[PATCH 2/3] oelib: utils: Support opting out of all features

[Paul Barker <paul@pbarker.dev>]

If '*' is present as a separate token in DISTRO_FEATURES_OPTED_OUT or
MACHINE_FEATURES_OPTED_OUT, interpret this as opting out of all default
features.

If '*' is part of a larger word, this is not treated specially - 'FOO*'
will not trigger removal of all features.

This is implemented in set_difference() so that the behaviour can be
reused in other similar processing we may need to do in the future.

Signed-off-by: Paul Barker <paul@pbarker.dev>
---
 meta/lib/oe/utils.py | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/meta/lib/oe/utils.py b/meta/lib/oe/utils.py
index 5c722d230842..639c037c1a01 100644
--- a/meta/lib/oe/utils.py
+++ b/meta/lib/oe/utils.py
@@ -93,6 +93,13 @@ def set_difference(variable1, variable2, d):
     s2 = "b c d"
     s3 = set_difference(s1, s2)
     => s3 = "a"
+
+    If '*' is present as a separate token (not part of a larger identifier) in
+    the second operand, this is interpreted as "remove all entries":
+    s1 = "a b c"
+    s2 = "*"
+    s3 = set_difference(s1, s2)
+    => s3 = ""
     """
     val1 = d.getVar(variable1)
     if not val1:
@@ -104,6 +111,9 @@ def set_difference(variable1, variable2, d):
     val1 = set(val1.split())
     val2 = set(val2.split())
 
+    if "*" in val2:
+        return ""
+
     # Return a sorted string to ensure that the result is consistent between
     # parser runs.
     return " ".join(sorted(val1 - val2))

-- 
2.43.0