less undefined #4492
less undefined #4492
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| /// This is wrong! Avoid using this! | ||
| /// Any use of this should be replaced with the type itself to the optional type. | ||
| /// The undefind is unspecified value, cant be compared to anything include itself. | ||
| /// In Debug mode, | ||
| /// Zig writes 0xaa bytes to undefined memory. | ||
| /// This is to catch bugs early, and to help detect use of undefined memory in a debugger. | ||
| /// However, this behavior is only an implementation feature, not a language semantic, | ||
| /// so it is not guaranteed to be *observable* to code. | ||
| /// ref: https://ziglang.org/documentation/master/#undefined | ||
| pub fn assertDefined(val: anytype) void { | ||
| if (comptime !Environment.allow_assert) return; | ||
| const Type = @TypeOf(val); |
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We should use the optional type when we need this
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@dylan-conway Please take a look. Sorry for so many changes in a single PR, but they're pretty straightforward. |
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I think this is an interesting start but we shouldn't replace all usages of undefined with optional. We can do this more gradually. It'll be too difficult to confidently merge in this current state. When they're not pointers, marking things as optional can increase the size and alignment of structs which can in of itself cause new bugs |
This PR only changes ptr fields in the struct that default initialized to undefined to optional ptr, as an optional pointer is guaranteed to be the same size as a pointer. The null of the optional is guaranteed to be address 0, and only few non ptr type changes, so it should not cause any new bugs |
What does this PR do?
How did you verify your code works?
This PR includes:
undefinedchanges tofoo: ?ptr = null, as.?will panic insafemodeinstead ofUB. Plus an optional pointer is guaranteed to be the same size as a pointer. The null of the optional is guaranteed to be address 0= undefinedis removed.?should be optimized away in non-safe mode, so these changes should not impact performance, just make use of these nullable pointers more explicitCloses: #4426