[PATCH] Avoid column limit violation in block comments in certain cases.

[Alexander Kornienko]

Hi djasper,

Add penalty when an excessively long line in a block comment can not be
broken on a leading whitespace. Lack of this addition can lead to severe column
width violations when they can be easily avoided.

http://llvm-reviews.chandlerc.com/D1071

Files:
  lib/Format/Format.cpp
  unittests/Format/FormatTest.cpp

Index: lib/Format/Format.cpp
===================================================================
--- lib/Format/Format.cpp
+++ lib/Format/Format.cpp
@@ -854,8 +854,13 @@
       while (RemainingTokenColumns > RemainingSpace) {
         BreakableToken::Split Split =
             Token->getSplit(LineIndex, TailOffset, getColumnLimit());
-        if (Split.first == StringRef::npos)
+        if (Split.first == StringRef::npos) {
+          // Penalty for the last line will be added outside.
+          if (LineIndex < EndIndex - 1)
+            Penalty += Style.PenaltyExcessCharacter *
+                       (RemainingTokenColumns - RemainingSpace);
           break;
+        }
         assert(Split.first != 0);
         unsigned NewRemainingTokenColumns = Token->getLineLengthAfterSplit(
             LineIndex, TailOffset + Split.first + Split.second,
Index: unittests/Format/FormatTest.cpp
===================================================================
--- unittests/Format/FormatTest.cpp
+++ unittests/Format/FormatTest.cpp
@@ -841,6 +841,23 @@
             "              aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa */",
             format("double *x; /* aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n"
                    "              aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa */"));
+  EXPECT_EQ(
+      "void ffffffffffff(\n"
+      "    int aaaaaaaa, int bbbbbbbb,\n"
+      "    int cccccccccccc) { /*\n"
+      "                           aaaaaaaaaa\n"
+      "                           aaaaaaaaaaaaa\n"
+      "                           bbbbbbbbbbbbbb\n"
+      "                           bbbbbbbbbb\n"
+      "                         */\n"
+      "}",
+      format("void ffffffffffff(int aaaaaaaa, int bbbbbbbb, int cccccccccccc)\n"
+             "{ /*\n"
+             "     aaaaaaaaaa aaaaaaaaaaaaa\n"
+             "     bbbbbbbbbbbbbb bbbbbbbbbb\n"
+             "   */\n"
+             "}",
+             getLLVMStyleWithColumns(40)));
 }
 
 TEST_F(FormatTest, SplitsLongCxxComments) {
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