clang-format: More eagerly wrap trailing return types.

Before:
  template <typename T>
  auto aaaaaaaaaaaaaaaaaaaaaa(T t) -> decltype(eaaaaaaaaaaaaaaa<T>(t.a)
                                                   .aaaaaaaa());

After:
  template <typename T>
  auto aaaaaaaaaaaaaaaaaaaaaa(T t)
      -> decltype(eaaaaaaaaaaaaaaa<T>(t.a).aaaaaaaa());

Also add a test case for a difficult template parsing case I stumbled accross.
Needs fixing.

llvm-svn: 239149

clang/lib/Format/ContinuationIndenter.cpp

@@ -329,7 +329,7 @@ void ContinuationIndenter::addTokenOnCurrentLine(LineState &State, bool DryRun,
       State.Column > getNewLineColumn(State))
     State.Stack.back().ContainsUnwrappedBuilder = true;
 
-  if (Current.is(TT_LambdaArrow))
+  if (Current.is(TT_LambdaArrow) && Style.Language == FormatStyle::LK_Java)
     State.Stack.back().NoLineBreak = true;
   if (Current.isMemberAccess() && Previous.is(tok::r_paren) &&
       (Previous.MatchingParen &&

clang/lib/Format/TokenAnnotator.cpp

@@ -754,8 +754,8 @@ private:
     // recovered from an error (e.g. failure to find the matching >).
     if (!CurrentToken->isOneOf(TT_LambdaLSquare, TT_ForEachMacro,
                                TT_FunctionLBrace, TT_ImplicitStringLiteral,
-                               TT_InlineASMBrace, TT_JsFatArrow,
+                               TT_InlineASMBrace, TT_JsFatArrow, TT_LambdaArrow,
-                               TT_RegexLiteral, TT_TrailingReturnArrow))
+                               TT_RegexLiteral))
       CurrentToken->Type = TT_Unknown;
     CurrentToken->Role.reset();
     CurrentToken->MatchingParen = nullptr;
@@ -844,6 +844,8 @@ private:
       Contexts.back().IsExpression = true;
     } else if (Current.is(TT_TrailingReturnArrow)) {
       Contexts.back().IsExpression = false;
+    } else if (Current.is(TT_LambdaArrow)) {
+      Contexts.back().IsExpression = Style.Language == FormatStyle::LK_Java;
     } else if (Current.is(tok::l_paren) && !Line.MustBeDeclaration &&
                !Line.InPPDirective &&
                (!Current.Previous ||
@@ -1646,7 +1648,7 @@ unsigned TokenAnnotator::splitPenalty(const AnnotatedLine &Line,
   }
   if (Right.is(TT_PointerOrReference))
     return 190;
-  if (Right.is(TT_TrailingReturnArrow))
+  if (Right.is(TT_LambdaArrow))
     return 110;
   if (Left.is(tok::equal) && Right.is(tok::l_brace))
     return 150;
@@ -1901,8 +1903,6 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
   } else if (Style.Language == FormatStyle::LK_Java) {
     if (Left.is(tok::r_square) && Right.is(tok::l_brace))
       return true;
-    if (Left.is(TT_LambdaArrow) || Right.is(TT_LambdaArrow))
-      return true;
     if (Left.is(Keywords.kw_synchronized) && Right.is(tok::l_paren))
       return Style.SpaceBeforeParens != FormatStyle::SBPO_Never;
     if ((Left.isOneOf(tok::kw_static, tok::kw_public, tok::kw_private,
@@ -1927,7 +1927,8 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
       (Right.is(tok::equal) || Left.is(tok::equal)))
     return false;
 
-  if (Right.is(TT_TrailingReturnArrow) || Left.is(TT_TrailingReturnArrow))
+  if (Right.isOneOf(TT_TrailingReturnArrow, TT_LambdaArrow) ||
+      Left.isOneOf(TT_TrailingReturnArrow, TT_LambdaArrow))
     return true;
   if (Left.is(tok::comma))
     return true;

clang/lib/Format/UnwrappedLineParser.cpp

@@ -953,7 +953,7 @@ bool UnwrappedLineParser::tryToParseLambda() {
       nextToken();
       break;
     case tok::arrow:
-      FormatTok->Type = TT_TrailingReturnArrow;
+      FormatTok->Type = TT_LambdaArrow;
       nextToken();
       break;
     default:

clang/unittests/Format/FormatTest.cpp

@@ -3956,6 +3956,9 @@ TEST_F(FormatTest, TrailingReturnType) {
   verifyFormat("auto SomeFunction(A aaaaaaaaaaaaaaaaaaaaa) const\n"
                "    -> decltype(f(aaaaaaaaaaaaaaaaaaaaa)) {}");
   verifyFormat("auto doSomething(Aaaaaa *aaaaaa) -> decltype(aaaaaa->f()) {}");
+  verifyFormat("template <typename T>\n"
+               "auto aaaaaaaaaaaaaaaaaaaaaa(T t)\n"
+               "    -> decltype(eaaaaaaaaaaaaaaa<T>(t.a).aaaaaaaa());");
 
   // Not trailing return types.
   verifyFormat("void f() { auto a = b->c(); }");
@@ -6606,6 +6609,7 @@ TEST_F(FormatTest, UnderstandContextOfRecordTypeKeywords) {
 
   // FIXME: This is still incorrectly handled at the formatter side.
   verifyFormat("template <> struct X < 15, i<3 && 42 < 50 && 33 < 28> {};");
+  verifyFormat("int i = SomeFunction(a<b, a> b);");
 
   // FIXME:
   // This now gets parsed incorrectly as class definition.