re PR c++/69631 (Bogus overflow in constant expression error)

	PR c++/69631

gcc/
	* convert.c (convert_to_integer_1): Check dofold on truncation
	distribution.
	(convert_to_pointer_maybe_fold, convert_to_real_maybe_fold)
	(convert_to_integer_maybe_fold, convert_to_complex_maybe_fold):
	Rename from *_nofold.
	* convert.h (convert_to_pointer_nofold, convert_to_integer_nofold)
	(convert_to_real_nofold, convert_to_complex_nofold): New inlines.
gcc/cp/
	* cp-tree.h (CONV_FOLD, CONV_BACKEND_CONVERT): New.
	* cvt.c (convert): Pass CONV_BACKEND_CONVERT.
	(ocp_convert): Use *_maybe_fold.
	(cp_convert_to_pointer): Add dofold parameter.
	* cp-gimplify.c (cp_fold) [CONVERT_EXPR]: Call convert.

From-SVN: r233216

gcc/ChangeLog

+2016-02-08  Jason Merrill  <jason@redhat.com>
+
+	PR c++/69631
+	* convert.c (convert_to_integer_1): Check dofold on truncation
+	distribution.
+	(convert_to_pointer_maybe_fold, convert_to_real_maybe_fold)
+	(convert_to_integer_maybe_fold, convert_to_complex_maybe_fold):
+	Rename from *_nofold.
+	* convert.h (convert_to_pointer_nofold, convert_to_integer_nofold)
+	(convert_to_real_nofold, convert_to_complex_nofold): New inlines.
+
 2016-02-08  Bernd Schmidt  <bschmidt@redhat.com>
 
 	PR rtl-optimization/68730

gcc/convert.c

@@ -105,12 +105,12 @@ convert_to_pointer (tree type, tree expr)
 }
 
 /* A wrapper around convert_to_pointer_1 that only folds the
-   expression if it is CONSTANT_CLASS_P.  */
+   expression if DOFOLD, or if it is CONSTANT_CLASS_P.  */
 
 tree
-convert_to_pointer_nofold (tree type, tree expr)
+convert_to_pointer_maybe_fold (tree type, tree expr, bool dofold)
 {
-  return convert_to_pointer_1 (type, expr, CONSTANT_CLASS_P (expr));
+  return convert_to_pointer_1 (type, expr, dofold || CONSTANT_CLASS_P (expr));
 }
 
 /* Convert EXPR to some floating-point type TYPE.
@@ -403,12 +403,12 @@ convert_to_real (tree type, tree expr)
 }
 
 /* A wrapper around convert_to_real_1 that only folds the
-   expression if it is CONSTANT_CLASS_P.  */
+   expression if DOFOLD, or if it is CONSTANT_CLASS_P.  */
 
 tree
-convert_to_real_nofold (tree type, tree expr)
+convert_to_real_maybe_fold (tree type, tree expr, bool dofold)
 {
-  return convert_to_real_1 (type, expr, CONSTANT_CLASS_P (expr));
+  return convert_to_real_1 (type, expr, dofold || CONSTANT_CLASS_P (expr));
 }
 
 /* Convert EXPR to some integer (or enum) type TYPE.
@@ -669,6 +669,7 @@ convert_to_integer_1 (tree type, tree expr, bool dofold)
 	 two narrow values can be combined in their narrow type even to
 	 make a wider result--are handled by "shorten" in build_binary_op.  */
 
+      if (dofold)
       switch (ex_form)
 	{
 	case RSHIFT_EXPR:
@@ -857,9 +858,6 @@ convert_to_integer_1 (tree type, tree expr, bool dofold)
 	  /* This is not correct for ABS_EXPR,
 	     since we must test the sign before truncation.  */
 	  {
-	    if (!dofold)
-	      break;
-
 	    /* Do the arithmetic in type TYPEX,
 	       then convert result to TYPE.  */
 	    tree typex = type;
@@ -895,7 +893,6 @@ convert_to_integer_1 (tree type, tree expr, bool dofold)
 	     the conditional and never loses.  A COND_EXPR may have a throw
 	     as one operand, which then has void type.  Just leave void
 	     operands as they are.  */
-	  if (dofold)
 	    return
 	      fold_build3 (COND_EXPR, type, TREE_OPERAND (expr, 0),
 			   VOID_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 1)))
@@ -968,19 +965,13 @@ convert_to_integer (tree type, tree expr)
   return convert_to_integer_1 (type, expr, true);
 }
 
-/* Convert EXPR to some integer (or enum) type TYPE.
-
-   EXPR must be pointer, integer, discrete (enum, char, or bool), float,
-   fixed-point or vector; in other cases error is called.
-
-   The result of this is always supposed to be a newly created tree node
-   not in use in any existing structure.  The tree node isn't folded,
-   beside EXPR is of constant class.  */
+/* A wrapper around convert_to_complex_1 that only folds the
+   expression if DOFOLD, or if it is CONSTANT_CLASS_P.  */
 
 tree
-convert_to_integer_nofold (tree type, tree expr)
+convert_to_integer_maybe_fold (tree type, tree expr, bool dofold)
 {
-  return convert_to_integer_1 (type, expr, CONSTANT_CLASS_P (expr));
+  return convert_to_integer_1 (type, expr, dofold || CONSTANT_CLASS_P (expr));
 }
 
 /* Convert EXPR to the complex type TYPE in the usual ways.  If FOLD_P is
@@ -1059,12 +1050,12 @@ convert_to_complex (tree type, tree expr)
 }
 
 /* A wrapper around convert_to_complex_1 that only folds the
-   expression if it is CONSTANT_CLASS_P.  */
+   expression if DOFOLD, or if it is CONSTANT_CLASS_P.  */
 
 tree
-convert_to_complex_nofold (tree type, tree expr)
+convert_to_complex_maybe_fold (tree type, tree expr, bool dofold)
 {
-  return convert_to_complex_1 (type, expr, CONSTANT_CLASS_P (expr));
+  return convert_to_complex_1 (type, expr, dofold || CONSTANT_CLASS_P (expr));
 }
 
 /* Convert EXPR to the vector type TYPE in the usual ways.  */

gcc/convert.h

@@ -21,14 +21,23 @@ along with GCC; see the file COPYING3.  If not see
 #define GCC_CONVERT_H
 
 extern tree convert_to_integer (tree, tree);
-extern tree convert_to_integer_nofold (tree, tree);
+extern tree convert_to_integer_maybe_fold (tree, tree, bool);
 extern tree convert_to_pointer (tree, tree);
-extern tree convert_to_pointer_nofold (tree, tree);
+extern tree convert_to_pointer_maybe_fold (tree, tree, bool);
 extern tree convert_to_real (tree, tree);
-extern tree convert_to_real_nofold (tree, tree);
+extern tree convert_to_real_maybe_fold (tree, tree, bool);
 extern tree convert_to_fixed (tree, tree);
 extern tree convert_to_complex (tree, tree);
-extern tree convert_to_complex_nofold (tree, tree);
+extern tree convert_to_complex_maybe_fold (tree, tree, bool);
 extern tree convert_to_vector (tree, tree);
 
+extern inline tree convert_to_integer_nofold (tree t, tree x)
+{ return convert_to_integer_maybe_fold (t, x, false); }
+extern inline tree convert_to_pointer_nofold (tree t, tree x)
+{ return convert_to_pointer_maybe_fold (t, x, false); }
+extern inline tree convert_to_real_nofold (tree t, tree x)
+{ return convert_to_real_maybe_fold (t, x, false); }
+extern inline tree convert_to_complex_nofold (tree t, tree x)
+{ return convert_to_complex_maybe_fold (t, x, false); }
+
 #endif /* GCC_CONVERT_H */

gcc/cp/ChangeLog

+2016-02-08  Jason Merrill  <jason@redhat.com>
+
+	* cp-tree.h (CONV_FOLD, CONV_BACKEND_CONVERT): New.
+	* cvt.c (convert): Pass CONV_BACKEND_CONVERT.
+	(ocp_convert): Use *_maybe_fold.
+	(cp_convert_to_pointer): Add dofold parameter.
+	* cp-gimplify.c (cp_fold) [CONVERT_EXPR]: Call convert.
+
 2016-02-05  Martin Sebor  <msebor@redhat.com>
 
 	PR c++/69662

gcc/cp/cp-gimplify.c

@@ -1953,7 +1953,13 @@ cp_fold (tree x)
       loc = EXPR_LOCATION (x);
       op0 = cp_fold_maybe_rvalue (TREE_OPERAND (x, 0), rval_ops);
 
-      if (op0 != TREE_OPERAND (x, 0))
+      if (code == CONVERT_EXPR
+	  && SCALAR_TYPE_P (TREE_TYPE (x))
+	  && op0 != void_node)
+	/* During parsing we used convert_to_*_nofold; re-convert now using the
+	   folding variants, since fold() doesn't do those transformations.  */
+	x = fold (convert (TREE_TYPE (x), op0));
+      else if (op0 != TREE_OPERAND (x, 0))
 	{
 	  if (op0 == error_mark_node)
 	    x = error_mark_node;

gcc/cp/cp-tree.h

@@ -5019,10 +5019,12 @@ enum overload_flags { NO_SPECIAL = 0, DTOR_FLAG, TYPENAME_FLAG };
 #define CONV_PRIVATE	 16
 /* #define CONV_NONCONVERTING 32 */
 #define CONV_FORCE_TEMP  64
+#define CONV_FOLD	 128
 #define CONV_OLD_CONVERT (CONV_IMPLICIT | CONV_STATIC | CONV_CONST \
 			  | CONV_REINTERPRET)
 #define CONV_C_CAST      (CONV_IMPLICIT | CONV_STATIC | CONV_CONST \
 			  | CONV_REINTERPRET | CONV_PRIVATE | CONV_FORCE_TEMP)
+#define CONV_BACKEND_CONVERT (CONV_OLD_CONVERT | CONV_FOLD)
 
 /* Used by build_expr_type_conversion to indicate which types are
    acceptable as arguments to the expression under consideration.  */

gcc/cp/cvt.c

@@ -34,7 +34,6 @@ along with GCC; see the file COPYING3.  If not see
 #include "intl.h"
 #include "convert.h"
 
-static tree cp_convert_to_pointer (tree, tree, tsubst_flags_t);
 static tree convert_to_pointer_force (tree, tree, tsubst_flags_t);
 static tree build_type_conversion (tree, tree);
 static tree build_up_reference (tree, tree, int, tree, tsubst_flags_t);
@@ -50,7 +49,7 @@ static void diagnose_ref_binding (location_t, tree, tree, tree);
 
    Here is a list of all the functions that assume that widening and
    narrowing is always done with a NOP_EXPR:
-     In convert.c, convert_to_integer[_nofold].
+     In convert.c, convert_to_integer[_maybe_fold].
      In c-typeck.c, build_binary_op_nodefault (boolean ops),
 	and c_common_truthvalue_conversion.
      In expr.c: expand_expr, for operands of a MULT_EXPR.
@@ -70,7 +69,8 @@ static void diagnose_ref_binding (location_t, tree, tree, tree);
    else try C-style pointer conversion.  */
 
 static tree
-cp_convert_to_pointer (tree type, tree expr, tsubst_flags_t complain)
+cp_convert_to_pointer (tree type, tree expr, bool dofold,
+		       tsubst_flags_t complain)
 {
   tree intype = TREE_TYPE (expr);
   enum tree_code form;
@@ -185,7 +185,7 @@ cp_convert_to_pointer (tree type, tree expr, tsubst_flags_t complain)
 	{
 	  if (TREE_CODE (expr) == PTRMEM_CST)
 	    return cp_convert_to_pointer (type, PTRMEM_CST_MEMBER (expr),
-					  complain);
+					  dofold, complain);
 	  else if (TREE_CODE (expr) == OFFSET_REF)
 	    {
 	      tree object = TREE_OPERAND (expr, 0);
@@ -237,7 +237,7 @@ cp_convert_to_pointer (tree type, tree expr, tsubst_flags_t complain)
       gcc_assert (GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (expr)))
 		  == GET_MODE_SIZE (TYPE_MODE (type)));
 
-      return convert_to_pointer_nofold (type, expr);
+      return convert_to_pointer_maybe_fold (type, expr, dofold);
     }
 
   if (type_unknown_p (expr))
@@ -296,7 +296,7 @@ convert_to_pointer_force (tree type, tree expr, tsubst_flags_t complain)
 	}
     }
 
-  return cp_convert_to_pointer (type, expr, complain);
+  return cp_convert_to_pointer (type, expr, /*fold*/false, complain);
 }
 
 /* We are passing something to a function which requires a reference.
@@ -670,6 +670,7 @@ ocp_convert (tree type, tree expr, int convtype, int flags,
   const char *invalid_conv_diag;
   tree e1;
   location_t loc = EXPR_LOC_OR_LOC (expr, input_location);
+  bool dofold = (convtype & CONV_FOLD);
 
   if (error_operand_p (e) || type == error_mark_node)
     return error_mark_node;
@@ -706,7 +707,7 @@ ocp_convert (tree type, tree expr, int convtype, int flags,
       /* For complex data types, we need to perform componentwise
 	 conversion.  */
       else if (TREE_CODE (type) == COMPLEX_TYPE)
-	return convert_to_complex_nofold (type, e);
+	return convert_to_complex_maybe_fold (type, e, dofold);
       else if (VECTOR_TYPE_P (type))
 	return convert_to_vector (type, e);
       else if (TREE_CODE (e) == TARGET_EXPR)
@@ -799,7 +800,7 @@ ocp_convert (tree type, tree expr, int convtype, int flags,
 	  return cp_truthvalue_conversion (e);
 	}
 
-      converted = convert_to_integer_nofold (type, e);
+      converted = convert_to_integer_maybe_fold (type, e, dofold);
 
       /* Ignore any integer overflow caused by the conversion.  */
       return ignore_overflows (converted, e);
@@ -811,7 +812,7 @@ ocp_convert (tree type, tree expr, int convtype, int flags,
       return nullptr_node;
     }
   if (POINTER_TYPE_P (type) || TYPE_PTRMEM_P (type))
-    return cp_convert_to_pointer (type, e, complain);
+    return cp_convert_to_pointer (type, e, dofold, complain);
   if (code == VECTOR_TYPE)
     {
       tree in_vtype = TREE_TYPE (e);
@@ -842,9 +843,9 @@ ocp_convert (tree type, tree expr, int convtype, int flags,
 		      TREE_TYPE (e));
 	}
       if (code == REAL_TYPE)
-	return convert_to_real_nofold (type, e);
+	return convert_to_real_maybe_fold (type, e, dofold);
       else if (code == COMPLEX_TYPE)
-	return convert_to_complex_nofold (type, e);
+	return convert_to_complex_maybe_fold (type, e, dofold);
     }
 
   /* New C++ semantics:  since assignment is now based on
@@ -1460,7 +1461,7 @@ convert (tree type, tree expr)
   if (POINTER_TYPE_P (type) && POINTER_TYPE_P (intype))
     return build_nop (type, expr);
 
-  return ocp_convert (type, expr, CONV_OLD_CONVERT,
+  return ocp_convert (type, expr, CONV_BACKEND_CONVERT,
 		      LOOKUP_NORMAL|LOOKUP_NO_CONVERSION,
 		      tf_warning_or_error);
 }

gcc/testsuite/g++.dg/delayedfold/fwrapv1.C

+// PR c++/69631
+// { dg-options -fwrapv }
+
+struct C {
+  static const unsigned short max = static_cast<unsigned short>((32767 * 2 + 1));
+};