r319642 - Fix bug where we wouldn't break columns over the limit.

[Manuel Klimek via cfe-commits]

Author: klimek
Date: Mon Dec  4 00:53:16 2017
New Revision: 319642

URL: http://llvm.org/viewvc/llvm-project?rev=319642&view=rev
Log:
Fix bug where we wouldn't break columns over the limit.

Before, we would not break:
  int a = foo(/* trailing */);
when the end of /* trailing */ was exactly the column limit; the reason
is that block comments can have an unbreakable tail length - in this case
2, for the trailing ");"; we would unconditionally account that when
calculating the column state at the end of the token, but not correctly
add it into the remaining column length before, as we do for string
literals.
The fix is to correctly account the trailing unbreakable sequence length
into our formatting decisions for block comments. Line comments cannot
have a trailing unbreakable sequence, so no change is needed for them.

Modified:
    cfe/trunk/lib/Format/BreakableToken.cpp
    cfe/trunk/lib/Format/BreakableToken.h
    cfe/trunk/unittests/Format/FormatTestComments.cpp

Modified: cfe/trunk/lib/Format/BreakableToken.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Format/BreakableToken.cpp?rev=319642&r1=319641&r2=319642&view=diff
==============================================================================
--- cfe/trunk/lib/Format/BreakableToken.cpp (original)
+++ cfe/trunk/lib/Format/BreakableToken.cpp Mon Dec  4 00:53:16 2017
@@ -316,7 +316,8 @@ BreakableBlockComment::BreakableBlockCom
     unsigned OriginalStartColumn, bool FirstInLine, bool InPPDirective,
     encoding::Encoding Encoding, const FormatStyle &Style)
     : BreakableComment(Token, StartColumn, InPPDirective, Encoding, Style),
-      DelimitersOnNewline(false) {
+      DelimitersOnNewline(false),
+      UnbreakableTailLength(Token.UnbreakableTailLength) {
   assert(Tok.is(TT_BlockComment) &&
          "block comment section must start with a block comment");
 
@@ -497,7 +498,8 @@ unsigned BreakableBlockComment::getRange
 unsigned BreakableBlockComment::getRemainingLength(unsigned LineIndex,
                                                    unsigned Offset,
                                                    unsigned StartColumn) const {
-  return getRangeLength(LineIndex, Offset, StringRef::npos, StartColumn);
+  return UnbreakableTailLength +
+         getRangeLength(LineIndex, Offset, StringRef::npos, StartColumn);
 }
 
 unsigned BreakableBlockComment::getContentStartColumn(unsigned LineIndex,

Modified: cfe/trunk/lib/Format/BreakableToken.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Format/BreakableToken.h?rev=319642&r1=319641&r2=319642&view=diff
==============================================================================
--- cfe/trunk/lib/Format/BreakableToken.h (original)
+++ cfe/trunk/lib/Format/BreakableToken.h Mon Dec  4 00:53:16 2017
@@ -405,6 +405,10 @@ private:
   // If true, make sure that the opening '/**' and the closing '*/' ends on a
   // line of itself. Styles like jsdoc require this for multiline comments.
   bool DelimitersOnNewline;
+
+  // Length of the sequence of tokens after this string literal that cannot
+  // contain line breaks.
+  unsigned UnbreakableTailLength;
 };
 
 class BreakableLineCommentSection : public BreakableComment {

Modified: cfe/trunk/unittests/Format/FormatTestComments.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/unittests/Format/FormatTestComments.cpp?rev=319642&r1=319641&r2=319642&view=diff
==============================================================================
--- cfe/trunk/unittests/Format/FormatTestComments.cpp (original)
+++ cfe/trunk/unittests/Format/FormatTestComments.cpp Mon Dec  4 00:53:16 2017
@@ -3080,6 +3080,15 @@ TEST_F(FormatTestComments, PythonStyleCo
                    getTextProtoStyleWithColumns(20)));
 }
 
+TEST_F(FormatTestComments, BreaksBeforeTrailingUnbreakableSequence) {
+  // The end of /* trail */ is exactly at 80 columns, but the unbreakable
+  // trailing sequence ); after it exceeds the column limit. Make sure we
+  // correctly break the line in that case.
+  verifyFormat("int a =\n"
+               "    foo(/* trail */);",
+               getLLVMStyleWithColumns(23));
+}
+
 } // end namespace
 } // end namespace format
 } // end namespace clang