authorgravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2025-07-07 21:47:32-07:00
committergravatar for andrew@ziglang.orgAndrew Kelley <andrew@ziglang.org> 2025-07-07 22:43:53-07:00
log043079d7655efefbec97d8338b7d7fa3f9fcbdb0
treef8854e91cd66e0366401f3cd9f2878efe1ce0a28
parenta983f5b90f21c09ccc9e3fca1565b1b84b540307

std.io.Writer.VectorWrapper: fix vtable not being a unique addr

2 files changed, 7 insertions(+), 4 deletions(-)

lib/std/io/Reader.zig+2-2
......@@ -323,7 +323,7 @@ pub fn readVecLimit(r: *Reader, data: []const []u8, limit: Limit) Error!usize {
323323 },
324324 .writer = .{
325325 .buffer = if (first.len >= r.buffer.len) first else r.buffer,
326 .vtable = &Writer.VectorWrapper.vtable,
326 .vtable = Writer.VectorWrapper.vtable,
327327 },
328328 };
329329 var n = r.vtable.stream(r, &wrapper.writer, .limited(remaining)) catch |err| switch (err) {
......@@ -599,7 +599,7 @@ pub fn readSliceShort(r: *Reader, buffer: []u8) ShortError!usize {
599599 },
600600 .writer = .{
601601 .buffer = if (remaining.len >= r.buffer.len) remaining else r.buffer,
602 .vtable = &Writer.VectorWrapper.vtable,
602 .vtable = Writer.VectorWrapper.vtable,
603603 },
604604 };
605605 const n = r.vtable.stream(r, &wrapper.writer, .unlimited) catch |err| switch (err) {
lib/std/io/Writer.zig+5-2
......@@ -392,11 +392,14 @@ pub const VectorWrapper = struct {
392392 it: WritableVectorIterator,
393393 /// Tracks whether the "writable vector" API was used.
394394 used: bool = false,
395 pub const vtable: VTable = .{ .drain = fixedDrain };
395 pub const vtable: *const VTable = &unique_vtable_allocation;
396 /// This is intended to be constant but it must be a unique address for
397 /// `@fieldParentPtr` to work.
398 var unique_vtable_allocation: VTable = .{ .drain = fixedDrain };
396399};
397400
398401pub fn writableVectorIterator(w: *Writer) Error!WritableVectorIterator {
399 if (w.vtable == &VectorWrapper.vtable) {
402 if (w.vtable == VectorWrapper.vtable) {
400403 const wrapper: *VectorWrapper = @fieldParentPtr("writer", w);
401404 wrapper.used = true;
402405 return wrapper.it;