std.mem.Allocator.free: also account for sentinel if it's a pointer to an array #23020
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change looks sus, needs a better writeup |
BlockOG
changed the title
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I believe the correct fix would be at Line 4308 in 5c44934 - return @as(cast_target, @ptrCast(slice))[0 .. slice.len * @sizeOf(std.meta.Elem(Slice))];
+ return @as(cast_target, @ptrCast(slice))[0 .. (slice.len + @intFromBool(std.meta.sentinel(Slice) != null)) * @sizeOf(std.meta.Elem(Slice))]; |
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agreed, cc #19984 |
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The correct fix is deprecating |
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Actually, I wasn't thinking clearly earlier. The change proposed by this PR is just plain incorrect. To free a pointer to an array |
ifreund
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Mar 26, 2025
Currently the only function that handles sentinel terminated slices properly is free. All other uses of mem.sliceAsBytes() in the allocator interface lack proper handling of a possible sentinel. This commit changes the Allocator interface to use @ptrCast() plus the new mem.absorbSentinel() instead. This also makes incorrectly passing a pointer to array to Allocator.free() a compile error. The proper function to free a pointer to an array is Allocator.destroy(). Reported-by: David Vanderson <[email protected]> References: ziglang#19984 References: ziglang#22706 References: ziglang#23020
ifreund
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Currently the only function that handles sentinel terminated slices properly is free. All other uses of mem.sliceAsBytes() in the allocator interface lack proper handling of a possible sentinel. This commit changes the Allocator interface to use @ptrCast() plus the new mem.absorbSentinel() instead. This also makes incorrectly passing a pointer to array to Allocator.free() a compile error. The proper function to free a pointer to an array is Allocator.destroy(). Reported-by: David Vanderson <[email protected]> References: ziglang#19984 References: ziglang#22706 References: ziglang#23020
mlugg
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May 18, 2025
Currently the only function that handles sentinel terminated slices properly is free. All other uses of mem.sliceAsBytes() in the allocator interface lack proper handling of a possible sentinel. This commit changes the Allocator interface to use @ptrCast() plus the new mem.absorbSentinel() instead. This also makes incorrectly passing a pointer to array to Allocator.free() a compile error. The proper function to free a pointer to an array is Allocator.destroy(). Reported-by: David Vanderson <[email protected]> References: ziglang#19984 References: ziglang#22706 References: ziglang#23020
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Fixes #23019 by checking the sentinel if it's a pointer to an array