Fix 'default' on non-visible choice symbols

Previously, 'default CHOICE_SYM [if <cond>]' in a choice would skip any
following 'default' properties if <cond> was non-'n'. However, those
other defaults should still be considered if CHOICE_SYM has visibility
'n'. Previously, we'd immediately fall back to selecting the first
visible symbol in the choice in that case.

get_selection_from_defaults() now exactly mirrors sym_choice_default()
from the C implementation, and got less convoluted too.

Nothing in the kernel defconfigs triggered this.

Add a new test case too.

1 files changed, 8 insertions, 12 deletions

diff --git a/kconfiglib.py b/kconfiglib.py
index 0cab18f..0865176 100644
--- a/kconfiglib.py
+++ b/kconfiglib.py
@@ -2872,23 +2872,19 @@ class Choice(Item):
         """Like Choice.get_selection(), but acts as if no symbol has been
         selected by the user and no 'optional' flag is in effect."""
 
-        if not self._actual_symbols:
-            return None
-
-        for symbol, cond_expr in self._def_exprs:
-            if self._config._eval_expr(cond_expr) != "n":
-                chosen_symbol = symbol
-                break
-        else:
-            chosen_symbol = self._actual_symbols[0]
+        # Does any 'default SYM [if <cond>]' property apply?
+        for sym, cond_expr in self._def_exprs:
+            if (self._config._eval_expr(cond_expr) != "n" and
+                # Must be visible too
+                _get_visibility(sym) != "n"):
+                return sym
 
-        # Is the chosen symbol visible?
-        if _get_visibility(chosen_symbol) != "n":
-            return chosen_symbol
         # Otherwise, pick the first visible symbol
         for sym in self._actual_symbols:
             if _get_visibility(sym) != "n":
                 return sym
+
+        # Couldn't find a default
         return None
 
     def get_user_selection(self):