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std.json: don't free struct default values

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Closes https://github.com/ziglang/zig/issues/9509.
This commit is contained in:
John Schmidt 2023-02-04 14:42:42 +01:00
parent b42caff2a2
commit b1dd4b17d8
2 changed files with 56 additions and 1 deletions
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32
lib/std/json.zig
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@ -1745,7 +1745,37 @@ pub fn parseFree(comptime T: type, value: T, options: ParseOptions) void {
.Struct => |structInfo| {
inline for (structInfo.fields) |field| {
if (!field.is_comptime) {
parseFree(field.type, @field(value, field.name), options);
var should_free = true;
if (field.default_value) |default| {
switch (@typeInfo(field.type)) {
// We must not attempt to free pointers to struct default values
.Pointer => |fieldPtrInfo| {
const field_value = @field(value, field.name);
const field_ptr = switch (fieldPtrInfo.size) {
.One => field_value,
.Slice => field_value.ptr,
else => unreachable, // Other pointer types are not parseable
};
const field_addr = @ptrToInt(field_ptr);
const casted_default = @ptrCast(*const field.type, @alignCast(@alignOf(field.type), default)).*;
const default_ptr = switch (fieldPtrInfo.size) {
.One => casted_default,
.Slice => casted_default.ptr,
else => unreachable, // Other pointer types are not parseable
};
const default_addr = @ptrToInt(default_ptr);
if (field_addr == default_addr) {
should_free = false;
}
},
else => {},
}
}
if (should_free) {
parseFree(field.type, @field(value, field.name), options);
}
}
}
},

25
lib/std/json/test.zig
View File

@ -2246,6 +2246,31 @@ test "parse into struct with default const pointer field" {
try testing.expectEqual(T{}, try parse(T, &ts, .{}));
}
const test_default_usize: usize = 123;
const test_default_usize_ptr: *align(1) const usize = &test_default_usize;
const test_default_str: []const u8 = "test str";
const test_default_str_slice: [2][]const u8 = [_][]const u8{
"test1",
"test2",
};
test "freeing parsed structs with pointers to default values" {
const T = struct {
int: *const usize = &test_default_usize,
int_ptr: *allowzero align(1) const usize = test_default_usize_ptr,
str: []const u8 = test_default_str,
str_slice: []const []const u8 = &test_default_str_slice,
};
var ts = json.TokenStream.init("{}");
const options = .{ .allocator = std.heap.page_allocator };
const parsed = try json.parse(T, &ts, options);
try testing.expectEqual(T{}, parsed);
json.parseFree(T, parsed, options);
}
test "parse into struct where destination and source lengths mismatch" {
const T = struct { a: [2]u8 };
var ts = TokenStream.init("{\"a\": \"bbb\"}");