When compiling C++ files, Zig unconditionally passes -nostdinc++ and,
if link_libcpp is set, adds its bundled libc++/libc++abi include paths
as replacements (see Compilation.zig). On MSVC targets this conflicts
with the MSVC C++ runtime headers (vcruntime_typeinfo.h,
vcruntime_exception.h, etc.), causing compilation failures in SIMD
C++ code.
The fix is to use linkLibC instead of linkLibCpp on MSVC. Zig always
passes -nostdinc to strip default search paths, but LibCDirs.detect
re-adds the MSVC SDK include directories, which contain both C and
C++ standard library headers. This gives us proper access to MSVC's
own <optional>, <iterator>, <cstddef>, etc. without the libc++
conflicts.
For the package builds (highway, simdutf, utfcpp) this means
switching from linkLibCpp to linkLibC on MSVC. For SharedDeps and
GhosttyZig, linkLibC is already called separately, so we just skip
linkLibCpp.
Zig's bundled libc++/libc++abi conflicts with the MSVC C++ runtime
headers (vcruntime_typeinfo.h, vcruntime_exception.h, etc.) when
targeting native-native-msvc. This caused compilation failures in
the SIMD C++ code due to -nostdinc++ suppressing MSVC headers and
libc++ types clashing with MSVC runtime types.
Skip linkLibCpp() for MSVC targets across all packages (highway,
simdutf, utfcpp) and the main build (SharedDeps, GhosttyZig) since
MSVC provides its own C++ standard library natively. Also add
missing <iterator> and <cstddef> includes that were previously
pulled in transitively through libc++ headers but are not
guaranteed by MSVC's headers.
Hi there, this is just a low-hanging fruit and it also prepares the way
for the future 0.15, which removes addStaticLibrary.
Please, let me know what to do on the `// TODO` comments.
This fixes an issue where Ghostty would not build against the macOS 15.5 SDK.
What was happening was that Zig was adding its embedded libc paths to
the clang command line, which included old headers that were
incompatible with the latest (macOS 15.5) SDK. Ghostty was adding the
newer paths but they were being overridden by the embedded libc paths.
The reason this was happening is because Zig was using its own logic to
find the libc paths and this was colliding with the paths we were
setting manually. To fix this, we now use a `libc.txt` file that
explicitly tells Zig where to find libc, and we base this on our own SDK
search logic.
Lazy dependencies are only fetched if the build script would actually
reach a usage of that dependency at runtime (when the `lazyDependency`
function is called). This can save a lot of network traffic, disk uage,
and time because we don't have to fetch and build dependencies that we
don't actually need.
Prior to this commit, Ghostty fetched almost everything for all
platforms and configurations all the time. This commit reverses that to
fetching almost nothing until it's actually needed.
There are very little downsides to doing this[1]. One downside is `zig
build --fetch` doesn't fetch lazy dependencies, but we don't rely on
this command for packaging and suggest using our custom shell script
that downloads a cached list of URLs (`build.zig.zon.txt`).
This commit doesn't cover 100% of dependencies, since some provide no
benefit to make lazy while the complexity to make them lazy is higher
(in code style typically).
Conversely, some simple dependencies are marked lazy even if they're
almost always needed if they don't introduce any real complexity to the
code, because there is very little downside to do so.
[1]: https://ziggit.dev/t/lazy-dependencies-best-dependencies/5509/5
This adds a new script `update-mirror.sh` which generates the proper
blob format for R2 (or any blob storage) to mirror all of our
dependencies.
It doesn't automate updating build.zig.zon but on an ongoing basis this
should be easy to do manually, and we can strive to automate it in the
future.
I omitted iTerm2 color themes because we auto-update that via CI and
updating all of the machinery to send it to our mirror and so on is a
pain. Additionally, this doesn't mirror transitive dependencies because
Zig doesn't have a way to fetch those from a mirror instead (unless you
pre-generate a full cache like packagers but that's not practical for
day to day development).
It's hugely beneficial just to get most of our dependencies mirrored.
