Use std.heap.FixedBufferAllocator combined with
std.heap.DirectAllocator instead.
std.mem.FixedBufferAllocator is moved to std.heap.FixedBufferAllocator
* DirectAllocator does the underlying syscall for every allocation.
* ArenaAllocator takes another allocator as an argument and
allocates bytes up front, falling back to DirectAllocator with
increasingly large allocation sizes, to avoid calling it too often.
Then the entire arena can be freed at once.
The self hosted parser is updated to take advantage of ArenaAllocator
for the AST that it returns. This significantly reduces the complexity
of cleanup code.
docgen and build runner are updated to use the combination of
ArenaAllocator and DirectAllocator instead of IncrementingAllocator,
which is now deprecated in favor of FixedBufferAllocator combined
with DirectAllocator.
The C allocator calls aligned_alloc instead of malloc, in order to
respect the alignment parameter.
Added asserts in Allocator to ensure that implementors of the
interface return slices of the correct size.
Fixed a bug in Allocator when you call realloc to grow the allocation.
* move std.io.File to std.os.File
* add `zig fmt` to self hosted compiler
* introduce std.io.BufferedAtomicFile API
* introduce std.os.AtomicFile API
* add `std.os.default_file_mode`
* change FileMode on posix from being a usize to a u32
* add std.os.File.mode to return mode of an open file
* std.os.copyFile copies the mode from the source file instead of
using the default file mode for the dest file
* move `std.os.line_sep` to `std.cstr.line_sep`
