release/18.x: [clang-format] Don't always break before << between str… (#94091)

…ing literals (#92214)

Author: owenca

clang/lib/Format/TokenAnnotator.cpp

@@ -5159,9 +5159,11 @@ bool TokenAnnotator::mustBreakBefore(const AnnotatedLine &Line,
     return true;
   if (Left.IsUnterminatedLiteral)
     return true;
-  if (Right.is(tok::lessless) && Right.Next && Left.is(tok::string_literal) &&
-      Right.Next->is(tok::string_literal)) {
-    return true;
+  if (const auto *BeforeLeft = Left.Previous, *AfterRight = Right.Next;
+      BeforeLeft && BeforeLeft->is(tok::lessless) &&
+      Left.is(tok::string_literal) && Right.is(tok::lessless) && AfterRight &&
+      AfterRight->is(tok::string_literal)) {
+    return Right.NewlinesBefore > 0;
   }
   if (Right.is(TT_RequiresClause)) {
     switch (Style.RequiresClausePosition) {

clang/unittests/Format/FormatTest.cpp

@@ -10426,6 +10426,17 @@ 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"