Escaped check: store to comptime variable depends on runtime condition

[DerryAlex]

Zig Version

0.10.0, 0.11.0-dev.923+a52dcdd3c

Steps to Reproduce and Observed Behavior

The example comes from Zorrow.

var cell = RefCell(usize, opaque {}).init(20);
// fixme: Borrow no longer alive!
{
    var mutborrow = cell.borrowMut(opaque {});
    defer mutborrow.release();
    try testing.expectEqual(mutborrow.read(opaque {}), 20);
    mutborrow.write(0, opaque {});
    try testing.expectEqual(mutborrow.read(opaque {}), 0);
}

This should be equate to the following

comptime var borrows: usize = 0;
comptime var mutborrows: usize = 0;
if (borrows > 0 and mutborrows > 0) {
    @compileError("Value has already been unwrapped!");
} else if (borrows > 0 or mutborrows > 0) {
    @compileError("There is a borrow[mut] active!");
}
mutborrows += 1;
var value: usize = 20;
comptime var alive: bool = true;
if (!alive) @compileError("BorrowMut no longer alive!");
testing.expectEqual(value, 20) catch |err| {
    alive = false;
    return err;
}
if (!alive) @compileError("BorrowMut no longer alive!");
value = 0;
if (!alive) @compileError("BorrowMut no longer alive!");
testing.expectEqual(value, 0) catch |err| {
    alive = false;
    return err;
}
alive = false;

Observed Behavior

error: BorrowMut no longer alive!
  @compileError("BorrowMut no longer alive!");

This seems to be

comptime var borrows: usize = 0;
comptime var mutborrows: usize = 0;
if (borrows > 0 and mutborrows > 0) {
    @compileError("Value has already been unwrapped!");
} else if (borrows > 0 or mutborrows > 0) {
    @compileError("There is a borrow[mut] active!");
}
mutborrows += 1;
comptime var alive: bool = true;
if (!alive) @compileError("BorrowMut no longer alive!");
alive = false;
if (!alive) @compileError("BorrowMut no longer alive!"); // compile error here
if (!alive) @compileError("BorrowMut no longer alive!");
alive = false;
alive = false;

Expected Behavior

error: store to comptime variable depends on runtime condition
  defer mutborrow.release();
note: runtime condition here
  try testing.expectEqual(mutborrow.read(opaque {}), 20);

[Vexu]

That library abuses bugs in the Zig compiler (#7396) and is not expected to work.