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| author | Jason Merrill <jason@redhat.com> | 2022-07-20 18:15:31 -0400 |
|---|---|---|
| committer | Jason Merrill <jason@redhat.com> | 2022-07-21 17:21:17 -0400 |
| commit | df118d7ba138cacb17203d4a1b5f27730347cc77 (patch) | |
| tree | 2bc6c1de497c59f06d877c77656ee3973c7266e3 | |
| parent | 142e6af6959cba0d4dfd5cba6c4f16e15d154156 (diff) | |
| download | gcc-df118d7ba138cacb17203d4a1b5f27730347cc77.zip gcc-df118d7ba138cacb17203d4a1b5f27730347cc77.tar.gz gcc-df118d7ba138cacb17203d4a1b5f27730347cc77.tar.bz2 | |
c++: defaulted ctor with DMI in union [PR94823]
CWG2084 clarifies that a variant member with a non-trivial constructor does
not make the union's defaulted default constructor deleted if another
variant member has a default member initializer.
DR 2084
PR c++/94823
gcc/cp/ChangeLog:
* method.cc (walk_field_subobs): Fix DMI in union case.
gcc/testsuite/ChangeLog:
* g++.dg/cpp0x/nsdmi-union7.C: New test.
| -rw-r--r-- | gcc/cp/method.cc | 35 | ||||
| -rw-r--r-- | gcc/testsuite/g++.dg/cpp0x/nsdmi-union7.C | 13 |
2 files changed, 44 insertions, 4 deletions
diff --git a/gcc/cp/method.cc b/gcc/cp/method.cc index f2050f6..573ef01 100644 --- a/gcc/cp/method.cc +++ b/gcc/cp/method.cc @@ -2315,8 +2315,19 @@ walk_field_subobs (tree fields, special_function_kind sfk, tree fnname, bool diag, int flags, tsubst_flags_t complain, bool dtor_from_ctor) { - tree field; - for (field = fields; field; field = DECL_CHAIN (field)) + if (!fields) + return; + + tree ctx = DECL_CONTEXT (fields); + + /* CWG2084: A defaulted default ctor for a union with a DMI only initializes + that member, so don't check other members. */ + enum { unknown, no, yes } + only_dmi_mem = (sfk == sfk_constructor && TREE_CODE (ctx) == UNION_TYPE + ? unknown : no); + + again: + for (tree field = fields; field; field = DECL_CHAIN (field)) { tree mem_type, argtype, rval; @@ -2331,9 +2342,18 @@ walk_field_subobs (tree fields, special_function_kind sfk, tree fnname, asking if this is deleted, don't even look up the function; we don't want an error about a deleted function we aren't actually calling. */ if (sfk == sfk_destructor && deleted_p == NULL - && TREE_CODE (DECL_CONTEXT (field)) == UNION_TYPE) + && TREE_CODE (ctx) == UNION_TYPE) break; + if (only_dmi_mem != no) + { + if (DECL_INITIAL (field)) + only_dmi_mem = yes; + else + /* Don't check this until we know there's no DMI. */ + continue; + } + mem_type = strip_array_types (TREE_TYPE (field)); if (SFK_ASSIGN_P (sfk)) { @@ -2416,7 +2436,7 @@ walk_field_subobs (tree fields, special_function_kind sfk, tree fnname, if (constexpr_p && cxx_dialect < cxx20 && !CLASS_TYPE_P (mem_type) - && TREE_CODE (DECL_CONTEXT (field)) != UNION_TYPE) + && TREE_CODE (ctx) != UNION_TYPE) { *constexpr_p = false; if (diag) @@ -2465,6 +2485,13 @@ walk_field_subobs (tree fields, special_function_kind sfk, tree fnname, process_subob_fn (rval, sfk, spec_p, trivial_p, deleted_p, constexpr_p, diag, field, dtor_from_ctor); } + + /* We didn't find a DMI in this union, now check all the members. */ + if (only_dmi_mem == unknown) + { + only_dmi_mem = no; + goto again; + } } /* Base walker helper for synthesized_method_walk. Inspect a direct diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-union7.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-union7.C new file mode 100644 index 0000000..c840ddf --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-union7.C @@ -0,0 +1,13 @@ +// PR c++/94823 +// { dg-do compile { target c++11 } } + +struct A{ + A(){} +}; +union C{ + A a; + int b = 0; +}; +int main(){ + C c; +} |