a18fd41064
Our usage of `ucontext_t` in the standard library was kind of problematic. We unnecessarily mimiced libc-specific structures, and our `getcontext` implementation was overkill for our use case of stack tracing. This commit introduces a new namespace, `std.debug.cpu_context`, which contains "context" types for various architectures (currently x86, x86_64, ARM, and AARCH64) containing the general-purpose CPU registers; the ones needed in practice for stack unwinding. Each implementation has a function `current` which populates the structure using inline assembly. The structure is user-overrideable, though that should only be necessary if the standard library does not have an implementation for the *architecture*: that is to say, none of this is OS-dependent. Of course, in POSIX signal handlers, we get a `ucontext_t` from the kernel. The function `std.debug.cpu_context.fromPosixSignalContext` converts this to a `std.debug.cpu_context.Native` with a big ol' target switch. This functionality is not exposed from `std.c` or `std.posix`, and neither are `ucontext_t`, `mcontext_t`, or `getcontext`. The rationale is that these types and functions do not conform to a specific ABI, and in fact tend to get updated over time based on CPU features and extensions; in addition, different libcs use different structures which are "partially compatible" with the kernel structure. Overall, it's a mess, but all we need is the kernel context, so we can just define a kernel-compatible structure as long as we don't claim C compatibility by putting it in `std.c` or `std.posix`. This change resulted in a few nice `std.debug` simplifications, but nothing too noteworthy. However, the main benefit of this change is that DWARF unwinding---sometimes necessary for collecting stack traces reliably---now requires far less target-specific integration. Also fix a bug I noticed in `PageAllocator` (I found this due to a bug in my distro's QEMU distribution; thanks, broken QEMU patch!) and I think a couple of minor bugs in `std.debug`. Resolves: #23801 Resolves: #23802
A general-purpose programming language and toolchain for maintaining robust, optimal, and reusable software.
Documentation
If you are looking at this README file in a source tree, please refer to the Release Notes, Language Reference, or Standard Library Documentation corresponding to the version of Zig that you are using by following the appropriate link on the download page.
Otherwise, you're looking at a release of Zig, so you can find the language
reference at doc/langref.html, and the standard library documentation by
running zig std, which will open a browser tab.
Installation
A Zig installation is composed of two things:
- The Zig executable
- The lib/ directory
At runtime, the executable searches up the file system for the lib/ directory, relative to itself:
- lib/
- lib/zig/
- ../lib/
- ../lib/zig/
- (and so on)
In other words, you can unpack a release of Zig anywhere, and then begin
using it immediately. There is no need to install it globally, although this
mechanism supports that use case too (i.e. /usr/bin/zig and /usr/lib/zig/).
Building from Source
Ensure you have the required dependencies:
- CMake >= 3.15
- System C/C++ Toolchain
- LLVM, Clang, LLD development libraries == 21.x
Then it is the standard CMake build process:
mkdir build
cd build
cmake ..
make install
For more options, tips, and troubleshooting, please see the Building Zig From Source page on the wiki.
Building from Source without LLVM
In this case, the only system dependency is a C compiler.
cc -o bootstrap bootstrap.c
./bootstrap
This produces a zig2 executable in the current working directory. This is a
"stage2" build of the compiler,
without LLVM extensions, and is
therefore lacking these features:
- Release mode optimizations
- aarch64 machine code backend
- @cImport
- zig translate-c
- Ability to compile assembly files
- Some ELF linking features
- Most COFF/PE linking features
- Some WebAssembly linking features
- Ability to create import libs from def files
- Ability to create static archives from object files
- Ability to compile C, C++, Objective-C, and Objective-C++ files
However, a compiler built this way does provide a C backend, which may be useful for creating system packages of Zig projects using the system C toolchain. In this case, LLVM is not needed!
Furthermore, a compiler built this way provides an LLVM backend that produces bitcode files, which may be compiled into object files via a system Clang package. This can be used to produce system packages of Zig applications without the Zig package dependency on LLVM.
Contributing
Zig is Free and Open Source Software. We welcome bug reports and patches from everyone. However, keep in mind that Zig governance is BDFN (Benevolent Dictator For Now) which means that Andrew Kelley has final say on the design and implementation of everything.
One of the best ways you can contribute to Zig is to start using it for an open-source personal project.
This leads to discovering bugs and helps flesh out use cases, which lead to further design iterations of Zig. Importantly, each issue found this way comes with real world motivations, making it straightforward to explain the reasoning behind proposals and feature requests.
You will be taken much more seriously on the issue tracker if you have a personal project that uses Zig.
The issue label Contributor Friendly exists to help you find issues that are limited in scope and/or knowledge of Zig internals.
Please note that issues labeled Proposal but do not also have the Accepted label are still under consideration, and efforts to implement such a proposal have a high risk of being wasted. If you are interested in a proposal which is still under consideration, please express your interest in the issue tracker, providing extra insights and considerations that others have not yet expressed. The most highly regarded argument in such a discussion is a real world use case.
For more tips, please see the Contributing page on the wiki.
Community
The Zig community is decentralized. Anyone is free to start and maintain their own space for Zig users to gather. There is no concept of "official" or "unofficial". Each gathering place has its own moderators and rules. Users are encouraged to be aware of the social structures of the spaces they inhabit, and work purposefully to facilitate spaces that align with their values.
Please see the Community wiki page for a public listing of social spaces.