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Writer: Delete writePreserve/writeAllPreserve

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This is one way of partially addressing https://github.com/ziglang/zig/issues/24767

- These functions are unused
- These functions are untested
- These functions are broken
  + The same dangling pointer bug from 6219c015d8 exists in `writePreserve`
  + The order of the bytes preserved in relation to the `bytes` being written can differ depending on unused buffer capacity at the time of the call and the drain implementation.

If there ends up being a need for these functions, they can be fixed and added back.
This commit is contained in:
Ryan Liptak 2025-08-10 12:43:21 -07:00 • committed by Andrew Kelley
parent b9a6dae2ae
commit 3280fc98f3
1 changed files with 0 additions and 31 deletions
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31
lib/std/Io/Writer.zig
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@ -498,25 +498,6 @@ pub fn write(w: *Writer, bytes: []const u8) Error!usize {
return w.vtable.drain(w, &.{bytes}, 1);
}
/// Asserts `buffer` capacity exceeds `preserve_len`.
pub fn writePreserve(w: *Writer, preserve_len: usize, bytes: []const u8) Error!usize {
assert(preserve_len <= w.buffer.len);
if (w.end + bytes.len <= w.buffer.len) {
@branchHint(.likely);
@memcpy(w.buffer[w.end..][0..bytes.len], bytes);
w.end += bytes.len;
return bytes.len;
}
const temp_end = w.end -| preserve_len;
const preserved = w.buffer[temp_end..w.end];
w.end = temp_end;
defer w.end += preserved.len;
const n = try w.vtable.drain(w, &.{bytes}, 1);
assert(w.end <= temp_end + preserved.len);
@memmove(w.buffer[w.end..][0..preserved.len], preserved);
return n;
}
/// Calls `drain` as many times as necessary such that all of `bytes` are
/// transferred.
pub fn writeAll(w: *Writer, bytes: []const u8) Error!void {
@ -524,18 +505,6 @@ pub fn writeAll(w: *Writer, bytes: []const u8) Error!void {
while (index < bytes.len) index += try w.write(bytes[index..]);
}
/// Calls `drain` as many times as necessary such that all of `bytes` are
/// transferred.
///
/// When draining the buffer, ensures that at least `preserve_len` bytes
/// remain buffered.
///
/// Asserts `buffer` capacity exceeds `preserve_len`.
pub fn writeAllPreserve(w: *Writer, preserve_len: usize, bytes: []const u8) Error!void {
var index: usize = 0;
while (index < bytes.len) index += try w.writePreserve(preserve_len, bytes[index..]);
}
/// Renders fmt string with args, calling `writer` with slices of bytes.
/// If `writer` returns an error, the error is returned from `format` and
/// `writer` is not called again.