[clang-format] Don't always break before << between string literals (#92214)

Instead, leave the line wrapping as is.

Fixes #43887.
Fixes #44363.

Author: owenca

clang/lib/Format/TokenAnnotator.cpp

@@ -5601,10 +5601,13 @@ bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
     return true;
   if (Left.IsUnterminatedLiteral)
     return true;
-  if (Right.is(tok::lessless) && AfterRight && Left.is(tok::string_literal) &&
+
+  if (BeforeLeft && BeforeLeft->is(tok::lessless) &&
+      Left.is(tok::string_literal) && Right.is(tok::lessless) && AfterRight &&
       AfterRight->is(tok::string_literal)) {
-    return true;
+    return Right.NewlinesBefore > 0;
   }
+
   if (Right.is(TT_RequiresClause)) {
     switch (Style.RequiresClausePosition) {
     case FormatStyle::RCPS_OwnLine:

clang/unittests/Format/FormatTest.cpp

@@ -10539,6 +10539,17 @@ TEST_F(FormatTest, KeepStringLabelValuePairsOnALine) {
       "                  bbbbbbbbbbbbbbbbbbbbbbb);");
 }
 
+TEST_F(FormatTest, WrapBeforeInsertionOperatorbetweenStringLiterals) {
+  verifyFormat("QStringList() << \"foo\" << \"bar\";");
+
+  verifyNoChange("QStringList() << \"foo\"\n"
+                 "              << \"bar\";");
+
+  verifyFormat("log_error(log, \"foo\" << \"bar\");",
+               "log_error(log, \"foo\"\n"
+               "                   << \"bar\");");
+}
+
 TEST_F(FormatTest, UnderstandsEquals) {
   verifyFormat(
       "aaaaaaaaaaaaaaaaa =\n"