73a2b8dd17
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 <jason@redhat.com>
18 lines
257 B
C
18 lines
257 B
C
// PR c++/93529
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// P1009: Array size deduction in new-expressions
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// { dg-do compile { target c++11 } }
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template<typename... T>
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int *fn(T... t)
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{
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return new int[]{t...};
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}
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int
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main ()
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{
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int *p0 = fn ();
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int *p1 = fn (1);
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int *p3 = fn (1, 2, 3);
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}
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