MAINT: remove support and testing on Python 3.8 (#14023)

According to NEP 29 it is now time to remove support for Python 3.8

This commit removes support for Python 3.8 from the codebase, as well as
removing the tests for Python 3.8 from the CI workflow.

It also updates the `pyproject.toml` file to reflect the removal of
Python 3.8 support.

.github/workflows/test.yml

@@ -19,12 +19,12 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest]
-        python-version: ["3.8", "3.9", "3.10", "3.11"]
+        python-version: ["3.9", "3.10", "3.11"]
         deps: [test_extra]
         # Test all on ubuntu, test ends on macos
         include:
           - os: macos-latest
-            python-version: "3.8"
+            python-version: "3.9"
             deps: test_extra
           - os: macos-latest
             python-version: "3.11"
@@ -39,13 +39,13 @@ jobs:
             deps: test
           # Installing optional dependencies stuff takes ages on PyPy
           - os: ubuntu-latest
-            python-version: "pypy-3.8"
+            python-version: "pypy-3.9"
             deps: test
           - os: windows-latest
-            python-version: "pypy-3.8"
+            python-version: "pypy-3.9"
             deps: test
           - os: macos-latest
-            python-version: "pypy-3.8"
+            python-version: "pypy-3.9"
             deps: test
 
     steps:

IPython/__init__.py

@@ -26,10 +26,11 @@
 #-----------------------------------------------------------------------------
 
 # Don't forget to also update setup.py when this changes!
-if sys.version_info < (3, 8):
+if sys.version_info < (3, 9):
     raise ImportError(
         """
-IPython 8+ supports Python 3.8 and above, following NEP 29.
+IPython 8.13+ supports Python 3.9 and above, following NEP 29.
+IPython 8.0-8.12 supports Python 3.8 and above, following NEP 29.
 When using Python 2.7, please install IPython 5.x LTS Long Term Support version.
 Python 3.3 and 3.4 were supported up to IPython 6.x.
 Python 3.5 was supported with IPython 7.0 to 7.9.

IPython/core/guarded_eval.py

@@ -508,9 +508,6 @@ def eval_node(node: Union[ast.AST, None], context: EvaluationContext):
         return all_true
     if isinstance(node, ast.Constant):
         return node.value
-    if isinstance(node, ast.Index):
-        # deprecated since Python 3.9
-        return eval_node(node.value, context)  # pragma: no cover
     if isinstance(node, ast.Tuple):
         return tuple(eval_node(e, context) for e in node.elts)
     if isinstance(node, ast.List):
@@ -530,9 +527,6 @@ def eval_node(node: Union[ast.AST, None], context: EvaluationContext):
             eval_node(node.upper, context),
             eval_node(node.step, context),
         )
-    if isinstance(node, ast.ExtSlice):
-        # deprecated since Python 3.9
-        return tuple([eval_node(dim, context) for dim in node.dims])  # pragma: no cover
     if isinstance(node, ast.UnaryOp):
         value = eval_node(node.operand, context)
         dunders = _find_dunder(node.op, UNARY_OP_DUNDERS)

IPython/core/tests/test_async_helpers.py

@@ -276,12 +276,12 @@ def test_autoawait(self):
         """
         )
 
-    if sys.version_info < (3, 9) and platform.python_implementation() != "PyPy":
-        # new pgen parser in 3.9 does not raise MemoryError on too many nested
-        # parens anymore
-        def test_memory_error(self):
-            with self.assertRaises(MemoryError):
-                iprc("(" * 200 + ")" * 200)
+    def test_memory_error(self):
+        """
+        The pgen parser in 3.8 or before use to raise MemoryError on too many
+        nested parens anymore"""
+
+        iprc("(" * 200 + ")" * 200)
 
     @skip_without('curio')
     def test_autoawait_curio(self):

IPython/core/tests/test_interactiveshell.py

@@ -713,12 +713,10 @@ def test_extraneous_loads(self):
 class Negator(ast.NodeTransformer):
     """Negates all number literals in an AST."""
 
-    # for python 3.7 and earlier
     def visit_Num(self, node):
         node.n = -node.n
         return node
 
-    # for python 3.8+
     def visit_Constant(self, node):
         if isinstance(node.value, int):
             return self.visit_Num(node)
@@ -900,7 +898,6 @@ class StringRejector(ast.NodeTransformer):
     not be executed by throwing an InputRejected.
     """
 
-    # 3.8 only
     def visit_Constant(self, node):
         if isinstance(node.value, str):
             raise InputRejected("test")

IPython/core/tests/test_iplib.py

@@ -166,93 +166,48 @@ def doctest_tb_sysexit():
     """
 
 
-if sys.version_info >= (3, 9):
-    if SV_VERSION < (0, 6):
-
-        def doctest_tb_sysexit_verbose_stack_data_05():
-            """
-            In [18]: %run simpleerr.py exit
-            An exception has occurred, use %tb to see the full traceback.
-            SystemExit: (1, 'Mode = exit')
-
-            In [19]: %run simpleerr.py exit 2
-            An exception has occurred, use %tb to see the full traceback.
-            SystemExit: (2, 'Mode = exit')
-
-            In [23]: %xmode verbose
-            Exception reporting mode: Verbose
-
-            In [24]: %tb
-            ---------------------------------------------------------------------------
-            SystemExit                                Traceback (most recent call last)
-            <BLANKLINE>
-            ...
-                30     except IndexError:
-                31         mode = 'div'
-            ---> 33     bar(mode)
-                    mode = 'exit'
-            <BLANKLINE>
-            ... in bar(mode='exit')
-                ...     except:
-                ...         stat = 1
-            ---> ...     sysexit(stat, mode)
-                    mode = 'exit'
-                    stat = 2
-                ...     else:
-                ...         raise ValueError('Unknown mode')
-            <BLANKLINE>
-            ... in sysexit(stat=2, mode='exit')
-                10 def sysexit(stat, mode):
-            ---> 11     raise SystemExit(stat, f"Mode = {mode}")
-                    stat = 2
-            <BLANKLINE>
-            SystemExit: (2, 'Mode = exit')
-            """
-
-    else:
-        # currently the only difference is
-        # + mode = 'exit'
-
-        def doctest_tb_sysexit_verbose_stack_data_06():
-            """
-            In [18]: %run simpleerr.py exit
-            An exception has occurred, use %tb to see the full traceback.
-            SystemExit: (1, 'Mode = exit')
-
-            In [19]: %run simpleerr.py exit 2
-            An exception has occurred, use %tb to see the full traceback.
-            SystemExit: (2, 'Mode = exit')
-
-            In [23]: %xmode verbose
-            Exception reporting mode: Verbose
-
-            In [24]: %tb
-            ---------------------------------------------------------------------------
-            SystemExit                                Traceback (most recent call last)
-            <BLANKLINE>
-            ...
-                 30     except IndexError:
-                 31         mode = 'div'
-            ---> 33     bar(mode)
-                    mode = 'exit'
-            <BLANKLINE>
-            ... in bar(mode='exit')
-                 ...     except:
-                 ...         stat = 1
-            ---> ...     sysexit(stat, mode)
-                    mode = 'exit'
-                    stat = 2
-                 ...     else:
-                 ...         raise ValueError('Unknown mode')
-            <BLANKLINE>
-            ... in sysexit(stat=2, mode='exit')
-                 10 def sysexit(stat, mode):
-            ---> 11     raise SystemExit(stat, f"Mode = {mode}")
-                    stat = 2
-                    mode = 'exit'
-            <BLANKLINE>
-            SystemExit: (2, 'Mode = exit')
-            """
+if SV_VERSION < (0, 6):
+
+    def doctest_tb_sysexit_verbose_stack_data_05():
+        """
+        In [18]: %run simpleerr.py exit
+        An exception has occurred, use %tb to see the full traceback.
+        SystemExit: (1, 'Mode = exit')
+
+        In [19]: %run simpleerr.py exit 2
+        An exception has occurred, use %tb to see the full traceback.
+        SystemExit: (2, 'Mode = exit')
+
+        In [23]: %xmode verbose
+        Exception reporting mode: Verbose
+
+        In [24]: %tb
+        ---------------------------------------------------------------------------
+        SystemExit                                Traceback (most recent call last)
+        <BLANKLINE>
+        ...
+            30     except IndexError:
+            31         mode = 'div'
+        ---> 33     bar(mode)
+                mode = 'exit'
+        <BLANKLINE>
+        ... in bar(mode='exit')
+            ...     except:
+            ...         stat = 1
+        ---> ...     sysexit(stat, mode)
+                mode = 'exit'
+                stat = 2
+            ...     else:
+            ...         raise ValueError('Unknown mode')
+        <BLANKLINE>
+        ... in sysexit(stat=2, mode='exit')
+            10 def sysexit(stat, mode):
+        ---> 11     raise SystemExit(stat, f"Mode = {mode}")
+                stat = 2
+        <BLANKLINE>
+        SystemExit: (2, 'Mode = exit')
+        """
+
 
 def test_run_cell():
     import textwrap

IPython/core/tests/test_oinspect.py

@@ -568,20 +568,12 @@ def long_function(
         signature(long_function),
         long_function.__name__,
     )
-    if sys.version_info >= (3, 9):
-        expected = """\
+    expected = """\
 long_function(
     a_really_long_parameter: int,
     and_another_long_one: bool = False,
     let_us_make_sure_this_is_looong: Optional[str] = None,
 ) -> bool\
 """
-    else:
-        expected = """\
-long_function(
-    a_really_long_parameter: int,
-    and_another_long_one: bool = False,
-    let_us_make_sure_this_is_looong: Union[str, NoneType] = None,
-) -> bool\
-"""
+
     assert sig == expected

IPython/core/tests/test_ultratb.py

@@ -244,15 +244,14 @@ def test_non_syntaxerror(self):
 
 import sys
 
-if sys.version_info < (3, 9) and platform.python_implementation() != "PyPy":
+if platform.python_implementation() != "PyPy":
     """
     New 3.9 Pgen Parser does not raise Memory error, except on failed malloc.
     """
     class MemoryErrorTest(unittest.TestCase):
         def test_memoryerror(self):
             memoryerror_code = "(" * 200 + ")" * 200
-            with tt.AssertPrints("MemoryError"):
-                ip.run_cell(memoryerror_code)
+            ip.run_cell(memoryerror_code)
 
 
 class Python3ChainedExceptionsTest(unittest.TestCase):

appveyor.yml

@@ -8,8 +8,8 @@ environment:
     COLUMNS: 120  # Appveyor web viewer window width is 130 chars
 
   matrix:
-   - PYTHON: "C:\\Python38"
-     PYTHON_VERSION: "3.8.x"
+   - PYTHON: "C:\\Python39"
+     PYTHON_VERSION: "3.9.x"
      PYTHON_ARCH: "32"
 
 init:

pyproject.toml

@@ -2,7 +2,7 @@
 requires = ["setuptools >= 51.0.0"]
 build-backend = "setuptools.build_meta"
 [tool.mypy]
-python_version = 3.8
+python_version = 3.9
 ignore_missing_imports = true
 follow_imports = 'silent'
 exclude = [

setup.py

@@ -23,7 +23,7 @@
 #
 # This check is also made in IPython/__init__, don't forget to update both when
 # changing Python version requirements.
-if sys.version_info < (3, 8):
+if sys.version_info < (3, 9):
     pip_message = 'This may be due to an out of date pip. Make sure you have pip >= 9.0.1.'
     try:
         import pip
@@ -39,7 +39,8 @@
 
 
     error = """
-IPython 8+ supports Python 3.8 and above, following NEP 29.
+IPython 8.13+ supports Python 3.8 and above, following NEP 29.
+IPython 8.0-8.12 supports Python 3.8 and above, following NEP 29.
 When using Python 2.7, please install IPython 5.x LTS Long Term Support version.
 Python 3.3 and 3.4 were supported up to IPython 6.x.
 Python 3.5 was supported with IPython 7.0 to 7.9.