re PR c++/65398 ([C++11] GCC rejects constexpr variable definitions with valid initia...

[gcc.git] / gcc / cp / constexpr.c

diff --git a/gcc/cp/constexpr.c b/gcc/cp/constexpr.c
index 2f0947215469b7723b4ebf4721209295ac9434fd..2100f94cdd050ca44d864efe5557ec01dcdf9f0f 100644 (file)
--- a/gcc/cp/constexpr.c
+++ b/gcc/cp/constexpr.c
@@ -2427,27 +2427,6 @@ cxx_fold_indirect_ref (location_t loc, tree type, tree op0, bool *empty_base)
                    break;
                  }
            }
-         /* *(&A[i] p+ j) => A[i + j] */
-         else if (TREE_CODE (op00) == ARRAY_REF
-                  && TREE_CODE (TREE_OPERAND (op00, 1)) == INTEGER_CST
-                  && TREE_CODE (op01) == INTEGER_CST)
-           {
-             tree t = fold_convert_loc (loc, ssizetype,
-                                        TREE_OPERAND (op00, 1));
-             tree nelts
-               = array_type_nelts_top (TREE_TYPE (TREE_OPERAND (op00, 0)));
-             /* Don't fold an out-of-bound access.  */
-             if (!tree_int_cst_le (t, nelts))
-               return NULL_TREE;
-             /* Make sure to treat the second operand of POINTER_PLUS_EXPR
-                as signed.  */
-             op01 = fold_build2_loc (loc, EXACT_DIV_EXPR, ssizetype,
-                                     cp_fold_convert (ssizetype, op01),
-                                     TYPE_SIZE_UNIT (type));
-             t = size_binop_loc (loc, PLUS_EXPR, op01, t);
-             return build4_loc (loc, ARRAY_REF, type, TREE_OPERAND (op00, 0),
-                                t, NULL_TREE, NULL_TREE);
-           }
        }
     }
   /* *(foo *)fooarrptr => (*fooarrptr)[0] */
@@ -2942,6 +2921,51 @@ cxx_eval_switch_expr (const constexpr_ctx *ctx, tree t,
   return NULL_TREE;
 }
 
+/* Subroutine of cxx_eval_constant_expression.
+   Attempt to reduce a POINTER_PLUS_EXPR expression T.  */
+
+static tree
+cxx_eval_pointer_plus_expression (const constexpr_ctx *ctx, tree t,
+                                 bool lval, bool *non_constant_p,
+                                 bool *overflow_p)
+{
+  tree op00 = TREE_OPERAND (t, 0);
+  tree op01 = TREE_OPERAND (t, 1);
+  location_t loc = EXPR_LOCATION (t);
+
+  STRIP_NOPS (op00);
+  if (TREE_CODE (op00) != ADDR_EXPR)
+    return NULL_TREE;
+
+  op00 = TREE_OPERAND (op00, 0);
+
+  /* &A[i] p+ j => &A[i + j] */
+  if (TREE_CODE (op00) == ARRAY_REF
+      && TREE_CODE (TREE_OPERAND (op00, 1)) == INTEGER_CST
+      && TREE_CODE (op01) == INTEGER_CST)
+    {
+      tree type = TREE_TYPE (op00);
+      t = fold_convert_loc (loc, ssizetype, TREE_OPERAND (op00, 1));
+      tree nelts = array_type_nelts_top (TREE_TYPE (TREE_OPERAND (op00, 0)));
+      /* Don't fold an out-of-bound access.  */
+      if (!tree_int_cst_le (t, nelts))
+       return NULL_TREE;
+      /* Make sure to treat the second operand of POINTER_PLUS_EXPR
+        as signed.  */
+      op01 = fold_build2_loc (loc, EXACT_DIV_EXPR, ssizetype,
+                             cp_fold_convert (ssizetype, op01),
+                             TYPE_SIZE_UNIT (type));
+      t = size_binop_loc (loc, PLUS_EXPR, op01, t);
+      t = build4_loc (loc, ARRAY_REF, type, TREE_OPERAND (op00, 0),
+                     t, NULL_TREE, NULL_TREE);
+      t = cp_build_addr_expr (t, tf_warning_or_error);
+      return cxx_eval_constant_expression (ctx, t, lval, non_constant_p,
+                                          overflow_p);
+    }
+
+  return NULL_TREE;
+}
+
 /* Attempt to reduce the expression T to a constant value.
    On failure, issue diagnostic and return error_mark_node.  */
 /* FIXME unify with c_fully_fold */
@@ -3247,6 +3271,12 @@ cxx_eval_constant_expression (const constexpr_ctx *ctx, tree t,
       break;
 
     case POINTER_PLUS_EXPR:
+      r = cxx_eval_pointer_plus_expression (ctx, t, lval, non_constant_p,
+                                           overflow_p);
+      if (r)
+       break;
+      /* else fall through */
+
     case PLUS_EXPR:
     case MINUS_EXPR:
     case MULT_EXPR: