Re: [PATCH] c++: Implement P1009: Array size deduction in new-expressions.
On 8/20/20 4:22 PM, Marek Polacek wrote:
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.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
gcc/cp/ChangeLog:
PR c++/93529
* init.c (build_new_1): Handle new char[]{"foo"}.
(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/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.
Co-authored-by: Jason Merrill
---
gcc/cp/init.c | 54 ++-
gcc/cp/parser.c | 11 ++--
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 ++
7 files changed, 180 insertions(+), 6 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
diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index 872c23453fd..ae1177079e4 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)
@@ -3917,6 +3926,47 @@ 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 = (**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
+ {
+ /* Create a CONSTRUCTOR from the vector INIT. */
+ tree list = build_tree_list_vec (*init);
+ tree ctor = build_constructor_from_list (init_list_type_node,
list);
+ CONSTRUCTOR_IS_DIRECT_INIT (ctor) = true;
+ CONSTRUCTOR_IS_PAREN_INIT
[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.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
gcc/cp/ChangeLog:
PR c++/93529
* init.c (build_new_1): Handle new char[]{"foo"}.
(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/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.
Co-authored-by: Jason Merrill
---
gcc/cp/init.c | 54 ++-
gcc/cp/parser.c | 11 ++--
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 ++
7 files changed, 180 insertions(+), 6 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
diff --git a/gcc/cp/init.c b/gcc/cp/init.c
index 872c23453fd..ae1177079e4 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)
@@ -3917,6 +3926,47 @@ 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 = (**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
+ {
+ /* Create a CONSTRUCTOR from the vector INIT. */
+ tree list = build_tree_list_vec (*init);
+ tree ctor = build_constructor_from_list (init_list_type_node,
list);
+ CONSTRUCTOR_IS_DIRECT_INIT (ctor) = true;
+ CONSTRUCTOR_IS_PAREN_INIT (ctor) = true;
+ elt = ctor;
+ /* We've
