[!372] [bugfix] Remove some codegen time evaluation of predicates

Merge branch 'bugfix/conditionals-with-function-calls' into 'master'

ref:extensions/dune-codegen This does not work if the predicate contains a
function call (you cannot infer the possible return values at codegen time).

See merge request [extensions/dune-codegen!372]

  [extensions/dune-codegen!372]: gitlab.dune-project.org/extensions/dune-codegen/merge_requests/372

python/dune/codegen/pdelab/localoperator.py

@@ -305,7 +305,7 @@ def boundary_predicates(measure, subdomain_id):
 
         subdomains = []
         for integral in original_form.integrals():
-            if integral.integral_type() == measure:
+            if integral.integral_type() == measure and integral.subdomain_id() == subdomain_id:
                 subdomains.append(integral.subdomain_data())
 
         subdomain_data, = set(subdomains)
@@ -315,17 +315,6 @@ def boundary_predicates(measure, subdomain_id):
             visitor = get_visitor(measure, subdomain_id)
             subdomain_data = visitor(subdomain_data, do_predicates=True)
 
-        # Often, boundary predicates are just nested conditionals. We try to find
-        # out which of these are unfulfillable in the first place.
-        def possible_values(expr):
-            if isinstance(expr, prim.If):
-                return set(possible_values(expr.then)).union(possible_values(expr.else_))
-            else:
-                return set({expr})
-
-        if subdomain_id not in possible_values(subdomain_data):
-            return frozenset({False})
-
         p = prim.Comparison(subdomain_data, '==', subdomain_id)
 
         # Try to find conditions that are always 0 or always 1