Checked C - Hackdot

Re:Checked C by gavinray on Wednesday December 21, 2022 @03:06PM (#34085713)

You might show an example of how to use D's templates (if it's possible) to emulate the more complex example of computing the bounds from an input argument

  char *strncpy(char * restrict dest : count(n),
              const char * restrict src : count(n),
              size_t n) : bounds(dest, (_Array_ptr<char>)dest + n);

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Re:Checked C by WalterBright on Wednesday December 21, 2022 @03:17PM (#34085848)

https://news.ycombinator.com/item?id=34085835

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Re:Checked C by gavinray on Wednesday December 21, 2022 @04:18PM (#34086534)

I meant something more like this (although this doesn't QUITE compile, but it's close I think):

    static ubyte* [n*2] requires_ptr_twice_as_large_as_input(n : uint)
    (
        ubyte*[n] input,
        ubyte*[n*2] output,
    ) {
        output[0..n] = input[0..n];
        output[n..2*n] = input[0..n];
        return output;
    }

    void main()
    {
        ubyte[10] input = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
        ubyte[20] output = new ubyte[20];
        requires_ptr_twice_as_large_as_input!(10)(&input, &output);
    }

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Re:Checked C by ntrel on Friday December 23, 2022 @05:50AM (#34104381)

This compiles:

    ref ubyte[n*2] requires_ptr_twice_as_large_as_input(uint n)
    (
        const ref ubyte[n] input,
        ref ubyte[n*2] output,
    ) {
        output[0..n] = input[0..n];
        output[n..2*n] = input[0..n];
        return output;
    }

    void main()
    {
        ubyte[10] input = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
        ubyte[20] output;
        requires_ptr_twice_as_large_as_input!(10)(input, output);

        import std.stdio;
        writeln(output);
        assert(output == input ~ input);
    }

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Re:Checked C by gavinray on Sunday December 25, 2022 @11:51AM (#34128694)

Thank you, neat to see it could be done (I had a hunch!)

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