitializerColon) &&
         Style.BreakConstructorInitializers == FormatStyle::BCIS_AfterColon;
     if (!(Previous.isOneOf(tok::l_paren, tok::l_brace, TT_BinaryOperator) ||
           PreviousIsBreakingCtorInitializerColon) ||
         (!Style.AllowAllParametersOfDeclarationOnNextLine &&
          State.Line->MustBeDeclaration) ||
         (!Style.AllowAllArgumentsOnNextLine &&
          !State.Line->MustBeDeclaration) ||
         (Style.PackConstructorInitializers != FormatStyle::PCIS_NextLine &&

clang/lib/Format/TokenAnnotator.cpp

if (Left.is(TT_PointerOrReference))
     return false;
   if (Right.isTrailingComment()) {
     // We rely on MustBreakBefore being set correctly here as we should not
     // change the "binding" behavior of a comment.
     // The first comment in a braced lists is always interpreted as belonging to
     // the first list element. Otherwise, it should be placed outside of the
     // list.
     return Left.is(BK_BracedInit) ||
-           (Left.is(TT_CtorInitializerColon) &&
+           (Left.is(TT_CtorInitializerColon) && Right.NewlinesBefore > 0 &&
             Style.BreakConstructorInitializers == FormatStyle::BCIS_AfterColon);
   }
   if (Left.is(tok::question) && Right.is(tok::colon))
     return false;
   if (Right.is(TT_ConditionalExpr) || Right.is(tok::question))
     return Style.BreakBeforeTernaryOperators;
   if (Left.is(TT_ConditionalExpr) || Left.is(tok::question))
     return !Style.BreakBeforeTernaryOperators;
bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
   }
 
   if (Left.is(tok::identifier) && Right.is(tok::string_literal))
     return true;
 
   if (Right.is(tok::identifier) && Right.Next && Right.Next->is(TT_DictLiteral))
     return true;
 
-  if (Left.is(TT_CtorInitializerColon))
-    return Style.BreakConstructorInitializers == FormatStyle::BCIS_AfterColon;
+  if (Left.is(TT_CtorInitializerColon)) {
+    return Style.BreakConstructorInitializers == FormatStyle::BCIS_AfterColon &&
+           (!Right.isTrailingComment() || Right.NewlinesBefore > 0);
+  }
   if (Right.is(TT_CtorInitializerColon))
     return Style.BreakConstructorInitializers != FormatStyle::BCIS_AfterColon;
   if (Left.is(TT_CtorInitializerComma) &&
       Style.BreakConstructorInitializers == FormatStyle::BCIS_BeforeComma) {
     return false;
   }
   if (Right.is(TT_CtorInitializerComma) &&
       Style.BreakConstructorInitializers == FormatStyle::BCIS_BeforeComma) {

clang/unittests/Format/FormatTest.cpp

TEST_F(FormatTest, BreakConstructorInitializersAfterColon) {
   verifyFormat("template <typename T>\n"
                "Constructor() : Initializer(FitsOnTheLine) {}",
                getStyleWithColumns(Style, 50));
   Style.PackConstructorInitializers = FormatStyle::PCIS_NextLine;
   verifyFormat(
       "SomeClass::Constructor() :\n"
       "    aaaaaaaaaaaaa(aaaaaaaaaaaaaa), aaaaaaaaaaaaaaa(aaaaaaaaaaaa) {}",
       Style);
+  verifyFormat(
+      "SomeClass::Constructor() : // NOLINT\n"
+      "    aaaaaaaaaaaaa(aaaaaaaaaaaaaa), aaaaaaaaaaaaaaa(aaaaaaaaaaaa) {}",
+      Style);
 
   Style.PackConstructorInitializers = FormatStyle::PCIS_BinPack;
   verifyFormat(
       "SomeClass::Constructor() :\n"
       "    aaaaaaaaaaaaa(aaaaaaaaaaaaaa), aaaaaaaaaaaaaaa(aaaaaaaaaaaa) {}",
       Style);
 
   verifyFormat(
TEST_F(FormatTest, BreakConstructorInitializersAfterColon) {
 
   FormatStyle OnePerLine = Style;
   OnePerLine.PackConstructorInitializers = FormatStyle::PCIS_CurrentLine;
   verifyFormat("SomeClass::Constructor() :\n"
                "    aaaaaaaaaaaaa(aaaaaaaaaaaaaa),\n"
                "    aaaaaaaaaaaaa(aaaaaaaaaaaaaa),\n"
                "    aaaaaaaaaaaaa(aaaaaaaaaaaaaa) {}",
                OnePerLine);
   verifyFormat("SomeClass::Constructor() :\n"
                "    aaaaaaaaaaaaa(aaaaaaaaaaaaaa), // Some comment\n"
                "    aaaaaaaaaaaaa(aaaaaaaaaaaaaa),\n"
                "    aaaaaaaaaaaaa(aaaaaaaaaaaaaa) {}",
                OnePerLine);
+  verifyFormat("Foo::Foo(int i, int j) : // NOLINT\n"
+               "    i(i),                // comment\n"
+               "    j(j) {}",
+               OnePerLine);
   verifyFormat("MyClass::MyClass(int var) :\n"
                "    some_var_(var),            // 4 space indent\n"
                "    some_other_var_(var + 1) { // lined up\n"
                "}",
                OnePerLine);
   verifyFormat("Constructor() :\n"
                "    aaaaa(aaaaaa),\n"
                "    aaaaa(aaaaaa),\n"
verifyFormat("Constructor() :\n"
                "    aaaaaaaaaaaaaaaaaaaa(a),\n"
                "    bbbbbbbbbbbbbbbbbbbbbbbb(b) {}",
                OnePerLine);
 
   verifyFormat("Constructor() :\n"
                "    // Comment forcing unwanted break.\n"
                "    aaaa(aaaa) {}",
                Style);
+  verifyFormat("Constructor() : // NOLINT\n"
+               "    aaaa(aaaa) {}",
+               Style);
+  verifyFormat("Constructor() : // A very long trailing comment that cannot fit"
+               " on a single\n"
+               "                // line.\n"
+               "    aaaa(aaaa) {}",
+               "Constructor() : // A very long trailing comment that cannot fit"
+               " on a single line.\n"
+               "    aaaa(aaaa) {}",
+               Style);
 
   Style.ColumnLimit = 0;
   verifyFormat("SomeClass::Constructor() :\n"
                "    a(a) {}",
                Style);
   verifyFormat("SomeClass::Constructor() noexcept :\n"
                "    a(a) {}",
                Style);