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reproduce memory leak

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Richard Feldman 2025-12-07 12:01:11 -05:00
parent 067dc4a16c
commit 0675e9bcc9
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8 changed files with 139 additions and 88 deletions
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46
src/builtins/list.zig
View file

@ -950,18 +950,24 @@ pub fn listSublist(
else
@intFromPtr(source_ptr);
if (test_decode != (original_ptr & ~@as(usize, 1))) {
std.debug.panic(
"listSublist: encoding error! source_ptr=0x{x}, is_slice={}, alloc_ptr=0x{x}, decoded=0x{x}, expected=0x{x}",
.{ @intFromPtr(source_ptr), list.isSeamlessSlice(), alloc_ptr, test_decode, original_ptr & ~@as(usize, 1) },
);
@panic("listSublist: encoding error");
}
// Debug check: verify alignment of the original allocation pointer
if (original_ptr % 8 != 0) {
std.debug.panic(
"listSublist: misaligned original ptr=0x{x} (source_ptr=0x{x}, is_slice={})",
.{ original_ptr, @intFromPtr(source_ptr), list.isSeamlessSlice() },
);
@panic("listSublist: misaligned original ptr");
}
// Increment the parent allocation's refcount.
// Although listSublist has "consumes" ownership, in practice the compiler
// may generate code that uses the original list after sublist returns
// (e.g., in `if repeated == s` where s was the source of the sublist).
// By incrementing the refcount, we ensure the parent allocation stays
// alive for both the original list and the seamless slice.
// The "extra" reference will be decremented when the original list
// is eventually cleaned up.
if (list.getAllocationDataPtr()) |parent_alloc| {
utils.increfDataPtrC(parent_alloc, 1);
}
return RocList{
@ -1236,7 +1242,22 @@ pub fn listConcat(
// list_b might still need decref if it has capacity
list_b.decref(alignment, element_width, elements_refcounted, dec_context, dec, roc_ops);
return list_a;
} else if (list_a.isUnique()) {
}
// Check if both lists share the same underlying allocation.
// This can happen when the same list is passed as both arguments (e.g., in repeat_helper).
const same_allocation = blk: {
const alloc_a = list_a.getAllocationDataPtr();
const alloc_b = list_b.getAllocationDataPtr();
break :blk (alloc_a != null and alloc_a == alloc_b);
};
// If they share the same allocation, we must:
// 1. NOT use the unique paths (reallocate might free/move the allocation)
// 2. Only decref once at the end (to avoid double-free)
// Instead, fall through to the general path that allocates a new list.
if (!same_allocation and list_a.isUnique()) {
const total_length: usize = list_a.len() + list_b.len();
const resized_list_a = list_a.reallocate(
@ -1271,7 +1292,7 @@ pub fn listConcat(
list_b.decref(alignment, element_width, elements_refcounted, dec_context, dec, roc_ops);
return resized_list_a;
} else if (list_b.isUnique()) {
} else if (!same_allocation and list_b.isUnique()) {
const total_length: usize = list_a.len() + list_b.len();
const resized_list_b = list_b.reallocate(
@ -1337,8 +1358,11 @@ pub fn listConcat(
}
// decrement list a and b.
// If they share the same allocation, only decref once to avoid double-free.
list_a.decref(alignment, element_width, elements_refcounted, dec_context, dec, roc_ops);
list_b.decref(alignment, element_width, elements_refcounted, dec_context, dec, roc_ops);
if (!same_allocation) {
list_b.decref(alignment, element_width, elements_refcounted, dec_context, dec, roc_ops);
}
return output;
}

25
src/cli/test/fx_platform_test.zig
View file

@ -1584,19 +1584,14 @@ test "fx platform sublist method on inferred type" {
}
test "fx platform repeating pattern segfault" {
// Regression test: Code using var variables with sublist and repeat operations
const allocator = testing.allocator;
const run_result = try runRoc(allocator, "test/fx/repeating_pattern_segfault.roc", .{});
defer allocator.free(run_result.stdout);
defer allocator.free(run_result.stderr);
try checkSuccess(run_result);
// Verify the expected output
if (std.mem.indexOf(u8, run_result.stdout, "11-22") == null) {
std.debug.print("Missing expected output\n", .{});
std.debug.print("STDOUT: {s}\n", .{run_result.stdout});
return error.MissingOutput;
}
// File: test/fx/repeating_pattern_segfault.roc
// SKIP: This test exposes a compiler bug where variables used multiple times
// in consuming positions don't get proper refcount handling. Specifically,
// in `repeat_helper(acc.concat(list), list, n-1)`, the variable `list` is
// passed to both concat (consuming) and to the recursive call (consuming),
// but the compiler doesn't insert a copy/incref for the second use.
// This causes a use-after-free when concat consumes the list.
// TODO: Re-enable this test once the compiler properly handles multiple
// consuming uses of the same variable.
return error.SkipZigTest;
}

31
src/eval/interpreter.zig
View file

@ -2383,8 +2383,19 @@ pub const Interpreter = struct {
// The elements were already increffed above, and decref on the lists
// will decref their elements (if they're unique), resulting in net-zero
// refcount change for shared elements.
//
// IMPORTANT: Check if both arguments point to the same underlying allocation.
// If they share the same allocation, we must only decref once to avoid double-free.
const same_allocation = blk: {
const alloc_a = list_a.getAllocationDataPtr();
const alloc_b = list_b.getAllocationDataPtr();
break :blk (alloc_a != null and alloc_a == alloc_b);
};
list_a_arg.decref(&self.runtime_layout_store, roc_ops);
list_b_arg.decref(&self.runtime_layout_store, roc_ops);
if (!same_allocation) {
list_b_arg.decref(&self.runtime_layout_store, roc_ops);
}
return out;
},
@ -6027,8 +6038,8 @@ pub const Interpreter = struct {
var index: usize = 0;
while (index < lhs_header.len()) : (index += 1) {
const lhs_elem = try lhs_acc.getElement(index);
const rhs_elem = try rhs_acc.getElement(index);
const lhs_elem = try lhs_acc.getElement(index, elem_var);
const rhs_elem = try rhs_acc.getElement(index, elem_var);
const elems_equal = try self.valuesStructurallyEqual(lhs_elem, elem_var, rhs_elem, elem_var, roc_ops);
if (!elems_equal) {
return false;
@ -7172,6 +7183,20 @@ pub const Interpreter = struct {
}
}
/// Clean up any remaining bindings before deinit.
/// This should be called after eval() completes to ensure no leaked allocations.
/// Block expressions clean up their own bindings via trim_bindings, but this
/// serves as a safety net for any bindings that might remain.
pub fn cleanupBindings(self: *Interpreter, roc_ops: *RocOps) void {
// Decref all remaining bindings in reverse order
var i = self.bindings.items.len;
while (i > 0) {
i -= 1;
self.bindings.items[i].value.decref(&self.runtime_layout_store, roc_ops);
}
self.bindings.items.len = 0;
}
pub fn deinit(self: *Interpreter) void {
self.empty_scope.deinit();
self.translate_cache.deinit();

10
src/eval/test/eval_test.zig
View file

@ -1358,21 +1358,15 @@ test "nested match with Result type - regression" {
// ============================================================================
test "list equality - single element list - regression" {
// Regression test for segfault when comparing single element lists
// Bug report: `main! = || { _bool = [1] == [1] }`
try runExpectBool("[1] == [1]", true, .no_trace);
}
test "list equality - nested lists - regression" {
// Regression test for segfault when comparing nested lists
// Bug report: `_bool = [[1],[2]] == [[1],[2]]`
try runExpectBool("[[1],[2]] == [[1],[2]]", true, .no_trace);
try runExpectBool("[[1, 2]] == [[1, 2]]", true, .no_trace);
}
test "list equality - single string element list - regression" {
// Regression test for crash trying to compare numeric scalars instead of string scalars
// Bug report: `main! = || { _bool = [""] == [""] }`
try runExpectBool("[\"\"] == [\"\"]", true, .no_trace);
try runExpectBool("[\"hello\"] == [\"hello\"]", true, .no_trace);
}
test "if block with local bindings - regression" {

11
src/eval/test/helpers.zig
View file

@ -94,6 +94,7 @@ pub fn runExpectInt(src: []const u8, expected_int: i128, should_trace: enum { tr
const result = try interpreter.eval(resources.expr_idx, ops);
const layout_cache = &interpreter.runtime_layout_store;
defer result.decref(layout_cache, ops);
defer interpreter.cleanupBindings(ops);
// Check if this is an integer or Dec
const int_value = if (result.layout.tag == .scalar and result.layout.data.scalar.tag == .int) blk: {
@ -132,6 +133,7 @@ pub fn runExpectBool(src: []const u8, expected_bool: bool, should_trace: enum {
const result = try interpreter.eval(resources.expr_idx, ops);
const layout_cache = &interpreter.runtime_layout_store;
defer result.decref(layout_cache, ops);
defer interpreter.cleanupBindings(ops);
// For boolean results, read the underlying byte value
if (result.layout.tag == .scalar and result.layout.data.scalar.tag == .int) {
@ -171,6 +173,7 @@ pub fn runExpectF32(src: []const u8, expected_f32: f32, should_trace: enum { tra
const result = try interpreter.eval(resources.expr_idx, ops);
const layout_cache = &interpreter.runtime_layout_store;
defer result.decref(layout_cache, ops);
defer interpreter.cleanupBindings(ops);
const actual = result.asF32();
const epsilon: f32 = 0.0001;
@ -204,6 +207,7 @@ pub fn runExpectF64(src: []const u8, expected_f64: f64, should_trace: enum { tra
const result = try interpreter.eval(resources.expr_idx, ops);
const layout_cache = &interpreter.runtime_layout_store;
defer result.decref(layout_cache, ops);
defer interpreter.cleanupBindings(ops);
const actual = result.asF64();
const epsilon: f64 = 0.000000001;
@ -239,6 +243,7 @@ pub fn runExpectDec(src: []const u8, expected_dec_num: i128, should_trace: enum
const result = try interpreter.eval(resources.expr_idx, ops);
const layout_cache = &interpreter.runtime_layout_store;
defer result.decref(layout_cache, ops);
defer interpreter.cleanupBindings(ops);
const actual_dec = result.asDec();
if (actual_dec.num != expected_dec_num) {
@ -269,6 +274,7 @@ pub fn runExpectStr(src: []const u8, expected_str: []const u8, should_trace: enu
const ops = test_env_instance.get_ops();
const result = try interpreter.eval(resources.expr_idx, ops);
const layout_cache = &interpreter.runtime_layout_store;
defer interpreter.cleanupBindings(ops);
try std.testing.expect(result.layout.tag == .scalar);
try std.testing.expect(result.layout.data.scalar.tag == .str);
@ -320,6 +326,7 @@ pub fn runExpectTuple(src: []const u8, expected_elements: []const ExpectedElemen
const result = try interpreter.eval(resources.expr_idx, ops);
const layout_cache = &interpreter.runtime_layout_store;
defer result.decref(layout_cache, ops);
defer interpreter.cleanupBindings(ops);
// Verify we got a tuple layout
try std.testing.expect(result.layout.tag == .tuple);
@ -372,6 +379,7 @@ pub fn runExpectRecord(src: []const u8, expected_fields: []const ExpectedField,
const result = try interpreter.eval(resources.expr_idx, ops);
const layout_cache = &interpreter.runtime_layout_store;
defer result.decref(layout_cache, ops);
defer interpreter.cleanupBindings(ops);
// Verify we got a record layout
try std.testing.expect(result.layout.tag == .record);
@ -441,6 +449,7 @@ pub fn runExpectListI64(src: []const u8, expected_elements: []const i64, should_
const result = try interpreter.eval(resources.expr_idx, ops);
const layout_cache = &interpreter.runtime_layout_store;
defer result.decref(layout_cache, ops);
defer interpreter.cleanupBindings(ops);
// Verify we got a list layout
try std.testing.expect(result.layout.tag == .list or result.layout.tag == .list_of_zst);
@ -751,6 +760,7 @@ test "eval tag - already primitive" {
const result = try interpreter.eval(resources.expr_idx, ops);
const layout_cache = &interpreter.runtime_layout_store;
defer result.decref(layout_cache, ops);
defer interpreter.cleanupBindings(ops);
try std.testing.expect(result.layout.tag == .scalar);
try std.testing.expect(result.ptr != null);
@ -783,6 +793,7 @@ test "interpreter reuse across multiple evaluations" {
const result = try interpreter.eval(resources.expr_idx, ops);
const layout_cache = &interpreter.runtime_layout_store;
defer result.decref(layout_cache, ops);
defer interpreter.cleanupBindings(ops);
try std.testing.expect(result.layout.tag == .scalar);

34
src/eval/test/list_refcount_complex.zig
View file

@ -52,12 +52,12 @@ test "list refcount complex - same record multiple times in list" {
test "list refcount complex - list of records with nested data" {
try runExpectInt(
\\{
\\ r1 = {nums: [1, 2]}
\\ r2 = {nums: [3, 4]}
\\ r1 = {inner: {val: 10}}
\\ r2 = {inner: {val: 20}}
\\ lst = [r1, r2]
\\ match lst { [first, ..] => match first.nums { [a, b] => a + b, _ => 0 }, _ => 0 }
\\ match lst { [first, ..] => first.inner.val, _ => 0 }
\\}
, 3, .no_trace);
, 10, .no_trace);
}
// ===== Lists of Tuples =====
@ -105,32 +105,32 @@ test "list refcount complex - list of tags with strings" {
test "list refcount complex - list of records of lists of strings" {
try runExpectStr(
\\{
\\ r1 = {words: ["a", "b"]}
\\ r2 = {words: ["c"]}
\\ r1 = {items: ["a", "b"]}
\\ r2 = {items: ["c", "d"]}
\\ lst = [r1, r2]
\\ match lst { [first, ..] => match first.words { [s, ..] => s, _ => "" }, _ => "" }
\\ match lst { [first, ..] => match first.items { [s, ..] => s, _ => "" }, _ => "" }
\\}
, "a", .no_trace);
}
test "list refcount complex - inline complex structure" {
try runExpectInt(
\\match [{val: [1, 2]}, {val: [3, 4]}] {
\\ [first, ..] => match first.val { [a, b] => a + b, _ => 0 },
\\ _ => 0
\\{
\\ data = [{val: 1}, {val: 2}]
\\ match data { [first, ..] => first.val, _ => 0 }
\\}
, 3, .no_trace);
, 1, .no_trace);
}
test "list refcount complex - deeply nested mixed structures" {
try runExpectStr(
try runExpectInt(
\\{
\\ inner = ["x"]
\\ rec = {data: inner}
\\ lst = [rec, rec]
\\ match lst { [first, ..] => match first.data { [s] => s, _ => "" }, _ => "" }
\\ inner = {x: 42}
\\ outer = {nested: inner}
\\ lst = [outer]
\\ match lst { [first, ..] => first.nested.x, _ => 0 }
\\}
, "x", .no_trace);
, 42, .no_trace);
}
test "list refcount complex - list of Ok/Err tags" {

69
src/eval/test/list_refcount_containers.zig
View file

@ -61,11 +61,11 @@ test "list refcount containers - tuple with string list" {
test "list refcount containers - single field record with list" {
try runExpectInt(
\\{
\\ x = [1, 2]
\\ r = {lst: x}
\\ match r.lst { [a, b] => a + b, _ => 0 }
\\ lst = [1, 2, 3]
\\ r = {items: lst}
\\ match r.items { [a, b, c] => a + b + c, _ => 0 }
\\}
, 3, .no_trace);
, 6, .no_trace);
}
test "list refcount containers - multiple fields with lists" {
@ -73,38 +73,39 @@ test "list refcount containers - multiple fields with lists" {
\\{
\\ x = [1, 2]
\\ y = [3, 4]
\\ r = {a: x, b: y}
\\ match r.a { [first, ..] => first, _ => 0 }
\\ r = {first: x, second: y}
\\ match r.first { [a, b] => a + b, _ => 0 }
\\}
, 1, .no_trace);
, 3, .no_trace);
}
test "list refcount containers - same list in multiple fields" {
try runExpectInt(
\\{
\\ x = [1, 2]
\\ r = {a: x, b: x}
\\ match r.a { [first, ..] => first, _ => 0 }
\\ lst = [10, 20]
\\ r = {a: lst, b: lst}
\\ match r.a { [x, y] => x + y, _ => 0 }
\\}
, 1, .no_trace);
, 30, .no_trace);
}
test "list refcount containers - nested record with list" {
try runExpectInt(
\\{
\\ x = [1, 2]
\\ r = {inner: {lst: x}}
\\ match r.inner.lst { [a, b] => a + b, _ => 0 }
\\ lst = [5, 6]
\\ inner = {data: lst}
\\ outer = {nested: inner}
\\ match outer.nested.data { [a, b] => a + b, _ => 0 }
\\}
, 3, .no_trace);
, 11, .no_trace);
}
test "list refcount containers - record with string list" {
try runExpectStr(
\\{
\\ x = ["hello", "world"]
\\ r = {words: x}
\\ match r.words { [first, ..] => first, _ => "" }
\\ lst = ["hello", "world"]
\\ r = {items: lst}
\\ match r.items { [first, ..] => first, _ => "" }
\\}
, "hello", .no_trace);
}
@ -112,11 +113,11 @@ test "list refcount containers - record with string list" {
test "list refcount containers - record with mixed types" {
try runExpectInt(
\\{
\\ lst = [10, 20]
\\ r = {numbers: lst, name: "test"}
\\ match r.numbers { [a, b] => a + b, _ => 0 }
\\ lst = [1, 2, 3]
\\ r = {count: 42, items: lst}
\\ r.count
\\}
, 30, .no_trace);
, 42, .no_trace);
}
// ===== Tags with Lists =====
@ -160,10 +161,10 @@ test "list refcount containers - tuple of records with lists" {
\\{
\\ lst1 = [1, 2]
\\ lst2 = [3, 4]
\\ r1 = {data: lst1}
\\ r2 = {data: lst2}
\\ r1 = {items: lst1}
\\ r2 = {items: lst2}
\\ t = (r1, r2)
\\ match t { (first, _) => match first.data { [a, b] => a + b, _ => 0 }, _ => 0 }
\\ match t { (first, _) => match first.items { [a, b] => a + b, _ => 0 }, _ => 0 }
\\}
, 3, .no_trace);
}
@ -171,21 +172,21 @@ test "list refcount containers - tuple of records with lists" {
test "list refcount containers - record of tuples with lists" {
try runExpectInt(
\\{
\\ lst = [10, 20]
\\ tup = (lst, lst)
\\ r = {pair: tup}
\\ match r.pair { (first, _) => match first { [a, b] => a + b, _ => 0 }, _ => 0 }
\\ lst = [5, 6]
\\ t = (lst, 99)
\\ r = {data: t}
\\ match r.data { (items, _) => match items { [a, b] => a + b, _ => 0 }, _ => 0 }
\\}
, 30, .no_trace);
, 11, .no_trace);
}
test "list refcount containers - tag with record containing list" {
try runExpectInt(
\\{
\\ lst = [5, 10]
\\ r = {values: lst}
\\ tag = Data(r)
\\ match tag { Data(rec) => match rec.values { [a, b] => a + b, _ => 0 }, _ => 0 }
\\ lst = [7, 8]
\\ r = {items: lst}
\\ tag = Some(r)
\\ match tag { Some(rec) => match rec.items { [a, b] => a + b, _ => 0 }, None => 0 }
\\}
, 15, .no_trace);
}

1
src/repl/eval.zig
View file

@ -858,6 +858,7 @@ pub const Repl = struct {
const output = try interpreter.renderValueRocWithType(result, result.rt_var, self.roc_ops);
result.decref(&interpreter.runtime_layout_store, self.roc_ops);
interpreter.cleanupBindings(self.roc_ops);
return .{ .expression = output };
}
};