Fix target attribute handling (PR c++/81355).

2017-08-10  Martin Liska  <mliska@suse.cz>

	PR c++/81355
	* c-attribs.c (handle_target_attribute):
	Report warning for an empty string argument of target attribute.
2017-08-10  Martin Liska  <mliska@suse.cz>

	PR c++/81355
	* g++.dg/other/pr81355.C: New test.

From-SVN: r251020

gcc/ChangeLog

+2017-08-10  Martin Liska  <mliska@suse.cz>
+
+	PR c++/81355
+	* c-attribs.c (handle_target_attribute):
+	Report warning for an empty string argument of target attribute.
+
 2017-08-09  Jakub Jelinek  <jakub@redhat.com>
 
 	PR c/81687

gcc/c-family/c-attribs.c

@@ -3139,6 +3139,19 @@ handle_target_attribute (tree *node, tree name, tree args, int flags,
 						      flags))
     *no_add_attrs = true;
 
+  /* Check that there's no empty string in values of the attribute.  */
+  for (tree t = args; t != NULL_TREE; t = TREE_CHAIN (t))
+    {
+      tree value = TREE_VALUE (t);
+      if (TREE_CODE (value) == STRING_CST
+	  && TREE_STRING_LENGTH (value) == 1
+	  && TREE_STRING_POINTER (value)[0] == '\0')
+	{
+	  warning (OPT_Wattributes, "empty string in attribute %<target%>");
+	  *no_add_attrs = true;
+	}
+    }
+
   return NULL_TREE;
 }
 

gcc/testsuite/ChangeLog

+2017-08-10  Martin Liska  <mliska@suse.cz>
+
+	PR c++/81355
+	* g++.dg/other/pr81355.C: New test.
+
 2017-08-09  David Malcolm  <dmalcolm@redhat.com>
 
 	* jit.dg/all-non-failing-tests.h: Add note about

gcc/testsuite/g++.dg/other/pr81355.C

+/* { dg-do compile { target x86_64-*-* } } */
+
+__attribute__((target("default")))
+int foo() {return 1;}
+
+__attribute__((target("arch=core2", "")))
+int foo2() {return 2;} /* { dg-warning "empty string in attribute .target." } */
+
+__attribute__((target("sse4.2", "", "")))
+int foo3() {return 2;} /* { dg-warning "empty string in attribute .target." } */
+
+int main() {
+    return foo() + foo2() + foo3();
+}