C++ Atomics in union: ::<unnamed union>::<unnamed struct>::field with constructor not allowed in anonymous aggregate

[mratsim]

The following compile with the C backend but not with C++

import atomics

type
  Pledge* {.exportc.} = object
    p: PledgePtr

  PledgeKind {.exportc.} = enum
    Single
    Iteration

  PledgePtr {.exportc.} = ptr object
    case kind: PledgeKind
    of Single:
      impl: PledgeImpl
    of Iteration:
      discard

  PledgeImpl {.exportc.} = object
    fulfilled: Atomic[bool]

var x: Pledge
echo x.repr

C++ code

  struct Pledge;
struct tyObject_PledgePtrcolonObjectType___yxB804f8EWpdMmtSWWPeFA;
...
struct PledgeImpl;
struct Pledge {
tyObject_PledgePtrcolonObjectType___yxB804f8EWpdMmtSWWPeFA* p;
};
...
typedef NU8 PledgeKind;
typedef std::atomic<NIM_BOOL>  TY__Z2iuRDrwY0WX5bGI2o2sLQ;
struct PledgeImpl {
TY__Z2iuRDrwY0WX5bGI2o2sLQ fulfilled;
};
struct tyObject_PledgePtrcolonObjectType___yxB804f8EWpdMmtSWWPeFA {
PledgeKind kind;
union{
struct {PledgeImpl impl;
};
};
};

Error:

error: member ‘PledgeImpl tyObject_PledgePtrcolonObjectType___yxB804f8EWpdMmtSWWPeFA::<unnamed union>::<unnamed struct>::impl’ with constructor not allowed in anonymous aggregate
   75 | struct {PledgeImpl impl;
      |                    ^~~~

[Araq]

Workaround, use

type
  PledgePtr {.exportc.} = ptr object
    kind: PledgeKind
    impl: PledgeImpl

[ringabout]

It works in Nim 1.2.6 and above(with c and cpp backend)

D:\QQPCmgr\Desktop\Nim>choosenim 1.2.6
      Info: Version 1.2.6 already selected

D:\QQPCmgr\Desktop\Nim>nim c -r tests/ccgbugs/t13062.nim
[p = nil]

D:\QQPCmgr\Desktop\Nim>nim cpp -r tests/ccgbugs/t13062.nim
[p = nil]