Move function definitions to cpp file

This allows making charm++ a PRIVATE dependency for the System library.

src/Utilities/System/CMakeLists.txt

@@ -9,6 +9,7 @@ spectre_target_sources(
   ${LIBRARY}
   PRIVATE
   Abort.cpp
+  Exit.cpp
   ParallelInfo.cpp
   Prefetch.cpp
   )

src/Utilities/System/Exit.cpp

@@ -0,0 +1,18 @@
+// Distributed under the MIT License.
+// See LICENSE.txt for details.
+
+#include "Utilities/System/Exit.hpp"
+
+#include <charm++.h>
+#include <exception>
+
+namespace sys {
+
+[[noreturn]] void exit(const int exit_code) {
+  CkExit(exit_code);
+  // the following call is never reached, but suppresses the warning that
+  // a 'noreturn' function does return
+  std::terminate();  // LCOV_EXCL_LINE
+}
+
+}  // namespace sys

src/Utilities/System/Exit.hpp

@@ -3,19 +3,11 @@
 
 #pragma once
 
-#include <charm++.h>
-#include <exception>
-
 namespace sys {
 
 /// \ingroup UtilitiesGroup
 /// \brief Exit the program normally.
 /// This should only be called once over all processors.
-[[noreturn]] inline void exit(const int exit_code = 0) {
-  CkExit(exit_code);
-  // the following call is never reached, but suppresses the warning that
-  // a 'noreturn' function does return
-  std::terminate();  // LCOV_EXCL_LINE
-}
+[[noreturn]] void exit(int exit_code = 0);
 
 }  // namespace sys

src/Utilities/System/ParallelInfo.cpp

@@ -1,12 +1,40 @@
 // Distributed under the MIT License.
 // See LICENSE.txt for details.
 
+#include <charm++.h>
 #include <iomanip>
 #include <sstream>
 
 #include "Utilities/System/ParallelInfo.hpp"
 
 namespace sys {
+int number_of_procs() { return CkNumPes(); }
+
+int my_proc() { return CkMyPe(); }
+
+int number_of_nodes() { return CkNumNodes(); }
+
+int my_node() { return CkMyNode(); }
+
+int procs_on_node([[maybe_unused]] const int node_index) {
+  return CkNodeSize(node_index);
+}
+
+int my_local_rank() { return CkMyRank(); }
+
+int first_proc_on_node([[maybe_unused]] const int node_index) {
+  return CkNodeFirst(node_index);
+}
+
+int node_of([[maybe_unused]] const int proc_index) {
+  return CkNodeOf(proc_index);
+}
+
+int local_rank_of([[maybe_unused]] const int proc_index) {
+  return CkRankOf(proc_index);
+}
+
+double wall_time() { return CkWallTimer(); }
 
 std::string pretty_wall_time(const double total_seconds) {
   // Subseconds don't really matter so just ignore them. This gives nice round

src/Utilities/System/ParallelInfo.hpp

@@ -9,90 +9,69 @@
 
 #pragma once
 
-#include <charm++.h>
 #include <string>
 
 namespace sys {
 /*!
  * \ingroup UtilitiesGroup
  * \brief Number of processing elements.
  */
-inline int number_of_procs() { return CkNumPes(); }
+int number_of_procs();
 
 /*!
  * \ingroup UtilitiesGroup
  * \brief %Index of my processing element.
  */
-inline int my_proc() { return CkMyPe(); }
+int my_proc();
 
 /*!
  * \ingroup UtilitiesGroup
  * \brief Number of nodes.
  */
-inline int number_of_nodes() { return CkNumNodes(); }
+int number_of_nodes();
 
 /*!
  * \ingroup UtilitiesGroup
  * \brief %Index of my node.
  */
-inline int my_node() { return CkMyNode(); }
+int my_node();
 
 /*!
  * \ingroup UtilitiesGroup
  * \brief Number of processing elements on the given node.
  */
-inline int procs_on_node(const int node_index) {
-  // When using the verbs-linux-x86_64 non-SMP build of Charm++ these
-  // functions have unused-parameter warnings. This is remedied by
-  // casting the integer to a void which results in no extra assembly
-  // code being generated. We use this instead of pragmas because we
-  // would require one pragma for GCC and one for clang, which would
-  // result in code duplication. Commenting out the variable
-  // nodeIndex gives compilation failures on most Charm++ builds since
-  // they actually use the variable. Charm++ plz...
-  static_cast<void>(node_index);
-  return CkNodeSize(node_index);
-}
+int procs_on_node(int node_index);
 
 /*!
  * \ingroup UtilitiesGroup
  * \brief The local index of my processing element on my node.
  * This is in the interval 0, ..., procs_on_node(my_node()) - 1.
  */
-inline int my_local_rank() { return CkMyRank(); }
+int my_local_rank();
 
 /*!
  * \ingroup UtilitiesGroup
  * \brief %Index of first processing element on the given node.
  */
-inline int first_proc_on_node(const int node_index) {
-  static_cast<void>(node_index);
-  return CkNodeFirst(node_index);
-}
+int first_proc_on_node(int node_index);
 
 /*!
  * \ingroup UtilitiesGroup
  * \brief %Index of the node for the given processing element.
  */
-inline int node_of(const int proc_index) {
-  static_cast<void>(proc_index);
-  return CkNodeOf(proc_index);
-}
+int node_of(int proc_index);
 
 /*!
  * \ingroup UtilitiesGroup
  * \brief The local index for the given processing element on its node.
  */
-inline int local_rank_of(const int proc_index) {
-  static_cast<void>(proc_index);
-  return CkRankOf(proc_index);
-}
+int local_rank_of(int proc_index);
 
 /*!
  * \ingroup UtilitiesGroup
  * \brief The elapsed wall time in seconds.
  */
-inline double wall_time() { return CkWallTimer(); }
+double wall_time();
 
 /// @{
 /// \ingroup UtilitiesGroup