clang-format: Fix string literal breaking.

Before this patch, it did not cooperate with
Style::AlwaysBreakBeforeMultilineStrings. Thus, it would turn

  aaaaaaaaaaaa(aaaaaaaaaaaaa, "aaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaa");

into:

  aaaaaaaaaaaa(aaaaaaaaaaaaa, "aaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaa "
                              "aaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaa");

and only a second format step would lead to the desired (with that
option):

  aaaaaaaaaaaa(aaaaaaaaaaaaa,
               "aaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaa "
               "aaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaa");

This could even lead to clang-format breaking the string at a different
character and thus leading to a completely different end result.

llvm-svn: 186154

clang/lib/Format/Format.cpp

@@ -297,7 +297,7 @@ public:
     State.IgnoreStackForComparison = false;
 
     // The first token has already been indented and thus consumed.
-    moveStateToNextToken(State, /*DryRun=*/false);
+    moveStateToNextToken(State, /*DryRun=*/false, /*Newline=*/false);
 
     // If everything fits on a single line, just put it there.
     unsigned ColumnLimit = Style.ColumnLimit;
@@ -729,12 +729,12 @@ private:
       }
     }
 
-    return moveStateToNextToken(State, DryRun) + ExtraPenalty;
+    return moveStateToNextToken(State, DryRun, Newline) + ExtraPenalty;
   }
 
   /// \brief Mark the next token as consumed in \p State and modify its stacks
   /// accordingly.
-  unsigned moveStateToNextToken(LineState &State, bool DryRun) {
+  unsigned moveStateToNextToken(LineState &State, bool DryRun, bool Newline) {
     const FormatToken &Current = *State.NextToken;
     assert(State.Stack.size());
 
@@ -875,6 +875,10 @@ private:
 
     State.NextToken = State.NextToken->Next;
 
+    if (!Newline && Style.AlwaysBreakBeforeMultilineStrings &&
+        Current.is(tok::string_literal))
+      return 0;
+
     return breakProtrudingToken(Current, State, DryRun);
   }
 

clang/unittests/Format/FormatTest.cpp

@@ -4958,6 +4958,16 @@ TEST_F(FormatTest, BreakStringLiterals) {
                    "rs\"",
                    getLLVMStyleWithColumns(20)));
 
+  // Verify that splitting the strings understands
+  // Style::AlwaysBreakBeforeMultilineStrings.
+  EXPECT_EQ("aaaaaaaaaaaa(aaaaaaaaaaaaa,\n"
+            "             \"aaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaa \"\n"
+            "             \"aaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaa\");",
+            format("aaaaaaaaaaaa(aaaaaaaaaaaaa, \"aaaaaaaaaaaaaaaaaaaaaa "
+                   "aaaaaaaaaaaaaaaaaaaaaa aaaaaaaaaaaaaaaaaaaaaa "
+                   "aaaaaaaaaaaaaaaaaaaaaa\");",
+                   getGoogleStyle()));
+
   FormatStyle AlignLeft = getLLVMStyleWithColumns(12);
   AlignLeft.AlignEscapedNewlinesLeft = true;
   EXPECT_EQ(