commit 48c930cb1e3400d2bf8fcdf53d786e19b96bd833
author Manuel Klimek <klimek@google.com> Mon Dec 04 08:53:16 2017 +0000
committer Manuel Klimek <klimek@google.com> Mon Dec 04 08:53:16 2017 +0000
tree f379e8d5263137f0d1f44adff916000b7199e15c
parent 4520d4f8ad017935d54c68762a0c2b1adc8b282c

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.

llvm-svn: 319642

clang/lib/Format/BreakableToken.cpp

diff --git a/clang/lib/Format/BreakableToken.cpp b/clang/lib/Format/BreakableToken.cpp
index a5fabfe..4735ab3 100644
--- a/clang/lib/Format/BreakableToken.cpp
+++ b/clang/lib/Format/BreakableToken.cpp
@@ -316,7 +316,8 @@
     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::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,

clang/lib/Format/BreakableToken.h

diff --git a/clang/lib/Format/BreakableToken.h b/clang/lib/Format/BreakableToken.h
index 8d9b2b2..8ef26ef 100644
--- a/clang/lib/Format/BreakableToken.h
+++ b/clang/lib/Format/BreakableToken.h
@@ -405,6 +405,10 @@
   // 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 {

clang/unittests/Format/FormatTestComments.cpp

diff --git a/clang/unittests/Format/FormatTestComments.cpp b/clang/unittests/Format/FormatTestComments.cpp
index 220ce08..ed11fbd 100644
--- a/clang/unittests/Format/FormatTestComments.cpp
+++ b/clang/unittests/Format/FormatTestComments.cpp
@@ -3080,6 +3080,15 @@
                    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