## Summary
Addresses #16965
This PR adds support for **opening and saving** files with legacy
encodings (non-UTF-8).
Previously, Zed failed to open files encoded in Shift-JIS, EUC-JP, Big5,
etc., displaying a "Could not open file" error screen. This PR
implements automatic encoding detection upon opening and ensures the
original encoding is preserved when saving.
## Implementation Details
1. **Worktree (Loading)**:
* Updated `load_file` to use `chardetng` for automatic encoding
detection.
* Files are decoded to UTF-8 internal strings for editing, while
preserving the detected `Encoding` metadata.
2. **Language / Buffer**:
* Added an `encoding` field to the `Buffer` struct to store the detected
encoding.
3. **Worktree (Saving)**:
* Updated `write_file` to accept the stored encoding.
* **Performance Optimization**:
* **UTF-8 Path**: Uses the existing optimized `fs.save` (streaming
chunks directly from Rope), ensuring no performance regression for the
vast majority of files.
* **Legacy Encoding Path**: Implemented a fallback that converts the
Rope to a contiguous `String/Bytes` in memory, re-encodes it to the
target format (e.g., Shift-JIS), and writes it to disk.
* *Note*: This fallback involves memory allocation, but it is necessary
to support legacy encodings without refactoring the `fs` crate's
streaming interfaces.
## Changes
- `crates/worktree`:
- Add dependencies: `encoding_rs`, `chardetng`.
- Update `load_file` to detect encoding and decode content.
- Update `write_file` to handle re-encoding on save.
- `crates/language`: Add `encoding` field and accessors to `Buffer`.
- `crates/project`: Pass encoding information between Worktree and
Buffer.
- `crates/vim`: Update `:w` command to use the new `write_file`
signature.
## Verification
I validated this manually using a Rust script to generate test files
with various encodings.
**Results:**
* ✅ **Success (Opened & Saved correctly):**
* **Japanese:** `Shift-JIS` (CP932), `EUC-JP`, `ISO-2022-JP`
* **Chinese:** `Big5` (Traditional), `GBK/GB2312` (Simplified)
* **Western/Unicode:** `Windows-1252` (CP1252), `UTF-16LE`, `UTF-16BE`
* ⚠️ **limitations (Detection accuracy):**
* Some specific encodings like `KOI8-R` or generic `Latin1` (ISO-8859-1)
may partially display replacement characters (`?`) depending on the file
content length. This is a known limitation of the heuristic detection
library (`chardetng`) rather than the saving logic.
Release Notes:
- Added support for opening and saving files with legacy encodings
(Shift-JIS, Big5, etc.)
---------
Co-authored-by: CrazyboyQCD <53971641+CrazyboyQCD@users.noreply.github.com>
Co-authored-by: Conrad Irwin <conrad.irwin@gmail.com>
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