Fix formatting of if statements with BlockIndent

A bug with BlockIndent prevents line breaks within if (and else if) clauses.
While fixing this bug, it appears that AlignAfterOpenBracket is not designed
to work with loop and if statements, but AlwaysBreak works on if clauses.
The documentation and tests are not clear on whether or not this is intended.
This patch preserves the AlwaysBreak behavior and supports BlockIndent on if
clauses while fixing the bug.

It may be reasonable to go the other way and create an explicit option for
alignment of if (and loop) clauses intentionally.

Fixes llvm#54663.

Differential Revision: https://reviews.llvm.org/D154755

Author: gedare

clang/lib/Format/ContinuationIndenter.cpp

@@ -775,8 +775,10 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
         Style.Cpp11BracedListStyle)) &&
       State.Column > getNewLineColumn(State) &&
       (!Previous.Previous ||
-       !Previous.Previous->isOneOf(TT_CastRParen, tok::kw_for, tok::kw_while,
-                                   tok::kw_switch)) &&
+       !(Previous.Previous->isOneOf(TT_CastRParen, tok::kw_for, tok::kw_while,
+                                    tok::kw_switch) ||
+         (Style.AlignAfterOpenBracket == FormatStyle::BAS_BlockIndent &&
+          Previous.Previous->isIf()))) &&
       // Don't do this for simple (no expressions) one-argument function calls
       // as that feels like needlessly wasting whitespace, e.g.:
       //

clang/unittests/Format/FormatTest.cpp

@@ -25889,8 +25889,8 @@ TEST_F(FormatTest, AlignAfterOpenBracketBlockIndentIfStatement) {
                "}",
                Style);
 
-  verifyFormat("if (quitelongarg !=\n"
-               "    (alsolongarg - 1)) { // ABC is a very longgggggggggggg "
+  verifyFormat("if (quiteLongArg !=\n"
+               "    (alsoLongArg - 1)) { // ABC is a very longgggggggggggg "
                "comment\n"
                "  return;\n"
                "}",
@@ -25903,12 +25903,44 @@ TEST_F(FormatTest, AlignAfterOpenBracketBlockIndentIfStatement) {
                "}",
                Style);
 
-  verifyFormat("if (quitelongarg !=\n"
-               "    (alsolongarg - 1)) { // ABC is a very longgggggggggggg "
+  verifyFormat("if (quiteLongArg !=\n"
+               "    (alsoLongArg - 1)) { // ABC is a very longgggggggggggg "
                "comment\n"
                "  return;\n"
                "}",
                Style);
+
+  verifyFormat("void foo() {\n"
+               "  if (camelCaseName < alsoLongName ||\n"
+               "      anotherEvenLongerName <=\n"
+               "          thisReallyReallyReallyReallyReallyReallyLongerName ||"
+               "\n"
+               "      otherName < thisLastName) {\n"
+               "    return;\n"
+               "  } else if (quiteLongName < alsoLongName ||\n"
+               "             anotherEvenLongerName <=\n"
+               "                 thisReallyReallyReallyReallyReallyReallyLonger"
+               "Name ||\n"
+               "             otherName < thisLastName) {\n"
+               "    return;\n"
+               "  }\n"
+               "}",
+               Style);
+
+  Style.ContinuationIndentWidth = 2;
+  verifyFormat("void foo() {\n"
+               "  if (ThisIsRatherALongIfClause && thatIExpectToBeBroken ||\n"
+               "      ontoMultipleLines && whenFormattedCorrectly) {\n"
+               "    if (false) {\n"
+               "      return;\n"
+               "    } else if (thisIsRatherALongIfClause && "
+               "thatIExpectToBeBroken ||\n"
+               "               ontoMultipleLines && whenFormattedCorrectly) {\n"
+               "      return;\n"
+               "    }\n"
+               "  }\n"
+               "}",
+               Style);
 }
 
 TEST_F(FormatTest, AlignAfterOpenBracketBlockIndentForStatement) {