f21455b7e7
### This is it! This one (and the other stacked PRs) and #11782 should finally give a clean test run on Windows! ## Summary - Increase `@setEvalBranchQuota` from 1M to 10M (too much? how much is too much?) in `checkGhosttyHEnum` (src/lib/enum.zig) - Fixes the only remaining test failure on Windows MSVC: `ghostty.h MouseShape` ## Context This one was fun! Claude started blabbering, diminishing returns it said. It couldn't figure out. So I called Dario and it worked. Nah, much easier than that. On MSVC, the translate-c output for `ghostty.h` is ~360KB with ~2173 declarations (vs ~112KB / ~1502 on Linux/Mac) because `<sys/types.h>` and `<BaseTsd.h>` pull in Windows SDK headers. The `checkGhosttyHEnum` function uses a nested `inline for` (enum fields x declarations) with comptime string comparisons. For MouseShape (34 variants), this generates roughly 34 x 2173 x ~20 = ~1.5M comptime branches, exceeding the 1M quota. The failure was confusing because it presented as a runtime error ("ghostty.h is missing value for GHOSTTY_MOUSE_SHAPE_DEFAULT") rather than a compile error. The constants exist in the translate-c output and the test compiles, but the comptime loop silently stops matching when it hits the branch limit, so `set.remove` is never called and the set reports all entries as missing at runtime. ## How we found it The translate-c output clearly had all 34 GHOSTTY_MOUSE_SHAPE_* constants, yet the test reported all of them as missing. I asked Claude to list 5 hypotheses (decl truncation, branch quota, string comparison bug, declaration ordering, field access failure) and to write 7 targeted POC tests in enum.zig to isolate each step of `checkGhosttyHEnum`: 1. POC1-2: Module access and declaration count (both passed) 2. POC3: `@hasDecl` for the constant (passed) 3. POC4: Direct field value access (passed) 4. POC5: `inline for` over decls with string comparison - **compile error: "evaluation exceeded 1000 backwards branches"** 5. POC6: Same but with 10M quota (passed) 6. POC7: Full `checkGhosttyHEnum` clone with 10M quota - **passed, confirming the fix** POC5 was the key: the default 1000 branch limit for test code confirmed the comptime budget mechanism. The existing 1M quota in `checkGhosttyHEnum` was enough for Linux/Mac (1502 declarations) but not for MSVC (2173 declarations) with larger enums. ## Stack Stacked on 016-windows/fix-libcxx-msvc. ## Test plan ### Cross-platform results (`zig build test` / `zig build -Dapp-runtime=none test` on Windows) | | Windows | Linux | Mac | |---|---|---|---| | **BEFORE** (016,ce9930051) | FAIL - 49/51, 2630/2654, 1 test failed, 23 skipped | PASS - 86/86, 2655/2678, 23 skipped | PASS - 160/160, 2655/2662, 7 skipped | | **AFTER** (017,68378a0bb) | FAIL - 49/51, 2631/2654, 23 skipped | PASS - 86/86, 2655/2678, 23 skipped | PASS - 160/160, 2655/2662, 7 skipped | ### Windows: what changed (2630 -> 2631 tests, MouseShape fixed) **Fixed by this PR:** - `ghostty.h MouseShape` test - was failing because comptime branch quota exhaustion silently prevented the inline for loop from matching any constants **Remaining failure (pre-existing, unrelated):** - `config.Config.test.clone can then change conditional state` - segfaults (exit code 3) on Windows. We investigated this and it looked familiar.. cherry-picking the `CommaSplitter `fix from PR #11782 resolved it! The backslash path handling in `CommaSplitter `breaks theme path parsing on Windows, which is exactly what that PR addresses. So once that lands, we should be in a good place... ready to ship to Windows users! (just kidding) ### Linux/macOS: no regressions Identical pass counts and test results before and after. ## What I Learnt - Comptime branch quota exhaustion in Zig does not always surface as a clean compile error. When it happens inside an `inline for` loop with `comptime` string comparisons that gate runtime code (like `set.remove`), the effect is that matching code is silently not generated. The test compiles and runs, but the runtime behavior is wrong because the matching branches were never emitted. This makes the failure look like a data issue (missing declarations) rather than a compile budget issue. - When debugging comptime issues, writing small isolated POC tests that exercise each step of the failing function independently is very effective. It took 7 targeted tests to pinpoint the exact failure point. - Cross-platform translate-c outputs can vary significantly in size. On MSVC, system headers are much larger than on Linux/Mac, which affects comptime budgets for any code that iterates over translated module declarations.
Ghostty
Fast, native, feature-rich terminal emulator pushing modern features.
A native GUI or embeddable library via libghostty.
About
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Download
·
Documentation
·
Contributing
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Developing
About
Ghostty is a terminal emulator that differentiates itself by being fast, feature-rich, and native. While there are many excellent terminal emulators available, they all force you to choose between speed, features, or native UIs. Ghostty provides all three.
libghostty is a cross-platform, zero-dependency C and Zig library
for building terminal emulators or utilizing terminal functionality
(such as style parsing). Anyone can use libghostty to build a terminal
emulator or embed a terminal into their own applications. See
Ghostling for a minimal complete project
example or the examples directory
for smaller examples of using libghostty in C and Zig.
For more details, see About Ghostty.
Download
See the download page on the Ghostty website.
Documentation
See the documentation on the Ghostty website.
Contributing and Developing
If you have any ideas, issues, etc. regarding Ghostty, or would like to contribute to Ghostty through pull requests, please check out our "Contributing to Ghostty" document. Those who would like to get involved with Ghostty's development as well should also read the "Developing Ghostty" document for more technical details.
Roadmap and Status
Ghostty is stable and in use by millions of people and machines daily.
The high-level ambitious plan for the project, in order:
| # | Step | Status |
|---|---|---|
| 1 | Standards-compliant terminal emulation | ✅ |
| 2 | Competitive performance | ✅ |
| 3 | Rich windowing features -- multi-window, tabbing, panes | ✅ |
| 4 | Native Platform Experiences | ✅ |
| 5 | Cross-platform libghostty for Embeddable Terminals |
✅ |
| 6 | Ghostty-only Terminal Control Sequences | ❌ |
Additional details for each step in the big roadmap below:
Standards-Compliant Terminal Emulation
Ghostty implements all of the regularly used control sequences and can run every mainstream terminal program without issue. For legacy sequences, we've done a comprehensive xterm audit comparing Ghostty's behavior to xterm and building a set of conformance test cases.
In addition to legacy sequences (what you'd call real "terminal" emulation), Ghostty also supports more modern sequences than almost any other terminal emulator. These features include things like the Kitty graphics protocol, Kitty image protocol, clipboard sequences, synchronized rendering, light/dark mode notifications, and many, many more.
We believe Ghostty is one of the most compliant and feature-rich terminal emulators available.
Terminal behavior is partially a de jure standard (i.e. ECMA-48) but mostly a de facto standard as defined by popular terminal emulators worldwide. Ghostty takes the approach that our behavior is defined by (1) standards, if available, (2) xterm, if the feature exists, (3) other popular terminals, in that order. This defines what the Ghostty project views as a "standard."
Competitive Performance
Ghostty is generally in the same performance category as the other highest performing terminal emulators.
"The same performance category" means that Ghostty is much faster than traditional or "slow" terminals and is within an unnoticeable margin of the well-known "fast" terminals. For example, Ghostty and Alacritty are usually within a few percentage points of each other on various benchmarks, but are both something like 100x faster than Terminal.app and iTerm. However, Ghostty is much more feature rich than Alacritty and has a much more native app experience.
This performance is achieved through high-level architectural decisions and low-level optimizations. At a high-level, Ghostty has a multi-threaded architecture with a dedicated read thread, write thread, and render thread per terminal. Our renderer uses OpenGL on Linux and Metal on macOS. Our read thread has a heavily optimized terminal parser that leverages CPU-specific SIMD instructions. Etc.
Rich Windowing Features
The Mac and Linux (build with GTK) apps support multi-window, tabbing, and splits with additional features such as tab renaming, coloring, etc. These features allow for a higher degree of organization and customization than single-window terminals.
Native Platform Experiences
Ghostty is a cross-platform terminal emulator but we don't aim for a least-common-denominator experience. There is a large, shared core written in Zig but we do a lot of platform-native things:
- The macOS app is a true SwiftUI-based application with all the things you would expect such as real windowing, menu bars, a settings GUI, etc.
- macOS uses a true Metal renderer with CoreText for font discovery.
- macOS supports AppleScript, Apple Shortcuts (AppIntents), etc.
- The Linux app is built with GTK.
- The Linux app integrates deeply with systemd if available for things like always-on, new windows in a single instance, cgroup isolation, etc.
Our goal with Ghostty is for users of whatever platform they run Ghostty on to think that Ghostty was built for their platform first and maybe even exclusively. We want Ghostty to feel like a native app on every platform, for the best definition of "native" on each platform.
Cross-platform libghostty for Embeddable Terminals
In addition to being a standalone terminal emulator, Ghostty is a
C-compatible library for embedding a fast, feature-rich terminal emulator
in any 3rd party project. This library is called libghostty.
Due to the scope of this project, we're breaking libghostty down into
separate actually libraries, starting with libghostty-vt. The goal of
this project is to focus on parsing terminal sequences and maintaining
terminal state. This is covered in more detail in this
blog post.
libghostty-vt is already available and usable today for Zig and C and
is compatible for macOS, Linux, Windows, and WebAssembly. The functionality
is extremely stable (since its been proven in Ghostty GUI for a long time),
but the API signatures are still in flux.
libghostty is already heavily in use. See examples
for small examples of using libghostty in C and Zig or the
Ghostling project for a
complete example. See awesome-libghostty
for a list of projects and resources related to libghostty.
We haven't tagged libghostty with a version yet and we're still working on a better docs experience, but our Doxygen website is a good resource for the C API.
Ghostty-only Terminal Control Sequences
We want and believe that terminal applications can and should be able to do so much more. We've worked hard to support a wide variety of modern sequences created by other terminal emulators towards this end, but we also want to fill the gaps by creating our own sequences.
We've been hesitant to do this up until now because we don't want to create more fragmentation in the terminal ecosystem by creating sequences that only work in Ghostty. But, we do want to balance that with the desire to push the terminal forward with stagnant standards and the slow pace of change in the terminal ecosystem.
We haven't done any of this yet.
Crash Reports
Ghostty has a built-in crash reporter that will generate and save crash
reports to disk. The crash reports are saved to the $XDG_STATE_HOME/ghostty/crash
directory. If $XDG_STATE_HOME is not set, the default is ~/.local/state.
Crash reports are not automatically sent anywhere off your machine.
Crash reports are only generated the next time Ghostty is started after a crash. If Ghostty crashes and you want to generate a crash report, you must restart Ghostty at least once. You should see a message in the log that a crash report was generated.
Note
Use the
ghostty +crash-reportCLI command to get a list of available crash reports. A future version of Ghostty will make the contents of the crash reports more easily viewable through the CLI and GUI.
Crash reports end in the .ghosttycrash extension. The crash reports are in
Sentry envelope format. You can
upload these to your own Sentry account to view their contents, but the format
is also publicly documented so any other available tools can also be used.
The ghostty +crash-report CLI command can be used to list any crash reports.
A future version of Ghostty will show you the contents of the crash report
directly in the terminal.
To send the crash report to the Ghostty project, you can use the following CLI command using the Sentry CLI:
SENTRY_DSN=https://e914ee84fd895c4fe324afa3e53dac76@o4507352570920960.ingest.us.sentry.io/4507850923638784 sentry-cli send-envelope --raw <path to ghostty crash>
Warning
The crash report can contain sensitive information. The report doesn't purposely contain sensitive information, but it does contain the full stack memory of each thread at the time of the crash. This information is used to rebuild the stack trace but can also contain sensitive data depending on when the crash occurred.