Prevent only breaking before "?" in conditional expressions.

This is almost always more readable.

Before:
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
    ? aaaaaaaaaaaaaaaaaaaaaaaaaaa : aaaaaaaaaaaaaaaaaaaaaaaaaaa;

After:
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
    ? aaaaaaaaaaaaaaaaaaaaaaaaaaa
    : aaaaaaaaaaaaaaaaaaaaaaaaaaa;

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@175262 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 25 insertions, 5 deletions

diff --git a/lib/Format/Format.cpp b/lib/Format/Format.cpp
index 92c138aa7e..4b63aa9322 100644
--- a/lib/Format/Format.cpp
+++ b/lib/Format/Format.cpp
@@ -290,7 +290,8 @@ private:
         : Indent(Indent), LastSpace(LastSpace), FirstLessLess(0),
           BreakBeforeClosingBrace(false), QuestionColumn(0),
           AvoidBinPacking(AvoidBinPacking), BreakBeforeParameter(false),
-          HasMultiParameterLine(HasMultiParameterLine), ColonPos(0) {
+          HasMultiParameterLine(HasMultiParameterLine), ColonPos(0),
+          BreakBeforeThirdOperand(false) {
     }
 
     /// \brief The position to which a specific parenthesis level needs to be
@@ -333,6 +334,9 @@ private:
 
     /// \brief The position of the colon in an ObjC method declaration/call.
     unsigned ColonPos;
+    
+    /// \brief Break before third operand in ternary expression.
+    bool BreakBeforeThirdOperand;
 
     bool operator<(const ParenState &Other) const {
       if (Indent != Other.Indent)
@@ -353,6 +357,8 @@ private:
         return HasMultiParameterLine;
       if (ColonPos != Other.ColonPos)
         return ColonPos < Other.ColonPos;
+      if (BreakBeforeThirdOperand != Other.BreakBeforeThirdOperand)
+        return BreakBeforeThirdOperand;
       return false;
     }
   };
@@ -465,6 +471,8 @@ private:
         State.Column = State.Stack.back().Indent;
       }
 
+      if (Current.is(tok::question))
+        State.Stack.back().BreakBeforeThirdOperand = true;
       if (Previous.is(tok::comma) && !State.Stack.back().AvoidBinPacking)
         State.Stack.back().BreakBeforeParameter = false;
 
@@ -794,6 +802,9 @@ private:
          (State.NextToken->Parent->ClosesTemplateDeclaration &&
           State.ParenLevel == 0)))
       return true;
+    if (State.NextToken->is(tok::colon) &&
+        State.Stack.back().BreakBeforeThirdOperand)
+      return true;
     return false;
   }
 
diff --git a/unittests/Format/FormatTest.cpp b/unittests/Format/FormatTest.cpp
index 9dab260512..8c45325ecc 100644
--- a/unittests/Format/FormatTest.cpp
+++ b/unittests/Format/FormatTest.cpp
@@ -1323,11 +1323,20 @@ TEST_F(FormatTest, BreaksConditionalExpressions) {
                "           : aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa(\n"
                "                 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa),\n"
                "       aaaaaaaaaaaaaaaaaaaaaaaaaaa);");
+
+  verifyFormat("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n"
+               "    ? aaaaaaaaaaaaaaaaaaaaaaaaaaa\n"
+               "    : aaaaaaaaaaaaaaaaaaaaaaaaaaa;");
+
+  // FIXME: The trailing third parameter here is kind of hidden. Prefer putting
+  // it on the next line.
   verifyFormat(
-      "unsigned Indent = formatFirstToken(\n"
-      "    TheLine.First, IndentForLevel[TheLine.Level] >= 0\n"
-      "                       ? IndentForLevel[TheLine.Level] : TheLine * 2,\n"
-      "    TheLine.InPPDirective, PreviousEndOfLineColumn);");
+      "unsigned Indent =\n"
+      "    format(TheLine.First, IndentForLevel[TheLine.Level] >= 0\n"
+      "                              ? IndentForLevel[TheLine.Level]\n"
+      "                              : TheLine * 2, TheLine.InPPDirective,\n"
+      "           PreviousEndOfLineColumn);", getLLVMStyleWithColumns(70));
+
 }
 
 TEST_F(FormatTest, DeclarationsOfMultipleVariables) {