ChannelStatistics breaks the cgo

[freakmaxi]

Hello,

When I use imagemagick 7.1.1-24 or higher. I'm getting this compile error

cgo: ../../../../../../../../imagick/imagick/channel_statistics.go:16:6: unexpected: 16-byte float type - long double

Because of this commit in imagemagick

ImageMagick/ImageMagick@1f241fd

that contains long double variable additions in ChannelStatistics (long double - that is not precisely defined in golang).

Do you have any idea to get over it? It is a long time problem for me when I use golang with C integration and I couldn't find any solution to fix the long double variable usage.

I'm able to compile the golang application if I convert long double variables to double in statistics.h file in imagemagick header file and it will be mapped to float64 in golang. I couldn't have done any deep test if it is working but I believe, it will not break something. However, it is not a proper solution and I'm looking for a solution out of the box.

Thanks.

[justinfx]

The only useful information I could find on long double handling in cgo is here: https://groups.google.com/g/golang-nuts/c/JnuXVK2lv_s?pli=1

If it's a struct field, there isn't really any best practice. Avoid
referring to the struct from Go, I guess.

It doesn't seem that any of the Imagick binding code is actually using ChannelStatistics as a input or output parameter. So that implies that it is just an unused binding right now and we could change it to fix compilation. The *C.ChannelStatistics is an unexported field as well, so we can do whatever we want to the Go ChannelStatistics struct.
The easiest fix would be to just remove the cs *C.ChannelStatistics field on the Go side for now until there are bindings added that actually make use of it. Otherwise, we could add a C shim to that file after the include that redefines the struct with a double.

[freakmaxi]

Yes, I've also reached to that google group post while I'm looking for a solution and also this (https://tip.golang.org/src/cmd/cgo/internal/testerrors/testdata/issue28069.go) which is related to the issue in golang side.

If there is no usage for that, I'll remove it and may be you can also put _ (underscore) to the file to omit from the compilation and create a new release so I can continue to use your repo other than my fork to have the future updates in your releases...

thank you for your quick response.

[justinfx]

I've tagged this fix as v3.5.1

[fghj1]

Ah ... I changed my program for three days. For three days I could die.
Oh My GOD!
Thank you!!!
I lived!!