passing slice to fixed array not working with variable offset

[dlangBugzillaToGithub]

Manu reported this on 2019-05-28T06:12:19Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=19907

CC List

• Nicholas Wilson

Description

Consider this function:

  void fun(ref char[4]);

You can call it like this:

  char[20] buffer;

  // pass a slice of buffer as the static array
  fun(buffer[10 .. 10 + 4]);

That works as expected, but this doesn't work:

  // pass a slice of buffer as the static array with variable offset
  int x = 10;
  fun(buffer[x .. x + 4]);

This is pretty annoying... only workaround some hideous casting:

  fun(*cast(char[4]*)(buffer.ptr + x));

Would be nice for the prior expression to work in @safe code.

[dlangBugzillaToGithub]

dfj1esp02 commented on 2019-05-28T06:55:51Z

Workaround: buffer[x..$][0..4]

[dlangBugzillaToGithub]

turkeyman commented on 2019-05-28T07:45:33Z

Nice.

[dlangBugzillaToGithub]

iamthewilsonator commented on 2019-06-10T04:53:29Z

Is the workaround sufficient to close this?

[dlangBugzillaToGithub]

turkeyman commented on 2019-06-10T05:04:51Z

I don't think it should be closed, seems like a legit issue to me...
Workaround is workable though, so it's not a priority.