gh-113993: Allow interned strings to be mortal, and fix related issues (GH-120520)

* Add an InternalDocs file describing how interning should work and how to use it.

* Add internal functions to *explicitly* request what kind of interning is done:
  - `_PyUnicode_InternMortal`
  - `_PyUnicode_InternImmortal`
  - `_PyUnicode_InternStatic`

* Switch uses of `PyUnicode_InternInPlace` to those.

* Disallow using `_Py_SetImmortal` on strings directly.
  You should use `_PyUnicode_InternImmortal` instead:
  - Strings should be interned before immortalization, otherwise you're possibly
    interning a immortalizing copy.
  - `_Py_SetImmortal` doesn't handle the `SSTATE_INTERNED_MORTAL` to
    `SSTATE_INTERNED_IMMORTAL` update, and those flags can't be changed in
    backports, as they are now part of public API and version-specific ABI.

* Add private `_only_immortal` argument for `sys.getunicodeinternedsize`, used in refleak test machinery.

* Make sure the statically allocated string singletons are unique. This means these sets are now disjoint:
  - `_Py_ID`
  - `_Py_STR` (including the empty string)
  - one-character latin-1 singletons

  Now, when you intern a singleton, that exact singleton will be interned.

* Add a `_Py_LATIN1_CHR` macro, use it instead of `_Py_ID`/`_Py_STR` for one-character latin-1 singletons everywhere (including Clinic).

* Intern `_Py_STR` singletons at startup.

* For free-threaded builds, intern `_Py_LATIN1_CHR` singletons at startup.

* Beef up the tests. Cover internal details (marked with `@cpython_only`).

* Add lots of assertions

Co-Authored-By: Eric Snow <ericsnowcurrently@gmail.com>
This commit is contained in:
Petr Viktorin 2024-06-21 17:19:31 +02:00 committed by GitHub
parent 7595e6743a
commit 6f1d448bc1
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42 changed files with 2464 additions and 1140 deletions

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@ -10,9 +10,7 @@
* See ast.unparse for a full unparser (written in Python)
*/
_Py_DECLARE_STR(open_br, "{");
_Py_DECLARE_STR(dbl_open_br, "{{");
_Py_DECLARE_STR(close_br, "}");
_Py_DECLARE_STR(dbl_close_br, "}}");
/* We would statically initialize this if doing so were simple enough. */
@ -580,11 +578,13 @@ escape_braces(PyObject *orig)
{
PyObject *temp;
PyObject *result;
temp = PyUnicode_Replace(orig, &_Py_STR(open_br), &_Py_STR(dbl_open_br), -1);
temp = PyUnicode_Replace(orig, _Py_LATIN1_CHR('{'),
&_Py_STR(dbl_open_br), -1);
if (!temp) {
return NULL;
}
result = PyUnicode_Replace(temp, &_Py_STR(close_br), &_Py_STR(dbl_close_br), -1);
result = PyUnicode_Replace(temp, _Py_LATIN1_CHR('}'),
&_Py_STR(dbl_close_br), -1);
Py_DECREF(temp);
return result;
}
@ -678,7 +678,7 @@ append_formattedvalue(_PyUnicodeWriter *writer, expr_ty e)
if (!temp_fv_str) {
return -1;
}
if (PyUnicode_Find(temp_fv_str, &_Py_STR(open_br), 0, 1, 1) == 0) {
if (PyUnicode_Find(temp_fv_str, _Py_LATIN1_CHR('{'), 0, 1, 1) == 0) {
/* Expression starts with a brace, split it with a space from the outer
one. */
outer_brace = "{ ";