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Cloning references in a variable may end up cloning the variable itself

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ayazhafiz 2022-05-02 20:55:09 -04:00 • committed by Ayaz Hafiz
parent 9bc6bb3664
commit 480b84bec1
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1 changed files with 47 additions and 51 deletions
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96
compiler/mono/src/copy.rs
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@ -51,7 +51,7 @@ pub fn deep_copy_type_vars<'a>(
let mark = desc.mark; let mark = desc.mark;
// Unlike `deep_copy_var` in solve, here we are cloning *all* flex and rigid vars. // Unlike `deep_copy_var` in solve, here we are cloning *all* flex and rigid vars.
// So we only want to fast-return if we've already done the cloning work for a particular // So we only want to short-circuit if we've already done the cloning work for a particular
// var. // var.
if let Some(copy) = desc.copy.into_variable() { if let Some(copy) = desc.copy.into_variable() {
return Some(copy); return Some(copy);
@ -86,6 +86,23 @@ pub fn deep_copy_type_vars<'a>(
}}; }};
} }
macro_rules! perform_clone {
($needs_clone:ident, $do_clone:expr) => {
if $needs_clone {
// It may the case that while deep-copying nested variables of this type, we
// ended up copying the type itself (notably if it was self-referencing, in a
// recursive type). In that case, short-circuit with the known copy.
if let Some(copy) = subs.get_ref(var).copy.into_variable() {
return Some(copy);
}
// Perform the clone.
Some($do_clone)
} else {
None
}
};
}
// Now we recursively copy the content of the variable. // Now we recursively copy the content of the variable.
// We have already marked the variable as copied, so we // We have already marked the variable as copied, so we
// will not repeat this work or crawl this variable again. // will not repeat this work or crawl this variable again.
@ -103,12 +120,10 @@ pub fn deep_copy_type_vars<'a>(
let mut needs_clone = false; let mut needs_clone = false;
descend_slice!(arguments, needs_clone); descend_slice!(arguments, needs_clone);
if needs_clone { perform_clone!(needs_clone, {
let new_arguments = clone_var_slice!(arguments); let new_arguments = clone_var_slice!(arguments);
Some(Structure(Apply(symbol, new_arguments))) Structure(Apply(symbol, new_arguments))
} else { })
None
}
} }
Func(arguments, closure_var, ret_var) => { Func(arguments, closure_var, ret_var) => {
let mut needs_clone = false; let mut needs_clone = false;
@ -118,12 +133,10 @@ pub fn deep_copy_type_vars<'a>(
let new_closure_var = descend_var!(closure_var, needs_clone); let new_closure_var = descend_var!(closure_var, needs_clone);
let new_ret_var = descend_var!(ret_var, needs_clone); let new_ret_var = descend_var!(ret_var, needs_clone);
if needs_clone { perform_clone!(needs_clone, {
let new_arguments = clone_var_slice!(arguments); let new_arguments = clone_var_slice!(arguments);
Some(Structure(Func(new_arguments, new_closure_var, new_ret_var))) Structure(Func(new_arguments, new_closure_var, new_ret_var))
} else { })
None
}
} }
Record(fields, ext_var) => { Record(fields, ext_var) => {
let mut needs_clone = false; let mut needs_clone = false;
@ -132,7 +145,7 @@ pub fn deep_copy_type_vars<'a>(
descend_slice!(fields.variables(), needs_clone); descend_slice!(fields.variables(), needs_clone);
if needs_clone { perform_clone!(needs_clone, {
let new_variables = clone_var_slice!(fields.variables()); let new_variables = clone_var_slice!(fields.variables());
let new_fields = { let new_fields = {
RecordFields { RecordFields {
@ -142,10 +155,9 @@ pub fn deep_copy_type_vars<'a>(
field_types_start: fields.field_types_start, field_types_start: fields.field_types_start,
} }
}; };
Some(Structure(Record(new_fields, new_ext_var)))
} else { Structure(Record(new_fields, new_ext_var))
None })
}
} }
TagUnion(tags, ext_var) => { TagUnion(tags, ext_var) => {
let mut needs_clone = false; let mut needs_clone = false;
@ -157,7 +169,7 @@ pub fn deep_copy_type_vars<'a>(
descend_slice!(variables_slice, needs_clone); descend_slice!(variables_slice, needs_clone);
} }
if needs_clone { perform_clone!(needs_clone, {
let new_variable_slices = let new_variable_slices =
SubsSlice::reserve_variable_slices(subs, tags.len()); SubsSlice::reserve_variable_slices(subs, tags.len());
let it = (new_variable_slices.indices()).zip(tags.variables()); let it = (new_variable_slices.indices()).zip(tags.variables());
@ -170,10 +182,8 @@ pub fn deep_copy_type_vars<'a>(
let new_union_tags = let new_union_tags =
UnionTags::from_slices(tags.tag_names(), new_variable_slices); UnionTags::from_slices(tags.tag_names(), new_variable_slices);
Some(Structure(TagUnion(new_union_tags, new_ext_var))) Structure(TagUnion(new_union_tags, new_ext_var))
} else { })
None
}
} }
RecursiveTagUnion(rec_var, tags, ext_var) => { RecursiveTagUnion(rec_var, tags, ext_var) => {
let mut needs_clone = false; let mut needs_clone = false;
@ -186,7 +196,7 @@ pub fn deep_copy_type_vars<'a>(
descend_slice!(variables_slice, needs_clone); descend_slice!(variables_slice, needs_clone);
} }
if needs_clone { perform_clone!(needs_clone, {
let new_variable_slices = let new_variable_slices =
SubsSlice::reserve_variable_slices(subs, tags.len()); SubsSlice::reserve_variable_slices(subs, tags.len());
let it = (new_variable_slices.indices()).zip(tags.variables()); let it = (new_variable_slices.indices()).zip(tags.variables());
@ -199,23 +209,15 @@ pub fn deep_copy_type_vars<'a>(
let new_union_tags = let new_union_tags =
UnionTags::from_slices(tags.tag_names(), new_variable_slices); UnionTags::from_slices(tags.tag_names(), new_variable_slices);
Some(Structure(RecursiveTagUnion( Structure(RecursiveTagUnion(new_rec_var, new_union_tags, new_ext_var))
new_rec_var, })
new_union_tags,
new_ext_var,
)))
} else {
None
}
} }
FunctionOrTagUnion(tag_name, symbol, ext_var) => { FunctionOrTagUnion(tag_name, symbol, ext_var) => {
let mut needs_clone = false; let mut needs_clone = false;
let new_ext_var = descend_var!(ext_var, needs_clone); let new_ext_var = descend_var!(ext_var, needs_clone);
if needs_clone { perform_clone!(needs_clone, {
Some(Structure(FunctionOrTagUnion(tag_name, symbol, new_ext_var))) Structure(FunctionOrTagUnion(tag_name, symbol, new_ext_var))
} else { })
None
}
} }
}, },
@ -227,14 +229,12 @@ pub fn deep_copy_type_vars<'a>(
let new_structure = descend_var!(structure, needs_clone); let new_structure = descend_var!(structure, needs_clone);
if needs_clone { perform_clone!(needs_clone, {
Some(RecursionVar { RecursionVar {
opt_name, opt_name,
structure: new_structure, structure: new_structure,
})
} else {
None
} }
})
} }
Alias(symbol, arguments, real_type_var, kind) => { Alias(symbol, arguments, real_type_var, kind) => {
@ -243,17 +243,15 @@ pub fn deep_copy_type_vars<'a>(
let new_real_type_var = descend_var!(real_type_var, needs_clone); let new_real_type_var = descend_var!(real_type_var, needs_clone);
descend_slice!(arguments.all_variables(), needs_clone); descend_slice!(arguments.all_variables(), needs_clone);
if needs_clone { perform_clone!(needs_clone, {
let new_variables = clone_var_slice!(arguments.all_variables()); let new_variables = clone_var_slice!(arguments.all_variables());
let new_arguments = AliasVariables { let new_arguments = AliasVariables {
variables_start: new_variables.start, variables_start: new_variables.start,
..arguments ..arguments
}; };
Some(Alias(symbol, new_arguments, new_real_type_var, kind)) Alias(symbol, new_arguments, new_real_type_var, kind)
} else { })
None
}
} }
RangedNumber(typ, range_vars) => { RangedNumber(typ, range_vars) => {
@ -262,13 +260,11 @@ pub fn deep_copy_type_vars<'a>(
let new_typ = descend_var!(typ, needs_clone); let new_typ = descend_var!(typ, needs_clone);
descend_slice!(range_vars, needs_clone); descend_slice!(range_vars, needs_clone);
if needs_clone { perform_clone!(needs_clone, {
let new_range_vars = clone_var_slice!(range_vars); let new_range_vars = clone_var_slice!(range_vars);
Some(RangedNumber(new_typ, new_range_vars)) RangedNumber(new_typ, new_range_vars)
} else { })
None
}
} }
Error => None, Error => None,
}; };