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Merge pull request 'Properly check variable assignment' (#36) from feat/variable-is-defined into main
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Reviewed-on: #36
This commit was merged in pull request #36.
This commit is contained in:
Louis Heredero
2026-07-08 17:30:40 +00:00
parent 2118c260ab 4ed78d3d7e
commit 62612bd8db
8 changed files with 2809 additions and 903 deletions
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12
midas/checker/python.py
View File

@@ -107,7 +107,7 @@ class PythonTyper(
tree: ast.Module = ast.parse(source, filename=path or "<unknown>")
parser = PythonParser()
stmts: list[p.Stmt] = parser.parse_module(tree)
resolver = Resolver()
resolver = Resolver(reporter)
resolver.resolve(*stmts)
self.env = self.global_env
@@ -601,6 +601,10 @@ class PythonTyper(
pass
def visit_for_stmt(self, stmt: p.ForStmt) -> None:
outer_env: Environment = self.env
inner_env: Environment = Environment(self.env)
self.env = inner_env
item_type: Type = UnknownType()
iterator_type: Type = self.type_of(stmt.iterator)
if iterator_type != UnknownType():
@@ -614,8 +618,10 @@ class PythonTyper(
self._assign(stmt.location, stmt.target, item_type)
self.judge(stmt.target, item_type)
env: Environment = Environment(self.env)
body_returned: bool = self.process_block(stmt.body, env)
body_returned: bool = self.process_block(stmt.body, inner_env)
self.env = outer_env
if body_returned:
raise ReturnException()

63
midas/checker/resolver.py
View File

@@ -1,4 +1,6 @@
import midas.ast.python as p
from midas.ast.location import Location
from midas.checker.reporter import FileReporter
class ResolverError(Exception): ...
@@ -11,9 +13,10 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
scope is referred to when a variable is referenced
"""
def __init__(self):
def __init__(self, reporter: FileReporter):
self.locals: dict[p.Expr, int] = {}
self.scopes: list[dict[str, bool]] = [{}]
self.reporter: FileReporter = reporter
def resolve(self, *objects: p.Stmt | p.Expr) -> None:
"""Resolve the given statements or expressions"""
@@ -25,29 +28,29 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
"""Begin a new scope inside the current one"""
self.scopes.append({})
def end_scope(self):
"""Close the current scope"""
self.scopes.pop()
def end_scope(self) -> dict[str, bool]:
"""Close and return the current scope"""
return self.scopes.pop()
def declare(self, name: str) -> None:
def declare(self, location: Location, name: str) -> None:
"""Declare a variable in the current scope
This method must be called *before* evaluating the variable initializer
Args:
location (Location): the location where the name is declared
name (str): the name of the variable
Raises:
ResolverError: if the variable has already been declared in the current scope
"""
if len(self.scopes) == 0:
return
scope: dict[str, bool] = self.scopes[-1]
if name in scope:
raise ResolverError(
f"A variable with the name {name} is already declared in this scope"
self.reporter.error(
location,
f"A variable with the name '{name}' is already declared in this scope",
)
scope[name] = False
else:
scope[name] = False
def define(self, name: str) -> None:
"""Define a variable in the current scope
@@ -77,7 +80,7 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
self.locals[expr] = i
return
def is_defined(self, name: str) -> bool:
def is_declared(self, name: str) -> bool:
"""Check whether the given variable is defined in any scope
Args:
@@ -106,7 +109,7 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
self.resolve(param.default)
for param in function.params.all:
self.declare(param.name)
self.declare(function.location, param.name)
self.define(param.name)
self.resolve(*function.body)
self.end_scope()
@@ -116,14 +119,12 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
def visit_function(self, stmt: p.Function) -> None:
# Declare before resolving body to allow recursion
self.declare(stmt.name)
self.declare(stmt.location, stmt.name)
self.define(stmt.name)
self.resolve_function(stmt)
def visit_type_assign(self, stmt: p.TypeAssign) -> None:
self.declare(stmt.name)
# NOTE: resolve type here?
self.define(stmt.name)
self.declare(stmt.location, stmt.name)
def visit_assign_stmt(self, stmt: p.AssignStmt) -> None:
self.resolve(stmt.value)
@@ -133,9 +134,9 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
def _visit_assign(self, target: p.Expr):
match target:
case p.VariableExpr(name=name):
if not self.is_defined(name):
self.declare(name)
self.define(name)
if not self.is_declared(name):
self.declare(target.location, name)
self.define(name)
target.accept(self)
case p.GetExpr():
@@ -145,7 +146,9 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
target.accept(self)
case _:
raise Exception(f"Unsupported assignment to {target}")
self.reporter.error(
target.location, f"Unsupported assignment to {target}"
)
def visit_return_stmt(self, stmt: p.ReturnStmt) -> None:
if stmt.value is not None:
@@ -162,20 +165,25 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
# Body
self.begin_scope()
self.resolve(*stmt.body)
self.end_scope()
body: dict[str, bool] = self.end_scope()
# Else
self.begin_scope()
self.resolve(*stmt.orelse)
self.end_scope()
else_: dict[str, bool] = self.end_scope()
# Define variables in this scope if it was defined in both body and else blocks
for name, is_defined in body.items():
if is_defined and else_.get(name, False):
self.define(name)
def visit_pass(self, stmt: p.Pass) -> None:
pass
def visit_for_stmt(self, stmt: p.ForStmt) -> None:
self.begin_scope()
self.resolve(stmt.iterator)
self._visit_assign(stmt.target)
self.begin_scope()
self.resolve(*stmt.body)
self.end_scope()
@@ -188,7 +196,7 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
def _resolve_imports(self, imports: list[p.ImportAlias]) -> None:
for import_ in imports:
name: str = import_.imported_name
self.declare(name)
self.declare(import_.location, name)
self.define(name)
def visit_raw_stmt(self, stmt: p.RawStmt) -> None:
@@ -220,8 +228,9 @@ class Resolver(p.Stmt.Visitor[None], p.Expr.Visitor[None]):
def visit_variable_expr(self, expr: p.VariableExpr) -> None:
if len(self.scopes) != 0 and self.scopes[-1].get(expr.name) is False:
raise ResolverError(
f"Cannot use local variable '{expr.name}' in its own initializer"
self.reporter.error(
expr.location,
f"Variable '{expr.name}' is declared but may not be defined",
) # aka. UnboundLocalError
self.resolve_local(expr, expr.name)

32
tests/cases/checker/07_variance.py
View File

@@ -11,16 +11,16 @@ from _ import (
Unused,
)
unused: Unused
covariant: Covariant
contravariant: Contravariant
invariant: Invariant
coco: Coco
cocontra: Cocontra
contraco: Contraco
contracontra: Contracontra
t1: T1
t2: T2
unused: Unused = object()
covariant: Covariant = object()
contravariant: Contravariant = object()
invariant: Invariant = object()
coco: Coco = object()
cocontra: Cocontra = object()
contraco: Contraco = object()
contracontra: Contracontra = object()
t1: T1 = object()
t2: T2 = object()
# Dummy print to prudce judgements for the expressions
print(
@@ -36,17 +36,17 @@ print(
t2,
)
cov1: Covariant[float]
cov2: Covariant[int]
cov1: Covariant[float] = object()
cov2: Covariant[int] = object()
cov1 = cov2 # Ok because int <: float => Covariant[int] <: Covariant[float]
cov2 = cov1 # Invalid
contra1: Contravariant[float]
contra2: Contravariant[int]
contra1: Contravariant[float] = object()
contra2: Contravariant[int] = object()
contra1 = contra2 # Invalid
contra2 = contra1 # Ok because int <: float => Covariant[float] <: Covariant[int]
inv1: Invariant[float]
inv2: Invariant[int]
inv1: Invariant[float] = object()
inv2: Invariant[int] = object()
inv1 = inv2 # Invalid
inv2 = inv1 # Invalid

960
tests/cases/checker/07_variance.py.ref.json
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File diff suppressed because it is too large Load Diff

5
tests/cases/checker/09_frame_ops.py
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@@ -1,8 +1,9 @@
# type: ignore
# ruff: disable [F821]
import pandas as pd
df1: Frame[i:int, a:int, b:float]
df2: Frame[i:int, a:int, b:float]
df1 = cast(Frame[i:int, a:int, b:float], pd.DataFrame())
df2 = cast(Frame[i:int, a:int, b:float], pd.DataFrame())
_: Any

1944
tests/cases/checker/09_frame_ops.py.ref.json
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File diff suppressed because it is too large Load Diff

45
tests/cases/checker/10_variable_defined.py Normal file
View File

@@ -0,0 +1,45 @@
# type: ignore
# ruff: disable[F821]
_: Any
_ = undeclared
declared: int
_ = declared
half_defined1: int
half_defined2: int
if False:
half_defined1 = 0
else:
half_defined2 = 1
_ = half_defined1
_ = half_defined2
fully_defined: int
if False:
fully_defined = 0
else:
fully_defined = 1
_ = fully_defined
defined: int = 0
_ = defined
no_annotation = 0
_ = no_annotation
self_ref1 = self_ref1
self_ref2: int = self_ref2
def fact(n: int) -> int:
if n <= 1:
return 1
return n * fact(n - 1)
for i in [1, 2, 3]:
_ = i
_ = i

651
tests/cases/checker/10_variable_defined.py.ref.json Normal file
View File

@@ -0,0 +1,651 @@
{
"diagnostics": [
{
"type": "Error",
"location": {
"start": [
9,
4
],
"end": [
9,
12
]
},
"message": "Variable 'declared' is declared but may not be defined"
},
{
"type": "Error",
"location": {
"start": [
17,
4
],
"end": [
17,
17
]
},
"message": "Variable 'half_defined1' is declared but may not be defined"
},
{
"type": "Error",
"location": {
"start": [
18,
4
],
"end": [
18,
17
]
},
"message": "Variable 'half_defined2' is declared but may not be defined"
},
{
"type": "Error",
"location": {
"start": [
34,
17
],
"end": [
34,
26
]
},
"message": "Variable 'self_ref2' is declared but may not be defined"
},
{
"type": "Warning",
"location": {
"start": [
6,
4
],
"end": [
6,
14
]
},
"message": "Unknown variable"
},
{
"type": "Warning",
"location": {
"start": [
33,
12
],
"end": [
33,
21
]
},
"message": "Unknown variable"
},
{
"type": "Warning",
"location": {
"start": [
45,
4
],
"end": [
45,
5
]
},
"message": "Unknown variable"
}
],
"judgments": [
{
"location": {
"from": "L6:4",
"to": "L6:14"
},
"expr": {
"_type": "VariableExpr",
"name": "undeclared"
},
"type": {}
},
{
"location": {
"from": "L9:4",
"to": "L9:12"
},
"expr": {
"_type": "VariableExpr",
"name": "declared"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L13:3",
"to": "L13:8"
},
"expr": {
"_type": "LiteralExpr",
"value": false
},
"type": {
"name": "bool"
}
},
{
"location": {
"from": "L14:20",
"to": "L14:21"
},
"expr": {
"_type": "LiteralExpr",
"value": 0
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L16:20",
"to": "L16:21"
},
"expr": {
"_type": "LiteralExpr",
"value": 1
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L17:4",
"to": "L17:17"
},
"expr": {
"_type": "VariableExpr",
"name": "half_defined1"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L18:4",
"to": "L18:17"
},
"expr": {
"_type": "VariableExpr",
"name": "half_defined2"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L21:3",
"to": "L21:8"
},
"expr": {
"_type": "LiteralExpr",
"value": false
},
"type": {
"name": "bool"
}
},
{
"location": {
"from": "L22:20",
"to": "L22:21"
},
"expr": {
"_type": "LiteralExpr",
"value": 0
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L24:20",
"to": "L24:21"
},
"expr": {
"_type": "LiteralExpr",
"value": 1
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L25:4",
"to": "L25:17"
},
"expr": {
"_type": "VariableExpr",
"name": "fully_defined"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L27:15",
"to": "L27:16"
},
"expr": {
"_type": "LiteralExpr",
"value": 0
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L28:4",
"to": "L28:11"
},
"expr": {
"_type": "VariableExpr",
"name": "defined"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L30:16",
"to": "L30:17"
},
"expr": {
"_type": "LiteralExpr",
"value": 0
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L31:4",
"to": "L31:17"
},
"expr": {
"_type": "VariableExpr",
"name": "no_annotation"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L33:12",
"to": "L33:21"
},
"expr": {
"_type": "VariableExpr",
"name": "self_ref1"
},
"type": {}
},
{
"location": {
"from": "L34:17",
"to": "L34:26"
},
"expr": {
"_type": "VariableExpr",
"name": "self_ref2"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L38:7",
"to": "L38:8"
},
"expr": {
"_type": "VariableExpr",
"name": "n"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L38:12",
"to": "L38:13"
},
"expr": {
"_type": "LiteralExpr",
"value": 1
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L38:7",
"to": "L38:13"
},
"expr": {
"_type": "CompareExpr",
"left": {
"_type": "VariableExpr",
"name": "n"
},
"operator": "<=",
"right": {
"_type": "LiteralExpr",
"value": 1
}
},
"type": {
"name": "bool"
}
},
{
"location": {
"from": "L39:15",
"to": "L39:16"
},
"expr": {
"_type": "LiteralExpr",
"value": 1
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L40:11",
"to": "L40:12"
},
"expr": {
"_type": "VariableExpr",
"name": "n"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L40:20",
"to": "L40:21"
},
"expr": {
"_type": "VariableExpr",
"name": "n"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L40:24",
"to": "L40:25"
},
"expr": {
"_type": "LiteralExpr",
"value": 1
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L40:20",
"to": "L40:25"
},
"expr": {
"_type": "BinaryExpr",
"left": {
"_type": "VariableExpr",
"name": "n"
},
"operator": "-",
"right": {
"_type": "LiteralExpr",
"value": 1
}
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L40:15",
"to": "L40:19"
},
"expr": {
"_type": "VariableExpr",
"name": "fact"
},
"type": {
"params": {
"pos": [],
"mixed": [
{
"pos": 0,
"name": "n",
"type": {
"name": "int"
},
"required": true,
"unsupported": false
}
],
"kw": []
},
"returns": {
"name": "int"
}
}
},
{
"location": {
"from": "L40:15",
"to": "L40:26"
},
"expr": {
"_type": "CallExpr",
"callee": {
"_type": "VariableExpr",
"name": "fact"
},
"arguments": [
{
"_type": "BinaryExpr",
"left": {
"_type": "VariableExpr",
"name": "n"
},
"operator": "-",
"right": {
"_type": "LiteralExpr",
"value": 1
}
}
],
"keywords": {}
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L40:11",
"to": "L40:26"
},
"expr": {
"_type": "BinaryExpr",
"left": {
"_type": "VariableExpr",
"name": "n"
},
"operator": "*",
"right": {
"_type": "CallExpr",
"callee": {
"_type": "VariableExpr",
"name": "fact"
},
"arguments": [
{
"_type": "BinaryExpr",
"left": {
"_type": "VariableExpr",
"name": "n"
},
"operator": "-",
"right": {
"_type": "LiteralExpr",
"value": 1
}
}
],
"keywords": {}
}
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L43:10",
"to": "L43:11"
},
"expr": {
"_type": "LiteralExpr",
"value": 1
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L43:13",
"to": "L43:14"
},
"expr": {
"_type": "LiteralExpr",
"value": 2
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L43:16",
"to": "L43:17"
},
"expr": {
"_type": "LiteralExpr",
"value": 3
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L43:9",
"to": "L43:18"
},
"expr": {
"_type": "ListExpr",
"items": [
{
"_type": "LiteralExpr",
"value": 1
},
{
"_type": "LiteralExpr",
"value": 2
},
{
"_type": "LiteralExpr",
"value": 3
}
]
},
"type": {
"name": "list",
"args": [
{
"name": "int"
}
],
"body": {
"name": "list"
}
}
},
{
"location": {
"from": "L43:4",
"to": "L43:5"
},
"expr": {
"_type": "VariableExpr",
"name": "i"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L44:8",
"to": "L44:9"
},
"expr": {
"_type": "VariableExpr",
"name": "i"
},
"type": {
"name": "int"
}
},
{
"location": {
"from": "L45:4",
"to": "L45:5"
},
"expr": {
"_type": "VariableExpr",
"name": "i"
},
"type": {}
}
]
}