re PR lto/83954 (LTO: Bogus -Wlto-type-mismatch warning for array of pointer to incomplete type)

	PR lto/83954
	* lto-symtab.c (warn_type_compatibility_p): Silence false positive
	for type match warning on arrays of pointers.
	* gcc.dg/lto/pr83954.h: New testcase.
	* gcc.dg/lto/pr83954_0.c: New testcase.
	* gcc.dg/lto/pr83954_1.c: New testcase.

From-SVN: r257183

gcc/lto/ChangeLog

+2018-01-30  Jan Hubicka  <hubicka@ucw.cz>
+
+	PR lto/83954
+	* lto-symtab.c (warn_type_compatibility_p): Silence false positive
+	for type match warning on arrays of pointers.
+
 2018-01-23  Martin Liska  <mliska@suse.cz>
 
 	PR lto/81440

gcc/lto/lto-symtab.c

@@ -284,12 +284,23 @@ warn_type_compatibility_p (tree prevailing_type, tree type,
       alias_set_type set1 = get_alias_set (type);
       alias_set_type set2 = get_alias_set (prevailing_type);
 
-      if (set1 && set2 && set1 != set2 
-          && (!POINTER_TYPE_P (type) || !POINTER_TYPE_P (prevailing_type)
+      if (set1 && set2 && set1 != set2)
+	{
+          tree t1 = type, t2 = prevailing_type;
+
+	  /* Alias sets of arrays are the same as alias sets of the inner
+	     types.  */
+	  while (TREE_CODE (t1) == ARRAY_TYPE && TREE_CODE (t2) == ARRAY_TYPE)
+	    {
+	      t1 = TREE_TYPE (t1);
+	      t2 = TREE_TYPE (t2);
+	    }
+          if ((!POINTER_TYPE_P (t1) || !POINTER_TYPE_P (t2))
 	      || (set1 != TYPE_ALIAS_SET (ptr_type_node)
-		  && set2 != TYPE_ALIAS_SET (ptr_type_node))))
+		  && set2 != TYPE_ALIAS_SET (ptr_type_node)))
              lev |= 5;
 	}
+    }
 
   return lev;
 }

gcc/testsuite/ChangeLog

+2018-01-30  Jan Hubicka  <hubicka@ucw.cz>
+
+	PR lto/83954
+	* gcc.dg/lto/pr83954.h: New testcase.
+	* gcc.dg/lto/pr83954_0.c: New testcase.
+	* gcc.dg/lto/pr83954_1.c: New testcase.
+
 2018-01-30  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>
 
 	PR bootstrap/84017

gcc/testsuite/gcc.dg/lto/pr83954.h

+struct foo;
+extern struct foo *FOO_PTR_ARR[1];
+

gcc/testsuite/gcc.dg/lto/pr83954_0.c

+/* { dg-lto-do link } */
+#include "pr83954.h"
+
+int main() { 
+  // just to prevent symbol removal
+  FOO_PTR_ARR[1] = 0;
+  return 0;
+}

gcc/testsuite/gcc.dg/lto/pr83954_1.c

+#include "pr83954.h"
+
+struct foo {
+ int x;
+};
+struct foo *FOO_PTR_ARR[1] = { 0 };
+