Add meson option to let user control use of PCH

Author: janisozaur

Source/meson.build

@@ -1,6 +1,9 @@
 
-#pch = meson.current_source_dir()/'System/StandardIncludes.h'
-pch = ''
+if use_pch
+  pch = meson.current_source_dir()/'System/StandardIncludes.h'
+else
+  pch = ''
+endif
 sources = []
 source_libs = []
 source_inc_dirs += [include_directories(

meson.build

@@ -25,6 +25,19 @@ if get_option('debug') and get_option('b_lto')
   warning('Link time optimization enabled in debug mode, debug symbols may not be fully available. Disable b_lto with "meson configure -Db_lto=false".')
 endif
 
+use_pch = get_option('use_pch').enabled()
+
+if get_option('use_pch').auto()
+  ccache = find_program('ccache', required : false)
+  if ccache.found()
+    message('Detected ccache, disabling precompiled headers')
+    use_pch = false
+  else
+    message('Using precompiled headers')
+    use_pch = true
+  endif
+endif
+
 if compiler.get_argument_syntax()== 'gcc' # used for gcc compatible compilers
   # Build against system libraries on linux
   message('gcc detected')

meson_options.txt

@@ -11,3 +11,4 @@ option('tracy_enable', type: 'boolean', value: true, description: 'Enable Tracy
 option('tracy_callstack', type : 'integer', value : 0, description : 'Enfore callstack collection for tracy regions')
 option('tracy_on_demand', type : 'boolean', value : true, description : 'On-demand profiling')
 option('tracy_debuginfod', type : 'boolean', value : false, description : 'Enable debuginfod support')
+option('use_pch', type : 'feature', value : 'auto')