CI: Cmake warnings should be errors

[maflcko]

It is brittle to silently ignore Cmake warnings in the CI.

They should be turned into errors.

This will uncover an issue in the centos task that the correct python version is missing. I guess this should be fixed by installing and activating an acceptable python version.

[hebasto]

It is brittle to silently ignore Cmake warnings in the CI.

They should be turned into errors.

When building with Berkeley DB > 4.8, this warning will be always emitted:

bitcoin/CMakeLists.txt

Lines 107 to 109 in 78f1bff

	message(WARNING "Found Berkeley DB (BDB) other than 4.8.\n"
	"BDB (legacy) wallets opened by this build will not be portable!"
	)

[maflcko]

I guess I was mostly thinking about configure_warnings.

An alternative would be to require python to be disabled explicitly. Otherwise, it seems odd that every setting in cmake has a static default that can only be overridden explicitly, except for some, which are silently downgraded?

[maflcko]

This will uncover an issue in the centos task that the correct python version is missing. I guess this should be fixed by installing and activating an acceptable python version.

Fixed in #31593

[Sjors]

This doesn't seem release blocking to me.

The only open PR that points to this issue is #31665 which isn't marked for v29.

[davidgumberg]

Is it possible that instead it is the case that we have some warnings which should in fact be errors? For example, having a python version below minimum?