python:

A wildcard case (`case _:`) should not be considered default
as the CFG library will then order it last.
Instead it is a `matchAll`

Author: yoff

python/ql/lib/semmle/python/controlflow/internal/AstNodeImpl.qll

@@ -993,9 +993,8 @@ module Ast implements AstSig<Py::Location> {
     }
   }
 
-  /** A wildcard case (`case _:`). */
   class DefaultCase extends Case {
-    DefaultCase() { this.isWildcard() }
+    DefaultCase() { none() }
   }
 
   /** A conditional expression (`x if cond else y`). */
@@ -1754,6 +1753,11 @@ private module Input implements InputSig1, InputSig2 {
       n2.isAdditional(assertStmt, assertThrowTag())
     )
   }
+
+  predicate matchAll(Ast::Case c) {
+    // A wildcard case (`case _:`) will match all values.
+    c.isWildcard()
+  }
 }
 
 import Public