Detect old CCache to prevent spurious failures (#1105)

Author: vector-of-bool

build/cmake/CCache.cmake

@@ -1,22 +1,44 @@
 #[[
-    This module enables CCache support by inserting a ccache executable as
+    This module enables Ccache support by inserting a ccache executable as
     the compiler launcher for C and C++ if there is a ccache executable availbale
     on the system.
 
-    CCache support will be automatically enabled if it is found on the system.
-    CCache can be forced on or off by setting the MONGO_USE_CCACHE CMake option to
+    Ccache support will be automatically enabled if it is found on the system.
+    Ccache can be forced on or off by setting the MONGO_USE_CCACHE CMake option to
     ON or OFF.
 ]]
 
 # Find and enable ccache for compiling
 find_program (CCACHE_EXECUTABLE ccache)
-if (CCACHE_EXECUTABLE)
-    message (STATUS "Found ccache: ${CCACHE_EXECUTABLE}")
-    option (MONGO_USE_CCACHE "Use CCache when compiling" ON)
+
+if (CCACHE_EXECUTABLE AND NOT DEFINED MONGO_USE_CCACHE)
+    message (STATUS "Found Ccache: ${CCACHE_EXECUTABLE}")
+    execute_process(
+        COMMAND "${CCACHE_EXECUTABLE}" --version
+        OUTPUT_VARIABLE _out
+        OUTPUT_STRIP_TRAILING_WHITESPACE
+        )
+    set (_enable TRUE)
+    # Avoid spurious "ccache.conf: No such file or directory" errors due to
+    # ccache being invoked in parallel, which was patched in ccache version 3.4.3.
+    if (_out MATCHES "^ccache version ([0-9]+\\.[0-9]+\\.[0-9]+)")
+        set (_version "${CMAKE_MATCH_1}")
+        message (STATUS "Detected Ccache version: ${_version}")
+        if (_version VERSION_LESS "3.4.3")
+            message (STATUS "Not using Ccache: Detected Ccache version ${_version} "
+                            "is less than 3.4.3, which may lead to spurious failures "
+                            "when run in parallel. See https://github.com/ccache/ccache/issues/260 "
+                            "for more information.")
+            set (_enable FALSE)
+        endif ()
+    else ()
+        message (STATUS "Note: Unable to automatically detect Ccache from from output: [[${_out}]]")
+    endif ()
+    option (MONGO_USE_CCACHE "Use Ccache when compiling" "${_enable}")
 endif ()
 
 if (MONGO_USE_CCACHE)
-    message (STATUS "Compiling with CCache enabled. Disable by setting MONGO_USE_CCACHE to OFF")
+    message (STATUS "Compiling with Ccache enabled. Disable by setting MONGO_USE_CCACHE to OFF")
     set (CMAKE_CXX_COMPILER_LAUNCHER "${CCACHE_EXECUTABLE}")
     set (CMAKE_C_COMPILER_LAUNCHER "${CCACHE_EXECUTABLE}")
 endif ()