Can't resolve inferred error set for function that returns conditional expression

[ghost]

const std = @import("std");

pub fn main() !void {
    const allocator = std.heap.page_allocator;
    const file = try openDataFile(allocator, .read);
    file.close();
}

fn openDataFile(
    allocator: *std.mem.Allocator,
    mode: enum { read, write },
) !std.fs.File {
    return switch (mode) {
        .read => std.fs.cwd().openFile("aaa", .{}),
        .write => std.fs.cwd().createFile("aaa", .{}),
    };
}

./asdf12.zig:12:10: error: cannot resolve inferred error set '@TypeOf(openDataFile).ReturnType.ErrorSet': function 'openDataFile' not fully analyzed yet
) !std.fs.File {
         ^
./asdf12.zig:5:18: note: referenced here
    const file = try openDataFile(allocator, .read);
                 ^

It also fails using return if (mode == .read) ... else ...;.

I can get it to work by adding trys:

• return try switch (mode) { ... };
• return switch (mode) { .read => try ... , .write => try ... };

Or by returning inside the switch statement:

• switch (mode) { .read => return ..., .write => return ... }

Or by assigning the conditional expression then returning the variable:

• const x = switch (mode) { .read => ... , .write => ... }; return x;

---

It becomes weirder if I have another try in the function. Now it does compile, but the compiler doesn't know about the possible error values from the return expression.

const std = @import("std");

pub fn main() !void {
    const allocator = std.heap.page_allocator;
    const file = openDataFile(allocator, .read) catch |err| {
        if (err == error.FileNotFound) {
            std.debug.warn("oh\n", .{});
        }
        return err;
    };
    file.close();
}

fn openDataFile(
    allocator: *std.mem.Allocator,
    mode: enum { read, write },
) !std.fs.File {
    const file_path = try std.fs.path.join(
        allocator,
        &[_][]const u8 { "one", "two" },
    );

    return switch (mode) {
        .read => std.fs.cwd().openFile(file_path, .{}),
        .write => std.fs.cwd().createFile(file_path, .{}),
    };
}

./asdf12.zig:6:17: error: error sets '@TypeOf(openDataFile).ReturnType.ErrorSet' and 'error{FileNotFound}' have no common errors
        if (err == error.FileNotFound) {
                ^

---

Note: I think this is a recent (as in the last week or two?) regression.