Modify string splitting to repeat prefix

Author: shivrm

clang/lib/Format/BreakableToken.cpp

@@ -298,7 +298,7 @@ BreakableStringLiteralUsingOperators::BreakableStringLiteralUsingOperators(
                                                                   : "\"",
           /*Postfix=*/QuoteStyle == SingleQuotes ? "'" : "\"",
           /*ContinuationPrefix=*/QuoteStyle == SingleQuotes ? "'"
-                               : QuoteStyle == AtDoubleQuotes                    ? "@\""
+          : QuoteStyle == AtDoubleQuotes                    ? "@\""
                                                             : "\"",
           /*ContinuationPostfix=*/QuoteStyle == SingleQuotes ? "'" : "\"",
           UnbreakableTailLength, InPPDirective, Encoding, Style),

clang/lib/Format/ContinuationIndenter.cpp

@@ -2570,8 +2570,8 @@ ContinuationIndenter::createBreakableToken(const FormatToken &Current,
            Text.starts_with(Prefix = "u8\"") ||
            Text.starts_with(Prefix = "L\""))) {
 
-        // Use quotes when breaking the string
-        llvm::StringRef ContinuationPrefix = "\"";
+        // Repeat the prefix on every line but don't repeat the suffix
+        llvm::StringRef ContinuationPrefix = Prefix;
         llvm::StringRef ContinuationPostfix = "\"";
         return std::make_unique<BreakableStringLiteral>(
             Current, StartColumn, Prefix, Postfix, ContinuationPrefix,