commit 5946e0026988259a71992e3a653556b76460919c
Author: Jason Merrill <jason@redhat.com>
Date: Wed Sep 16 15:27:10 2015 -0400
Implement N4295 fold-expressions.
* cp-tree.def: Add UNARY_LEFT_FOLD_EXPR, UNARY_RIGHT_FOLD_EXPR,
BINARY_LEFT_FOLD_EXPR, BINARY_RIGHT_FOLD_EXPR.
* cp-objcp-common.c (cp_common_init_ts): Handle them.
* cp-tree.h (FOLD_EXPR_CHECK, BINARY_FOLD_EXPR_CHECK, FOLD_EXPR_P)
(FOLD_EXPR_MODIFY_P, FOLD_EXPR_OP, FOLD_EXPR_PACK, FOLD_EXPR_INIT): New.
* parser.c (cp_parser_skip_to_closing_parenthesis): Split out...
(cp_parser_skip_to_closing_parenthesis_1): This function. Change
or_comma parameter to or_ttype.
(cp_parser_fold_operator, cp_parser_fold_expr_p)
(cp_parser_fold_expression): New.
(cp_parser_primary_expression): Use them.
* pt.c (expand_empty_fold, fold_expression, tsubst_fold_expr_pack)
(tsubst_fold_expr_init, expand_left_fold, tsubst_unary_left_fold)
(tsubst_binary_left_fold, expand_right_fold)
(tsubst_unary_right_fold, tsubst_binary_right_fold): New.
(tsubst_copy): Use them.
(type_dependent_expression_p): Handle fold-expressions.
* semantics.c (finish_unary_fold_expr)
(finish_left_unary_fold_expr, finish_right_unary_fold_expr)
(finish_binary_fold_expr): New.
@@ -311,6 +311,10 @@ cp_common_init_ts (void)
MARK_TS_TYPED (CTOR_INITIALIZER);
MARK_TS_TYPED (ARRAY_NOTATION_REF);
MARK_TS_TYPED (REQUIRES_EXPR);
+ MARK_TS_TYPED (UNARY_LEFT_FOLD_EXPR);
+ MARK_TS_TYPED (UNARY_RIGHT_FOLD_EXPR);
+ MARK_TS_TYPED (BINARY_LEFT_FOLD_EXPR);
+ MARK_TS_TYPED (BINARY_RIGHT_FOLD_EXPR);
}
#include "gt-cp-cp-objcp-common.h"
@@ -432,6 +432,26 @@ DEFTREECODE (EXPR_PACK_EXPANSION, "expr_pack_expansion", tcc_expression, 3)
index is a machine integer. */
DEFTREECODE (ARGUMENT_PACK_SELECT, "argument_pack_select", tcc_exceptional, 0)
+/* Fold expressions allow the expansion of a template argument pack
+ over a binary operator.
+
+ FOLD_EXPR_MOD_P is true when the fold operation is a compound assignment
+ operator.
+
+ FOLD_EXPR_OP is an INTEGER_CST storing the tree code for the folded
+ expression. Note that when FOLDEXPR_MOD_P is true, the operator is
+ a compound assignment operator for that kind of expression.
+
+ FOLD_EXPR_PACK is an expression containing an unexpanded parameter pack;
+ when expanded, each term becomes an argument of the folded expression.
+
+ In a BINARY_FOLD_EXPRESSION, FOLD_EXPR_INIT is the non-pack argument. */
+DEFTREECODE (UNARY_LEFT_FOLD_EXPR, "unary_left_fold_expr", tcc_expression, 2)
+DEFTREECODE (UNARY_RIGHT_FOLD_EXPR, "unary_right_fold_expr", tcc_expression, 2)
+DEFTREECODE (BINARY_LEFT_FOLD_EXPR, "binary_left_fold_expr", tcc_expression, 3)
+DEFTREECODE (BINARY_RIGHT_FOLD_EXPR, "binary_right_fold_expr", tcc_expression, 3)
+
+
/** C++ extensions. */
/* Represents a trait expression during template expansion. */
@@ -80,6 +80,7 @@ c-common.h, not after.
COMPOUND_REQ_NOEXCEPT_P (in COMPOUND_REQ)
WILDCARD_PACK_P (in WILDCARD_DECL)
BLOCK_OUTER_CURLY_BRACE_P (in BLOCK)
+ FOLD_EXPR_MODOP_P (*_FOLD_EXPR)
1: IDENTIFIER_VIRTUAL_P (in IDENTIFIER_NODE)
TI_PENDING_TEMPLATE_FLAG.
TEMPLATE_PARMS_FOR_INLINE.
@@ -3249,6 +3250,37 @@ extern void decl_shadowed_for_var_insert (tree, tree);
TREE_VEC_ELT (ARGUMENT_PACK_ARGS (ARGUMENT_PACK_SELECT_FROM_PACK (NODE)), \
ARGUMENT_PACK_SELECT_INDEX (NODE))
+#define FOLD_EXPR_CHECK(NODE) \
+ TREE_CHECK4 (NODE, UNARY_LEFT_FOLD_EXPR, UNARY_RIGHT_FOLD_EXPR, \
+ BINARY_LEFT_FOLD_EXPR, BINARY_RIGHT_FOLD_EXPR)
+
+#define BINARY_FOLD_EXPR_CHECK(NODE) \
+ TREE_CHECK2 (NODE, BINARY_LEFT_FOLD_EXPR, BINARY_RIGHT_FOLD_EXPR)
+
+/* True if NODE is UNARY_FOLD_EXPR or a BINARY_FOLD_EXPR */
+#define FOLD_EXPR_P(NODE) \
+ TREE_CODE (NODE) == UNARY_LEFT_FOLD_EXPR \
+ || TREE_CODE (NODE) == UNARY_RIGHT_FOLD_EXPR \
+ || TREE_CODE (NODE) == BINARY_LEFT_FOLD_EXPR \
+ || TREE_CODE (NODE) == BINARY_RIGHT_FOLD_EXPR
+
+/* True when NODE is a fold over a compound assignment operator. */
+#define FOLD_EXPR_MODIFY_P(NODE) \
+ TREE_LANG_FLAG_0 (FOLD_EXPR_CHECK (NODE))
+
+/* An INTEGER_CST containing the tree code of the folded operator. */
+#define FOLD_EXPR_OP(NODE) \
+ TREE_OPERAND (FOLD_EXPR_CHECK (NODE), 0)
+
+/* The expression containing an unexpanded parameter pack. */
+#define FOLD_EXPR_PACK(NODE) \
+ TREE_OPERAND (FOLD_EXPR_CHECK (NODE), 1)
+
+/* In a binary fold expression, the argument with no unexpanded
+ parameter packs. */
+#define FOLD_EXPR_INIT(NODE) \
+ TREE_OPERAND (BINARY_FOLD_EXPR_CHECK (NODE), 2)
+
/* In a FUNCTION_DECL, the saved language-specific per-function data. */
#define DECL_SAVED_FUNCTION_DATA(NODE) \
(LANG_DECL_FN_CHECK (FUNCTION_DECL_CHECK (NODE)) \
@@ -6567,6 +6599,10 @@ extern bool check_literal_operator_args (const_tree, bool *, bool *);
extern void maybe_warn_about_useless_cast (tree, tree, tsubst_flags_t);
extern tree cp_perform_integral_promotions (tree, tsubst_flags_t);
+extern tree finish_left_unary_fold_expr (tree, int);
+extern tree finish_right_unary_fold_expr (tree, int);
+extern tree finish_binary_fold_expr (tree, tree, int);
+
/* in typeck2.c */
extern void require_complete_eh_spec_types (tree, tree);
extern void cxx_incomplete_type_diagnostic (const_tree, const_tree, diagnostic_t);
@@ -3175,20 +3175,20 @@ cp_parser_parse_and_diagnose_invalid_type_name (cp_parser *parser)
/* Consume tokens up to, and including, the next non-nested closing `)'.
Returns 1 iff we found a closing `)'. RECOVERING is true, if we
- are doing error recovery. Returns -1 if OR_COMMA is true and we
- found an unnested comma. */
+ are doing error recovery. Returns -1 if OR_TTYPE is not CPP_EOF and we
+ found an unnested token of that type. */
static int
-cp_parser_skip_to_closing_parenthesis (cp_parser *parser,
- bool recovering,
- bool or_comma,
- bool consume_paren)
+cp_parser_skip_to_closing_parenthesis_1 (cp_parser *parser,
+ bool recovering,
+ cpp_ttype or_ttype,
+ bool consume_paren)
{
unsigned paren_depth = 0;
unsigned brace_depth = 0;
unsigned square_depth = 0;
- if (recovering && !or_comma
+ if (recovering && or_ttype == CPP_EOF
&& cp_parser_uncommitted_to_tentative_parse_p (parser))
return 0;
@@ -3196,6 +3196,11 @@ cp_parser_skip_to_closing_parenthesis (cp_parser *parser,
{
cp_token * token = cp_lexer_peek_token (parser->lexer);
+ /* Have we found what we're looking for before the closing paren? */
+ if (token->type == or_ttype && or_ttype != CPP_EOF
+ && !brace_depth && !paren_depth && !square_depth)
+ return -1;
+
switch (token->type)
{
case CPP_EOF:
@@ -3226,12 +3231,6 @@ cp_parser_skip_to_closing_parenthesis (cp_parser *parser,
return 0;
break;
- case CPP_COMMA:
- if (recovering && or_comma && !brace_depth && !paren_depth
- && !square_depth)
- return -1;
- break;
-
case CPP_OPEN_PAREN:
if (!brace_depth)
++paren_depth;
@@ -3255,6 +3254,22 @@ cp_parser_skip_to_closing_parenthesis (cp_parser *parser,
}
}
+/* Consume tokens up to, and including, the next non-nested closing `)'.
+ Returns 1 iff we found a closing `)'. RECOVERING is true, if we
+ are doing error recovery. Returns -1 if OR_COMMA is true and we
+ found an unnested token of that type. */
+
+static int
+cp_parser_skip_to_closing_parenthesis (cp_parser *parser,
+ bool recovering,
+ bool or_comma,
+ bool consume_paren)
+{
+ cpp_ttype ttype = or_comma ? CPP_COMMA : CPP_EOF;
+ return cp_parser_skip_to_closing_parenthesis_1 (parser, recovering,
+ ttype, consume_paren);
+}
+
/* Consume tokens until we reach the end of the current statement.
Normally, that will be just before consuming a `;'. However, if a
non-nested `}' comes first, then we stop before consuming that. */
@@ -4260,6 +4275,186 @@ cp_parser_statement_expr (cp_parser *parser)
/* Expressions [gram.expr] */
+/* Parse a fold-operator.
+
+ fold-operator:
+ - * / % ^ & | = < > << >>
+ = -= *= /= %= ^= &= |= <<= >>=
+ == != <= >= && || , .* ->*
+
+ This returns the tree code corresponding to the matched operator
+ as an int. When the current token matches a compound assignment
+ opertor, the resulting tree code is the negative value of the
+ non-assignment operator. */
+
+static int
+cp_parser_fold_operator (cp_token *token)
+{
+ switch (token->type)
+ {
+ case CPP_PLUS: return PLUS_EXPR;
+ case CPP_MINUS: return MINUS_EXPR;
+ case CPP_MULT: return MULT_EXPR;
+ case CPP_DIV: return TRUNC_DIV_EXPR;
+ case CPP_MOD: return TRUNC_MOD_EXPR;
+ case CPP_XOR: return BIT_XOR_EXPR;
+ case CPP_AND: return BIT_AND_EXPR;
+ case CPP_OR: return BIT_IOR_EXPR;
+ case CPP_LSHIFT: return LSHIFT_EXPR;
+ case CPP_RSHIFT: return RSHIFT_EXPR;
+
+ case CPP_EQ: return -NOP_EXPR;
+ case CPP_PLUS_EQ: return -PLUS_EXPR;
+ case CPP_MINUS_EQ: return -MINUS_EXPR;
+ case CPP_MULT_EQ: return -MULT_EXPR;
+ case CPP_DIV_EQ: return -TRUNC_DIV_EXPR;
+ case CPP_MOD_EQ: return -TRUNC_MOD_EXPR;
+ case CPP_XOR_EQ: return -BIT_XOR_EXPR;
+ case CPP_AND_EQ: return -BIT_AND_EXPR;
+ case CPP_OR_EQ: return -BIT_IOR_EXPR;
+ case CPP_LSHIFT_EQ: return -LSHIFT_EXPR;
+ case CPP_RSHIFT_EQ: return -RSHIFT_EXPR;
+
+ case CPP_EQ_EQ: return EQ_EXPR;
+ case CPP_NOT_EQ: return NE_EXPR;
+ case CPP_LESS: return LT_EXPR;
+ case CPP_GREATER: return GT_EXPR;
+ case CPP_LESS_EQ: return LE_EXPR;
+ case CPP_GREATER_EQ: return GE_EXPR;
+
+ case CPP_AND_AND: return TRUTH_ANDIF_EXPR;
+ case CPP_OR_OR: return TRUTH_ORIF_EXPR;
+
+ case CPP_COMMA: return COMPOUND_EXPR;
+
+ case CPP_DOT_STAR: return DOTSTAR_EXPR;
+ case CPP_DEREF_STAR: return MEMBER_REF;
+
+ default: return ERROR_MARK;
+ }
+}
+
+/* If the next token is a suitable fold operator, consume it and return as
+ the function above. */
+
+static int
+cp_parser_fold_operator (cp_parser *parser)
+{
+ cp_token* token = cp_lexer_peek_token (parser->lexer);
+ int code = cp_parser_fold_operator (token);
+ if (code != ERROR_MARK)
+ cp_lexer_consume_token (parser->lexer);
+ return code;
+}
+
+/* Returns true iff we're at the beginning of an N4191 fold-expression, after
+ the left parenthesis. Rather than do tentative parsing, we scan the tokens
+ up to the matching right paren for an ellipsis next to a binary
+ operator. */
+
+static bool
+cp_parser_fold_expr_p (cp_parser *parser)
+{
+ /* An ellipsis right after the left paren always indicates a
+ fold-expression. */
+ if (cp_lexer_next_token_is (parser->lexer, CPP_ELLIPSIS))
+ {
+ /* But if there isn't a fold operator after the ellipsis,
+ give a different error. */
+ cp_token *token = cp_lexer_peek_nth_token (parser->lexer, 2);
+ return (cp_parser_fold_operator (token) != ERROR_MARK);
+ }
+
+ /* Otherwise, look for an ellipsis. */
+ cp_lexer_save_tokens (parser->lexer);
+ int ret = cp_parser_skip_to_closing_parenthesis_1 (parser, false,
+ CPP_ELLIPSIS, false);
+ bool found = (ret == -1);
+ if (found)
+ {
+ /* We found an ellipsis, is the previous token an operator? */
+ cp_token *token = cp_lexer_peek_token (parser->lexer);
+ --token;
+ if (cp_parser_fold_operator (token) == ERROR_MARK)
+ found = false;
+ }
+ cp_lexer_rollback_tokens (parser->lexer);
+ return found;
+}
+
+/* Parse a fold-expression.
+
+ fold-expression:
+ ( ... folding-operator cast-expression)
+ ( cast-expression folding-operator ... )
+ ( cast-expression folding operator ... folding-operator cast-expression)
+
+ Note that the '(' and ')' are matched in primary expression. */
+
+static tree
+cp_parser_fold_expression (cp_parser *parser)
+{
+ cp_id_kind pidk;
+
+ if (cxx_dialect < cxx1z && !in_system_header_at (input_location))
+ pedwarn (input_location, 0, "fold-expressions only available with "
+ "-std=c++1z or -std=gnu++1z");
+
+ // Left fold.
+ if (cp_lexer_next_token_is (parser->lexer, CPP_ELLIPSIS))
+ {
+ cp_lexer_consume_token (parser->lexer);
+ int op = cp_parser_fold_operator (parser);
+ if (op == ERROR_MARK)
+ {
+ cp_parser_error (parser, "expected binary operator");
+ return error_mark_node;
+ }
+
+ tree expr = cp_parser_cast_expression (parser, false, false,
+ false, &pidk);
+ if (expr == error_mark_node)
+ return error_mark_node;
+ return finish_left_unary_fold_expr (expr, op);
+ }
+
+ tree expr1 = cp_parser_cast_expression (parser, false, false, false, &pidk);
+ if (expr1 == error_mark_node)
+ return error_mark_node;
+
+ const cp_token* token = cp_lexer_peek_token (parser->lexer);
+ int op = cp_parser_fold_operator (parser);
+ if (op == ERROR_MARK)
+ {
+ cp_parser_error (parser, "expected binary operator");
+ return error_mark_node;
+ }
+
+ if (cp_lexer_next_token_is_not (parser->lexer, CPP_ELLIPSIS))
+ {
+ cp_parser_error (parser, "expected ...");
+ return error_mark_node;
+ }
+ cp_lexer_consume_token (parser->lexer);
+
+ // Right fold.
+ if (cp_lexer_next_token_is (parser->lexer, CPP_CLOSE_PAREN))
+ return finish_right_unary_fold_expr (expr1, op);
+
+ if (cp_lexer_next_token_is_not (parser->lexer, token->type))
+ {
+ cp_parser_error (parser, "mismatched operator in fold-expression");
+ return error_mark_node;
+ }
+ cp_lexer_consume_token (parser->lexer);
+
+ // Binary left or right fold.
+ tree expr2 = cp_parser_cast_expression (parser, false, false, false, &pidk);
+ if (expr2 == error_mark_node)
+ return error_mark_node;
+ return finish_binary_fold_expr (expr1, expr2, op);
+}
+
/* Parse a primary-expression.
primary-expression:
@@ -4468,6 +4663,14 @@ cp_parser_primary_expression (cp_parser *parser,
= parser->greater_than_is_operator_p;
parser->greater_than_is_operator_p = true;
+ // Handle a fold-expression.
+ if (cp_parser_fold_expr_p (parser))
+ {
+ tree fold = cp_parser_fold_expression (parser);
+ cp_parser_require (parser, CPP_CLOSE_PAREN, RT_CLOSE_PAREN);
+ return fold;
+ }
+
/* Parse the parenthesized expression. */
expr = cp_parser_expression (parser, idk, cast_p, decltype_p);
/* Let the front end know that this expression was
@@ -10506,6 +10506,208 @@ gen_elem_of_pack_expansion_instantiation (tree pattern,
return t;
}
+/* When the unexpanded parameter pack in a fold expression expands to an empty
+ sequence, the value of the expression is as follows; the program is
+ ill-formed if the operator is not listed in this table.
+
+ * 1
+ + 0
+ & -1
+ | 0
+ && true
+ || false
+ , void() */
+
+tree
+expand_empty_fold (tree t, tsubst_flags_t complain)
+{
+ tree_code code = (tree_code)TREE_INT_CST_LOW (TREE_OPERAND (t, 0));
+ if (!FOLD_EXPR_MODIFY_P (t))
+ switch (code)
+ {
+ case MULT_EXPR:
+ return integer_one_node;
+ case PLUS_EXPR:
+ return integer_zero_node;
+ case BIT_AND_EXPR:
+ return integer_minus_one_node;
+ case BIT_IOR_EXPR:
+ return integer_zero_node;
+ case TRUTH_ANDIF_EXPR:
+ return boolean_true_node;
+ case TRUTH_ORIF_EXPR:
+ return boolean_false_node;
+ case COMPOUND_EXPR:
+ return void_node;
+ default:
+ break;
+ }
+
+ if (complain & tf_error)
+ error_at (location_of (t),
+ "fold of empty expansion over %O", code);
+ return error_mark_node;
+}
+
+/* Given a fold-expression T and a current LEFT and RIGHT operand,
+ form an expression that combines the two terms using the
+ operator of T. */
+
+static tree
+fold_expression (tree t, tree left, tree right, tsubst_flags_t complain)
+{
+ tree op = FOLD_EXPR_OP (t);
+ tree_code code = (tree_code)TREE_INT_CST_LOW (op);
+
+ // Handle compound assignment operators.
+ if (FOLD_EXPR_MODIFY_P (t))
+ return build_x_modify_expr (input_location, left, code, right, complain);
+
+ switch (code)
+ {
+ case COMPOUND_EXPR:
+ return build_x_compound_expr (input_location, left, right, complain);
+ case DOTSTAR_EXPR:
+ return build_m_component_ref (left, right, complain);
+ default:
+ return build_x_binary_op (input_location, code,
+ left, TREE_CODE (left),
+ right, TREE_CODE (right),
+ /*overload=*/NULL,
+ complain);
+ }
+}
+
+/* Substitute ARGS into the pack of a fold expression T. */
+
+static inline tree
+tsubst_fold_expr_pack (tree t, tree args, tsubst_flags_t complain, tree in_decl)
+{
+ return tsubst_pack_expansion (FOLD_EXPR_PACK (t), args, complain, in_decl);
+}
+
+/* Substitute ARGS into the pack of a fold expression T. */
+
+static inline tree
+tsubst_fold_expr_init (tree t, tree args, tsubst_flags_t complain, tree in_decl)
+{
+ return tsubst_expr (FOLD_EXPR_INIT (t), args, complain, in_decl, false);
+}
+
+/* Expand a PACK of arguments into a grouped as left fold.
+ Given a pack containing elements A0, A1, ..., An and an
+ operator @, this builds the expression:
+
+ ((A0 @ A1) @ A2) ... @ An
+
+ Note that PACK must not be empty.
+
+ The operator is defined by the original fold expression T. */
+
+static tree
+expand_left_fold (tree t, tree pack, tsubst_flags_t complain)
+{
+ tree left = TREE_VEC_ELT (pack, 0);
+ for (int i = 1; i < TREE_VEC_LENGTH (pack); ++i)
+ {
+ tree right = TREE_VEC_ELT (pack, i);
+ left = fold_expression (t, left, right, complain);
+ }
+ return left;
+}
+
+/* Substitute into a unary left fold expression. */
+
+static tree
+tsubst_unary_left_fold (tree t, tree args, tsubst_flags_t complain,
+ tree in_decl)
+{
+ tree pack = tsubst_fold_expr_pack (t, args, complain, in_decl);
+ if (TREE_VEC_LENGTH (pack) == 0)
+ return expand_empty_fold (t, complain);
+ else
+ return expand_left_fold (t, pack, complain);
+}
+
+/* Substitute into a binary left fold expression.
+
+ Do ths by building a single (non-empty) vector of argumnts and
+ building the expression from those elements. */
+
+static tree
+tsubst_binary_left_fold (tree t, tree args, tsubst_flags_t complain,
+ tree in_decl)
+{
+ tree pack = tsubst_fold_expr_pack (t, args, complain, in_decl);
+ tree init = tsubst_fold_expr_init (t, args, complain, in_decl);
+
+ tree vec = make_tree_vec (TREE_VEC_LENGTH (pack) + 1);
+ TREE_VEC_ELT (vec, 0) = init;
+ for (int i = 0; i < TREE_VEC_LENGTH (pack); ++i)
+ TREE_VEC_ELT (vec, i + 1) = TREE_VEC_ELT (pack, i);
+
+ return expand_left_fold (t, vec, complain);
+}
+
+/* Expand a PACK of arguments into a grouped as right fold.
+ Given a pack containing elementns A0, A1, ..., and an
+ operator @, this builds the expression:
+
+ A0@ ... (An-2 @ (An-1 @ An))
+
+ Note that PACK must not be empty.
+
+ The operator is defined by the original fold expression T. */
+
+tree
+expand_right_fold (tree t, tree pack, tsubst_flags_t complain)
+{
+ // Build the expression.
+ int n = TREE_VEC_LENGTH (pack);
+ tree right = TREE_VEC_ELT (pack, n - 1);
+ for (--n; n != 0; --n)
+ {
+ tree left = TREE_VEC_ELT (pack, n - 1);
+ right = fold_expression (t, left, right, complain);
+ }
+ return right;
+}
+
+/* Substitute into a unary right fold expression. */
+
+static tree
+tsubst_unary_right_fold (tree t, tree args, tsubst_flags_t complain,
+ tree in_decl)
+{
+ tree pack = tsubst_fold_expr_pack (t, args, complain, in_decl);
+ if (TREE_VEC_LENGTH (pack) == 0)
+ return expand_empty_fold (t, complain);
+ else
+ return expand_right_fold (t, pack, complain);
+}
+
+/* Substitute into a binary right fold expression.
+
+ Do ths by building a single (non-empty) vector of arguments and
+ building the expression from those elements. */
+
+static tree
+tsubst_binary_right_fold (tree t, tree args, tsubst_flags_t complain,
+ tree in_decl)
+{
+ tree pack = tsubst_fold_expr_pack (t, args, complain, in_decl);
+ tree init = tsubst_fold_expr_init (t, args, complain, in_decl);
+
+ int n = TREE_VEC_LENGTH (pack);
+ tree vec = make_tree_vec (n + 1);
+ for (int i = 0; i < n; ++i)
+ TREE_VEC_ELT (vec, i) = TREE_VEC_ELT (pack, i);
+ TREE_VEC_ELT (vec, n) = init;
+
+ return expand_right_fold (t, vec, complain);
+}
+
+
/* Substitute ARGS into T, which is an pack expansion
(i.e. TYPE_PACK_EXPANSION or EXPR_PACK_EXPANSION). Returns a
TREE_VEC with the substituted arguments, a PACK_EXPANSION_* node
@@ -14050,6 +14252,15 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
gcc_assert (!uses_template_parms (t));
return t;
+ case UNARY_LEFT_FOLD_EXPR:
+ return tsubst_unary_left_fold (t, args, complain, in_decl);
+ case UNARY_RIGHT_FOLD_EXPR:
+ return tsubst_unary_right_fold (t, args, complain, in_decl);
+ case BINARY_LEFT_FOLD_EXPR:
+ return tsubst_binary_left_fold (t, args, complain, in_decl);
+ case BINARY_RIGHT_FOLD_EXPR:
+ return tsubst_binary_right_fold (t, args, complain, in_decl);
+
default:
/* We shouldn't get here, but keep going if !ENABLE_CHECKING. */
gcc_checking_assert (false);
@@ -22052,6 +22263,13 @@ type_dependent_expression_p (tree expression)
|| TREE_CODE (expression) == WILDCARD_DECL)
return true;
+ /* A fold expression is type-dependent. */
+ if (TREE_CODE (expression) == UNARY_LEFT_FOLD_EXPR
+ || TREE_CODE (expression) == UNARY_RIGHT_FOLD_EXPR
+ || TREE_CODE (expression) == BINARY_LEFT_FOLD_EXPR
+ || TREE_CODE (expression) == BINARY_RIGHT_FOLD_EXPR)
+ return true;
+
/* Some expression forms are never type-dependent. */
if (TREE_CODE (expression) == PSEUDO_DTOR_EXPR
|| TREE_CODE (expression) == SIZEOF_EXPR
@@ -7763,4 +7763,73 @@ capture_decltype (tree decl)
return type;
}
+/* Build a unary fold expression of EXPR over OP. If IS_RIGHT is true,
+ this is a right unary fold. Otherwise it is a left unary fold. */
+
+static tree
+finish_unary_fold_expr (tree expr, int op, tree_code dir)
+{
+ // Build a pack expansion (assuming expr has pack type).
+ if (!uses_parameter_packs (expr))
+ {
+ error_at (location_of (expr), "operand of fold expression has no "
+ "unexpanded parameter packs");
+ return error_mark_node;
+ }
+ tree pack = make_pack_expansion (expr);
+
+ // Build the fold expression.
+ tree code = build_int_cstu (integer_type_node, abs (op));
+ tree fold = build_min (dir, unknown_type_node, code, pack);
+ FOLD_EXPR_MODIFY_P (fold) = (op < 0);
+ return fold;
+}
+
+tree
+finish_left_unary_fold_expr (tree expr, int op)
+{
+ return finish_unary_fold_expr (expr, op, UNARY_LEFT_FOLD_EXPR);
+}
+
+tree
+finish_right_unary_fold_expr (tree expr, int op)
+{
+ return finish_unary_fold_expr (expr, op, UNARY_RIGHT_FOLD_EXPR);
+}
+
+/* Build a binary fold expression over EXPR1 and EXPR2. The
+ associativity of the fold is determined by EXPR1 and EXPR2 (whichever
+ has an unexpanded parameter pack). */
+
+tree
+finish_binary_fold_expr (tree pack, tree init, int op, tree_code dir)
+{
+ pack = make_pack_expansion (pack);
+ tree code = build_int_cstu (integer_type_node, abs (op));
+ tree fold = build_min (dir, unknown_type_node, code, pack, init);
+ FOLD_EXPR_MODIFY_P (fold) = (op < 0);
+ return fold;
+}
+
+tree
+finish_binary_fold_expr (tree expr1, tree expr2, int op)
+{
+ // Determine which expr has an unexpanded parameter pack and
+ // set the pack and initial term.
+ bool pack1 = uses_parameter_packs (expr1);
+ bool pack2 = uses_parameter_packs (expr2);
+ if (pack1 && !pack2)
+ return finish_binary_fold_expr (expr1, expr2, op, BINARY_RIGHT_FOLD_EXPR);
+ else if (pack2 && !pack1)
+ return finish_binary_fold_expr (expr2, expr1, op, BINARY_LEFT_FOLD_EXPR);
+ else
+ {
+ if (pack1)
+ error ("both arguments in binary fold have unexpanded parameter packs");
+ else
+ error ("no unexpanded parameter packs in binary fold");
+ }
+ return error_mark_node;
+}
+
#include "gt-cp-semantics.h"
new file mode 100644
@@ -0,0 +1,56 @@
+// { dg-do run }
+// { dg-options "-std=c++1z" }
+
+#include <cassert>
+
+// Check the semantics of a couple of operations to make sure
+// that the expressions are formed correctly.
+
+#define COMMA ,
+
+#define MAKE_FNS(name, op) \
+ template<typename... Ts> \
+ auto unary_left_ ## name (Ts... ts) { return (... op ts); } \
+ template<typename... Ts> \
+ auto unary_right_ ## name (Ts... ts) { return (ts op ...); } \
+ template<typename T, typename... Ts> \
+ auto binary_left_ ## name (T x, Ts... ts) { return (x op ... op ts); } \
+ template<typename T, typename... Ts> \
+ auto binary_right_ ## name (T x, Ts... ts) { return (ts op ... op x); }
+
+MAKE_FNS (add, +);
+MAKE_FNS (sub, -);
+
+int main() {
+ assert(unary_left_add() == 0);
+ assert(unary_left_add(1) == 1);
+ assert(unary_left_add(1, 2, 3) == 6);
+
+ assert(unary_right_add() == 0);
+ assert(unary_right_add(1) == 1);
+ assert(unary_right_add(1, 2, 3) == 6);
+
+ assert(binary_left_add(1) == 1);
+ assert(binary_left_add(1, 1) == 2);
+ assert(binary_left_add(1, 1, 2, 3) == 7);
+
+ assert(binary_right_add(1) == 1);
+ assert(binary_right_add(1, 1) == 2);
+ assert(binary_right_add(1, 1, 2, 3) == 7);
+
+ // unary_left_sub(); // { dg-error "empty"}
+ assert(unary_left_sub(1) == 1);
+ assert(unary_left_sub(1, 2, 3) == -4);
+
+ // unary_right_sub(); // { dg-error "empty"}
+ assert(unary_right_sub(1) == 1);
+ assert(unary_right_sub(1, 2, 3) == 2);
+
+ assert(binary_left_sub(1) == 1);
+ assert(binary_left_sub(1, 1) == 0);
+ assert(binary_left_sub(1, 1, 2, 3) == -5);
+
+ assert(binary_right_sub(1) == 1);
+ assert(binary_right_sub(1, 1) == 0);
+ assert(binary_right_sub(1, 1, 2, 3) == 1);
+}
new file mode 100644
@@ -0,0 +1,118 @@
+// { dg-do compile }
+// { dg-options "-std=c++1z" }
+
+// Check that we can fold over all of the operators required
+// by the standard in every possible way.
+
+#define COMMA ,
+
+#define MAKE_FNS(name, op) \
+ template<typename... Ts> \
+ auto unary_left_ ## name (Ts... ts) { return (... op ts); } \
+ template<typename... Ts> \
+ auto unary_right_ ## name (Ts... ts) { return (ts op ...); } \
+ template<typename T, typename... Ts> \
+ auto binary_left_ ## name (T x, Ts... ts) { return (x op ... op ts); } \
+ template<typename T, typename... Ts> \
+ auto binary_right_ ## name (T x, Ts... ts) { return (ts op ... op x); }
+
+// TODO: These are compile-only tests...
+#define CHECK_FN(name) \
+ unary_left_ ## name (a); \
+ unary_left_ ## name (a, b, c); \
+ unary_right_ ## name (a); \
+ unary_right_ ## name (a, b, c); \
+ binary_left_ ## name (a); \
+ binary_left_ ## name (a, b, c, d); \
+ binary_right_ ## name (d); \
+ binary_right_ ## name (d, a, b, c);
+
+MAKE_FNS (add, +);
+MAKE_FNS (sub, -);
+MAKE_FNS (mul, *);
+MAKE_FNS (div, /);
+MAKE_FNS (mod, %);
+MAKE_FNS (bxor, ^);
+MAKE_FNS (bor, |);
+MAKE_FNS (band, &);
+MAKE_FNS (lsh, <<);
+MAKE_FNS (rsh, >>);
+
+MAKE_FNS (assign, =);
+MAKE_FNS (addi, +=);
+MAKE_FNS (subi, -=);
+MAKE_FNS (muli, *=);
+MAKE_FNS (divi, /=);
+MAKE_FNS (modi, %=);
+MAKE_FNS (bxori, ^=);
+MAKE_FNS (bori, |=);
+MAKE_FNS (bandi, &=);
+MAKE_FNS (lshi, <<=);
+MAKE_FNS (rshi, >>=);
+
+MAKE_FNS (eq, ==);
+MAKE_FNS (ne, !=);
+MAKE_FNS (lt, <);
+MAKE_FNS (gt, >);
+MAKE_FNS (le, <);
+MAKE_FNS (ge, >);
+
+MAKE_FNS (land, &&);
+MAKE_FNS (lor, ||);
+
+MAKE_FNS (comma, COMMA);
+MAKE_FNS (dot_star, .*);
+MAKE_FNS (arrow_star, ->*);
+
+int main() {
+ int a = 0, b = 0, c = 0, d = 0;
+
+ CHECK_FN (add);
+ CHECK_FN (sub);
+ CHECK_FN (mul);
+ CHECK_FN (div);
+ CHECK_FN (mod);
+ CHECK_FN (bxor);
+ CHECK_FN (bor);
+ CHECK_FN (band);
+ CHECK_FN (lsh);
+ CHECK_FN (rsh);
+
+ // CHECK_FN (assign);
+ CHECK_FN (addi);
+ CHECK_FN (subi);
+ CHECK_FN (muli);
+ CHECK_FN (divi);
+ CHECK_FN (modi);
+ CHECK_FN (bxori);
+ CHECK_FN (bori);
+ CHECK_FN (bandi);
+ CHECK_FN (lshi);
+ CHECK_FN (rshi);
+
+ CHECK_FN (eq);
+ CHECK_FN (ne);
+ CHECK_FN (lt);
+ CHECK_FN (gt);
+ CHECK_FN (le);
+ CHECK_FN (ge);
+ CHECK_FN (eq);
+ CHECK_FN (ne);
+
+ CHECK_FN (comma);
+
+ struct X {
+ int a;
+ } x, *px = &x;
+
+ int X::* pm = &X::a;
+ unary_left_arrow_star (px, pm); // px ->* pm
+ unary_right_arrow_star (px, pm); // px ->* pm
+ binary_left_arrow_star (px, pm); // px ->* pm
+ binary_right_arrow_star (pm, px); // px ->* pm
+
+ unary_left_dot_star (x, pm); // x ->* pm
+ unary_right_dot_star (x, pm); // x ->* pm
+ binary_left_dot_star (x, pm); // x ->* pm
+ binary_right_dot_star (pm, x); // x ->* pm
+}
new file mode 100644
@@ -0,0 +1,85 @@
+// { dg-do compile }
+// { dg-options "-std=c++1z" }
+
+// Check that empty expansions and required failures.
+
+#define COMMA ,
+
+#define MAKE_FN(name, op) \
+ template<typename... Ts> \
+ constexpr auto name (Ts... ts) { return (... op ts); } // { dg-error "empty" }
+
+MAKE_FN (add, +);
+MAKE_FN (sub, -);
+MAKE_FN (mul, *);
+MAKE_FN (div, /);
+MAKE_FN (mod, %);
+MAKE_FN (bxor, ^);
+MAKE_FN (bor, |);
+MAKE_FN (band, &);
+MAKE_FN (lsh, <<);
+MAKE_FN (rsh, >>);
+
+MAKE_FN (assign, =);
+MAKE_FN (addi, +=);
+MAKE_FN (subi, -=);
+MAKE_FN (muli, *=);
+MAKE_FN (divi, /=);
+MAKE_FN (modi, %=);
+MAKE_FN (bxori, ^=);
+MAKE_FN (bori, |=);
+MAKE_FN (bandi, &=);
+MAKE_FN (lshi, <<=);
+MAKE_FN (rshi, >>=);
+
+MAKE_FN (eq, ==);
+MAKE_FN (ne, !=);
+MAKE_FN (lt, <);
+MAKE_FN (gt, >);
+MAKE_FN (le, <);
+MAKE_FN (ge, >);
+
+MAKE_FN (land, &&);
+MAKE_FN (lor, ||);
+
+MAKE_FN (comma, COMMA);
+MAKE_FN (dot_star, .*);
+MAKE_FN (arrow_star, ->*);
+
+int main() {
+ static_assert(add() == int(), "");
+ static_assert(mul() == 1, "");
+ static_assert(bor() == int(), "");
+ static_assert(band() == -1, "");
+ static_assert(land() == true, "");
+ static_assert(lor() == false, "");
+ comma(); // No value to theck
+
+ // These are all errors, but the error is emitted at the point
+ // of instantiation (line 10).
+ sub(); // { dg-message "required from here" }
+ div(); // { dg-message "required from here" }
+ mod(); // { dg-message "required from here" }
+ lsh(); // { dg-message "required from here" }
+ rsh(); // { dg-message "required from here" }
+ assign(); // { dg-message "required from here" }
+ addi(); // { dg-message "required from here" }
+ subi(); // { dg-message "required from here" }
+ muli(); // { dg-message "required from here" }
+ divi(); // { dg-message "required from here" }
+ modi(); // { dg-message "required from here" }
+ bxor(); // { dg-message "required from here" }
+ bxori(); // { dg-message "required from here" }
+ bori(); // { dg-message "required from here" }
+ bandi(); // { dg-message "required from here" }
+ lshi(); // { dg-message "required from here" }
+ rshi(); // { dg-message "required from here" }
+ eq(); // { dg-message "required from here" }
+ ne(); // { dg-message "required from here" }
+ lt(); // { dg-message "required from here" }
+ gt(); // { dg-message "required from here" }
+ le(); // { dg-message "required from here" }
+ ge(); // { dg-message "required from here" }
+ dot_star(); // { dg-message "required from here" }
+ arrow_star(); // { dg-message "required from here" }
+}
new file mode 100644
@@ -0,0 +1,10 @@
+// { dg-options -std=c++1z }
+
+template <class...T>
+constexpr auto f(T... t)
+{
+ return (... + *t);
+}
+
+const int i = 42, j = 24;
+static_assert (f(&i,&j) == i+j);
new file mode 100644
@@ -0,0 +1,8 @@
+// Test that we complain about fold-expressions in C++11 and C++14.
+// { dg-do compile { target c++11 } }
+
+template <class...T>
+constexpr int f(T... t)
+{
+ return (... + t); // { dg-error "fold" }
+}