feat: make ccache usable on all platforms

CMakeLists.txt

@@ -175,12 +175,8 @@ include(cmake/CPM.cmake)
 # excluded from the generated target lists for the various tools.
 set(FETCHCONTENT_BASE_DIR ${CMAKE_BINARY_DIR}/third_party_deps)
 
-# ---- Speedup build using ccache ----
-# see https://github.com/TheLartians/Ccache.cmake enables CCACHE support through
-# the USE_CCACHE flag possible values are: YES, NO or equivalent
-if(USE_CCACHE)
-  cpmaddpackage("gh:TheLartians/Ccache.cmake@1.2.3")
-endif()
+# ---- Speedup build using ccache (needs CPM) ----
+include(cmake/FasterBuild.cmake)
 
 # ------------------------------------------------------------------------------
 # Testing

cmake/FasterBuild.cmake

@@ -0,0 +1,22 @@
+# ===-----------------------------------------------------------------------===#
+# Distributed under the 3-Clause BSD License. See accompanying file LICENSE or
+# copy at https://opensource.org/licenses/BSD-3-Clause).
+# SPDX-License-Identifier: BSD-3-Clause
+# ===-----------------------------------------------------------------------===#
+
+# ------------------------------------------------------------------------------
+# Reduce build time by using ccache when available
+# ------------------------------------------------------------------------------
+
+find_program(CCACHE_TOOL_PATH ccache)
+
+if(NOT WIN32 AND USE_CCACHE AND CCACHE_TOOL_PATH)
+  message(STATUS "Using ccache (${CCACHE_TOOL_PATH}) (via wrapper).")
+  # see https://github.com/TheLartians/Ccache.cmake enables CCACHE support through
+  # the USE_CCACHE flag possible values are: YES, NO or equivalent
+  cpmaddpackage("gh:TheLartians/Ccache.cmake@1.2.3")
+elseif(WIN32 AND USE_CCACHE AND CCACHE_TOOL_PATH)
+  set(CMAKE_C_COMPILER_LAUNCHER ${CCACHE_TOOL_PATH} CACHE STRING "" FORCE)
+  set(CMAKE_CXX_COMPILER_LAUNCHER ${CCACHE_TOOL_PATH} CACHE STRING "" FORCE)
+  message(STATUS "Using ccache (${CCACHE_TOOL_PATH}).")
+endif()