Change clang-format's affinity for breaking after return types.

Function declarations are now broken with the following preferences:
1) break amongst arguments.
2) break after return type.
3) break after (.
4) break before after nested name specifiers.

Options #2 or #3 are preferred over #1 only if a substantial number of
lines can be saved by that.

llvm-svn: 179287

clang/lib/Format/Format.cpp

@@ -48,7 +48,7 @@ FormatStyle getLLVMStyle() {
   LLVMStyle.AllowShortIfStatementsOnASingleLine = false;
   LLVMStyle.ObjCSpaceBeforeProtocolList = true;
   LLVMStyle.PenaltyExcessCharacter = 1000000;
-  LLVMStyle.PenaltyReturnTypeOnItsOwnLine = 5;
+  LLVMStyle.PenaltyReturnTypeOnItsOwnLine = 75;
   return LLVMStyle;
 }
 
@@ -68,7 +68,7 @@ FormatStyle getGoogleStyle() {
   GoogleStyle.AllowShortIfStatementsOnASingleLine = false;
   GoogleStyle.ObjCSpaceBeforeProtocolList = false;
   GoogleStyle.PenaltyExcessCharacter = 1000000;
-  GoogleStyle.PenaltyReturnTypeOnItsOwnLine = 100;
+  GoogleStyle.PenaltyReturnTypeOnItsOwnLine = 200;
   return GoogleStyle;
 }
 
@@ -1395,7 +1395,7 @@ public:
 
     // Adapt level to the next line if this is a comment.
     // FIXME: Can/should this be done in the UnwrappedLineParser?
-    const AnnotatedLine* NextNoneCommentLine = NULL;
+    const AnnotatedLine *NextNoneCommentLine = NULL;
     for (unsigned i = AnnotatedLines.size() - 1; i > 0; --i) {
       if (NextNoneCommentLine && AnnotatedLines[i].First.is(tok::comment) &&
           AnnotatedLines[i].First.Children.empty())

clang/lib/Format/TokenAnnotator.cpp

@@ -81,7 +81,7 @@ public:
   AnnotatingParser(SourceManager &SourceMgr, Lexer &Lex, AnnotatedLine &Line,
                    IdentifierInfo &Ident_in)
       : SourceMgr(SourceMgr), Lex(Lex), Line(Line), CurrentToken(&Line.First),
-        KeywordVirtualFound(false), Ident_in(Ident_in) {
+        KeywordVirtualFound(false), NameFound(false), Ident_in(Ident_in) {
     Contexts.push_back(Context(tok::unknown, 1, /*IsExpression=*/ false));
   }
 
@@ -347,7 +347,7 @@ private:
     case tok::l_paren:
       if (!parseParens())
         return false;
-      if (Line.MustBeDeclaration)
+      if (Line.MustBeDeclaration && NameFound && !Contexts.back().IsExpression)
         Line.MightBeFunctionDecl = true;
       break;
     case tok::l_square:
@@ -602,6 +602,7 @@ private:
            Current.Parent->Type == TT_TemplateCloser)) {
         Contexts.back().FirstStartOfName = &Current;
         Current.Type = TT_StartOfName;
+        NameFound = true;
       } else if (Current.isOneOf(tok::star, tok::amp, tok::ampamp)) {
         Current.Type =
             determineStarAmpUsage(Current, Contexts.back().IsExpression);
@@ -759,6 +760,7 @@ private:
   AnnotatedLine &Line;
   AnnotatedToken *CurrentToken;
   bool KeywordVirtualFound;
+  bool NameFound;
   IdentifierInfo &Ident_in;
 };
 
@@ -916,7 +918,7 @@ unsigned TokenAnnotator::splitPenalty(const AnnotatedLine &Line,
       // FIXME: Clean up hack of using BindingStrength to find top-level names.
       return Style.PenaltyReturnTypeOnItsOwnLine;
     else
-      return 100;
+      return 200;
   }
   if (Left.is(tok::equal) && Right.is(tok::l_brace))
     return 150;
@@ -954,6 +956,8 @@ unsigned TokenAnnotator::splitPenalty(const AnnotatedLine &Line,
   if (Left.is(tok::colon) && Left.Type == TT_ObjCMethodExpr)
     return 20;
 
+  if (Left.is(tok::l_paren) && Line.MightBeFunctionDecl)
+    return 100;
   if (Left.opensScope())
     return Left.ParameterCount > 1 ? prec::Comma : 20;
 

clang/unittests/Format/FormatTest.cpp

@@ -1199,8 +1199,8 @@ TEST_F(FormatTest, FormatsSmallMacroDefinitionsInSingleLine) {
 
 TEST_F(FormatTest, DoesNotBreakPureVirtualFunctionDefinition) {
   verifyFormat(
-      "virtual void\n"
+      "virtual void write(ELFWriter *writerrr,\n"
-      "write(ELFWriter *writerrr, OwningPtr<FileOutputBuffer> &buffer) = 0;");
+      "                   OwningPtr<FileOutputBuffer> &buffer) = 0;");
 }
 
 TEST_F(FormatTest, LayoutUnknownPPDirective) {
@@ -1700,6 +1700,56 @@ TEST_F(FormatTest, BreaksAsHighAsPossible) {
                "    Intervals[i - 1].getRange().getLast()) {\n}");
 }
 
+TEST_F(FormatTest, BreaksFunctionDeclarations) {
+  // Principially, we break function declarations in a certain order:
+  // 1) break amongst arguments.
+  verifyFormat("Aaaaaaaaaaaaaa bbbbbbbbbbbbbb(Cccccccccccccc cccccccccccccc,\n"
+               "                              Cccccccccccccc cccccccccccccc);");
+
+  // 2) break after return type.
+  verifyFormat("Aaaaaaaaaaaaaaaaaaaaaaaa\n"
+               "bbbbbbbbbbbbbb(Cccccccccccccc cccccccccccccccccccccccccc);");
+
+  // 3) break after (.
+  verifyFormat(
+      "Aaaaaaaaaaaaaaaaaaaaaaaa bbbbbbbbbbbbbbbbbb(\n"
+      "    Cccccccccccccccccccccccccccccc cccccccccccccccccccccccccccccccc);");
+
+  // 4) break before after nested name specifiers.
+  verifyFormat(
+      "Aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n"
+      "SomeClasssssssssssssssssssssssssssssssssssssss::\n"
+      "    bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb(Cccccccccccccc cccccccccc);");
+
+  // However, there are exceptions, if a sufficient amount of lines can be
+  // saved.
+  // FIXME: The precise cut-offs wrt. the number of saved lines might need some
+  // more adjusting.
+  verifyFormat("Aaaaaaaaaaaaaaaaaa bbbbbbbbbbbbbb(Cccccccccccccc cccccccccc,\n"
+               "                                  Cccccccccccccc cccccccccc,\n"
+               "                                  Cccccccccccccc cccccccccc,\n"
+               "                                  Cccccccccccccc cccccccccc,\n"
+               "                                  Cccccccccccccc cccccccccc);");
+  verifyFormat(
+      "Aaaaaaaaaaaaaaaaaa\n"
+      "bbbbbbbbbbbbbb(Cccccccccccccc cccccccccc, Cccccccccccccc cccccccccc,\n"
+      "               Cccccccccccccc cccccccccc, Cccccccccccccc cccccccccc,\n"
+      "               Cccccccccccccc cccccccccc, Cccccccccccccc cccccccccc);");
+  verifyFormat(
+      "Aaaaaaaaaa bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb(Cccccccccccccc cccccccccc,\n"
+      "                                          Cccccccccccccc cccccccccc,\n"
+      "                                          Cccccccccccccc cccccccccc,\n"
+      "                                          Cccccccccccccc cccccccccc,\n"
+      "                                          Cccccccccccccc cccccccccc,\n"
+      "                                          Cccccccccccccc cccccccccc,\n"
+      "                                          Cccccccccccccc cccccccccc);");
+  verifyFormat("Aaaaaaaaaa bbbbbbbbbbbbbbbbbbbbbbbbbbbbbb(\n"
+               "    Cccccccccccccc cccccccccc, Cccccccccccccc cccccccccc,\n"
+               "    Cccccccccccccc cccccccccc, Cccccccccccccc cccccccccc,\n"
+               "    Cccccccccccccc cccccccccc, Cccccccccccccc cccccccccc,\n"
+               "    Cccccccccccccc cccccccccc, Cccccccccccccc cccccccccc);");
+}
+
 TEST_F(FormatTest, BreaksDesireably) {
   verifyFormat("if (aaaaaaaaaaaaaaaaaaa(aaaaaaaaaaaaaaa) ||\n"
                "    aaaaaaaaaaaaaaaaaaa(aaaaaaaaaaaaaaa) ||\n"
@@ -2600,9 +2650,9 @@ TEST_F(FormatTest, BreaksLongDeclarations) {
   verifyFormat("int *someFunction(int LoooooooooooooooooooongParam1,\n"
                "                  int LoooooooooooooooooooongParam2) {}");
   verifyFormat(
-      "TypeSpecDecl *\n"
+      "TypeSpecDecl *TypeSpecDecl::Create(ASTContext &C, DeclContext *DC,\n"
-      "TypeSpecDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation L,\n"
+      "                                   SourceLocation L, IdentifierIn *II,\n"
-      "                     IdentifierIn *II, Type *T) {}");
+      "                                   Type *T) {}");
   verifyFormat("ReallyLongReturnType<TemplateParam1, TemplateParam2>\n"
                "ReallyReallyLongFunctionName(\n"
                "    const std::string &SomeParameter,\n"