c-pragma.c (handle_pragma_scalar_storage_order): Expand on error message for…

c-pragma.c (handle_pragma_scalar_storage_order): Expand on error message for non-uniform endianness and issue a warning in C++.

	* c-pragma.c (handle_pragma_scalar_storage_order): Expand on error
	message for non-uniform endianness and issue a warning in C++.

From-SVN: r252831

gcc/c-family/ChangeLog

+2017-09-15  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* c-pragma.c (handle_pragma_scalar_storage_order): Expand on error
+	message for non-uniform endianness and issue a warning in C++.
+
 2017-09-15  Jakub Jelinek  <jakub@redhat.com>
 
 	* c.opt (Wc++1z-compat): Change from option to undocumented alias.

gcc/c-family/c-pragma.c

@@ -415,7 +415,19 @@ handle_pragma_scalar_storage_order (cpp_reader *ARG_UNUSED(dummy))
   tree x;
 
   if (BYTES_BIG_ENDIAN != WORDS_BIG_ENDIAN)
-    error ("scalar_storage_order is not supported");
+    {
+      error ("scalar_storage_order is not supported because endianness "
+	     "is not uniform");
+      return;
+    }
+
+  if (c_dialect_cxx ())
+    {
+      if (warn_unknown_pragmas > in_system_header_at (input_location))
+	warning (OPT_Wunknown_pragmas,
+		 "%<#pragma scalar_storage_order%> is not supported for C++");
+      return;
+    }
 
   token = pragma_lex (&x);
   if (token != CPP_NAME)

gcc/testsuite/ChangeLog

-2017-09-13  Paolo Carlini  <paolo.carlini@oracle.com>
+2017-09-15  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* g++.dg/sso-1.C: New test.
+	* g++.dg/sso-2.C: Likewise.
+
+2017-09-15  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	PR c++/78648
 	* g++.dg/cpp0x/lambda/lambda-ice21.C: New.

gcc/testsuite/g++.dg/sso-1.C

+/* Test support of scalar_storage_order attribute */
+
+/* { dg-do compile } */
+
+struct __attribute__((scalar_storage_order("little-endian"))) Rec /* { dg-warning "attribute ignored" } */
+{
+  int i;
+};

gcc/testsuite/g++.dg/sso-2.C

+/* Test support of scalar_storage_order pragma */
+
+/* { dg-do compile } */
+/* { dg-options "-Wall" } */
+
+#pragma scalar_storage_order little-endian /* { dg-warning "not supported" } */