r236589 - clang-format: Fix another assertion discovered by the fuzzer.

[Daniel Jasper]

Author: djasper
Date: Wed May  6 06:16:43 2015
New Revision: 236589

URL: http://llvm.org/viewvc/llvm-project?rev=236589&view=rev
Log:
clang-format: Fix another assertion discovered by the fuzzer.

In the process, fix an old todo that I don't really know how to write
tests for. The problem is that Clang's lexer creates very strange token
sequences for these. However, the new approach seems generally better
and easier to read so I am submitting it nonetheless.

Modified:
    cfe/trunk/lib/Format/Format.cpp
    cfe/trunk/unittests/Format/FormatTest.cpp

Modified: cfe/trunk/lib/Format/Format.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Format/Format.cpp?rev=236589&r1=236588&r2=236589&view=diff
==============================================================================
--- cfe/trunk/lib/Format/Format.cpp (original)
+++ cfe/trunk/lib/Format/Format.cpp Wed May  6 06:16:43 2015
@@ -1000,18 +1000,25 @@ private:
     // Consume and record whitespace until we find a significant token.
     unsigned WhitespaceLength = TrailingWhitespace;
     while (FormatTok->Tok.is(tok::unknown)) {
+      StringRef Text = FormatTok->TokenText;
+      auto EscapesNewline = [&](int pos) {
+        // A '\r' here is just part of '\r\n'. Skip it.
+        if (pos >= 0 && Text[pos] == '\r')
+          --pos;
+        // See whether there is an odd number of '\' before this.
+        unsigned count = 0;
+        for (; pos >= 0; --pos, ++count)
+          if (Text[count] != '\\')
+            break;
+        return count & 1;
+      };
       // FIXME: This miscounts tok:unknown tokens that are not just
       // whitespace, e.g. a '`' character.
-      for (int i = 0, e = FormatTok->TokenText.size(); i != e; ++i) {
-        switch (FormatTok->TokenText[i]) {
+      for (int i = 0, e = Text.size(); i != e; ++i) {
+        switch (Text[i]) {
         case '\n':
           ++FormatTok->NewlinesBefore;
-          // FIXME: This is technically incorrect, as it could also
-          // be a literal backslash at the end of the line.
-          if (i == 0 || (FormatTok->TokenText[i - 1] != '\\' &&
-                         (FormatTok->TokenText[i - 1] != '\r' || i == 1 ||
-                          FormatTok->TokenText[i - 2] != '\\')))
-            FormatTok->HasUnescapedNewline = true;
+          FormatTok->HasUnescapedNewline = !EscapesNewline(i - 1);
           FormatTok->LastNewlineOffset = WhitespaceLength + i + 1;
           Column = 0;
           break;
@@ -1030,8 +1037,7 @@ private:
           Column += Style.TabWidth - Column % Style.TabWidth;
           break;
         case '\\':
-          if (i + 1 == e || (FormatTok->TokenText[i + 1] != '\r' &&
-                             FormatTok->TokenText[i + 1] != '\n'))
+          if (i + 1 == e || (Text[i + 1] != '\r' && Text[i + 1] != '\n'))
             FormatTok->Type = TT_ImplicitStringLiteral;
           break;
         default:
@@ -1056,6 +1062,7 @@ private:
            FormatTok->TokenText[1] == '\n') {
       ++FormatTok->NewlinesBefore;
       WhitespaceLength += 2;
+      FormatTok->LastNewlineOffset = 2;
       Column = 0;
       FormatTok->TokenText = FormatTok->TokenText.substr(2);
     }

Modified: cfe/trunk/unittests/Format/FormatTest.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/unittests/Format/FormatTest.cpp?rev=236589&r1=236588&r2=236589&view=diff
==============================================================================
--- cfe/trunk/unittests/Format/FormatTest.cpp (original)
+++ cfe/trunk/unittests/Format/FormatTest.cpp Wed May  6 06:16:43 2015
@@ -2951,15 +2951,13 @@ TEST_F(FormatTest, FormatUnbalancedStruc
             format("#define A } }\nint i;", getLLVMStyleWithColumns(11)));
 }
 
-TEST_F(FormatTest, EscapedNewlineAtStartOfToken) {
+TEST_F(FormatTest, EscapedNewlines) {
   EXPECT_EQ(
       "#define A \\\n  int i;  \\\n  int j;",
       format("#define A \\\nint i;\\\n  int j;", getLLVMStyleWithColumns(11)));
   EXPECT_EQ("template <class T> f();", format("\\\ntemplate <class T> f();"));
-}
-
-TEST_F(FormatTest, NoEscapedNewlineHandlingInBlockComments) {
   EXPECT_EQ("/* \\  \\  \\\n*/", format("\\\n/* \\  \\  \\\n*/"));
+  EXPECT_EQ("<a\n\\\\\n>", format("<a\n\\\\\n>"));
 }
 
 TEST_F(FormatTest, DontCrashOnBlockComments) {