re PR c++/85662 ("error: non-constant condition for static assertion" from __builtin_offsetof in C++)

	PR c++/85662
	* c-common.h (fold_offsetof_1): Removed.
	(fold_offsetof): Add TYPE argument defaulted to size_type_node and
	CTX argument defaulted to ERROR_MARK.
	* c-common.c (fold_offsetof_1): Renamed to ...
	(fold_offsetof): ... this.  Remove wrapper function.  Add TYPE
	argument, convert the pointer constant to TYPE and use size_binop
	with PLUS_EXPR instead of fold_build_pointer_plus if type is not
	a pointer type.  Adjust recursive calls.

	* c-fold.c (c_fully_fold_internal): Use fold_offsetof rather than
	fold_offsetof_1, pass TREE_TYPE (expr) as TYPE to it and drop the
	fold_convert_loc.
	* c-typeck.c (build_unary_op): Use fold_offsetof rather than
	fold_offsetof_1, pass argtype as TYPE to it and drop the
	fold_convert_loc.

	* cp-gimplify.c (cp_fold): Use fold_offsetof rather than
	fold_offsetof_1, pass TREE_TYPE (x) as TYPE to it and drop the
	fold_convert.

	* g++.dg/ext/offsetof2.C: New test.

From-SVN: r260119

10 files changed, 54 insertions, 20 deletions

diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 6ea5eaf..052b222 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,15 @@
+2018-05-10  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/85662
+	* c-common.h (fold_offsetof_1): Removed.
+	(fold_offsetof): Add TYPE argument defaulted to size_type_node and
+	CTX argument defaulted to ERROR_MARK.
+	* c-common.c (fold_offsetof_1): Renamed to ...
+	(fold_offsetof): ... this.  Remove wrapper function.  Add TYPE
+	argument, convert the pointer constant to TYPE and use size_binop
+	with PLUS_EXPR instead of fold_build_pointer_plus if type is not
+	a pointer type.  Adjust recursive calls.
+
 2018-05-10  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR c++/85400
diff --git a/gcc/c-family/c-common.c b/gcc/c-family/c-common.c
index 7e6905e..e8bb3eb 100644
--- a/gcc/c-family/c-common.c
+++ b/gcc/c-family/c-common.c
@@ -6168,10 +6168,11 @@ c_common_to_target_charset (HOST_WIDE_INT c)
 
 /* Fold an offsetof-like expression.  EXPR is a nested sequence of component
    references with an INDIRECT_REF of a constant at the bottom; much like the
-   traditional rendering of offsetof as a macro.  Return the folded result.  */
+   traditional rendering of offsetof as a macro.  TYPE is the desired type of
+   the whole expression.  Return the folded result.  */
 
 tree
-fold_offsetof_1 (tree expr, enum tree_code ctx)
+fold_offsetof (tree expr, tree type, enum tree_code ctx)
 {
   tree base, off, t;
   tree_code code = TREE_CODE (expr);
@@ -6196,10 +6197,10 @@ fold_offsetof_1 (tree expr, enum tree_code ctx)
 	  error ("cannot apply %<offsetof%> to a non constant address");
 	  return error_mark_node;
 	}
-      return TREE_OPERAND (expr, 0);
+      return convert (type, TREE_OPERAND (expr, 0));
 
     case COMPONENT_REF:
-      base = fold_offsetof_1 (TREE_OPERAND (expr, 0), code);
+      base = fold_offsetof (TREE_OPERAND (expr, 0), type, code);
       if (base == error_mark_node)
 	return base;
 
@@ -6216,7 +6217,7 @@ fold_offsetof_1 (tree expr, enum tree_code ctx)
       break;
 
     case ARRAY_REF:
-      base = fold_offsetof_1 (TREE_OPERAND (expr, 0), code);
+      base = fold_offsetof (TREE_OPERAND (expr, 0), type, code);
       if (base == error_mark_node)
 	return base;
 
@@ -6273,23 +6274,16 @@ fold_offsetof_1 (tree expr, enum tree_code ctx)
       /* Handle static members of volatile structs.  */
       t = TREE_OPERAND (expr, 1);
       gcc_checking_assert (VAR_P (get_base_address (t)));
-      return fold_offsetof_1 (t);
+      return fold_offsetof (t, type);
 
     default:
       gcc_unreachable ();
     }
 
+  if (!POINTER_TYPE_P (type))
+    return size_binop (PLUS_EXPR, base, convert (type, off));
   return fold_build_pointer_plus (base, off);
 }
-
-/* Likewise, but convert it to the return type of offsetof.  */
-
-tree
-fold_offsetof (tree expr)
-{
-  return convert (size_type_node, fold_offsetof_1 (expr));
-}
-
 
 /* *PTYPE is an incomplete array.  Complete it with a domain based on
    INITIAL_VALUE.  If INITIAL_VALUE is not present, use 1 if DO_DEFAULT
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 6cf7614..f2c6662 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -1033,8 +1033,8 @@ extern bool c_dump_tree (void *, tree);
 
 extern void verify_sequence_points (tree);
 
-extern tree fold_offsetof_1 (tree, tree_code ctx = ERROR_MARK);
-extern tree fold_offsetof (tree);
+extern tree fold_offsetof (tree, tree = size_type_node,
+			   tree_code ctx = ERROR_MARK);
 
 extern int complete_array_type (tree *, tree, bool);
 
diff --git a/gcc/c/ChangeLog b/gcc/c/ChangeLog
index d88d70d..a8e2128 100644
--- a/gcc/c/ChangeLog
+++ b/gcc/c/ChangeLog
@@ -1,3 +1,13 @@
+2018-05-10  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/85662
+	* c-fold.c (c_fully_fold_internal): Use fold_offsetof rather than
+	fold_offsetof_1, pass TREE_TYPE (expr) as TYPE to it and drop the
+	fold_convert_loc.
+	* c-typeck.c (build_unary_op): Use fold_offsetof rather than
+	fold_offsetof_1, pass argtype as TYPE to it and drop the
+	fold_convert_loc.
+
 2018-05-02  David Pagan  <dave.pagan@oracle.com>
 
 	PR c/30552
diff --git a/gcc/c/c-fold.c b/gcc/c/c-fold.c
index 480e34c..d276e63 100644
--- a/gcc/c/c-fold.c
+++ b/gcc/c/c-fold.c
@@ -473,7 +473,7 @@ c_fully_fold_internal (tree expr, bool in_init, bool *maybe_const_operands,
 	  && (op1 = get_base_address (op0)) != NULL_TREE
 	  && INDIRECT_REF_P (op1)
 	  && TREE_CONSTANT (TREE_OPERAND (op1, 0)))
-	ret = fold_convert_loc (loc, TREE_TYPE (expr), fold_offsetof_1 (op0));
+	ret = fold_offsetof (op0, TREE_TYPE (expr));
       else if (op0 != orig_op0 || in_init)
 	ret = in_init
 	  ? fold_build1_initializer_loc (loc, code, TREE_TYPE (expr), op0)
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c
index 5b3ea28..45a4529 100644
--- a/gcc/c/c-typeck.c
+++ b/gcc/c/c-typeck.c
@@ -4676,7 +4676,7 @@ build_unary_op (location_t location, enum tree_code code, tree xarg,
       if (val && INDIRECT_REF_P (val)
           && TREE_CONSTANT (TREE_OPERAND (val, 0)))
 	{
-	  ret = fold_convert_loc (location, argtype, fold_offsetof_1 (arg));
+	  ret = fold_offsetof (arg, argtype);
 	  goto return_build_unary_op;
 	}
 
diff --git a/gcc/cp/ChangeLog b/gcc/cp/ChangeLog
index a2de8f6..e21afc7 100644
--- a/gcc/cp/ChangeLog
+++ b/gcc/cp/ChangeLog
@@ -1,3 +1,10 @@
+2018-05-10  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/85662
+	* cp-gimplify.c (cp_fold): Use fold_offsetof rather than
+	fold_offsetof_1, pass TREE_TYPE (x) as TYPE to it and drop the
+	fold_convert.
+
 2018-05-10  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR c++/85400
diff --git a/gcc/cp/cp-gimplify.c b/gcc/cp/cp-gimplify.c
index 7449065..84882f8 100644
--- a/gcc/cp/cp-gimplify.c
+++ b/gcc/cp/cp-gimplify.c
@@ -2232,7 +2232,7 @@ cp_fold (tree x)
 	      val = TREE_OPERAND (val, 0);
 	      STRIP_NOPS (val);
 	      if (TREE_CODE (val) == INTEGER_CST)
-		return fold_convert (TREE_TYPE (x), fold_offsetof_1 (op0));
+		return fold_offsetof (op0, TREE_TYPE (x));
 	    }
 	}
       goto finish_unary;
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 694857b..89f6440 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2018-05-10  Jakub Jelinek  <jakub@redhat.com>
+
+	PR c++/85662
+	* g++.dg/ext/offsetof2.C: New test.
+
 2018-05-10  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/68846
diff --git a/gcc/testsuite/g++.dg/ext/offsetof2.C b/gcc/testsuite/g++.dg/ext/offsetof2.C
new file mode 100644
index 0000000..647cf8d
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/offsetof2.C
@@ -0,0 +1,6 @@
+// PR c++/85662
+// { dg-do compile { target c++11 } }
+
+struct S { unsigned long x[31]; };
+struct T { bool b; S f; };
+static_assert (__builtin_offsetof (T, f.x[31 - 1]) == __builtin_offsetof (T, f.x[30]), "");