Define more linker requirements

pytensor/link/basic.py

@@ -283,6 +283,9 @@ class PerformLinker(LocalLinker):
 
     """
 
+    required_rewrites: tuple[str, ...] = ("minimum_compile", "py_only")
+    incompatible_rewrites: tuple[str, ...] = ("cxx",)
+
     def __init__(
         self, allow_gc: bool | None = None, schedule: Callable | None = None
     ) -> None:
@@ -584,6 +587,9 @@ class JITLinker(PerformLinker):
 
     """
 
+    required_rewrites: tuple[str, ...] = ("minimum_compile",)
+    incompatible_rewrites: tuple[str, ...] = ()
+
     @abstractmethod
     def fgraph_convert(
         self, fgraph, order, input_storage, output_storage, storage_map, **kwargs

pytensor/link/vm.py

@@ -812,6 +812,10 @@ class VMLinker(LocalLinker):
 
     """
 
+    # We can only set these correctly after `__init__`, as it depends on `c_thunks`
+    required_rewrites: tuple[str, ...] = ("minimum_compile",)
+    incompatible_rewrites: tuple[str, ...] = ()
+
     def __init__(
         self,
         allow_gc=None,
@@ -834,6 +838,9 @@ class VMLinker(LocalLinker):
         self.lazy = lazy
         if c_thunks is None:
             c_thunks = bool(config.cxx)
+        if not c_thunks:
+            self.required_rewrites: tuple[str, ...] = ("minimum_compile", "py_only")
+            self.incompatible_rewrites: tuple[str, ...] = ("cxx",)
         self.c_thunks = c_thunks
         self.allow_partial_eval = allow_partial_eval
         self.updated_vars = {}

tests/compile/test_mode.py

@@ -56,11 +56,12 @@ def test_NoOutputFromInplace():
 
 def test_including():
     mode = Mode(linker="py", optimizer="merge")
-    assert set(mode._optimizer.include) == {"minimum_compile", "merge"}
+    assert set(mode._optimizer.include) == {"minimum_compile", "py_only", "merge"}
 
     new_mode = mode.including("fast_compile")
     assert set(new_mode._optimizer.include) == {
         "minimum_compile",
+        "py_only",
         "merge",
         "fast_compile",
     }