* add runtime safety for slicing pointers, arrays, and slices.
* slicing without a sentinel value results in non-sentineled slice
* improved `std.debug.panic` handling of panic-during-panic
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.
Having ConstGlobalRefs be a pointer in ZigValue was a hack that caused
plenty of bugs. It was used to work around difficulties in type coercing
array values into slices.
However, after #3787 is merged, array values no longer type coerce into
slices, and so this provided an opportunity to clean up the code.
This has the nice effect of reducing stage1 peak RAM usage during the
std lib tests from 3.443 GiB to 3.405 GiB (saving 39 MiB).
There is one behavior test failing in this branch, which I plan to debug
after merging #3787.
- extracted functions
- factorised extern "C" into a block containing all function prototypes instead of writing macros all over the place
- using intermediate buffers instead of writing directly to the output file
this also deletes C string literals from the language, and then makes
the std lib changes and compiler changes necessary to get the behavior
tests and std lib tests passing again.
This removes the remaining hack in the implementation of anonymous
struct literals, and they can now therefore now have greater than 16
fields/elements.
