Ignore (and warn about) simple type-tuples in annotations (like "(int, int)") and require "tuple[int, int]" instead.

Closes https://github.com/cython/cython/issues/5397

3 files changed, 33 insertions, 6 deletions

diff --git a/Cython/Compiler/ExprNodes.py b/Cython/Compiler/ExprNodes.py
index 6469000f7..242a97d6a 100644
--- a/Cython/Compiler/ExprNodes.py
+++ b/Cython/Compiler/ExprNodes.py
@@ -14549,6 +14549,10 @@ class AnnotationNode(ExprNode):
                     annotation = value
             if explicit_pytype and explicit_ctype:
                 warning(annotation.pos, "Duplicate type declarations found in signature annotation", level=1)
+        elif isinstance(annotation, TupleNode):
+            warning(annotation.pos,
+                    "Tuples cannot be declared as simple tuples of types. Use 'tuple[type1, type2, ...]'.", level=1)
+            return [], None
 
         with env.new_c_type_context(in_c_type_context=explicit_ctype):
             arg_type = annotation.analyse_as_type(env)
diff --git a/tests/run/annotation_typing.pyx b/tests/run/annotation_typing.pyx
index f2086789d..7c49fea40 100644
--- a/tests/run/annotation_typing.pyx
+++ b/tests/run/annotation_typing.pyx
@@ -149,6 +149,15 @@ def return_tuple_for_carray() -> tuple:
     return x
 
 
+def invalid_ctuple_syntax(a: (cython.int, cython.int), b: (int, int)):
+    """
+    >>> invalid_ctuple_syntax([1, 2], [3, 4])
+    [1, 2, 3, 4]
+    """
+    result: (cython.int, cython.int, cython.int, cython.int) = a + b
+    return result
+
+
 MyStruct = cython.struct(x=cython.int, y=cython.int, data=cython.double)
 
 
@@ -394,14 +403,17 @@ _WARNINGS = """
 63:70: PEP-484 recommends 'typing.Optional[...]' for arguments that can be None.
 90:44: Found Python 2.x type 'long' in a Python annotation. Did you mean to use 'cython.long'?
 90:70: PEP-484 recommends 'typing.Optional[...]' for arguments that can be None.
-283:44: Unknown type declaration in annotation, ignoring
-311:15: Annotation ignored since class-level attributes must be Python objects. Were you trying to set up an instance attribute?
+152:30: Tuples cannot be declared as simple tuples of types. Use 'tuple[type1, type2, ...]'.
+152:59: Tuples cannot be declared as simple tuples of types. Use 'tuple[type1, type2, ...]'.
+157:13: Tuples cannot be declared as simple tuples of types. Use 'tuple[type1, type2, ...]'.
+292:44: Unknown type declaration in annotation, ignoring
+320:15: Annotation ignored since class-level attributes must be Python objects. Were you trying to set up an instance attribute?
 # DUPLICATE:
 63:44: Found Python 2.x type 'long' in a Python annotation. Did you mean to use 'cython.long'?
 # BUG:
 63:6: 'pytypes_cpdef' redeclared
-155:0: 'struct_io' redeclared
-190:0: 'struct_convert' redeclared
-209:0: 'exception_default' redeclared
-240:0: 'exception_default_uint' redeclared
+164:0: 'struct_io' redeclared
+199:0: 'struct_convert' redeclared
+218:0: 'exception_default' redeclared
+249:0: 'exception_default_uint' redeclared
 """
diff --git a/tests/run/ctuple.pyx b/tests/run/ctuple.pyx
index 4053df42b..2d92f8bad 100644
--- a/tests/run/ctuple.pyx
+++ b/tests/run/ctuple.pyx
@@ -225,6 +225,17 @@ def test_mul((int, int) ab, int c):
     """
     return ab * c
 
+def test_mul_to_ctuple((int, int) ab, int c):
+    """
+    >>> test_mul_to_ctuple((1, 2), 2)
+    (1, 2, 1, 2)
+    >>> test_mul_to_ctuple((1, 2), 3)
+    Traceback (most recent call last):
+    TypeError: Expected a tuple of size 4, got tuple
+    """
+    result: tuple[cython.int, cython.int, cython.int, cython.int] = ab * c
+    return result
+
 def test_unop((int, int) ab):
     """
     >>> test_unop((1, 2))