Today I downloaded the latest version of master. I notice that the following code is now failing:
fn ArgumentStruct(comptime function: anytype) type {
const info = @typeInfo(@TypeOf(function)).Fn;
var fields: [info.params.len + 1]std.builtin.Type.StructField = undefined;
var count = 0;
for (info.params) |param| {
if (param.type != std.mem.Allocator) {
const name = std.fmt.comptimePrint("{d}", .{count});
fields[count] = .{
.name = name,
.type = param.type orelse void,
.is_comptime = false,
.alignment = @alignOf(param.type orelse void),
.default_value = null,
};
count += 1;
}
}
fields[count] = .{
.name = "retval",
.type = info.return_type orelse void,
.is_comptime = false,
.alignment = @alignOf(info.return_type orelse void),
.default_value = null,
};
count += 1;
return @Type(.{
.Struct = .{
.layout = Auto,
.decls = &.{},
.fields = fields[0..count],
.is_tuple = false,
},
});
}
test "ArgumentStruct" {
const Test = struct {
fn A(a: i32, b: bool) bool {
return if (a > 10 and b) true else false;
}
fn B(s: []const u8) void {
_ = s;
}
fn C(alloc: std.mem.Allocator, arg1: i32, arg2: i32) bool {
_ = alloc;
return arg1 < arg2;
}
};
const ArgA = ArgumentStruct(Test.A);
const fieldsA = std.meta.fields(ArgA);
assert(fieldsA.len == 3);
assert(fieldsA[0].name[0] == '0');
assert(fieldsA[1].name[0] == '1');
assert(fieldsA[2].name[0] == 'r');
const ArgB = ArgumentStruct(Test.B);
const fieldsB = std.meta.fields(ArgB);
assert(fieldsB.len == 2);
assert(fieldsB[0].name[0] == '0');
assert(fieldsB[1].name[0] == 'r');
const ArgC = ArgumentStruct(Test.C);
const fieldsC = std.meta.fields(ArgC);
assert(fieldsC.len == 3);
}
exporter.zig:1688:19: error: comptime dereference requires '[3]builtin.Type.StructField' to have a well-defined layout, but it does not.
return @Type(.{
~^
exporter.zig:1724:32: note: called from here
const ArgC = ArgumentStruct(Test.C);
~~~~~~~~~~~~~~^~~~~~~~
The function is failing for function C because field[0..count] would actually create a slice. I managed to work around the issue already, but I’m wondering whether this is how Zig is going to work from now on or a regression that will get fixed.