From fb7561a7f20872b63f2bef25fb72fddf8c0442ae Mon Sep 17 00:00:00 2001
From: Bung <crc32@qq.com>
Date: Sun, 23 Apr 2023 16:28:43 +0800
Subject: [PATCH] fix #13093 C++ Atomics: operator= is implicitly deleted
 because the default definition would be ill-formed

---
 compiler/cgen.nim                |  4 ++++
 compiler/semstmts.nim            |  6 +++++-
 lib/pure/concurrency/atomics.nim |  2 +-
 tests/cpp/t13093.nim             | 24 ++++++++++++++++++++++++
 4 files changed, 34 insertions(+), 2 deletions(-)
 create mode 100644 tests/cpp/t13093.nim

diff --git a/compiler/cgen.nim b/compiler/cgen.nim
index f6457f1e015c..96decbaf1514 100644
--- a/compiler/cgen.nim
+++ b/compiler/cgen.nim
@@ -491,6 +491,10 @@ proc constructLoc(p: BProc, loc: var TLoc, isTemp = false) =
       nilLoc.r = rope("NIM_NIL")
       genRefAssign(p, loc, nilLoc)
     else:
+      if typ.kind == tyVar:
+        let tt = typ.skipTypes({tyVar})
+        if isImportedType(tt) and tfRequiresInit in tt.flags:
+          return
       linefmt(p, cpsStmts, "$1 = ($2)0;$n", [rdLoc(loc),
         getTypeDesc(p.module, typ, mapTypeChooser(loc))])
   else:
diff --git a/compiler/semstmts.nim b/compiler/semstmts.nim
index 96883255c4fd..60170176e5a5 100644
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -717,7 +717,11 @@ proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
                                           tyUserTypeClassInst})
         if actualType.kind in {tyObject, tyDistinct} and
            actualType.requiresInit:
-          defaultConstructionError(c, v.typ, v.info)
+           # imported type use requiresInit pragma prevent implicit initialization
+          if (tfRequiresInit in actualType.flags and sfImportc in actualType.sym.flags):
+            discard
+          else:
+            defaultConstructionError(c, v.typ, v.info)
         else:
           checkNilable(c, v)
         # allow let to not be initialised if imported from C:
diff --git a/lib/pure/concurrency/atomics.nim b/lib/pure/concurrency/atomics.nim
index c7b881bc55c1..49204bd4d530 100644
--- a/lib/pure/concurrency/atomics.nim
+++ b/lib/pure/concurrency/atomics.nim
@@ -89,7 +89,7 @@ when defined(cpp) or defined(nimdoc):
         ## with other moSequentiallyConsistent operations.
 
   type
-    Atomic*[T] {.importcpp: "std::atomic", completeStruct.} = object
+    Atomic*[T] {.importcpp: "std::atomic", completeStruct, requiresInit.} = object
       ## An atomic object with underlying type `T`.
       raw: T
 
diff --git a/tests/cpp/t13093.nim b/tests/cpp/t13093.nim
new file mode 100644
index 000000000000..17c730d16a73
--- /dev/null
+++ b/tests/cpp/t13093.nim
@@ -0,0 +1,24 @@
+discard """
+  targets: "cpp"
+  action: reject
+  errormsg: "The PledgeObj type requires the following fields to be initialized: refCount"
+"""
+
+import atomics
+
+type
+  Pledge* = object
+    p: PledgePtr
+
+  PledgePtr = ptr PledgeObj
+  PledgeObj = object
+    refCount: Atomic[int32]
+
+proc main() =
+  var pledge: Pledge
+  pledge.p = createShared(PledgeObj)
+  let tmp = PledgeObj() # <---- not allowed: atomics are not copyable
+
+  pledge.p[] = tmp
+
+main()