ENH: parse complex special cases from stubs of unary functions

array-api-strict-skips.txt

@@ -32,3 +32,18 @@ array_api_tests/test_data_type_functions.py::test_finfo
 array_api_tests/test_data_type_functions.py::test_finfo_dtype
 array_api_tests/test_data_type_functions.py::test_iinfo
 array_api_tests/test_data_type_functions.py::test_iinfo_dtype
+
+
+# complex special cases which failed "forever"
+array_api_tests/test_special_cases.py::test_unary[expm1(real(x_i) is +infinity and imag(x_i) is +0) -> +infinity + 0j]
+array_api_tests/test_special_cases.py::test_unary[expm1(real(x_i) is -infinity and imag(x_i) is +infinity) -> -1 + 0j]
+array_api_tests/test_special_cases.py::test_unary[expm1(real(x_i) is +infinity and imag(x_i) is +infinity) -> infinity + NaN j]
+array_api_tests/test_special_cases.py::test_unary[expm1(real(x_i) is -infinity and imag(x_i) is NaN) -> -1 + 0j]
+array_api_tests/test_special_cases.py::test_unary[expm1(real(x_i) is +infinity and imag(x_i) is NaN) -> infinity + NaN j]
+array_api_tests/test_special_cases.py::test_unary[expm1(real(x_i) is NaN and imag(x_i) is +0) -> NaN + 0j]
+array_api_tests/test_special_cases.py::test_unary[expm1((real(x_i) is +0 or real(x_i) == -0) and imag(x_i) is +0) -> 0 + 0j]
+
+array_api_tests/test_special_cases.py::test_unary[sign((real(x_i) is -0 or real(x_i) == +0) and (imag(x_i) is -0 or imag(x_i) == +0)) -> 0 + 0j]
+array_api_tests/test_special_cases.py::test_unary[tanh(real(x_i) is +infinity and isfinite(imag(x_i)) and imag(x_i) > 0) -> 1 + 0j]
+
+array_api_tests/test_special_cases.py::test_unary[sqrt(real(x_i) is +infinity and isfinite(imag(x_i)) and imag(x_i) > 0) -> +0 + infinity j]

array_api_tests/dtype_helpers.py

@@ -199,6 +199,39 @@ def is_scalar(x):
     return isinstance(x, (int, float, complex, bool))
 
 
+def complex_dtype_for(dtyp):
+    """Complex dtype for a float or complex."""
+    if dtyp in complex_dtypes:
+        return dtyp
+    if dtyp not in real_float_dtypes:
+        raise ValueError(f"no complex dtype to match {dtyp}")
+
+    real_name = dtype_to_name[dtyp]
+    complex_name = {"float32": "complex64", "float64": "complex128"}[real_name]
+
+    complex_dtype = _name_to_dtype.get(complex_name, None)
+    if complex_dtype is None:
+        raise ValueError(f"no complex dtype to match {dtyp}")
+    return complex_dtype
+
+
+def real_dtype_for(dtyp):
+    """Real float dtype for a float or complex."""
+    if dtyp in real_float_dtypes:
+        return dtyp
+    if dtyp not in complex_dtypes:
+        raise ValueError(f"no real float dtype to match {dtyp}")
+
+    complex_name = dtype_to_name[dtyp]
+    real_name = {"complex64": "float32", "complex128": "float64"}[complex_name]
+
+    real_dtype = _name_to_dtype.get(real_name, None)
+    if real_dtype is None:
+        raise ValueError(f"no real dtype to match {dtyp}")
+    return real_dtype
+
+
+
 def _make_dtype_mapping_from_names(mapping: Dict[str, Any]) -> EqualityMapping:
     dtype_value_pairs = []
     for name, value in mapping.items():