From 73a2b8dd17dbc02c0c7e6286e90f17833aa50906 Mon Sep 17 00:00:00 2001 From: Marek Polacek Date: Thu, 13 Aug 2020 14:56:13 -0400 Subject: [PATCH] c++: Implement P1009: Array size deduction in new-expressions. This patch implements C++20 P1009, allowing code like new double[]{1,2,3}; // array bound will be deduced Since this proposal makes the initialization rules more consistent, it is applied to all previous versions of C++ (thus, effectively, all the way back to C++11). My patch is based on Jason's patch that handled the basic case. I've extended it to work with ()-init and also the string literal case. Further testing revealed that to handle stuff like new int[]{t...}; in a template, we have to consider such a NEW_EXPR type-dependent. Obviously, we first have to expand the pack to be able to deduce the number of elements in the array. Curiously, while implementing this proposal, I noticed that we fail to accept new char[4]{"abc"}; so I've assigned 77841 to self. I think the fix will depend on the build_new_1 hunk in this patch. The new tree.c function build_constructor_from_vec helps us morph a vector into a CONSTRUCTOR more efficiently. gcc/cp/ChangeLog: PR c++/93529 * call.c (build_new_method_call_1): Use build_constructor_from_vec instead of build_tree_list_vec + build_constructor_from_list. * init.c (build_new_1): Handle new char[]{"foo"}. Use build_constructor_from_vec instead of build_tree_list_vec + build_constructor_from_list. (build_new): Deduce the array size in new-expression if not present. Handle ()-init. Handle initializing an array from a string literal. * parser.c (cp_parser_new_type_id): Leave [] alone. (cp_parser_direct_new_declarator): Allow []. * pt.c (type_dependent_expression_p): In a NEW_EXPR, consider array types whose dimension has to be deduced type-dependent. gcc/ChangeLog: PR c++/93529 * tree.c (build_constructor_from_vec): New. * tree.h (build_constructor_from_vec): Declare. gcc/testsuite/ChangeLog: PR c++/93529 * g++.dg/cpp0x/sfinae4.C: Adjust expected result after P1009. * g++.dg/cpp2a/new-array1.C: New test. * g++.dg/cpp2a/new-array2.C: New test. * g++.dg/cpp2a/new-array3.C: New test. * g++.dg/cpp2a/new-array4.C: New test. Co-authored-by: Jason Merrill --- gcc/cp/call.c | 4 +- gcc/cp/init.c | 55 +++++++++++++++++-- gcc/cp/parser.c | 13 +++-- gcc/cp/pt.c | 4 ++ gcc/testsuite/g++.dg/cpp0x/sfinae4.C | 8 ++- gcc/testsuite/g++.dg/cpp2a/new-array1.C | 70 +++++++++++++++++++++++++ gcc/testsuite/g++.dg/cpp2a/new-array2.C | 22 ++++++++ gcc/testsuite/g++.dg/cpp2a/new-array3.C | 17 ++++++ gcc/testsuite/g++.dg/cpp2a/new-array4.C | 10 ++++ gcc/tree.c | 15 ++++++ gcc/tree.h | 1 + 11 files changed, 209 insertions(+), 10 deletions(-) create mode 100644 gcc/testsuite/g++.dg/cpp2a/new-array1.C create mode 100644 gcc/testsuite/g++.dg/cpp2a/new-array2.C create mode 100644 gcc/testsuite/g++.dg/cpp2a/new-array3.C create mode 100644 gcc/testsuite/g++.dg/cpp2a/new-array4.C diff --git a/gcc/cp/call.c b/gcc/cp/call.c index 4726e57a30d..61bbb38bd2b 100644 --- a/gcc/cp/call.c +++ b/gcc/cp/call.c @@ -10297,8 +10297,8 @@ build_new_method_call_1 (tree instance, tree fns, vec **args, && !vec_safe_is_empty (user_args)) { /* Create a CONSTRUCTOR from ARGS, e.g. {1, 2} from <1, 2>. */ - tree list = build_tree_list_vec (user_args); - tree ctor = build_constructor_from_list (init_list_type_node, list); + tree ctor = build_constructor_from_vec (init_list_type_node, + user_args); CONSTRUCTOR_IS_DIRECT_INIT (ctor) = true; CONSTRUCTOR_IS_PAREN_INIT (ctor) = true; if (is_dummy_object (instance)) diff --git a/gcc/cp/init.c b/gcc/cp/init.c index 872c23453fd..360ab8c0b52 100644 --- a/gcc/cp/init.c +++ b/gcc/cp/init.c @@ -3559,8 +3559,8 @@ build_new_1 (vec **placement, tree type, tree nelts, else if (array_p) { tree vecinit = NULL_TREE; - if (vec_safe_length (*init) == 1 - && DIRECT_LIST_INIT_P ((**init)[0])) + const size_t len = vec_safe_length (*init); + if (len == 1 && DIRECT_LIST_INIT_P ((**init)[0])) { vecinit = (**init)[0]; if (CONSTRUCTOR_NELTS (vecinit) == 0) @@ -3578,6 +3578,15 @@ build_new_1 (vec **placement, tree type, tree nelts, vecinit = digest_init (arraytype, vecinit, complain); } } + /* This handles code like new char[]{"foo"}. */ + else if (len == 1 + && char_type_p (TYPE_MAIN_VARIANT (type)) + && TREE_CODE (tree_strip_any_location_wrapper ((**init)[0])) + == STRING_CST) + { + vecinit = (**init)[0]; + STRIP_ANY_LOCATION_WRAPPER (vecinit); + } else if (*init) { if (complain & tf_error) @@ -3634,8 +3643,7 @@ build_new_1 (vec **placement, tree type, tree nelts, && AGGREGATE_TYPE_P (type) && (*init)->length () > 1) { - ie = build_tree_list_vec (*init); - ie = build_constructor_from_list (init_list_type_node, ie); + ie = build_constructor_from_vec (init_list_type_node, *init); CONSTRUCTOR_IS_DIRECT_INIT (ie) = true; CONSTRUCTOR_IS_PAREN_INIT (ie) = true; ie = digest_init (type, ie, complain); @@ -3917,6 +3925,45 @@ build_new (location_t loc, vec **placement, tree type, return error_mark_node; } + /* P1009: Array size deduction in new-expressions. */ + if (TREE_CODE (type) == ARRAY_TYPE + && !TYPE_DOMAIN (type) + && *init) + { + /* This means we have 'new T[]()'. */ + if ((*init)->is_empty ()) + { + tree ctor = build_constructor (init_list_type_node, NULL); + CONSTRUCTOR_IS_DIRECT_INIT (ctor) = true; + vec_safe_push (*init, ctor); + } + tree &elt = (**init)[0]; + /* The C++20 'new T[](e_0, ..., e_k)' case allowed by P0960. */ + if (!DIRECT_LIST_INIT_P (elt) && cxx_dialect >= cxx20) + { + /* Handle new char[]("foo"). */ + if (vec_safe_length (*init) == 1 + && char_type_p (TYPE_MAIN_VARIANT (TREE_TYPE (type))) + && TREE_CODE (tree_strip_any_location_wrapper (elt)) + == STRING_CST) + /* Leave it alone: the string should not be wrapped in {}. */; + else + { + tree ctor = build_constructor_from_vec (init_list_type_node, *init); + CONSTRUCTOR_IS_DIRECT_INIT (ctor) = true; + CONSTRUCTOR_IS_PAREN_INIT (ctor) = true; + elt = ctor; + /* We've squashed all the vector elements into the first one; + truncate the rest. */ + (*init)->truncate (1); + } + } + /* Otherwise we should have 'new T[]{e_0, ..., e_k}'. */ + if (BRACE_ENCLOSED_INITIALIZER_P (elt)) + elt = reshape_init (type, elt, complain); + cp_complete_array_type (&type, elt, /*do_default*/false); + } + /* The type allocated must be complete. If the new-type-id was "T[N]" then we are just checking that "T" is complete here, but that is equivalent, since the value of "N" doesn't matter. */ diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c index 147d5374907..9849e59d5aa 100644 --- a/gcc/cp/parser.c +++ b/gcc/cp/parser.c @@ -9011,7 +9011,9 @@ cp_parser_new_type_id (cp_parser* parser, tree *nelts) if (*nelts == error_mark_node) *nelts = integer_one_node; - if (outer_declarator) + if (*nelts == NULL_TREE) + /* Leave [] in the declarator. */; + else if (outer_declarator) outer_declarator->declarator = declarator->declarator; else new_declarator = NULL; @@ -9072,6 +9074,7 @@ static cp_declarator * cp_parser_direct_new_declarator (cp_parser* parser) { cp_declarator *declarator = NULL; + bool first_p = true; while (true) { @@ -9082,14 +9085,17 @@ cp_parser_direct_new_declarator (cp_parser* parser) cp_parser_require (parser, CPP_OPEN_SQUARE, RT_OPEN_SQUARE); token = cp_lexer_peek_token (parser->lexer); - expression = cp_parser_expression (parser); + if (token->type == CPP_CLOSE_SQUARE && first_p) + expression = NULL_TREE; + else + expression = cp_parser_expression (parser); /* The standard requires that the expression have integral type. DR 74 adds enumeration types. We believe that the real intent is that these expressions be handled like the expression in a `switch' condition, which also allows classes with a single conversion to integral or enumeration type. */ - if (!processing_template_decl) + if (expression && !processing_template_decl) { expression = build_expr_type_conversion (WANT_INT | WANT_ENUM, @@ -9114,6 +9120,7 @@ cp_parser_direct_new_declarator (cp_parser* parser) bounds. */ if (cp_lexer_next_token_is_not (parser->lexer, CPP_OPEN_SQUARE)) break; + first_p = false; } return declarator; diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c index ad8c988d41e..a7b7a12b59f 100644 --- a/gcc/cp/pt.c +++ b/gcc/cp/pt.c @@ -26872,6 +26872,10 @@ type_dependent_expression_p (tree expression) return dependent_type_p (TREE_VALUE (TREE_PURPOSE (type))) || value_dependent_expression_p (TREE_OPERAND (TREE_VALUE (type), 1)); + /* Array type whose dimension has to be deduced. */ + else if (TREE_CODE (type) == ARRAY_TYPE + && TREE_OPERAND (expression, 2) == NULL_TREE) + return true; else return dependent_type_p (type); } diff --git a/gcc/testsuite/g++.dg/cpp0x/sfinae4.C b/gcc/testsuite/g++.dg/cpp0x/sfinae4.C index 1b24966e051..f271cf1df6a 100644 --- a/gcc/testsuite/g++.dg/cpp0x/sfinae4.C +++ b/gcc/testsuite/g++.dg/cpp0x/sfinae4.C @@ -19,5 +19,11 @@ template static const bool value = sizeof(__test<_Tp, _Args...>(0)) == 1; }; -static_assert( !is_constructible_mini::value, ""); +// int[](...) will work with P0960 and P1009. +#if __cpp_aggregate_paren_init +constexpr bool r = true; +#else +constexpr bool r = false; +#endif +static_assert( is_constructible_mini::value == r, ""); static_assert( !is_constructible_mini::value, ""); diff --git a/gcc/testsuite/g++.dg/cpp2a/new-array1.C b/gcc/testsuite/g++.dg/cpp2a/new-array1.C new file mode 100644 index 00000000000..2353c384359 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/new-array1.C @@ -0,0 +1,70 @@ +// PR c++/93529 +// P1009: Array size deduction in new-expressions +// { dg-do run { target c++11 } } + +// When the array bound is deduced to 0, malloc(0) returns +// a non-dereferenceable pointer. +int *p0 = new int[]{}; +int *p1 = new int[]{ 1 }; +int *p2 = new int[]{ 1, 2, 3 }; +char *c1 = new char[]{"foo"}; +#if __cpp_aggregate_paren_init +int *q0 = new int[](); +int *q1 = new int[](1); +int *q2 = new int[](1, 2, 3); +char *d1 = new char[]("foo"); +char *d2 = new char[4]("foo"); +char *d3 = new char[]((("foo"))); +#endif + +struct Aggr { int a; int b; int c; }; +Aggr *a1 = new Aggr[]{}; +Aggr *a2 = new Aggr[]{ 1, 2, 3 }; +Aggr *a3 = new Aggr[]{ 1, 2, 3, 4 }; +Aggr *a4 = new Aggr[]{ { 1, 2, 3 } }; +Aggr *a5 = new Aggr[]{ { 1 }, { 6, 7 } }; +#if __cpp_designated_initializers +Aggr *a9 = new Aggr[]{ { .a = 1, .b = 2, .c = 3 } }; +#endif +#if __cpp_aggregate_paren_init +Aggr *a6 = new Aggr[](); +Aggr *a7 = new Aggr[]({ 1, 2, 3 }); +Aggr *a8 = new Aggr[]({ 1 }, { 6, 7 }); +#endif + +int +main () +{ + if (p1[0] != 1 || p2[0] != 1 || p2[1] != 2 || p2[2] != 3) + __builtin_abort (); + if (__builtin_strcmp (c1, "foo")) + __builtin_abort (); + if (a2->a != 1 || a2->b != 2 || a2->c != 3) + __builtin_abort (); + if (a3[0].a != 1 || a3[0].b != 2 || a3[0].c != 3 + || a3[1].a != 4 || a3[1].b != 0 || a3[1].c != 0) + __builtin_abort (); + if (a4->a != 1 || a4->b != 2 || a4->c != 3) + __builtin_abort (); + if (a5[0].a != 1 || a5[0].b != 0 || a5[0].c != 0 + || a5[1].a != 6 || a5[1].b != 7 || a5[1].c != 0) + __builtin_abort (); +#if __cpp_designated_initializers + if (a9->a != 1 || a9->b != 2 || a9->c != 3) + __builtin_abort (); +#endif +#if __cpp_aggregate_paren_init + if (q1[0] != 1) + __builtin_abort (); + if (q2[0] != 1 || q2[1] != 2 || q2[2] != 3) + __builtin_abort (); + if (__builtin_strcmp (d1, "foo") || __builtin_strcmp (d2, "foo") + || __builtin_strcmp (d3, "foo")) + __builtin_abort (); + if (a7[0].a != 1 || a7[0].b != 2 || a7[0].c != 3) + __builtin_abort (); + if (a8[0].a != 1 || a8[0].b != 0 || a8[0].c != 0 + || a8[1].a != 6 || a8[1].b != 7 || a8[1].c != 0) + __builtin_abort (); +#endif +} diff --git a/gcc/testsuite/g++.dg/cpp2a/new-array2.C b/gcc/testsuite/g++.dg/cpp2a/new-array2.C new file mode 100644 index 00000000000..9fa3f9ea7a3 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/new-array2.C @@ -0,0 +1,22 @@ +// PR c++/93529 +// P1009: Array size deduction in new-expressions +// { dg-do compile { target c++11 } } + +// Test error cases. +int *p = new double[] = { 1, 2, 3}; // { dg-error "invalid use of array with unspecified bounds" } +int *p2 = new double[] = (1, 2, 3); // { dg-error "invalid use of array with unspecified bounds" } +struct Aggr { int a; int b; int c; }; +Aggr *p3 = new Aggr[]( 1, 2, 3 ); // { dg-error "could not convert|parenthesized initializer" } +char *p4 = new char[]("foo", "a"); // { dg-error "invalid conversion|parenthesized initializer" } + +template +int *fn(T... t) +{ + return new int[]{t...}; // { dg-error "invalid conversion" } +} + +void +g () +{ + int *p = fn ("a"); +} diff --git a/gcc/testsuite/g++.dg/cpp2a/new-array3.C b/gcc/testsuite/g++.dg/cpp2a/new-array3.C new file mode 100644 index 00000000000..f35124e159d --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/new-array3.C @@ -0,0 +1,17 @@ +// PR c++/93529 +// P1009: Array size deduction in new-expressions +// { dg-do compile { target c++11 } } + +template +int *fn(T... t) +{ + return new int[]{t...}; +} + +int +main () +{ + int *p0 = fn (); + int *p1 = fn (1); + int *p3 = fn (1, 2, 3); +} diff --git a/gcc/testsuite/g++.dg/cpp2a/new-array4.C b/gcc/testsuite/g++.dg/cpp2a/new-array4.C new file mode 100644 index 00000000000..2c327ebc853 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp2a/new-array4.C @@ -0,0 +1,10 @@ +// PR c++/93529 +// P1009: Array size deduction in new-expressions +// { dg-do compile { target c++11 } } + +void +fn () +{ + new int[][3]{ { 1, 2, 3 } }; + new int[][]{ { 1, 2, 3 } }; // { dg-error "expected primary-expression" } +} diff --git a/gcc/tree.c b/gcc/tree.c index d0202c3f785..45aacadbe2d 100644 --- a/gcc/tree.c +++ b/gcc/tree.c @@ -2123,6 +2123,21 @@ build_constructor_from_list (tree type, tree vals) return build_constructor (type, v); } +/* Return a new CONSTRUCTOR node whose type is TYPE and whose values + are in a vector pointed to by VALS. Note that the TREE_PURPOSE + fields in the constructor remain null. */ + +tree +build_constructor_from_vec (tree type, const vec *vals) +{ + vec *v = NULL; + + for (tree t : *vals) + CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, t); + + return build_constructor (type, v); +} + /* Return a new CONSTRUCTOR node whose type is TYPE. NELTS is the number of elements, provided as index/value pairs. */ diff --git a/gcc/tree.h b/gcc/tree.h index 910f4aa5406..b0ef14b6cd9 100644 --- a/gcc/tree.h +++ b/gcc/tree.h @@ -4407,6 +4407,7 @@ extern void verify_constructor_flags (tree); extern tree build_constructor (tree, vec * CXX_MEM_STAT_INFO); extern tree build_constructor_single (tree, tree, tree); extern tree build_constructor_from_list (tree, tree); +extern tree build_constructor_from_vec (tree, const vec *); extern tree build_constructor_va (tree, int, ...); extern tree build_clobber (tree); extern tree build_real_from_int_cst (tree, const_tree); -- 2.30.2