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feat: implement closure RC - environments are now memory-managed

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Closures and their environments are now properly reference-counted:

- Allocate closures with lux_rc_alloc(sizeof(LuxClosure), LUX_TAG_CLOSURE)
- Allocate environments with lux_rc_alloc(sizeof(LuxEnv_N), LUX_TAG_ENV)
- Enable Lambda in expr_creates_rc_value() to track closure variables
- Add lux_decref() after List higher-order operations (map, filter, fold,
  find, any, all) to clean up inline lambdas

Test results:
- Closure test: [RC] No leaks: 8 allocs, 8 frees
- List RC test: [RC] No leaks: 31 allocs, 31 frees
- All 263 tests pass

Remaining for full memory safety: ADT RC, early returns, conditionals.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
This commit is contained in:
Brandon Lucas
2026-02-14 13:12:40 -05:00
parent b2f4beeaa2
commit c68694294b
3 changed files with 51 additions and 24 deletions
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38
src/codegen/c_backend.rs
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@@ -1583,16 +1583,18 @@ impl CBackend {
let temp_env = format!("_env_{}", id);
let temp_closure = format!("_closure_{}", id);
// Allocate and initialize environment struct
// Allocate and initialize environment struct (RC-managed)
if env_fields.is_empty() {
self.writeln(&format!("LuxClosure* {} = malloc(sizeof(LuxClosure));", temp_closure));
self.writeln(&format!("LuxClosure* {} = lux_rc_alloc(sizeof(LuxClosure), LUX_TAG_CLOSURE);", temp_closure));
self.writeln(&format!("{}->env = NULL;", temp_closure));
} else {
self.writeln(&format!("LuxEnv_{}* {} = malloc(sizeof(LuxEnv_{}));", id, temp_env, id));
// Allocate RC-managed environment
self.writeln(&format!("LuxEnv_{}* {} = lux_rc_alloc(sizeof(LuxEnv_{}), LUX_TAG_ENV);", id, temp_env, id));
for (name, _) in &env_fields {
self.writeln(&format!("{}->{} = {};", temp_env, name, name));
}
self.writeln(&format!("LuxClosure* {} = malloc(sizeof(LuxClosure));", temp_closure));
// Allocate RC-managed closure
self.writeln(&format!("LuxClosure* {} = lux_rc_alloc(sizeof(LuxClosure), LUX_TAG_CLOSURE);", temp_closure));
self.writeln(&format!("{}->env = {};", temp_closure, temp_env));
}
self.writeln(&format!("{}->fn_ptr = (void*)lambda_{};", temp_closure, id));
@@ -2056,6 +2058,10 @@ impl CBackend {
self.indent -= 1;
self.writeln("}");
self.writeln(&format!("{}->length = {}->length;", result_var, list));
// Decref the closure if it was a temporary (inline lambda)
if closure.starts_with("_closure_") {
self.writeln(&format!("lux_decref({});", closure));
}
Ok(result_var)
}
@@ -2090,6 +2096,10 @@ impl CBackend {
self.indent -= 1;
self.writeln("}");
self.writeln(&format!("{}->length = {};", result_var, count_var));
// Decref the closure if it was a temporary (inline lambda)
if closure.starts_with("_closure_") {
self.writeln(&format!("lux_decref({});", closure));
}
Ok(result_var)
}
@@ -2114,6 +2124,10 @@ impl CBackend {
self.writeln(&format!("{} = ((LuxInt(*)(void*, LuxInt, LuxInt)){}->fn_ptr)({}->env, {}, lux_unbox_int({}));", result_var, fn_var, fn_var, result_var, elem_var));
self.indent -= 1;
self.writeln("}");
// Decref the closure if it was a temporary (inline lambda)
if closure.starts_with("_closure_") {
self.writeln(&format!("lux_decref({});", closure));
}
Ok(result_var)
}
@@ -2144,6 +2158,10 @@ impl CBackend {
self.writeln("}");
self.indent -= 1;
self.writeln("}");
// Decref the closure if it was a temporary (inline lambda)
if closure.starts_with("_closure_") {
self.writeln(&format!("lux_decref({});", closure));
}
Ok(result_var)
}
@@ -2172,6 +2190,10 @@ impl CBackend {
self.writeln("}");
self.indent -= 1;
self.writeln("}");
// Decref the closure if it was a temporary (inline lambda)
if closure.starts_with("_closure_") {
self.writeln(&format!("lux_decref({});", closure));
}
Ok(result_var)
}
@@ -2200,6 +2222,10 @@ impl CBackend {
self.writeln("}");
self.indent -= 1;
self.writeln("}");
// Decref the closure if it was a temporary (inline lambda)
if closure.starts_with("_closure_") {
self.writeln(&format!("lux_decref({});", closure));
}
Ok(result_var)
}
@@ -2651,8 +2677,8 @@ impl CBackend {
// List literals create new RC lists
Expr::List { .. } => true,
// Lambdas create closures (though we don't RC closures yet)
Expr::Lambda { .. } => false, // TODO: enable when closures are RC
// Lambdas create RC-managed closures
Expr::Lambda { .. } => true,
// Calls to List.* that return lists
Expr::Call { func, .. } => {