downgrade gcc-libs (7.4.0-1 -> 5.3.0-3) breaks with message GPGME error: Invalid crypto engine

[andry81]

Steps:

1. Install: http://repo.msys2.org/distrib/i686/msys2-i686-20181211.exe
2. Upgrade as said here: https://www.msys2.org
   2.1. pacman -Syu
   Close the terminal window as was said at the end
   2.2. Restart msys2.exe and update again: pacman -Su
3. Start installing old gcc:
   3.1. pacman -U http://repo.msys2.org/msys/i686/gcc-libs-5.3.0-3-i686.pkg.tar.xz
   [2019-03-28 11:02] [ALPM] downgraded gcc-libs (7.4.0-1 -> 5.3.0-3)
   [2019-03-28 11:02] [ALPM] transaction completed
   3.2. pacman -U http://repo.msys2.org/msys/i686/gcc-5.3.0-3-i686.pkg.tar.xz
   list of errors beginning from GPGME and corrupted mingw32/mingw64/msys databases

From now and on nothing works. For example, pacman -Su generates the same errors.

I've tried to dig in from here: #393
But most "fast-to-try" workarounds does not work and i don't have the mentioned MacType.

[andry81]

If try to use a version suggested from here: https://www.msys2.org (in the top of the page):
http://repo.msys2.org/distrib/i686/msys2-i686-20180531.exe

And ignore step (2), then the downgrade performs without errors.

[StarWolf3000]

Why would you try to downgrade from 7.4.0-1 to 5.3.0-3?

[mati865]

By downgrading this library you have big chance on breaking everything that is dynamically linked to libs listed at the end of this page: https://msys2.duckdns.org/package/gcc-libs?repo=msys&variant=x86_64

It's not a bug.

[andry81]

By downgrading this library you have big chance on breaking everything that is dynamically linked to libs listed at the end of this page: https://msys2.duckdns.org/package/gcc-libs?repo=msys&variant=x86_64

I didn't want to downgrade particularly that library, i have had a need to build something with old compiler.
The packager itself stated to downgrade that library as a dependency to the old compiler.

[cbrt64]

You could try http://repo.msys2.org/distrib/i686/msys2-i686-20161025.exe (if you make it a separate installation, it will not interfere with your regular install). You can then do pacman -Su --needed base-devel msys2-devel ${whatever} to install your gcc/devel tools. Not giving -y to pacman will keep the repo database from back then, which is the last one to include gcc-5.3.0-3 as far as I can tell. All the packages you will need from back then should still be available in the repo.

And of course, keep in mind that there may be unfixed vulnerabilities in some of these older tools.