• d-bugmail puremagic.com (50/50) Jan 09 2019 https://issues.dlang.org/show_bug.cgi?id=19568

d-bugmail puremagic.com writes:

https://issues.dlang.org/show_bug.cgi?id=19568

          Issue ID: 19568
           Summary: hashOf should not unnecessarily call a struct's
                    fields' postblits & dtors in CTFE
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: druntime
          Assignee: nobody puremagic.com
          Reporter: n8sh.secondary hotmail.com

Example of code that doesn't work because a CTFE-only path in hashOf
unnecessarily calls an impure destructor and tries to call a disabled postblit:

---
void main()
{
    static struct S1
    {
         disable this(this);

        ~this()  nogc nothrow
        {
            import core.stdc.stdio;
            if (mptr) puts("impure");
        }

        size_t[2] pad;
        void* mptr;
    }

    static struct S2
    {
         disable this(this);

        ~this()  nogc nothrow
        {
            import core.stdc.stdio;
            if (fd != -1) puts("impure");
        }

        int fd = -1;
        S1 s1;
    }

    static struct S3
    {
        private S2 s2;
    }

    S3 s3;
    size_t h = ((ref S3 s3) pure => hashOf(s3))(s3);
}
---

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