Merge branch 'main' into emscripten-dependencies

Author: hoodmane

Doc/c-api/unicode.rst

@@ -1867,7 +1867,7 @@ object.
    On success, return ``0``.
    On error, set an exception, leave the writer unchanged, and return ``-1``.
 
-.. c:function:: int PyUnicodeWriter_WriteUCS4(PyUnicodeWriter *writer, Py_UCS4 *str, Py_ssize_t size)
+.. c:function:: int PyUnicodeWriter_WriteUCS4(PyUnicodeWriter *writer, const Py_UCS4 *str, Py_ssize_t size)
 
    Writer the UCS4 string *str* into *writer*.
 

Include/cpython/unicodeobject.h

@@ -496,7 +496,7 @@ PyAPI_FUNC(int) PyUnicodeWriter_WriteWideChar(
     Py_ssize_t size);
 PyAPI_FUNC(int) PyUnicodeWriter_WriteUCS4(
     PyUnicodeWriter *writer,
-    Py_UCS4 *str,
+    const Py_UCS4 *str,
     Py_ssize_t size);
 
 PyAPI_FUNC(int) PyUnicodeWriter_WriteStr(

Misc/NEWS.d/next/C_API/2026-03-18-23-44-29.gh-issue-146143.pwIrJq.rst

@@ -0,0 +1,2 @@
+:c:func:`PyUnicodeWriter_WriteUCS4` now accepts a pointer to a constant buffer
+of ``Py_UCS4``.

Objects/unicodeobject.c

@@ -2224,7 +2224,7 @@ _PyUnicode_FromUCS4(const Py_UCS4 *u, Py_ssize_t size)
 
 int
 PyUnicodeWriter_WriteUCS4(PyUnicodeWriter *pub_writer,
-                          Py_UCS4 *str,
+                          const Py_UCS4 *str,
                           Py_ssize_t size)
 {
     _PyUnicodeWriter *writer = (_PyUnicodeWriter*)pub_writer;

Platforms/emscripten/__main__.py

@@ -413,15 +413,46 @@ def make_mpdec(context, working_dir):
     write_library_config(prefix, "mpdec", mpdec_config, context.quiet)
 
 
-def make_dependencies(context, working_dir):
-    make_emscripten_libffi(context, working_dir)
-    make_mpdec(context, working_dir)
+def make_dependencies(context):
+    make_emscripten_libffi(context)
+    make_mpdec(context)
+
+
+def calculate_node_path():
+    node_version = os.environ.get("PYTHON_NODE_VERSION", None)
+    if node_version is None:
+        node_version = load_config_toml()["node-version"]
+
+    subprocess.run(
+        [
+            "bash",
+            "-c",
+            f"source ~/.nvm/nvm.sh && nvm install {node_version}",
+        ],
+        check=True,
+    )
+
+    res = subprocess.run(
+        [
+            "bash",
+            "-c",
+            f"source ~/.nvm/nvm.sh && nvm which {node_version}",
+        ],
+        text=True,
+        capture_output=True,
+        check=True,
+    )
+    return res.stdout.strip()
 
 
 @subdir("host_dir", clean_ok=True)
 def configure_emscripten_python(context, working_dir):
     """Configure the emscripten/host build."""
     validate_emsdk_version(context.emsdk_cache)
+    host_runner = context.host_runner
+    if host_runner is None:
+        host_runner = calculate_node_path()
+
     paths = context.build_paths
     config_site = os.fsdecode(EMSCRIPTEN_DIR / "config.site-wasm32-emscripten")
 
@@ -440,19 +471,6 @@ def configure_emscripten_python(context, working_dir):
     )
     if pydebug:
         sysconfig_data += "-pydebug"
-
-    host_runner = context.host_runner
-    if node_version := os.environ.get("PYTHON_NODE_VERSION", None):
-        res = subprocess.run(
-            [
-                "bash",
-                "-c",
-                f"source ~/.nvm/nvm.sh && nvm which {node_version}",
-            ],
-            text=True,
-            capture_output=True,
-        )
-        host_runner = res.stdout.strip()
     pkg_config_path_dir = (paths["prefix_dir"] / "lib/pkgconfig/").resolve()
     env_additions = {
         "CONFIG_SITE": config_site,
@@ -618,8 +636,6 @@ def add_cross_build_dir_option(subcommand):
 
 
 def main():
-    default_host_runner = "node"
-
     parser = argparse.ArgumentParser()
     subcommands = parser.add_subparsers(dest="subcommand")
 
@@ -755,10 +771,10 @@ def main():
         subcommand.add_argument(
             "--host-runner",
             action="store",
-            default=default_host_runner,
+            default=None,
             dest="host_runner",
-            help="Command template for running the emscripten host"
-            f"`{default_host_runner}`)",
+            help="Command template for running the emscripten host "
+            "(default: use nvm to install the node version specified in config.toml)",
         )
 
     context = parser.parse_args()

Platforms/emscripten/config.toml

@@ -2,6 +2,7 @@
 # This allows for blanket copying of the Emscripten build code between supported
 # Python versions.
 emscripten-version = "4.0.12"
+node-version = "24"
 
 [libffi]
 url = "https://github.com/libffi/libffi/releases/download/v{version}/libffi-{version}.tar.gz"