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Syntax errors

crates/ty_python_semantic/resources/mdtest/invalid_syntax.md

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Syntax errors

Test cases to ensure that ty does not panic if there are syntax errors in the source code.

The parser cannot recover from certain syntax errors completely which is why the number of syntax errors could be more than expected in the following examples. For instance, if there's a keyword (like for) in the middle of another statement (like function definition), then it's more likely that the rest of the tokens are going to be part of the for statement and not the function definition. But, it's not necessary that the remaining tokens are valid in the context of a for statement.

Keyword as identifiers

When keywords are used as identifiers, the parser recovers from this syntax error by emitting an error and including the text value of the keyword to create the Identifier node.

Name expression

Assignment

py
# error: [invalid-syntax]
pass = 1

Type alias

py
# error: [invalid-syntax]
# error: [invalid-syntax]
type pass = 1

Function definition

py
# error: [invalid-syntax]
# error: [invalid-syntax]
# error: [invalid-syntax]
# error: [invalid-syntax]
# error: [invalid-syntax]
def True(for):
    # error: [invalid-syntax]
    # error: [invalid-syntax]
    pass

For

py
# error: [invalid-syntax]
# error: [invalid-syntax]
# error: [unresolved-reference] "Name `pass` used when not defined"
for while in pass:
    pass

While

py
# error: [invalid-syntax]
# error: [unresolved-reference] "Name `in` used when not defined"
while in:
    pass

Match

py
# error: [invalid-syntax]
# error: [invalid-syntax]
# error: [unresolved-reference] "Name `match` used when not defined"
match while:
    # error: [invalid-syntax]
    # error: [invalid-syntax]
    # error: [invalid-syntax]
    # error: [unresolved-reference] "Name `case` used when not defined"
    case in:
        # error: [invalid-syntax]
        # error: [invalid-syntax]
        pass

Attribute expression

py
# TODO: Check when support for attribute expressions is added

# error: [invalid-syntax]
# error: [unresolved-reference] "Name `foo` used when not defined"
for x in foo.pass:
    pass

Invalid annotation

typing.Callable

py
from typing import Callable

# error: [invalid-syntax] "Expected index or slice expression"
# error: [invalid-type-form] "Special form `typing.Callable` expected exactly two arguments (parameter types and return type)"
def _(c: Callable[]):
    reveal_type(c)  # revealed: (...) -> Unknown

typing.Tuple

py
from typing import Tuple

# error: [invalid-syntax] "Expected index or slice expression"
InvalidEmptyTuple = Tuple[]

def _(t: InvalidEmptyTuple):
    reveal_type(t)  # revealed: tuple[Unknown]

typing.Union

py
from typing import Union

# error: [invalid-syntax] "Expected index or slice expression"
InvalidEmptyUnion = Union[]

def _(u: InvalidEmptyUnion):
    reveal_type(u)  # revealed: Unknown

typing.Annotated

py
from typing import Annotated

# error: [invalid-syntax] "Expected index or slice expression"
# error: [invalid-type-form] "Special form `typing.Annotated` expected at least 2 arguments (one type and at least one metadata element)"
InvalidEmptyAnnotated = Annotated[]

def _(a: InvalidEmptyAnnotated):
    reveal_type(a)  # revealed: Unknown