BUG: masterUncollated readStream causes checkOut/checkIn (#2952)

- updating the header information (by copying) was closing the stream,
  removing all watches and doing a checkOut/checkIn, which could lead to
  dangling references.
  Now just close the stream and simply copy the IOobject header
  information directly.

STYLE: mark regIOobject assignment operator as possibly deprecated

- will revisit to revise or remove in the future

src/OpenFOAM/db/regIOobject/regIOobject.H

@@ -6,7 +6,7 @@
      \\/     M anipulation  |
 -------------------------------------------------------------------------------
     Copyright (C) 2011-2017 OpenFOAM Foundation
-    Copyright (C) 2018-2022 OpenCFD Ltd.
+    Copyright (C) 2018-2023 OpenCFD Ltd.
 -------------------------------------------------------------------------------
 License
     This file is part of OpenFOAM.
@@ -116,9 +116,6 @@ private:
         //- Construct object stream, read header if not already constructed
         void readStream(const bool readOnProc);
 
-        //- No copy assignment
-        void operator=(const regIOobject&) = delete;
-
 
 public:
 
@@ -127,6 +124,12 @@ public:
         friend class fileOperations::uncollatedFileOperation;
 
 
+    // Generated Methods
+
+        //- No copy assignment
+        void operator=(const regIOobject&) = delete;
+
+
     // Static Data
 
         //- Runtime type information
@@ -366,6 +369,7 @@ public:
     // Member Operators
 
         //- Copy assignment
+        FOAM_DEPRECATED_STRICT(2023-12, "possibly remove in the future")
         void operator=(const IOobject& io);
 
 

src/OpenFOAM/global/fileOperations/masterUncollatedFileOperation/masterUncollatedFileOperation.C

@@ -2007,6 +2007,8 @@ Foam::fileOperations::masterUncollatedFileOperation::readStream
             << " fName : " << fName << " readOnProc:" << readOnProc << endl;
     }
 
+    // Close old stream
+    io.close();
 
     autoPtr<ISstream> isPtr;
     bool isCollated = false;
@@ -2044,7 +2046,9 @@ Foam::fileOperations::masterUncollatedFileOperation::readStream
                             << " doing straight IFstream input from "
                             << fName << endl;
                     }
-                    io = headerIO;
+
+                    // Copy IOobject header information
+                    io.IOobject::operator=(headerIO);
                     return isPtr;
                 }
             }