Update codeop from Python 3.11

Lib/codeop.py

@@ -10,30 +10,6 @@ and:
   syntax error (OverflowError and ValueError can be produced by
   malformed literals).
 
-Approach:
-
-First, check if the source consists entirely of blank lines and
-comments; if so, replace it with 'pass', because the built-in
-parser doesn't always do the right thing for these.
-
-Compile three times: as is, with \n, and with \n\n appended.  If it
-compiles as is, it's complete.  If it compiles with one \n appended,
-we expect more.  If it doesn't compile either way, we compare the
-error we get when compiling with \n or \n\n appended.  If the errors
-are the same, the code is broken.  But if the errors are different, we
-expect more.  Not intuitive; not even guaranteed to hold in future
-releases; but this matches the compiler's behavior from Python 1.4
-through 2.2, at least.
-
-Caveat:
-
-It is possible (but not likely) that the parser stops parsing with a
-successful outcome before reaching the end of the source; in this
-case, trailing symbols may be ignored instead of causing an error.
-For example, a backslash followed by two newlines may be followed by
-arbitrary garbage.  This will be fixed once the API for the parser is
-better.
-
 The two interfaces are:
 
 compile_command(source, filename, symbol):
@@ -64,54 +40,50 @@ _features = [getattr(__future__, fname)
 
 __all__ = ["compile_command", "Compile", "CommandCompiler"]
 
-PyCF_DONT_IMPLY_DEDENT = 0x200          # Matches pythonrun.h
-
+# The following flags match the values from Include/cpython/compile.h
+# Caveat emptor: These flags are undocumented on purpose and depending
+# on their effect outside the standard library is **unsupported**.
+PyCF_DONT_IMPLY_DEDENT = 0x200
+PyCF_ALLOW_INCOMPLETE_INPUT = 0x4000
 
 def _maybe_compile(compiler, source, filename, symbol):
-    # Check for source consisting of only blank lines and comments
+    # Check for source consisting of only blank lines and comments.
     for line in source.split("\n"):
         line = line.strip()
         if line and line[0] != '#':
-            break               # Leave it alone
+            break               # Leave it alone.
     else:
         if symbol != "eval":
             source = "pass"     # Replace it with a 'pass' statement
 
-    err = err1 = err2 = None
-    code = code1 = code2 = None
-
-    try:
-        code = compiler(source, filename, symbol)
-    except SyntaxError:
-        pass
-
-    # Catch syntax warnings after the first compile
-    # to emit warnings (SyntaxWarning, DeprecationWarning) at most once.
+    # Disable compiler warnings when checking for incomplete input.
     with warnings.catch_warnings():
-        warnings.simplefilter("error")
-
+        warnings.simplefilter("ignore", (SyntaxWarning, DeprecationWarning))
         try:
-            code1 = compiler(source + "\n", filename, symbol)
-        except SyntaxError as e:
-            err1 = e
+            compiler(source, filename, symbol)
+        except SyntaxError:  # Let other compile() errors propagate.
+            try:
+                compiler(source + "\n", filename, symbol)
+                return None
+            except SyntaxError as e:
+                if "incomplete input" in str(e):
+                    return None
+                # fallthrough
 
-        try:
-            code2 = compiler(source + "\n\n", filename, symbol)
-        except SyntaxError as e:
-            err2 = e
+    return compiler(source, filename, symbol)
 
-    try:
-        if code:
-            return code
-        if not code1 and repr(err1) == repr(err2):
-            raise err1
-    finally:
-        err1 = err2 = None
 
+def _is_syntax_error(err1, err2):
+    rep1 = repr(err1)
+    rep2 = repr(err2)
+    if "was never closed" in rep1 and "was never closed" in rep2:
+        return False
+    if rep1 == rep2:
+        return True
+    return False
 
 def _compile(source, filename, symbol):
-    return compile(source, filename, symbol, PyCF_DONT_IMPLY_DEDENT)
-
+    return compile(source, filename, symbol, PyCF_DONT_IMPLY_DEDENT | PyCF_ALLOW_INCOMPLETE_INPUT)
 
 def compile_command(source, filename="<input>", symbol="single"):
     r"""Compile a command and determine whether it is incomplete.
@@ -134,15 +106,13 @@ def compile_command(source, filename="<input>", symbol="single"):
     """
     return _maybe_compile(_compile, source, filename, symbol)
 
-
 class Compile:
     """Instances of this class behave much like the built-in compile
     function, but if one is used to compile text containing a future
     statement, it "remembers" and compiles all subsequent program texts
     with the statement in force."""
-
     def __init__(self):
-        self.flags = PyCF_DONT_IMPLY_DEDENT
+        self.flags = PyCF_DONT_IMPLY_DEDENT | PyCF_ALLOW_INCOMPLETE_INPUT
 
     def __call__(self, source, filename, symbol):
         codeob = compile(source, filename, symbol, self.flags, True)
@@ -151,7 +121,6 @@ class Compile:
                 self.flags |= feature.compiler_flag
         return codeob
 
-
 class CommandCompiler:
     """Instances of this class have __call__ methods identical in
     signature to compile_command; the difference is that if the