[clang-format] Fix incorrect indentation of C++ constructor initializer list

[owenpan]

Summary

See https://bugs.llvm.org/show_bug.cgi?id=41407 for more info.

[MyDeveloperDay]

Thanks for doing this, it LGTM, I like your solution better ;-)

I will abandon D60361: [clang-format] [PR41407] Constructor initializer list indented incorrectly

clang/lib/Format/ContinuationIndenter.cpp

if (NextNonComment->isOneOf(TT_CtorInitializerColon, TT_InheritanceColon,
                               TT_InheritanceComma))
     return State.FirstIndent + Style.ConstructorInitializerIndentWidth;
   if (Previous.is(tok::r_paren) && !Current.isBinaryOperator() &&
       !Current.isOneOf(tok::colon, tok::comment))
     return ContinuationIndent;
   if (Current.is(TT_ProtoExtensionLSquare))
     return State.Stack.back().Indent;
   if (State.Stack.back().Indent == State.FirstIndent && PreviousNonComment &&
-      PreviousNonComment->isNot(tok::r_brace))
+      !PreviousNonComment->isOneOf(tok::r_brace, TT_CtorInitializerComma))
     // Ensure that we fall back to the continuation indent width instead of
     // just flushing continuations left.
     return State.Stack.back().Indent + Style.ContinuationIndentWidth;
   return State.Stack.back().Indent;
 }
 
 unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
                                                     bool DryRun, bool Newline) {

clang/unittests/Format/FormatTest.cpp

TEST_F(FormatTest, ConstructorInitializerIndentWidth) {
   verifyFormat(
       "SomeLongTemplateVariableName<\n"
       "    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaa, aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa>",
       Style);
   verifyFormat(
       "bool smaller = 1 < bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb(\n"
       "                       aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa);",
       Style);
+
+  Style.BreakConstructorInitializers = FormatStyle::BCIS_AfterColon;
+  verifyFormat(
+      "SomeClass::Constructor() :\n"
+      "aaaaaaaaaaaaaaaaaaaa(aaaaaaaaaaaaaaaaaaaa),\n"
+      "aaaaaaaaaaaaaaaaaaaa(aaaaaaaaaaaaaaaaaaaa) {}",
+      Style);
 }
 
 TEST_F(FormatTest, BreakConstructorInitializersBeforeComma) {
   FormatStyle Style = getLLVMStyle();
   Style.BreakConstructorInitializers = FormatStyle::BCIS_BeforeComma;
   Style.ConstructorInitializerIndentWidth = 4;
   verifyFormat("SomeClass::Constructor()\n"
                "    : a(a)\n"