properly use nullptr on pointers (with a little help from clang-tidy)

src/INTEL/fix_intel.cpp

@@ -71,11 +71,11 @@ FixIntel::FixIntel(LAMMPS *lmp, int narg, char **arg) :  Fix(lmp, narg, arg)
   _offload_threads = 0;
   _offload_tpc = 4;
 
-  _force_array_s = 0;
+  _force_array_s = nullptr;
-  _force_array_m = 0;
+  _force_array_m = nullptr;
-  _force_array_d = 0;
+  _force_array_d = nullptr;
-  _ev_array_s = 0;
+  _ev_array_s = nullptr;
-  _ev_array_d = 0;
+  _ev_array_d = nullptr;
 
   #ifdef _LMP_INTEL_OFFLOAD
   if (ncops < 0) error->all(FLERR,"Illegal package intel command");
@@ -557,30 +557,30 @@ void FixIntel::_sync_main_arrays(const int prereverse)
   if (!prereverse) _zero_master = 1;
   int done_this_step = prereverse;
   if (_pair_hybrid_zero == 0) done_this_step = 1;
-  if (_force_array_m != 0) {
+  if (_force_array_m != nullptr) {
     if (_need_reduce) {
       reduce_results(&_force_array_m[0].x);
       _need_reduce = 0;
     }
     add_results(_force_array_m, _ev_array_d, _results_eatom, _results_vatom,0);
-    if (done_this_step) _force_array_m = 0;
+    if (done_this_step) _force_array_m = nullptr;
-    else _ev_array_d = 0;
+    else _ev_array_d = nullptr;
-  } else if (_force_array_d != 0) {
+  } else if (_force_array_d != nullptr) {
     if (_need_reduce) {
       reduce_results(&_force_array_d[0].x);
       _need_reduce = 0;
     }
     add_results(_force_array_d, _ev_array_d, _results_eatom, _results_vatom,0);
-    if (done_this_step) _force_array_d = 0;
+    if (done_this_step) _force_array_d = nullptr;
-    else _ev_array_d = 0;
+    else _ev_array_d = nullptr;
-  } else if (_force_array_s != 0) {
+  } else if (_force_array_s != nullptr) {
     if (_need_reduce) {
       reduce_results(&_force_array_s[0].x);
       _need_reduce = 0;
     }
     add_results(_force_array_s, _ev_array_s, _results_eatom, _results_vatom,0);
-    if (done_this_step) _force_array_s = 0;
+    if (done_this_step) _force_array_s = nullptr;
-    else _ev_array_s = 0;
+    else _ev_array_s = nullptr;
   }
 
   #ifdef _LMP_INTEL_OFFLOAD

src/INTEL/fix_nh_intel.cpp

@@ -46,7 +46,7 @@ typedef struct { double x,y,z; } dbl3_t;
 FixNHIntel::FixNHIntel(LAMMPS *lmp, int narg, char **arg) :
   FixNH(lmp, narg, arg)
 {
-  _dtfm = 0;
+  _dtfm = nullptr;
   _nlocal3 = 0;
   _nlocal_max = 0;
 }

src/INTEL/fix_nve_intel.cpp

@@ -32,7 +32,7 @@ using namespace FixConst;
 FixNVEIntel::FixNVEIntel(LAMMPS *lmp, int narg, char **arg) :
   FixNVE(lmp, narg, arg)
 {
-  _dtfm = 0;
+  _dtfm = nullptr;
   _nlocal3 = 0;
   _nlocal_max = 0;
 }

src/INTEL/intel_buffers.cpp

@@ -26,18 +26,18 @@ using namespace LAMMPS_NS;
 
 template <class flt_t, class acc_t>
 IntelBuffers<flt_t, acc_t>::IntelBuffers(class LAMMPS *lmp_in) :
-    lmp(lmp_in), _x(0), _q(0), _quat(0), _f(0), _off_threads(0),
+    lmp(lmp_in), _x(nullptr), _q(nullptr), _quat(nullptr), _f(nullptr), _off_threads(0),
     _n_list_ptrs(1), _max_list_ptrs(4), _buf_size(0), _buf_local_size(0) {
   _neigh_list_ptrs = new IntelNeighListPtrs[_max_list_ptrs];
-  _neigh_list_ptrs[0].cnumneigh = 0;
+  _neigh_list_ptrs[0].cnumneigh = nullptr;
   _list_alloc_atoms = 0;
   _ntypes = 0;
   _off_map_listlocal = 0;
-  _ccachex = 0;
+  _ccachex = nullptr;
   _ncache_alloc = 0;
-  _ncachetag = 0;
+  _ncachetag = nullptr;
-  _cutneighsq = 0;
+  _cutneighsq = nullptr;
-  _cutneighghostsq = 0;
+  _cutneighghostsq = nullptr;
   _need_tag = 0;
   #ifdef _LMP_INTEL_OFFLOAD
   _separate_buffers = 0;
@@ -104,8 +104,8 @@ void IntelBuffers<flt_t, acc_t>::free_buffers()
     #endif
 
     lmp->memory->destroy(x);
-    if (q != 0) lmp->memory->destroy(q);
+    if (q != nullptr) lmp->memory->destroy(q);
-    if (quat != 0) lmp->memory->destroy(quat);
+    if (quat != nullptr) lmp->memory->destroy(quat);
     lmp->memory->destroy(_f);
     _buf_size = _buf_local_size = 0;
   }
@@ -251,7 +251,7 @@ void IntelBuffers<flt_t, acc_t>::free_list_local()
   if (_off_map_listlocal > 0) {
     if (_neigh_list_ptrs[0].cnumneigh) {
       int * cnumneigh = _neigh_list_ptrs[0].cnumneigh;
-      _neigh_list_ptrs[0].cnumneigh = 0;
+      _neigh_list_ptrs[0].cnumneigh = nullptr;
       #ifdef _LMP_INTEL_OFFLOAD
       if (_off_map_ilist != nullptr) {
         #pragma offload_transfer target(mic:_cop) \
@@ -286,7 +286,7 @@ void IntelBuffers<flt_t, acc_t>::free_list_ptrs()
       lmp->memory->destroy(_neigh_list_ptrs[list_num].numneighhalf);
     }
     _neigh_list_ptrs[list_num].size = 0;
-    _neigh_list_ptrs[list_num].list_ptr = 0;
+    _neigh_list_ptrs[list_num].list_ptr = nullptr;
   }
   _n_list_ptrs = 1;
 }
@@ -447,7 +447,7 @@ void IntelBuffers<flt_t, acc_t>::free_ccache()
     lmp->memory->destroy(ccachef);
     #endif
 
-    _ccachex = 0;
+    _ccachex = nullptr;
   }
 }
 
@@ -546,7 +546,7 @@ void IntelBuffers<flt_t, acc_t>::free_ncache()
     if (ncachetag)
       lmp->memory->destroy(ncachetag);
     _ncache_alloc = 0;
-    _ncachetag = 0;
+    _ncachetag = nullptr;
   }
 }
 
@@ -563,7 +563,7 @@ void IntelBuffers<flt_t, acc_t>::grow_ncache(const int off_flag,
   const int vsize = _ncache_stride * nt;
 
   if (_ncache_alloc) {
-    if (vsize > _ncache_alloc || (need_tag() && _ncachetag == 0))
+    if (vsize > _ncache_alloc || (need_tag() && _ncachetag == nullptr))
       free_ncache();
     #ifdef _LMP_INTEL_OFFLOAD
     else if (off_flag && _off_ncache == 0)
@@ -660,7 +660,7 @@ void IntelBuffers<flt_t, acc_t>::set_ntypes(const int ntypes,
       }
       #endif
       lmp->memory->destroy(_cutneighsq);
-      if (_cutneighghostsq != 0) lmp->memory->destroy(_cutneighghostsq);
+      if (_cutneighghostsq != nullptr) lmp->memory->destroy(_cutneighghostsq);
     }
     if (ntypes > 0) {
       lmp->memory->create(_cutneighsq, ntypes, ntypes, "_cutneighsq");

src/INTEL/npair_skip_intel.cpp

@@ -36,7 +36,7 @@ NPairSkipIntel::NPairSkipIntel(LAMMPS *lmp) : NPair(lmp) {
   if (!_fix) error->all(FLERR, "The 'package intel' command is required for /intel styles");
   _inum_starts = new int[comm->nthreads];
   _inum_counts = new int[comm->nthreads];
-  _full_props = 0;
+  _full_props = nullptr;
 }
 
 /* ---------------------------------------------------------------------- */
@@ -203,11 +203,11 @@ void NPairSkipIntel::build(NeighList *list)
   if (_fix->three_body_neighbor()==0 ||
       _full_props[list->listskip->index] == 0) {
     if (_fix->precision() == FixIntel::PREC_MODE_MIXED)
-      build_t<float,0>(list, 0, 0, 0);
+      build_t<float,0>(list, nullptr, nullptr, nullptr);
     else if (_fix->precision() == FixIntel::PREC_MODE_DOUBLE)
-      build_t<double,0>(list, 0, 0, 0);
+      build_t<double,0>(list, nullptr, nullptr, nullptr);
     else
-      build_t<float,0>(list, 0, 0, 0);
+      build_t<float,0>(list, nullptr, nullptr, nullptr);
   } else {
     int *nhalf, *cnumneigh, *nhalf_skip, *u;
     if (_fix->precision() == FixIntel::PREC_MODE_MIXED) {

src/INTEL/pair_buck_coul_cut_intel.cpp

@@ -401,7 +401,7 @@ void PairBuckCoulCutIntel::eval(const int offload, const int vflag,
   if (EFLAG || vflag)
     fix->add_result_array(f_start, ev_global, offload, eatom, 0, vflag);
   else
-    fix->add_result_array(f_start, 0, offload);
+    fix->add_result_array(f_start, nullptr, offload);
 }
 
 /* ---------------------------------------------------------------------- */

src/INTEL/pair_buck_coul_long_intel.cpp

@@ -477,7 +477,7 @@ void PairBuckCoulLongIntel::eval(const int offload, const int vflag,
   if (EFLAG || vflag)
     fix->add_result_array(f_start, ev_global, offload, eatom, 0, vflag);
   else
-    fix->add_result_array(f_start, 0, offload);
+    fix->add_result_array(f_start, nullptr, offload);
 }
 
 /* ---------------------------------------------------------------------- */

src/INTEL/pair_buck_intel.cpp

@@ -368,7 +368,7 @@ void PairBuckIntel::eval(const int offload, const int vflag,
   if (EFLAG || vflag)
     fix->add_result_array(f_start, ev_global, offload, eatom, 0, vflag);
   else
-    fix->add_result_array(f_start, 0, offload);
+    fix->add_result_array(f_start, nullptr, offload);
 }
 
 void PairBuckIntel::init_style()

src/INTEL/pair_lj_charmm_coul_long_intel.cpp

@@ -513,7 +513,7 @@ void PairLJCharmmCoulLongIntel::eval(const int offload, const int vflag,
   if (EFLAG || vflag)
     fix->add_result_array(f_start, ev_global, offload, eatom, 0, vflag);
   else
-    fix->add_result_array(f_start, 0, offload);
+    fix->add_result_array(f_start, nullptr, offload);
 }
 
 /* ---------------------------------------------------------------------- */

src/INTEL/pair_lj_cut_coul_long_intel.cpp

@@ -478,7 +478,7 @@ void PairLJCutCoulLongIntel::eval(const int offload, const int vflag,
   if (EFLAG || vflag)
     fix->add_result_array(f_start, ev_global, offload, eatom, 0, vflag);
   else
-    fix->add_result_array(f_start, 0, offload);
+    fix->add_result_array(f_start, nullptr, offload);
 }
 
 /* ---------------------------------------------------------------------- */

src/INTEL/pair_lj_cut_intel.cpp

@@ -384,7 +384,7 @@ void PairLJCutIntel::eval(const int offload, const int vflag,
   if (EFLAG || vflag)
     fix->add_result_array(f_start, ev_global, offload, eatom, 0, vflag);
   else
-    fix->add_result_array(f_start, 0, offload);
+    fix->add_result_array(f_start, nullptr, offload);
 }
 
 /* ---------------------------------------------------------------------- */

src/INTEL/verlet_lrt_intel.cpp

@@ -81,7 +81,7 @@ void VerletLRTIntel::init()
 
 void VerletLRTIntel::setup(int flag)
 {
-  if (_intel_kspace == 0) {
+  if (_intel_kspace == nullptr) {
     Verlet::setup(flag);
     return;
   }
@@ -202,7 +202,7 @@ void VerletLRTIntel::setup(int flag)
 
 void VerletLRTIntel::run(int n)
 {
-  if (_intel_kspace == 0) {
+  if (_intel_kspace == nullptr) {
     Verlet::run(n);
     return;
   }

src/STUBS/mpi.cpp

@@ -183,7 +183,7 @@ double MPI_Wtime()
   double time;
   struct timeval tv;
 
-  gettimeofday(&tv, NULL);
+  gettimeofday(&tv, nullptr);
   time = 1.0 * tv.tv_sec + 1.0e-6 * tv.tv_usec;
   return time;
 #endif
@@ -223,7 +223,7 @@ static int stubtypesize(MPI_Datatype datatype)
 
 int MPI_Type_size(MPI_Datatype datatype, int *size)
 {
-  if (size == NULL) return MPI_ERR_ARG;
+  if (size == nullptr) return MPI_ERR_ARG;
 
   *size = stubtypesize(datatype);
   return 0;