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core: Do not keep unification result for function arguments

For some reason, when unifying a function call parameter with an
argument, subsequent calls to the same function will only accept the
type of the substituted argument.

This affect snippets like:

```
def make1() -> C[Literal[1]]:
    return ...

def make2() -> C[Literal[2]]:
    return ...

def consume(instance: C[Literal[1, 2]]):
    pass

consume(make1())
consume(make2())
```

The last statement will result in a compiler error, as the parameter of
consume is replaced with C[Literal[1]].

We fix this by getting a snapshot before performing unification, and
restoring the snapshot after unification succeeds.
This commit is contained in:
David Mak 2023-12-13 21:55:30 +08:00 committed by sb10q
parent 0bbc9ce6f5
commit f09f3c27a5
2 changed files with 26 additions and 12 deletions

View File

@ -529,10 +529,12 @@ impl Unifier {
}
required.pop();
let (name, expected) = all_names.pop().unwrap();
let snapshot = self.unification_table.get_snapshot();
self.unify_impl(expected, *t, false).map_err(|_| {
self.restore_snapshot();
TypeError::new(TypeErrorKind::IncorrectArgType { name, expected, got: *t }, *loc)
})?;
self.unification_table.restore_snapshot(snapshot);
}
for (k, t) in kwargs {
if let Some(i) = required.iter().position(|v| v == k) {
@ -546,10 +548,12 @@ impl Unifier {
TypeError::new(TypeErrorKind::UnknownArgName(*k), *loc)
})?;
let (name, expected) = all_names.remove(i);
let snapshot = self.unification_table.get_snapshot();
self.unify_impl(expected, *t, false).map_err(|_| {
self.restore_snapshot();
TypeError::new(TypeErrorKind::IncorrectArgType { name, expected, got: *t }, *loc)
})?;
self.unification_table.restore_snapshot(snapshot);
}
if !required.is_empty() {
self.restore_snapshot();
@ -746,18 +750,21 @@ impl Unifier {
(TVar { range: tys, is_const_generic: true, .. }, TLiteral { values, .. }) => {
assert_eq!(tys.len(), 1);
assert_eq!(values.len(), 1);
let primitives = &self.primitive_store
.expect("Expected PrimitiveStore to be present");
let ty = tys[0];
let value= &values[0];
let value_ty = value.get_type(primitives, self);
// If the types don't match, try to implicitly promote integers
if !self.unioned(ty, value_ty) {
for value in values {
let value_ty = value.get_type(primitives, self);
if self.unioned(ty, value_ty) {
self.set_a_to_b(a, b);
return Ok(())
}
// The types don't match, try to implicitly promote integers
let num_val = match *value {
SymbolValue::I32(v) => v as i128,
SymbolValue::I64(v) => v as i128,
@ -778,19 +785,18 @@ impl Unifier {
false
};
if !can_convert {
return self.incompatible_types(a, b)
if can_convert {
self.set_a_to_b(a, b);
return Ok(())
}
}
self.set_a_to_b(a, b);
return self.incompatible_types(a, b)
}
(TLiteral { values: val1, .. }, TLiteral { values: val2, .. }) => {
for (v1, v2) in zip(val1, val2) {
if v1 != v2 {
return self.incompatible_types(a, b)
}
if val2.iter().any(|val| !val1.contains(val)) {
return self.incompatible_types(a, b)
}
self.set_a_to_b(a, b);

View File

@ -16,6 +16,9 @@ class HybridGenericClass2(Generic[A, T]):
class HybridGenericClass3(Generic[T, A, B]):
pass
def make_generic_1() -> ConstGenericClass[Literal[1]]:
return ...
def make_generic_2() -> ConstGenericClass[Literal[2]]:
return ...
@ -28,6 +31,9 @@ def make_hybrid_class_2_int32() -> HybridGenericClass2[Literal[2], int32]:
def make_hybrid_class_i32_0_1() -> HybridGenericClass3[int32, Literal[0], Literal[1]]:
return ...
def consume_generic_1_or_2(instance: ConstGenericClass[Literal[1, 2]]):
pass
def consume_generic_2(instance: ConstGenericClass[Literal[2]]):
pass
@ -42,6 +48,8 @@ def consume_hybrid_class_i32_0_1(instance: HybridGenericClass3[int32, Literal[0]
def f():
consume_generic_2(make_generic_2())
consume_generic_1_or_2(make_generic_1())
consume_generic_1_or_2(make_generic_2())
consume_generic2_1_2(make_generic2_1_2())
consume_hybrid_class_2_i32(make_hybrid_class_2_int32())
consume_hybrid_class_i32_0_1(make_hybrid_class_i32_0_1())