Need another overload of the operator= for ParticleIDWrapper and Part…

…icleCPUWrapper. (AMReX-Codes#1317)

The proposed changes:
- [x] fix a bug or incorrect behavior in AMReX
- [ ] add new capabilities to AMReX
- [ ] changes answers in the test suite to more than roundoff level
- [ ] are likely to significantly affect the results of downstream AMReX users
- [ ] are described in the proposed changes to the AMReX documentation, if appropriate

Src/Particle/AMReX_Particle.H

@@ -31,6 +31,12 @@ struct ParticleIDWrapper
         : m_idata(idata)
     {}
 
+    AMREX_GPU_HOST_DEVICE
+    ParticleIDWrapper& operator= (const ParticleIDWrapper& pidw) noexcept
+    {
+        return this->operator=(Long(pidw));
+    }
+
     AMREX_GPU_HOST_DEVICE
     ParticleIDWrapper& operator= (const Long id) noexcept
     {
@@ -80,6 +86,12 @@ struct ParticleCPUWrapper
         : m_idata(idata)
     {}
 
+    AMREX_GPU_HOST_DEVICE
+    ParticleCPUWrapper& operator= (const ParticleCPUWrapper& pcpuw) noexcept
+    {
+        return this->operator=(int(pcpuw));
+    }
+
     AMREX_GPU_HOST_DEVICE
     ParticleCPUWrapper& operator= (const int cpu) noexcept
     {
@@ -94,7 +106,7 @@ struct ParticleCPUWrapper
     }
 
     AMREX_GPU_HOST_DEVICE
-    operator int () noexcept
+    operator int () const noexcept
     {
         return (m_idata & 0x00FFFFFF);
     }
@@ -133,7 +145,7 @@ struct ConstParticleCPUWrapper
     {}
 
     AMREX_GPU_HOST_DEVICE
-    operator int () noexcept { return (m_idata & 0x00FFFFFF); }
+    operator int () const noexcept { return (m_idata & 0x00FFFFFF); }
 };
 
 /** \brief The struct used to store particles.