ccache.bbclass: Add allowed list for native recipes

Native recipes are not able to use ccache currently, due to a circular
dependency between ccache-native and cmake-native.
This affects also other native recipes, but not all, imposing a
limitation in build time optimizations.

The introduction of CCACHE_NATIVE_RECIPES_ALLOWED allows the user to specify
which native recipes should use ccache, keeping it disable by default for all
native recipes.

(From OE-Core rev: 87cb2be71e0c0c123eaae6a5ae135900c95535db)

Signed-off-by: Angelo Ribeiro <Angelo.Ribeiro@criticaltechworks.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/ccache.bbclass

@@ -28,6 +28,11 @@
 # be shared between different builds.
 CCACHE_TOP_DIR ?= "${TMPDIR}/ccache"
 
+# ccache-native and cmake-native have a circular dependency
+# that affects other native recipes, but not all.
+# Allows to use ccache in specified native recipes.
+CCACHE_NATIVE_RECIPES_ALLOWED ?= ""
+
 # ccahe removes CCACHE_BASEDIR from file path, so that hashes will be the same
 # in different builds.
 export CCACHE_BASEDIR ?= "${TMPDIR}"
@@ -54,9 +59,9 @@ python() {
     Enable ccache for the recipe
     """
     pn = d.getVar('PN')
-    # quilt-native doesn't need ccache since no c files
-    if not (bb.data.inherits_class("native", d) or
-            bb.utils.to_boolean(d.getVar('CCACHE_DISABLE'))):
+    if (pn in d.getVar('CCACHE_NATIVE_RECIPES_ALLOWED') or
+        not (bb.data.inherits_class("native", d) or
+        bb.utils.to_boolean(d.getVar('CCACHE_DISABLE')))):
         d.appendVar('DEPENDS', ' ccache-native')
         d.setVar('CCACHE', 'ccache ')
 }

meta/conf/documentation.conf

@@ -106,6 +106,7 @@ BUSYBOX_SPLIT_SUID[doc] = "For the BusyBox recipe, specifies whether to split th
 #C
 
 CACHE[doc]  = "The directory holding the cache of the metadata."
+CCACHE_NATIVE_RECIPES_ALLOWED[doc] = "A list of native recipes to use Ccache, this variable is useful to bypass a circular dependency between ccache-native and cmake-native that inhibits to use Ccache in other native recipes."
 CFLAGS[doc] = "Flags passed to the C compiler for the target system. This variable evaluates to the same as TARGET_CFLAGS."
 CLASSOVERRIDE[doc] = "An internal variable specifying the special class override that should currently apply (e.g. "class-target", "class-native", and so forth)."
 CLEANBROKEN[doc] = "Specifies if 'make clean' does not work for a recipe (and therefore the build system should not try to use it during do_configure)"