Imply 3.8+ when annotated assigments used with unparenthesized tuples (#2708)

[etc/vim.git] / src / black / parsing.py

diff --git a/src/black/parsing.py b/src/black/parsing.py
index ee6aae1e7ff9db26be2f5f4c439a25d31baf2b7d..c101643fe11f2e5473de5cc0a39f578804aa4397 100644 (file)
--- a/src/black/parsing.py
+++ b/src/black/parsing.py
@@ -4,18 +4,27 @@ Parse Python code and perform AST validation.
 import ast
 import platform
 import sys
-from typing import Iterable, Iterator, List, Set, Union, Tuple
+from typing import Any, Iterable, Iterator, List, Set, Tuple, Type, Union
+
+if sys.version_info < (3, 8):
+    from typing_extensions import Final
+else:
+    from typing import Final
 
 # lib2to3 fork
 from blib2to3.pytree import Node, Leaf
-from blib2to3 import pygram, pytree
+from blib2to3 import pygram
 from blib2to3.pgen2 import driver
 from blib2to3.pgen2.grammar import Grammar
 from blib2to3.pgen2.parse import ParseError
+from blib2to3.pgen2.tokenize import TokenError
 
 from black.mode import TargetVersion, Feature, supports_feature
 from black.nodes import syms
 
+ast3: Any
+ast27: Any
+
 _IS_PYPY = platform.python_implementation() == "PyPy"
 
 try:
@@ -34,6 +43,11 @@ except ImportError:
         ast3 = ast27 = ast
 
 
+PY310_HINT: Final[
+    str
+] = "Consider using --target-version py310 to parse Python 3.10 code."
+
+
 class InvalidInput(ValueError):
     """Raised when input source code fails all parse attempts."""
 
@@ -67,8 +81,10 @@ def get_grammars(target_versions: Set[TargetVersion]) -> List[Grammar]:
         # Python 3.10+
         grammars.append(pygram.python_grammar_soft_keywords)
     # If we have to parse both, try to parse async as a keyword first
-    if not supports_feature(target_versions, Feature.ASYNC_IDENTIFIERS):
-        # Python 3.7+
+    if not supports_feature(
+        target_versions, Feature.ASYNC_IDENTIFIERS
+    ) and not supports_feature(target_versions, Feature.PATTERN_MATCHING):
+        # Python 3.7-3.9
         grammars.append(
             pygram.python_grammar_no_print_statement_no_exec_statement_async_keywords
         )
@@ -85,8 +101,9 @@ def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -
     if not src_txt.endswith("\n"):
         src_txt += "\n"
 
-    for grammar in get_grammars(set(target_versions)):
-        drv = driver.Driver(grammar, pytree.convert)
+    grammars = get_grammars(set(target_versions))
+    for grammar in grammars:
+        drv = driver.Driver(grammar)
         try:
             result = drv.parse_string(src_txt, True)
             break
@@ -99,7 +116,19 @@ def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -
             except IndexError:
                 faulty_line = "<line number missing in source>"
             exc = InvalidInput(f"Cannot parse: {lineno}:{column}: {faulty_line}")
+
+        except TokenError as te:
+            # In edge cases these are raised; and typically don't have a "faulty_line".
+            lineno, column = te.args[1]
+            exc = InvalidInput(f"Cannot parse: {lineno}:{column}: {te.args[0]}")
+
     else:
+        if pygram.python_grammar_soft_keywords not in grammars and matches_grammar(
+            src_txt, pygram.python_grammar_soft_keywords
+        ):
+            original_msg = exc.args[0]
+            msg = f"{original_msg}\n{PY310_HINT}"
+            raise InvalidInput(msg) from None
         raise exc from None
 
     if isinstance(result, Leaf):
@@ -107,6 +136,16 @@ def lib2to3_parse(src_txt: str, target_versions: Iterable[TargetVersion] = ()) -
     return result
 
 
+def matches_grammar(src_txt: str, grammar: Grammar) -> bool:
+    drv = driver.Driver(grammar)
+    try:
+        drv.parse_string(src_txt, True)
+    except (ParseError, TokenError, IndentationError):
+        return False
+    else:
+        return True
+
+
 def lib2to3_unparse(node: Node) -> str:
     """Given a lib2to3 node, return its string representation."""
     code = str(node)
@@ -148,6 +187,10 @@ def parse_ast(src: str) -> Union[ast.AST, ast3.AST, ast27.AST]:
     raise SyntaxError(first_error)
 
 
+ast3_AST: Final[Type[ast3.AST]] = ast3.AST
+ast27_AST: Final[Type[ast27.AST]] = ast27.AST
+
+
 def stringify_ast(
     node: Union[ast.AST, ast3.AST, ast27.AST], depth: int = 0
 ) -> Iterator[str]:
@@ -157,6 +200,7 @@ def stringify_ast(
 
     yield f"{'  ' * depth}{node.__class__.__name__}("
 
+    type_ignore_classes: Tuple[Type[Any], ...]
     for field in sorted(node._fields):  # noqa: F402
         # TypeIgnore will not be present using pypy < 3.8, so need for this
         if not (_IS_PYPY and sys.version_info < (3, 8)):
@@ -189,7 +233,13 @@ def stringify_ast(
                 elif isinstance(item, (ast.AST, ast3.AST, ast27.AST)):
                     yield from stringify_ast(item, depth + 2)
 
-        elif isinstance(value, (ast.AST, ast3.AST, ast27.AST)):
+        # Note that we are referencing the typed-ast ASTs via global variables and not
+        # direct module attribute accesses because that breaks mypyc. It's probably
+        # something to do with the ast3 / ast27 variables being marked as Any leading
+        # mypy to think this branch is always taken, leaving the rest of the code
+        # unanalyzed. Tighting up the types for the typed-ast AST types avoids the
+        # mypyc crash.
+        elif isinstance(value, (ast.AST, ast3_AST, ast27_AST)):
             yield from stringify_ast(value, depth + 2)
 
         else: