the last line of the function should be blamed when return is missing

python/deps/untypy/untypy/util/__init__.py

@@ -2,9 +2,9 @@
 import types
 from typing import Optional, Union, List
 
-from untypy.util.display import IndicatorStr
 from untypy.error import UntypyTypeError, Frame, Location
 from untypy.interfaces import ExecutionContext, TypeChecker, WrappedFunction
+from untypy.util.display import IndicatorStr
 from untypy.util.return_traces import get_last_return
 
 
@@ -126,8 +126,15 @@ def wrap(self, err: UntypyTypeError) -> UntypyTypeError:
 
         declared = WrappedFunction.find_location(self.fn)
         responsable = declared
+
         if responsable is not None:
-            responsable = responsable.narrow_in_span(self.reti_loc)
+            if err.expected is not None and err.given is None:
+                # Missing Return-Value?
+                err = err.with_note("Did you miss an return statement?")
+                last_line = responsable.line_no + responsable.line_span - 1
+                responsable = responsable.narrow_in_span((responsable.file, last_line))
+            else:
+                responsable = responsable.narrow_in_span(self.reti_loc)
 
         return err.with_frame(Frame(
             return_id.ty,

python/fileTests

@@ -142,6 +142,7 @@ checkWithOutputAux yes 1 test-data/testForwardRef2.py
 checkWithOutputAux yes 0 test-data/testForwardRef3.py
 checkWithOutputAux yes 1 test-data/testForwardRef4.py
 checkWithOutputAux yes 1 test-data/testTypesReturn.py
+checkWithOutputAux yes 1 test-data/testMissingReturn.py
 checkWithOutputAux yes 1 test-data/testTypesSequence1.py
 checkWithOutputAux yes 1 test-data/testTypesSequence2.py
 checkWithOutputAux yes 1 test-data/testTypesTuple1.py

python/test-data/testMissingReturn.err

@@ -0,0 +1,14 @@
+Traceback (most recent call last):
+  File "test-data/testMissingReturn.py", line 6, in <module>
+    print(billigStrom(500))
+WyppTypeError: got value of wrong type
+Did you miss an return statement?
+
+given:    None
+expected: value of type float
+
+context: billigStrom(kwh: float) -> float
+                                    ^^^^^
+declared at: test-data/testMissingReturn.py:3
+caused by: test-data/testMissingReturn.py:4
+  |     pass

python/test-data/testMissingReturn.py

@@ -0,0 +1,6 @@
+# See: https://github.com/skogsbaer/write-your-python-program/issues/15
+
+def billigStrom(kwh: float) -> float:
+    pass
+
+print(billigStrom(500))