feat: custom Pylint plugin

for now, it catches the following incorrect function:

async def show_foo() -> Awaitable[None]:
    return show_something_else("foo")

because to correctly show the result, the caller would have to "await (await show_foo())"

(this should either be "async def show_foo() -> None", or "def show_foo() -> Awaitable[None]")

poetry.lock

@@ -1,4 +1,4 @@
-# This file is automatically @generated by Poetry 1.6.1 and should not be changed by hand.
+# This file is automatically @generated by Poetry 1.5.1 and should not be changed by hand.
 
 [[package]]
 name = "astroid"
@@ -1550,7 +1550,7 @@ testing = ["flaky (>=3.4.0)", "freezegun (>=0.3.11)", "pathlib2 (>=2.3.3)", "psu
 
 [[package]]
 name = "trezor"
-version = "0.13.8"
+version = "0.13.9"
 description = "Python library for communicating with Trezor Hardware Wallet"
 optional = false
 python-versions = ">=3.6"
@@ -1568,17 +1568,34 @@ requests = ">=2.4.0"
 typing_extensions = ">=3.10"
 
 [package.extras]
-ethereum = ["rlp (>=1.1.0)", "web3 (>=4.8)"]
+ethereum = ["rlp (>=1.1.0)", "web3 (>=5)"]
 extra = ["Pillow"]
-full = ["Pillow", "PyQt5", "hidapi (>=0.7.99.post20)", "rlp (>=1.1.0)", "stellar-sdk (>=4.0.0,<6.0.0)", "web3 (>=4.8)"]
+full = ["Pillow", "PyQt5", "hidapi (>=0.7.99.post20)", "rlp (>=1.1.0)", "stellar-sdk (>=6)", "web3 (>=5)"]
 hidapi = ["hidapi (>=0.7.99.post20)"]
 qt-widgets = ["PyQt5"]
-stellar = ["stellar-sdk (>=4.0.0,<6.0.0)"]
+stellar = ["stellar-sdk (>=6)"]
 
 [package.source]
 type = "directory"
 url = "python"
 
+[[package]]
+name = "trezor-pylint-plugin"
+version = "0.1.0"
+description = ""
+optional = false
+python-versions = "^3.8"
+files = []
+develop = true
+
+[package.dependencies]
+astroid = "*"
+pylint = "*"
+
+[package.source]
+type = "directory"
+url = "tools/trezor-pylint-plugin"
+
 [[package]]
 name = "typing-extensions"
 version = "4.0.1"
@@ -1744,4 +1761,4 @@ testing = ["func-timeout", "jaraco.itertools", "pytest (>=6)", "pytest-black (>=
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.8"
-content-hash = "b8063d1d5d0a67a71bbcba204e0e542fbab5ea2bbe7b05c41f77b8e0fa736f0e"
+content-hash = "72019b6396c9c15ee87968b735b954908a9e9e89d0c828b1e115293a0efb9f05"

pyproject.toml

@@ -74,6 +74,7 @@ vulture = "^2.6"
 # tools
 binsize = "^0.1.3"
 toiftool = {path = "./python/tools/toiftool", develop = true, python = ">=3.8"}
+trezor-pylint-plugin = {path = "./tools/trezor-pylint-plugin", develop = true}
 
 [tool.poetry.dev-dependencies]
 scan-build = "*"

tools/trezor-pylint-plugin/.gitignore

@@ -0,0 +1,2 @@
+*.egg-info
+/build

tools/trezor-pylint-plugin/README.md

@@ -0,0 +1,23 @@
+# Custom Pylint rule checker
+
+For now, it catches the following problem (`async-awaitable-return`):
+
+```python
+async def show_foo() -> Awaitable[None]:
+    return show_something("foo")
+```
+
+This is almost certainly a mistake -- the caller would need to say `await (await
+show_foo())` to actually show the foo.
+
+The function should be one of:
+
+```python
+async def show_foo() -> None:
+    return await show_something("foo")
+
+# ... or ...
+
+def show_foo() -> Awaitable[None]:
+    return show_something("foo")
+```

tools/trezor-pylint-plugin/pyproject.toml

@@ -0,0 +1,15 @@
+[tool.poetry]
+name = "trezor-pylint-plugin"
+version = "0.1.0"
+description = ""
+authors = ["matejcik <ja@matejcik.cz>"]
+readme = "README.md"
+
+[tool.poetry.dependencies]
+python = "^3.8"
+pylint = "*"
+astroid = "*"
+
+[build-system]
+requires = ["poetry-core"]
+build-backend = "poetry.core.masonry.api"

tools/trezor-pylint-plugin/trezor_pylint_plugin.py

@@ -0,0 +1,29 @@
+from astroid import AsyncFunctionDef
+from pylint.checkers import BaseChecker
+from pylint.checkers.utils import check_messages
+from pylint.interfaces import IAstroidChecker
+
+
+class AsyncAwaitableChecker(BaseChecker):
+    __implements__ = IAstroidChecker
+
+    name = "async-awaitable-checker"
+    priority = -1
+    msgs = {
+        "W9999": (
+            'Async function "%s" is likely not meant to return an Awaitable.',
+            "async-awaitable-return",
+            "Used when an async function returns an Awaitable instead of the result.",
+        ),
+    }
+
+    @check_messages("async-awaitable-return")
+    def visit_asyncfunctiondef(self, node: AsyncFunctionDef):
+        # Check if the return type is explicitly an Awaitable
+        if node.returns and "Awaitable" in node.returns.as_string():
+            self.add_message("async-awaitable-return", node=node, args=(node.name,))
+
+
+def register(linter):
+    """Required method to auto register this checker."""
+    linter.register_checker(AsyncAwaitableChecker(linter))