[clang] [clang-format] revert to string << string handling to previous default (PR #88490)

[via cfe-commits]

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@@ -5598,10 +5598,34 @@ bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
   // FIXME: Breaking after newlines seems useful in general. Turn this into an
   // option and recognize more cases like endl etc, and break independent of
   // what comes after operator lessless.
-  if (Right.is(tok::lessless) && Right.Next &&
-      Right.Next->is(tok::string_literal) && Left.is(tok::string_literal) &&
-      Left.TokenText.ends_with("\\n\"")) {
-    return true;
+  if (Style.BreakChevronOperator == FormatStyle::BCOS_BetweenStrings) {
+    if (Right.is(tok::lessless) && Right.Next && Left.is(tok::string_literal) &&
+        Right.Next->is(tok::string_literal)) {
+      return true;
+    }
+  }
+  if (Style.BreakChevronOperator == FormatStyle::BCOS_BetweenNewlineStrings) {
+    if (Right.is(tok::lessless) && Right.Next &&
+        Right.Next->is(tok::string_literal) && Left.is(tok::string_literal) &&
+        Left.TokenText.ends_with("\\n\"")) {
+      return true;
+    }
+  }
+  if (Style.BreakChevronOperator == FormatStyle::BCOS_Always) {
+    // can be std::os or os
----------------
mydeveloperday wrote:

when you have 

os <<  "A" 
     << "B"

you don't want to break between os and << so the loop tracks back to determine if this is the first << in the line, this must also handle std::os << and a::b::os etc..  whats its really saying is don't break before the first <<.

https://github.com/llvm/llvm-project/pull/88490