Merge #19: build: Add CMake-based build system (9 of N)

ac7bc5b [FIXUP] Rename CCACHE_EXECUTABLE --> CCACHE_COMMAND for consistency (Hennadii Stepanov)
0476509 [FIXUP] Learn to work with recent ccache in MSVC builds (Hennadii Stepanov)
2fd67c7 [FIXUP] Do not disable `TrackFileAccess` in MSVC builds (Hennadii Stepanov)
a53ae12 [FIXUP] Use Multi-ToolTask in MSVC builds by default (Hennadii Stepanov)

Pull request description:

  The parent PR: bitcoin#25797.
  The previous PRs in the staging branch: #5, #6, #7, #10, #13, #15, #17, #18.

  This PR consists of fixups related to using [Ccache](https://ccache.dev/) in MSVC builds.

Top commit has no ACKs.

Tree-SHA512: dc01202b054aaeb5b46607bc93126bee0df523df3b4f2df54b566b2e2d6306d784a723fd4a999d0d84fdf31e926a72304790f94b9d57034db0c112ee9f52070e

CMakeLists.txt

@@ -102,6 +102,9 @@ if(WIN32)
   if(MSVC)
     set(CMAKE_MSVC_RUNTIME_LIBRARY "MultiThreaded$<$<CONFIG:Debug>:Debug>")
     add_compile_options(/utf-8 /Zc:__cplusplus)
+    # Improve parallelism in MSBuild.
+    # See: https://devblogs.microsoft.com/cppblog/improved-parallelism-in-msbuild/.
+    list(APPEND CMAKE_VS_GLOBALS "UseMultiToolTask=true")
   endif()
 
   if(MINGW)

cmake/optional.cmake

@@ -5,31 +5,40 @@
 # Optional features and packages.
 
 if(CCACHE)
-  find_program(CCACHE_EXECUTABLE ccache)
-  if(CCACHE_EXECUTABLE)
-    set(CCACHE ON)
+  find_program(CCACHE_COMMAND ccache)
+  if(CCACHE_COMMAND)
     if(MSVC)
-      # See https://github.com/ccache/ccache/wiki/MS-Visual-Studio
-      set(MSVC_CCACHE_WRAPPER_CONTENT "\"${CCACHE_EXECUTABLE}\" \"${CMAKE_CXX_COMPILER}\"")
-      set(MSVC_CCACHE_WRAPPER_FILENAME wrapped-cl.bat)
-      file(WRITE ${CMAKE_BINARY_DIR}/${MSVC_CCACHE_WRAPPER_FILENAME} "${MSVC_CCACHE_WRAPPER_CONTENT} %*")
-      set(CMAKE_VS_GLOBALS
-        "CLToolExe=${MSVC_CCACHE_WRAPPER_FILENAME}"
-        "CLToolPath=${CMAKE_BINARY_DIR}"
-        "TrackFileAccess=false"
-        "UseMultiToolTask=true"
-        "DebugInformationFormat=OldStyle"
-      )
+      if(CMAKE_VERSION VERSION_GREATER_EQUAL 3.24)
+        # ccache >= 4.8 requires compile batching turned off that is available since CMake 3.24.
+        # See https://github.com/ccache/ccache/wiki/MS-Visual-Studio
+        set(CCACHE ON)
+        set(MSVC_CCACHE_WRAPPER_CONTENT "\"${CCACHE_COMMAND}\" \"${CMAKE_CXX_COMPILER}\"")
+        set(MSVC_CCACHE_WRAPPER_FILENAME wrapped-cl.bat)
+        file(WRITE ${CMAKE_BINARY_DIR}/${MSVC_CCACHE_WRAPPER_FILENAME} "${MSVC_CCACHE_WRAPPER_CONTENT} %*")
+        list(APPEND CMAKE_VS_GLOBALS
+          "CLToolExe=${MSVC_CCACHE_WRAPPER_FILENAME}"
+          "CLToolPath=${CMAKE_BINARY_DIR}"
+          "DebugInformationFormat=OldStyle"
+        )
+        set(CMAKE_VS_NO_COMPILE_BATCHING ON)
+      elseif(CCACHE STREQUAL "AUTO")
+        message(WARNING "ccache requested and found, but CMake >= 3.24 is required to use it properly. Disabling.\n"
+                        "To skip ccache check, use \"-DCCACHE=OFF\".\n")
+        set(CCACHE OFF)
+      else()
+        message(FATAL_ERROR "ccache requested and found, but CMake >= 3.24 is required to use it properly.")
+      endif()
     else()
-      list(APPEND CMAKE_C_COMPILER_LAUNCHER ${CCACHE_EXECUTABLE})
-      list(APPEND CMAKE_CXX_COMPILER_LAUNCHER ${CCACHE_EXECUTABLE})
+      set(CCACHE ON)
+      list(APPEND CMAKE_C_COMPILER_LAUNCHER ${CCACHE_COMMAND})
+      list(APPEND CMAKE_CXX_COMPILER_LAUNCHER ${CCACHE_COMMAND})
     endif()
   elseif(CCACHE STREQUAL "AUTO")
     set(CCACHE OFF)
   else()
     message(FATAL_ERROR "ccache requested, but not found.")
   endif()
-  mark_as_advanced(CCACHE_EXECUTABLE)
+  mark_as_advanced(CCACHE_COMMAND)
 endif()
 
 if(WITH_NATPMP)