Previously, the compiler had special logic to determine whether to
include the startup code, which was in `std/special/start.zig`. Now,
the file is moved to `std/start.zig`, and there is no special logic
in the compiler. Instead, the standard library unconditionally imports
the `start.zig` file, which then has a `comptime` block that does the
logic of determining what, if any, start symbols to export. Instead of
`start.zig` being in its own special package, it is just another normal
file that is part of the standard library.
`std.builtin.TestFn` is now part of the standard library rather than
specially generated by the compiler.
* All the data types from `@import("builtin")` are moved to
`@import("std").builtin`. The target-related types are moved
to `std.Target`. This allows the data types to have methods, such as
`std.Target.current.isDarwin()`.
* `std.os.windows.subsystem` is moved to
`std.Target.current.subsystem`.
* Remove the concept of the panic package from the compiler
implementation. Instead, `std.builtin.panic` is always the panic
function. It checks for `@hasDecl(@import("root"), "panic")`,
or else provides a default implementation.
This is an important step for multibuilds (#3028). Without this change,
the types inside the builtin namespace look like different types, when
trying to merge builds with different target settings. With this change,
Zig can figure out that, e.g., `std.builtin.Os` (the enum type) from one
compilation and `std.builtin.Os` from another compilation are the same
type, even if the target OS value differs.
Andrew Kelley
Christine Dodrill
kprotty
daurnimator