| Summary: | Implement P0960R3: Parenthesized initialization of aggregates | ||
|---|---|---|---|
| Product: | gcc | Reporter: | Marek Polacek <mpolacek> |
| Component: | c++ | Assignee: | Marek Polacek <mpolacek> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | jakub, webrown.cpp |
| Priority: | P3 | Keywords: | patch |
| Version: | 10.0 | ||
| Target Milestone: | 10.0 | ||
| Host: | Target: | ||
| Build: | Known to work: | ||
| Known to fail: | Last reconfirmed: | 2019-08-05 00:00:00 | |
| Bug Depends on: | |||
| Bug Blocks: | 88323 | ||
|
Description
Marek Polacek
2019-08-05 16:24:36 UTC
Working on it. This test now runs fine with -std=c++2a with my WIP patch:
struct A {
int i;
int j;
int k; // value-init
};
int i;
A a(1, 2);
A a2(1.0, 2);
A a3(++i, ++i); // left-to-right eval
int
main ()
{
if (a.i != 1 || a.j != 2 || a.k != 0)
__builtin_abort ();
if (a2.i != 1 || a2.j != 2 || a.k != 0)
__builtin_abort ();
if (a3.i != 1 || a3.j != 2 || a.k != 0)
__builtin_abort ();
}
What's the status of this? Need to respond to Jason's feedback: https://gcc.gnu.org/ml/gcc-patches/2019-11/msg00034.html But there's very little time left for stage1 and I've been trying to get P1327 done, and then hopefully also P1331. Author: mpolacek Date: Tue Dec 3 15:59:40 2019 New Revision: 278939 URL: https://gcc.gnu.org/viewcvs?rev=278939&root=gcc&view=rev Log: PR c++/91363 - P0960R3: Parenthesized initialization of aggregates. This patch implements C++20 P0960R3: Parenthesized initialization of aggregates (<wg21.link/p0960>; see R0 for more background info). Essentially, if you have an aggregate, you can now initialize it by (x, y), similarly to {x, y}. E.g. struct A { int x, y; // no A(int, int) ctor (see paren-init14.C for = delete; case) }; A a(1, 2); The difference between ()-init and {}-init is that narrowing conversions are permitted, designators are not permitted, a temporary object bound to a reference does not have its lifetime extended, and there is no brace elision. Further, things like int a[](1, 2, 3); // will deduce the array size const A& r(1, 2.3, 3); // narrowing is OK int (&&rr)[](1, 2, 3); int b[3](1, 2); // b[2] will be value-initialized now work as expected. Note that char f[]("fluff"); has always worked and this patch keeps it that way. Also note that A a((1, 2)) is not the same as A a{{1,2}}; the inner (1, 2) remains a COMPOUND_EXPR. The approach I took was to handle (1, 2) similarly to {1, 2} -- conjure up a CONSTRUCTOR, and introduce LOOKUP_AGGREGATE_PAREN_INIT to distinguish between the two. This kind of initialization is only supported in C++20; I've made no attempt to support it in earlier standards, like we don't support CTAD pre-C++17, for instance. * c-cppbuiltin.c (c_cpp_builtins): Predefine __cpp_aggregate_paren_init=201902 for -std=c++2a. * call.c (build_new_method_call_1): Handle parenthesized initialization of aggregates by building up a CONSTRUCTOR. (extend_ref_init_temps): Do nothing for CONSTRUCTOR_IS_PAREN_INIT. * cp-tree.h (CONSTRUCTOR_IS_PAREN_INIT, LOOKUP_AGGREGATE_PAREN_INIT): Define. * decl.c (grok_reference_init): Handle aggregate initialization from a parenthesized list of values. (reshape_init): Do nothing for CONSTRUCTOR_IS_PAREN_INIT. (check_initializer): Handle initialization of an array from a parenthesized list of values. Use NULL_TREE instead of NULL. * tree.c (build_cplus_new): Handle BRACE_ENCLOSED_INITIALIZER_P. * typeck2.c (digest_init_r): Set LOOKUP_AGGREGATE_PAREN_INIT if it receives a CONSTRUCTOR with CONSTRUCTOR_IS_PAREN_INIT set. Allow narrowing when LOOKUP_AGGREGATE_PAREN_INIT. (massage_init_elt): Don't lose LOOKUP_AGGREGATE_PAREN_INIT when passing flags to digest_init_r. * g++.dg/cpp0x/constexpr-99.C: Only expect an error in C++17 and lesser. * g++.dg/cpp0x/explicit7.C: Likewise. * g++.dg/cpp0x/initlist12.C: Adjust dg-error. * g++.dg/cpp0x/pr31437.C: Likewise. * g++.dg/cpp2a/feat-cxx2a.C: Add __cpp_aggregate_paren_init test. * g++.dg/cpp2a/paren-init1.C: New test. * g++.dg/cpp2a/paren-init10.C: New test. * g++.dg/cpp2a/paren-init11.C: New test. * g++.dg/cpp2a/paren-init12.C: New test. * g++.dg/cpp2a/paren-init13.C: New test. * g++.dg/cpp2a/paren-init14.C: New test. * g++.dg/cpp2a/paren-init15.C: New test. * g++.dg/cpp2a/paren-init16.C: New test. * g++.dg/cpp2a/paren-init17.C: New test. * g++.dg/cpp2a/paren-init18.C: New test. * g++.dg/cpp2a/paren-init19.C: New test. * g++.dg/cpp2a/paren-init2.C: New test. * g++.dg/cpp2a/paren-init3.C: New test. * g++.dg/cpp2a/paren-init4.C: New test. * g++.dg/cpp2a/paren-init5.C: New test. * g++.dg/cpp2a/paren-init6.C: New test. * g++.dg/cpp2a/paren-init7.C: New test. * g++.dg/cpp2a/paren-init8.C: New test. * g++.dg/cpp2a/paren-init9.C: New test. * g++.dg/ext/desig10.C: Adjust dg-error. * g++.dg/template/crash107.C: Likewise. * g++.dg/template/crash95.C: Likewise. * g++.old-deja/g++.jason/crash3.C: Likewise. * g++.old-deja/g++.law/ctors11.C: Likewise. * g++.old-deja/g++.law/ctors9.C: Likewise. * g++.old-deja/g++.mike/net22.C: Likewise. * g++.old-deja/g++.niklas/t128.C: Likewise. Added: trunk/gcc/testsuite/g++.dg/cpp2a/paren-init1.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init10.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init11.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init12.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init13.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init14.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init15.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init16.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init17.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init18.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init19.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init2.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init3.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init4.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init5.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init6.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init7.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init8.C trunk/gcc/testsuite/g++.dg/cpp2a/paren-init9.C Modified: trunk/gcc/c-family/ChangeLog trunk/gcc/c-family/c-cppbuiltin.c trunk/gcc/cp/ChangeLog trunk/gcc/cp/call.c trunk/gcc/cp/cp-tree.h trunk/gcc/cp/decl.c trunk/gcc/cp/tree.c trunk/gcc/cp/typeck2.c trunk/gcc/testsuite/ChangeLog trunk/gcc/testsuite/g++.dg/cpp0x/constexpr-99.C trunk/gcc/testsuite/g++.dg/cpp0x/explicit7.C trunk/gcc/testsuite/g++.dg/cpp0x/initlist12.C trunk/gcc/testsuite/g++.dg/cpp0x/pr31437.C trunk/gcc/testsuite/g++.dg/cpp2a/feat-cxx2a.C trunk/gcc/testsuite/g++.dg/ext/desig10.C trunk/gcc/testsuite/g++.dg/template/crash107.C trunk/gcc/testsuite/g++.dg/template/crash95.C trunk/gcc/testsuite/g++.old-deja/g++.jason/crash3.C trunk/gcc/testsuite/g++.old-deja/g++.law/ctors11.C trunk/gcc/testsuite/g++.old-deja/g++.law/ctors9.C trunk/gcc/testsuite/g++.old-deja/g++.mike/net22.C trunk/gcc/testsuite/g++.old-deja/g++.niklas/t128.C Implemented for GCC 10. |