report @pure functions without return or yield

deal/linter/_extractors/__init__.py

@@ -7,17 +7,18 @@
 from .globals import get_globals
 from .imports import get_imports
 from .prints import get_prints
-from .returns import get_returns
+from .returns import get_returns, has_returns
 
 
 __all__ = [
     'get_asserts',
     'get_contracts',
-    'get_exceptions',
     'get_exceptions_stubs',
+    'get_exceptions',
     'get_globals',
     'get_imports',
     'get_name',
     'get_prints',
     'get_returns',
+    'has_returns',
 ]

deal/linter/_extractors/common.py

@@ -26,6 +26,7 @@
     TRY=(ast.Try, astroid.TryExcept, astroid.TryFinally),
     UNARY_OP=(ast.UnaryOp, astroid.UnaryOp),
     WITH=(ast.With, astroid.With),
+    YIELD=(ast.Yield, astroid.Yield),
 )
 
 

deal/linter/_extractors/returns.py

@@ -6,13 +6,20 @@
 import astroid
 
 # app
-from .common import TOKENS, Extractor, Token, infer
+from .common import TOKENS, Extractor, Token, infer, traverse
 
 
 get_returns = Extractor()
 inner_extractor = Extractor()
 
 
+def has_returns(body: list) -> bool:
+    for expr in traverse(body=body):
+        if isinstance(expr, TOKENS.RETURN + TOKENS.YIELD):
+            return True
+    return False
+
+
 @get_returns.register(*TOKENS.RETURN)
 def handle_returns(expr) -> Optional[Token]:
     # inner_extractor

deal/linter/_func.py

@@ -18,12 +18,14 @@
 
 
 class Func:
-    __slots__ = ('body', 'contracts', 'name')
+    __slots__ = ('body', 'contracts', 'name', 'line', 'col')
 
-    def __init__(self, *, body: list, contracts: Iterable[Contract], name: str):
+    def __init__(self, *, body: list, contracts: Iterable[Contract], name: str, line: int, col: int):
         self.body = body
         self.contracts = contracts
         self.name = name
+        self.line = line
+        self.col = col
 
     @classmethod
     def from_path(cls, path: Path) -> List['Func']:
@@ -50,6 +52,8 @@ def from_ast(cls, tree: ast.Module) -> List['Func']:
                 name=expr.name,
                 body=expr.body,
                 contracts=contracts,
+                line=expr.lineno,
+                col=expr.col_offset,
             ))
         return funcs
 
@@ -68,6 +72,8 @@ def from_astroid(cls, tree: astroid.Module) -> List['Func']:
                 name=expr.name,
                 body=expr.body,
                 contracts=contracts,
+                line=expr.lineno,
+                col=expr.col_offset,
             ))
         return funcs
 

deal/linter/_rules.py

@@ -10,6 +10,7 @@
 from ._extractors import (
     get_exceptions, get_exceptions_stubs, get_globals,
     get_imports, get_prints, get_returns, get_asserts,
+    has_returns,
 )
 from ._func import Func
 from ._stub import StubsManager
@@ -158,6 +159,14 @@ def __call__(self, func: Func, stubs: StubsManager = None) -> Iterator[Error]:
             return
 
     def _check(self, func: Func, stubs: StubsManager = None) -> Iterator[Error]:
+        if not has_returns(body=func.body):
+            yield Error(
+                code=self.code,
+                text=self.message,
+                value='return',
+                row=func.line,
+                col=func.col,
+            )
         for token in get_globals(body=func.body):
             yield Error(
                 code=self.code,

tests/test_linter/test_rules.py

@@ -147,6 +147,7 @@ def test_check_pure():
     @deal.pure
     def test(a):
         global b
+        return b
     """
     text = dedent(text).strip()
     funcs1 = Func.from_ast(ast.parse(text))