[PATCH] preprocessor stringizing raw strings

https://gcc.gnu.org/ml/gcc-patches/2017-10/msg00611.html
	libcpp/
	PR preprocessor/82506
	* macro.c (cpp_quote_string): Escape raw LFs.

	gcc/testsuite/
	PR preprocessor/82506
	* g++.dg/cpp/string-3.C: New.

From-SVN: r253605

libcpp/ChangeLog

@@ -1,3 +1,8 @@
+2017-10-10  Nathan Sidwell  <nathan@acm.org>
+
+	PR preprocessor/82506
+	* macro.c (cpp_quote_string): Escape raw LFs.
+
 2017-09-15  Andrew Sutton  <andrew.n.sutton@gmail.com>
 	    Jakub Jelinek  <jakub@redhat.com>
 

libcpp/macro.c

@@ -502,13 +502,21 @@ cpp_quote_string (uchar *dest, const uchar *src, unsigned int len)
     {
       uchar c = *src++;
 
-      if (c == '\\' || c == '"')
+      switch (c)
 	{
+	case '\n':
+	  /* Naked LF can appear in raw string literals  */
+	  c = 'n';
+	  /* FALLTHROUGH */
+
+	case '\\':
+	case '"':
 	  *dest++ = '\\';
+	  /* FALLTHROUGH */
+
+	default:
 	  *dest++ = c;
 	}
-      else
-	  *dest++ = c;
     }
 
   return dest;