commit 448d6065bcfb24d5d5aa904d93a740b552855aa5
Author: Jason Merrill <jason@redhat.com>
Date:   Fri May 8 22:55:30 2015 -0500

    libcpp/
    	* lex.c (lex_string): Add -Wc++11-compat warning.
    	* include/cpplib.h: Add CPP_W_CXX11_COMPAT.
    	(struct cpp_options): Add cpp_warn_cxx11_compat.
    	* init.c (cpp_create_reader): Initialize it.
    gcc/c-family/
    	* c.opt (Wc++0x-compat): Set it.

diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index 3774a89..8f48d84 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -312,7 +312,7 @@ C ObjC Var(warn_cxx_compat) CPP(warn_cxx_operator_names) CppReason(CPP_W_CXX_OPE
 Warn about C constructs that are not in the common subset of C and C++
 
 Wc++0x-compat
-C++ ObjC++ Var(warn_cxx0x_compat) Warning LangEnabledBy(C++ ObjC++,Wall)
+C++ ObjC++ Var(warn_cxx0x_compat) Warning LangEnabledBy(C++ ObjC++,Wall) Init(0) CPP(cpp_warn_cxx11_compat) CppReason(CPP_W_CXX11_COMPAT)
 Deprecated in favor of -Wc++11-compat
 
 Wc++11-compat
diff --git a/gcc/testsuite/g++.dg/cpp0x/warn_cxx0x4.C b/gcc/testsuite/g++.dg/cpp0x/warn_cxx0x4.C
new file mode 100644
index 0000000..c3f0cf5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/warn_cxx0x4.C
@@ -0,0 +1,4 @@
+// { dg-options "-Wall" }
+
+#define FOO "foo"
+const char *p = "bar"FOO;	// { dg-warning "macro" }
diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 5e08014..0152ec8 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -484,6 +484,9 @@ struct cpp_options
   /* True if warn about differences between C90 and C99.  */
   signed char cpp_warn_c90_c99_compat;
 
+  /* True if warn about differences between C++98 and C++11.  */
+  bool cpp_warn_cxx11_compat;
+
   /* Dependency generation.  */
   struct
   {
@@ -960,7 +963,8 @@ enum {
   CPP_W_LITERAL_SUFFIX,
   CPP_W_DATE_TIME,
   CPP_W_PEDANTIC,
-  CPP_W_C90_C99_COMPAT
+  CPP_W_C90_C99_COMPAT,
+  CPP_W_CXX11_COMPAT
 };
 
 /* Output a diagnostic of some kind.  */
diff --git a/libcpp/init.c b/libcpp/init.c
index 45a4d13..1ebd709 100644
--- a/libcpp/init.c
+++ b/libcpp/init.c
@@ -180,6 +180,7 @@ cpp_create_reader (enum c_lang lang, cpp_hash_table *table,
   CPP_OPTION (pfile, warn_trigraphs) = 2;
   CPP_OPTION (pfile, warn_endif_labels) = 1;
   CPP_OPTION (pfile, cpp_warn_c90_c99_compat) = -1;
+  CPP_OPTION (pfile, cpp_warn_cxx11_compat) = 0;
   CPP_OPTION (pfile, cpp_warn_deprecated) = 1;
   CPP_OPTION (pfile, cpp_warn_long_long) = 0;
   CPP_OPTION (pfile, dollars_in_ident) = 1;
diff --git a/libcpp/lex.c b/libcpp/lex.c
index ac96ff8..c7296a1 100644
--- a/libcpp/lex.c
+++ b/libcpp/lex.c
@@ -1905,6 +1905,12 @@ lex_string (cpp_reader *pfile, cpp_token *token, const uchar *base)
 	    ++cur;
 	}
     }
+  else if (CPP_OPTION (pfile, cpp_warn_cxx11_compat)
+	   && is_macro (pfile, cur)
+	   && !pfile->state.skipping)
+    cpp_warning_with_line (pfile, CPP_W_CXX11_COMPAT,
+			   token->src_loc, 0, "C++11 requires a space "
+			   "between string literal and macro");
 
   pfile->buffer->cur = cur;
   create_literal (pfile, token, base, cur - base, type);