gh-81087: Add str.dedent and cache it at compile time

Doc/library/stdtypes.rst

@@ -1549,6 +1549,19 @@ expression support in the :mod:`re` module).
    interpreted as in slice notation.
 
 
+.. method:: str.dedent()
+
+   Return without any common leading whitespace from every line.
+
+   This can be used to make triple-quoted strings line up with the left edge of the
+   display, while still presenting them in the source code in indented form.
+
+   Note that tabs and spaces are both treated as whitespace, but they are not
+   equal: the lines ``"  hello"`` and ``"\thello"`` are considered to have no
+   common leading whitespace.
+
+   .. versionadded:: 3.10
+
 .. method:: str.removeprefix(prefix, /)
 
    If the string starts with the *prefix* string, return

Lib/collections/__init__.py

@@ -1324,3 +1324,4 @@ def translate(self, *args):
         return self.__class__(self.data.translate(*args))
     def upper(self): return self.__class__(self.data.upper())
     def zfill(self, width): return self.__class__(self.data.zfill(width))
+    def dedent(self): return self.__class__(self.data.dedent())

Lib/distutils/tests/test_build_ext.py

@@ -1,7 +1,6 @@
 import sys
 import os
 from io import StringIO
-import textwrap
 
 from distutils.core import Distribution
 from distutils.command.build_ext import build_ext
@@ -82,7 +81,7 @@ def test_build_ext(self):
         else:
             ALREADY_TESTED = type(self).__name__
 
-        code = textwrap.dedent(f"""
+        code = f"""
             tmp_dir = {self.tmp_dir!r}
 
             import sys
@@ -108,7 +107,7 @@ def test_xx(self):
 
 
             unittest.main()
-        """)
+        """.dedent()
         assert_python_ok('-c', code)
 
     def test_solaris_enable_shared(self):
@@ -474,7 +473,7 @@ def _try_compile_deployment_target(self, operator, target):
         deptarget_c = os.path.join(self.tmp_dir, 'deptargetmodule.c')
 
         with open(deptarget_c, 'w') as fp:
-            fp.write(textwrap.dedent('''\
+            fp.write(('''\
                 #include <AvailabilityMacros.h>
 
                 int dummy;
@@ -484,7 +483,7 @@ def _try_compile_deployment_target(self, operator, target):
                 #error "Unexpected target"
                 #endif
 
-            ''' % operator))
+            ''' % operator).dedent())
 
         # get the deployment target that the interpreter was built with
         target = sysconfig.get_config_var('MACOSX_DEPLOYMENT_TARGET')

Lib/distutils/tests/test_check.py

@@ -1,6 +1,5 @@
 """Tests for distutils.command.check."""
 import os
-import textwrap
 import unittest
 from test.support import run_unittest
 
@@ -118,22 +117,22 @@ def test_check_restructuredtext_with_syntax_highlight(self):
         # Don't fail if there is a `code` or `code-block` directive
 
         example_rst_docs = []
-        example_rst_docs.append(textwrap.dedent("""\
+        example_rst_docs.append("""\
             Here's some code:
 
             .. code:: python
 
                 def foo():
                     pass
-            """))
-        example_rst_docs.append(textwrap.dedent("""\
+            """.dedent())
+        example_rst_docs.append("""\
             Here's some code:
 
             .. code-block:: python
 
                 def foo():
                     pass
-            """))
+            """.dedent())
 
         for rest_with_code in example_rst_docs:
             pkg_info, dist = self.create_dist(long_description=rest_with_code)

Lib/distutils/tests/test_dist.py

@@ -4,7 +4,6 @@
 import sys
 import unittest
 import warnings
-import textwrap
 
 from unittest import mock
 
@@ -421,11 +420,11 @@ def test_download_url(self):
         self.assertIn('Metadata-Version: 1.1', meta)
 
     def test_long_description(self):
-        long_desc = textwrap.dedent("""\
+        long_desc = """\
         example::
               We start here
             and continue here
-          and end here.""")
+          and end here.""".dedent()
         attrs = {"name": "package",
                  "version": "1.0",
                  "long_description": long_desc}

Lib/distutils/tests/test_sdist.py

@@ -5,7 +5,6 @@
 import warnings
 import zipfile
 from os.path import join
-from textwrap import dedent
 from test.support import captured_stdout, check_warnings, run_unittest
 
 try:
@@ -393,11 +392,11 @@ def test_manifest_marker(self):
     @unittest.skipUnless(ZLIB_SUPPORT, "Need zlib support to run")
     def test_manifest_comments(self):
         # make sure comments don't cause exceptions or wrong includes
-        contents = dedent("""\
+        contents = """\
             # bad.py
             #bad.py
             good.py
-            """)
+            """.dedent()
         dist, cmd = self.get_cmd()
         cmd.ensure_finalized()
         self.write_file((self.tmp_dir, cmd.manifest), contents)

Lib/distutils/tests/test_sysconfig.py

@@ -4,7 +4,6 @@
 import shutil
 import subprocess
 import sys
-import textwrap
 import unittest
 
 from distutils import sysconfig
@@ -249,13 +248,13 @@ def test_customize_compiler_before_get_config_vars(self):
         # instance can be called without an explicit call to
         # get_config_vars().
         with open(TESTFN, 'w') as f:
-            f.writelines(textwrap.dedent('''\
+            f.writelines('''\
                 from distutils.core import Distribution
                 config = Distribution().get_command_obj('config')
                 # try_compile may pass or it may fail if no compiler
                 # is found but it should not raise an exception.
                 rc = config.try_compile('int x;')
-                '''))
+                '''.dedent())
         p = subprocess.Popen([str(sys.executable), TESTFN],
                 stdout=subprocess.PIPE,
                 stderr=subprocess.STDOUT,

Lib/idlelib/idle_test/htest.py

@@ -67,7 +67,6 @@ def _wrapper(parent):  # htest #
 
 import idlelib.pyshell  # Set Windows DPI awareness before Tk().
 from importlib import import_module
-import textwrap
 import tkinter as tk
 from tkinter.ttk import Scrollbar
 tk.NoDefaultRoot()
@@ -209,7 +208,7 @@ def _wrapper(parent):  # htest #
 _linenumbers_drag_scrolling_spec = {
     'file': 'sidebar',
     'kwds': {},
-    'msg': textwrap.dedent("""\
+    'msg': """\
         1. Click on the line numbers and drag down below the edge of the
         window, moving the mouse a bit and then leaving it there for a while.
         The text and line numbers should gradually scroll down, with the
@@ -223,7 +222,7 @@ def _wrapper(parent):  # htest #
         numbers should gradually scroll up, with the selection updated
         continuously.
 
-        4. Repeat step #2, clicking a line number below the selection."""),
+        4. Repeat step #2, clicking a line number below the selection.""".dedent(),
     }
 
 _multi_call_spec = {

Lib/idlelib/run.py

@@ -309,7 +309,7 @@ def fix_scaling(root):
 
 def fixdoc(fun, text):
     tem = (fun.__doc__ + '\n\n') if fun.__doc__ is not None else ''
-    fun.__doc__ = tem + textwrap.fill(textwrap.dedent(text))
+    fun.__doc__ = tem + textwrap.fill(text.dedent())
 
 RECURSIONLIMIT_DELTA = 30
 

Lib/lib2to3/tests/support.py

@@ -5,7 +5,6 @@
 import unittest
 import os
 import os.path
-from textwrap import dedent
 
 # Local imports
 from lib2to3 import pytree, refactor
@@ -32,7 +31,7 @@ def run_all_tests(test_mod=None, tests=None):
     unittest.TextTestRunner(verbosity=2).run(tests)
 
 def reformat(string):
-    return dedent(string) + "\n\n"
+    return string.dedent() + "\n\n"
 
 def get_refactorer(fixer_pkg="lib2to3", fixers=None, options=None):
     """

Lib/lib2to3/tests/test_parser.py

@@ -599,7 +599,7 @@ def test_extended_unpacking(self):
 class TestLiterals(GrammarTest):
 
     def validate(self, s):
-        driver.parse_string(support.dedent(s) + "\n\n")
+        driver.parse_string(s.dedent() + "\n\n")
 
     def test_multiline_bytes_literals(self):
         s = """

Lib/site.py

@@ -635,8 +635,7 @@ def _script():
         else:
             sys.exit(3)
     else:
-        import textwrap
-        print(textwrap.dedent(help % (sys.argv[0], os.pathsep)))
+        print((help % (sys.argv[0], os.pathsep)).dedent())
         sys.exit(10)
 
 if __name__ == '__main__':

Lib/test/mod_generics_cache.py

@@ -1,12 +1,11 @@
 """Module for testing the behavior of generics across different modules."""
 
 import sys
-from textwrap import dedent
 from typing import TypeVar, Generic, Optional
 
 
 if sys.version_info[:2] >= (3, 6):
-    exec(dedent("""
+    exec("""
     default_a: Optional['A'] = None
     default_b: Optional['B'] = None
 
@@ -24,7 +23,7 @@ class A(Generic[T]):
         my_inner_a1: 'B.A'
         my_inner_a2: A
         my_outer_a: 'A'  # unless somebody calls get_type_hints with localns=B.__dict__
-    """))
+    """.dedent())
 else:  # This should stay in sync with the syntax above.
     __annotations__ = dict(
         default_a=Optional['A'],

Lib/test/pickletester.py

@@ -13,7 +13,6 @@
 import threading
 import unittest
 import weakref
-from textwrap import dedent
 from http.cookies import SimpleCookie
 
 try:
@@ -1353,16 +1352,16 @@ def test_truncated_data(self):
     @reap_threads
     def test_unpickle_module_race(self):
         # https://bugs.python.org/issue34572
-        locker_module = dedent("""
+        locker_module = """
         import threading
         barrier = threading.Barrier(2)
-        """)
-        locking_import_module = dedent("""
+        """.dedent()
+        locking_import_module = """
         import locker
         locker.barrier.wait()
         class ToBeUnpickled(object):
             pass
-        """)
+        """.dedent()
 
         os.mkdir(TESTFN)
         self.addCleanup(shutil.rmtree, TESTFN)