gh-109276, gh-109508: Fix libregrtest stdout (#109903)

Remove replace_stdout(): call sys.stdout.reconfigure() instead of set
the error handler to backslashreplace.

display_header() logs an empty line and flush stdout.

Remove encoding workaround in display_header() since stdout error
handler is now set to backslashreplace earlier.

1 files changed, 13 insertions, 48 deletions

diff --git a/Lib/test/libregrtest/utils.py b/Lib/test/libregrtest/utils.py
index f3f0eb53b32..acf35723a1a 100644
--- a/Lib/test/libregrtest/utils.py
+++ b/Lib/test/libregrtest/utils.py
@@ -1,4 +1,3 @@
-import atexit
 import contextlib
 import faulthandler
 import locale
@@ -495,32 +494,6 @@ def normalize_test_name(test_full_name, *, is_error=False):
     return short_name
 
 
-def replace_stdout():
-    """Set stdout encoder error handler to backslashreplace (as stderr error
-    handler) to avoid UnicodeEncodeError when printing a traceback"""
-    stdout = sys.stdout
-    try:
-        fd = stdout.fileno()
-    except ValueError:
-        # On IDLE, sys.stdout has no file descriptor and is not a TextIOWrapper
-        # object. Leaving sys.stdout unchanged.
-        #
-        # Catch ValueError to catch io.UnsupportedOperation on TextIOBase
-        # and ValueError on a closed stream.
-        return
-
-    sys.stdout = open(fd, 'w',
-        encoding=stdout.encoding,
-        errors="backslashreplace",
-        closefd=False,
-        newline='\n')
-
-    def restore_stdout():
-        sys.stdout.close()
-        sys.stdout = stdout
-    atexit.register(restore_stdout)
-
-
 def adjust_rlimit_nofile():
     """
     On macOS the default fd limit (RLIMIT_NOFILE) is sometimes too low (256)
@@ -548,20 +521,12 @@ def adjust_rlimit_nofile():
 
 
 def display_header(use_resources: tuple[str, ...]):
-    encoding = sys.stdout.encoding
-
     # Print basic platform information
     print("==", platform.python_implementation(), *sys.version.split())
     print("==", platform.platform(aliased=True),
                   "%s-endian" % sys.byteorder)
     print("== Python build:", ' '.join(get_build_info()))
-
-    cwd = os.getcwd()
-    # gh-109508: support.os_helper.FS_NONASCII, used by get_work_dir(), cannot
-    # be encoded to the filesystem encoding on purpose, escape non-encodable
-    # characters with backslashreplace error handler.
-    formatted_cwd = cwd.encode(encoding, "backslashreplace").decode(encoding)
-    print("== cwd:", formatted_cwd)
+    print("== cwd:", os.getcwd())
 
     cpu_count = os.cpu_count()
     if cpu_count:
@@ -588,18 +553,18 @@ def display_header(use_resources: tuple[str, ...]):
         sanitizers.append("memory")
     if ubsan:
         sanitizers.append("undefined behavior")
-    if not sanitizers:
-        return
-
-    print(f"== sanitizers: {', '.join(sanitizers)}")
-    for sanitizer, env_var in (
-        (asan, "ASAN_OPTIONS"),
-        (msan, "MSAN_OPTIONS"),
-        (ubsan, "UBSAN_OPTIONS"),
-    ):
-        options= os.environ.get(env_var)
-        if sanitizer and options is not None:
-            print(f"== {env_var}={options!r}")
+    if sanitizers:
+        print(f"== sanitizers: {', '.join(sanitizers)}")
+        for sanitizer, env_var in (
+            (asan, "ASAN_OPTIONS"),
+            (msan, "MSAN_OPTIONS"),
+            (ubsan, "UBSAN_OPTIONS"),
+        ):
+            options= os.environ.get(env_var)
+            if sanitizer and options is not None:
+                print(f"== {env_var}={options!r}")
+
+    print(flush=True)
 
 
 def cleanup_temp_dir(tmp_dir: StrPath):