Improve formatting of stream operators.

If there are string literals on either side of a '<<', chances are
high that they represent logically separate concepts. Otherwise,
the author could just have just a single literal (possible split
over multiple lines).

So, we can now nicely format things like:
cout << "somepacket = {\n"
     << "  val a = " << ValueA << "\n"
     << "  val b = " << ValueB << "\n"
     << "}";

llvm-svn: 174310

Author: djasper-gh

clang/lib/Format/TokenAnnotator.cpp

@@ -669,6 +669,10 @@ void TokenAnnotator::calculateFormattingInformation(AnnotatedToken &Current) {
              (Current.is(tok::string_literal) &&
               Current.Parent->is(tok::string_literal))) {
     Current.MustBreakBefore = true;
+  } else if (Current.is(tok::lessless) && !Current.Children.empty() &&
+             Current.Parent->is(tok::string_literal) &&
+             Current.Children[0].is(tok::string_literal)) {
+    Current.MustBreakBefore = true;
   } else {
     Current.MustBreakBefore = false;
   }

clang/unittests/Format/FormatTest.cpp

@@ -1289,6 +1289,13 @@ TEST_F(FormatTest, AlignsPipes) {
       "aaaaaaaa << (aaaaaaaaaaaaaaaaaaa << aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n"
       "                                 << aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa)\n"
       "         << aaaaaaaaaaaaaaaaaaaaaaaaaaaaa;");
+
+  verifyFormat("return out << \"somepacket = {\\n\"\n"
+               "           << \"  aaaaaa = \" << pkt.aaaaaa << \"\\n\"\n"
+               "           << \"  bbbb = \" << pkt.bbbb << \"\\n\"\n"
+               "           << \"  cccccc = \" << pkt.cccccc << \"\\n\"\n"
+               "           << \"  ddd = [\" << pkt.ddd << \"]\\n\"\n"
+               "           << \"}\";");
 }
 
 TEST_F(FormatTest, UnderstandsEquals) {