Generated foreach-body functions: Fix index when NOT using size_t

[kinke]

Similar to issue #21456, the druntime autodecoding helpers pass a pointer to the size_t array index. The generated foreach-body lambda used to load its index from that pointer, without verifying that the types match. So if the user uses an int index, it used to load the first 4 bytes, thus truncating to 32 bits on little-endian, but using the 32 upper bits for 64-bit big-endian targets. Solve this by adding a cast if needed.

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[kinke]

FYI @ibuclaw - I assume you've had to work around this somewhere too, to fix this for big-endian targets.

[ibuclaw]

FYI @ibuclaw - I assume you've had to work around this somewhere too, to fix this for big-endian targets.

Probably, PPCBE for example is not really given much love nowadays.

Though I don't think the sparc-solaris port has raised this - I can give it a try on one of the port boxes to check the current behaviour. As this is a patch from 2013, have you tried runtime without this?

[kinke]

At first I thought/hoped the old fix is superfluous by now, but I've checked the LLVM IR and seen that this is still a problem - the druntime helpers passing a pointer to a size_t, and the generated foreach-function treating it as a ref to the user-specified index type. I haven't run this on a big-endian target though, wouldn't know how to (and don't wanna use qemu for that).

[ibuclaw]

Running bootstrap on sparcv9-sun-solaris2.11, will test gdc-11 (last C++) and gdc-15.

[ibuclaw]

Yep, both exhibit runtime failure, I do see:

warning: foreach: loop index implicitly converted from ‘size_t’ to ‘short’ [-Wdeprecated]
    3 |     foreach (short i, dchar c; "ab")
      |     ^

So that's probably why no one's hit it on that target, library is built with -Werror and druntime is bug-free.