fix: detect conditional hook usage when hook is used as decorator

maartenbreddels · claude · maartenbreddels · commit 71e34b8f08bd · 2026-02-24T17:31:39.000+01:00
The HookValidator only checked ast.Call nodes, so hooks used as
decorators without parentheses (e.g. @solara.use_effect) were not
flagged when inside conditional/loop/try scopes. This inspects
decorator_list on FunctionDef/AsyncFunctionDef nodes as well.

Co-Authored-By: Claude Opus 4.6 &lt;noreply@anthropic.com&gt;
diff --git a/solara/validate_hooks.py b/solara/validate_hooks.py
@@ -169,13 +169,31 @@ def visit_Try(self, node: ast.Try) -> t.Any:
         def visit_TryStar(self, node: ast.TryStar) -> t.Any:
             self._visit_children_using_scope(node)
 
+    def _check_decorator_hooks(self, node: t.Union[ast.FunctionDef, ast.AsyncFunctionDef]):
+        """Check if any decorators are hooks (e.g. @use_effect, @solara.use_effect, or @use_task(...))."""
+        for decorator in node.decorator_list:
+            id_ = None
+            check_node = decorator
+            if isinstance(decorator, ast.Call):
+                # e.g. @use_task(dependencies=[...])
+                check_node = decorator.func
+            if isinstance(check_node, ast.Name):
+                id_ = check_node.id
+            elif isinstance(check_node, ast.Attribute):
+                id_ = check_node.attr
+            if id_ is not None and self.matches_use_function(id_):
+                self.error_on_early_return(decorator, id_)
+                self.error_on_invalid_scope(decorator, id_)
+
     def visit_FunctionDef(self, node: ast.FunctionDef):
+        self._check_decorator_hooks(node)
         old_function_scope = self.function_scope
         self.function_scope = node
         self._visit_children_using_scope(node)
         self.function_scope = old_function_scope
 
     def visit_AsyncFunctionDef(self, node: ast.AsyncFunctionDef):
+        self._check_decorator_hooks(node)
         old_function_scope = self.function_scope
         self.function_scope = node
         self._visit_children_using_scope(node)
@@ -213,7 +231,7 @@ def error_on_invalid_assign(self, node: ast.Assign):
                 f"{self.get_source_context(line)}: {message}",
             )
 
-    def error_on_early_return(self, use_node: ast.Call, use_node_id: str):
+    def error_on_early_return(self, use_node: ast.expr, use_node_id: str):
         """
         Checks if the latest use of a reactive function occurs after the earliest return
         """
@@ -231,7 +249,7 @@ def error_on_early_return(self, use_node: ast.Call, use_node_id: str):
 {_hint_supress(line, cause)}""",
             )
 
-    def error_on_invalid_scope(self, use_node: ast.Call, use_node_id: str):
+    def error_on_invalid_scope(self, use_node: ast.expr, use_node_id: str):
         """
         Checks if the latest use of a reactive function occurs after the earliest return or in an invalid scope
         such as try-except blocks.
diff --git a/tests/unit/hook_use_invalid_test.py b/tests/unit/hook_use_invalid_test.py
@@ -168,6 +168,79 @@ def Page2():  # noqa: SH106
             pass
 
 
+def test_hook_use_invalid_conditional_decorator():
+    with hook_check_raise(), pytest.raises(HookValidationError):
+
+        @solara.component
+        def Page():
+            if 1 > 3:
+
+                @solara.use_effect
+                def effect():
+                    pass
+
+            solara.Text("Done")
+
+    with hook_check_warn(), pytest.warns(UserWarning):
+
+        @solara.component
+        def Page2():
+            if 1 > 3:
+
+                @solara.use_effect
+                def effect():
+                    pass
+
+            solara.Text("Done")
+
+    @solara.component
+    def Page3():
+        if 1 > 3:
+
+            @solara.use_effect  # noqa: SH102
+            def effect():
+                pass
+
+        solara.Text("Done")
+
+
+def test_hook_use_invalid_conditional_decorator_call():
+    """Test that @use_effect(dependencies=[...]) style call-decorators are also caught."""
+    with hook_check_raise(), pytest.raises(HookValidationError):
+
+        @solara.component
+        def Page():
+            if 1 > 3:
+
+                @solara.use_effect(dependencies=[])  # type: ignore[call-arg]
+                def task():
+                    pass
+
+            solara.Text("Done")
+
+    with hook_check_warn(), pytest.warns(UserWarning):
+
+        @solara.component
+        def Page2():
+            if 1 > 3:
+
+                @solara.use_effect(dependencies=[])  # type: ignore[call-arg]
+                def task():
+                    pass
+
+            solara.Text("Done")
+
+    @solara.component
+    def Page3():
+        if 1 > 3:
+
+            @solara.use_effect(dependencies=[])  # type: ignore[call-arg]  # noqa: SH102
+            def task():
+                pass
+
+        solara.Text("Done")
+
+
 def test_hook_use_invalid_assign():
     # sometimes we know that the use of a hook is stable, even when in a loop
 
