Improve handling of trailing 'const'.

Reduce the preference for breaking before a trailing 'const' according
to review comments on r182362.

llvm-svn: 182455

clang/lib/Format/TokenAnnotator.cpp

@@ -959,6 +959,10 @@ unsigned TokenAnnotator::splitPenalty(const AnnotatedLine &Line,
     return 150;
   }
 
+  // Breaking before a trailing 'const' is bad.
+  if (Left.is(tok::r_paren) && Right.is(tok::kw_const))
+    return 150;
+
   // In for-loops, prefer breaking at ',' and ';'.
   if (Line.First.is(tok::kw_for) && Left.is(tok::equal))
     return 4;
@@ -1165,6 +1169,11 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
     // change the "binding" behavior of a comment.
     return false;
 
+  // We only break before r_brace if there was a corresponding break before
+  // the l_brace, which is tracked by BreakBeforeClosingBrace.
+  if (Right.isOneOf(tok::r_brace, tok::r_paren, tok::greater))
+    return false;
+
   // Allow breaking after a trailing 'const', e.g. after a method declaration,
   // unless it is follow by ';', '{' or '='.
   if (Left.is(tok::kw_const) && Left.Parent != NULL &&
@@ -1174,10 +1183,6 @@ bool TokenAnnotator::canBreakBefore(const AnnotatedLine &Line,
   if (Right.is(tok::kw___attribute))
     return true;
 
-  // We only break before r_brace if there was a corresponding break before
-  // the l_brace, which is tracked by BreakBeforeClosingBrace.
-  if (Right.isOneOf(tok::r_brace, tok::r_paren, tok::greater))
-    return false;
   if (Left.is(tok::identifier) && Right.is(tok::string_literal))
     return true;
   return (Left.isBinaryOperator() && Left.isNot(tok::lessless)) ||

clang/unittests/Format/FormatTest.cpp

@@ -1929,9 +1929,23 @@ TEST_F(FormatTest, BreaksFunctionDeclarations) {
 }
 
 TEST_F(FormatTest, BreaksFunctionDeclarationsWithTrailingTokens) {
-  verifyFormat("void someLongFunction(int someLongParameter)\n"
-               "    const;",
-               getLLVMStyleWithColumns(45));
+  verifyFormat("void someLongFunction(\n"
+               "    int someLongParameter) const {}",
+               getLLVMStyleWithColumns(46));
+  FormatStyle Style = getGoogleStyle();
+  Style.ColumnLimit = 47;
+  verifyFormat("void\n"
+               "someLongFunction(int someLongParameter) const {\n}",
+               getLLVMStyleWithColumns(47));
+  verifyFormat("void someLongFunction(\n"
+               "    int someLongParameter) const {}",
+               Style);
+  verifyFormat("LoooooongReturnType\n"
+               "someLoooooooongFunction() const {}",
+               getLLVMStyleWithColumns(47));
+  verifyFormat("LoooooongReturnType someLoooooooongFunction()\n"
+               "    const {}",
+               Style);
 
   verifyFormat("void aaaaaaaaaaaa(int aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa)\n"
                "    LOCKS_EXCLUDED(aaaaaaaaaaaaa);");