bug[next]: foast2gtir lowering of broadcasted field (#1701)

Wrap every broadcast in an `as_fieldop` (not only scalars). The
materialization of intermediate broadcasted fields need to be optimized
by transformations.

src/gt4py/next/ffront/foast_to_gtir.py

@@ -374,9 +374,7 @@ def create_if(true_: itir.Expr, false_: itir.Expr) -> itir.FunCall:
 
     def _visit_broadcast(self, node: foast.Call, **kwargs: Any) -> itir.FunCall:
         expr = self.visit(node.args[0], **kwargs)
-        if isinstance(node.args[0].type, ts.ScalarType):
-            return im.as_fieldop(im.ref("deref"))(expr)
-        return expr
+        return im.as_fieldop(im.ref("deref"))(expr)
 
     def _visit_math_built_in(self, node: foast.Call, **kwargs: Any) -> itir.FunCall:
         return self._map(self.visit(node.func, **kwargs), *node.args)

tests/next_tests/unit_tests/ffront_tests/test_foast_to_gtir.py

@@ -915,7 +915,7 @@ def foo(inp: gtx.Field[[TDim], float64]):
     lowered = FieldOperatorLowering.apply(parsed)
 
     assert lowered.id == "foo"
-    assert lowered.expr == im.ref("inp")
+    assert lowered.expr == im.as_fieldop("deref")(im.ref("inp"))
 
 
 def test_scalar_broadcast():