[clang-format] Stop ctor initializer from being inlined (#150361)

The colon in a constructor's initializer list triggers the inlining of a
nested block as if it was a conditional operator expression. This
prevents line breaks under certain circumstances when the initializer
list contains braced initializers, which in turn prevents the line
formatter from finding a solution.

In this commit we exclude colons that are a constructor initializer
colon from consideration of nested block inlining.

Fixes #97242.
Fixes #81822.

Author: tJener

clang/lib/Format/ContinuationIndenter.cpp

@@ -1725,7 +1725,8 @@ unsigned ContinuationIndenter::moveStateToNextToken(LineState &State,
   }
   if (Previous && (Previous->isOneOf(TT_BinaryOperator, TT_ConditionalExpr) ||
                    (Previous->isOneOf(tok::l_paren, tok::comma, tok::colon) &&
-                    !Previous->isOneOf(TT_DictLiteral, TT_ObjCMethodExpr)))) {
+                    !Previous->isOneOf(TT_DictLiteral, TT_ObjCMethodExpr,
+                                       TT_CtorInitializerColon)))) {
     CurrentState.NestedBlockInlined =
         !Newline && hasNestedBlockInlined(Previous, Current, Style);
   }

clang/unittests/Format/FormatTest.cpp

@@ -7783,6 +7783,16 @@ TEST_F(FormatTest, ConstructorInitializers) {
                "Constructor() :\n"
                "    // Comment forcing unwanted break.\n"
                "    aaaa(aaaa) {}");
+
+  // Braced initializers with trailing commas.
+  verifyFormat("MyClass::MyClass()\n"
+               "    : aaaa{\n"
+               "          0,\n"
+               "      },\n"
+               "      bbbb{\n"
+               "          0,\n"
+               "      } {}",
+               "MyClass::MyClass():aaaa{0,},bbbb{0,}{}");
 }
 
 TEST_F(FormatTest, AllowAllConstructorInitializersOnNextLine) {