Don't search system paths for Boost

[davisp]

Title says it all.

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TYPE: NO_HISTORY
DESC: Don't search system paths for Boost

[eddelbuettel]

Beautiful.

[eddelbuettel]

This unblocks the breakage seen before the PR and following the recent container changes.

[davisp]

I've opened [sc-40951] for tracking this.

[shortcut-integration]

This pull request has been linked to Shortcut Story #40951: Fix find_packge(Boost ...) picking system installed versions.

[teo-tsirpanis]

The root cause of the nightly failures is that we run them with vcpkg disabled and don't have an ExternalProject that downloads Boost if not found in the system.

I might be missing something but I don't see how this PR will fix it. If Boost will not be found from the system, where will it come from?

[teo-tsirpanis]

Launched a nightly build run for this branch.

[davisp]

@teo-tsirpanis We what now? This wasn't for nightlies, it was for avoiding using a system installed boost and forcing the use of the vcpkg installed version.

I had no idea we were still running ExternalProject builds so that'll take some doing to fix.

[teo-tsirpanis]

Since we added Boost in vcpkg.json the vcpkg-provided Boost already takes precedence.

[davisp]

Since we added Boost in vcpkg.json the vcpkg-provided Boost already takes precedence.

It would if Boost ports provided CMake config files, but they do not. See this issue for more background: microsoft/vcpkg#23460

[eddelbuettel]

Since we added Boost in vcpkg.json the vcpkg-provided Boost already takes precedence.

@teo-tsirpanis No. See the slack thread I started.

[teo-tsirpanis]

Nightlies still fail.

[teo-tsirpanis]

After looking at the documentation, Boost_NO_SYSTEM_PATHS means that CMake will only look at the paths specified by certain hint variables, which neither we nor vcpkg set. So we likely shouldn't merge this.

[davisp]

After looking at the documentation, Boost_NO_SYSTEM_PATHS means that CMake will only look at the paths specified by certain hint variables, which neither we nor vcpkg set. So we likely shouldn't merge this.

I saw that too. But... it works? If you know how to reliably get a path for ${VCPKG_INSTALLED_DIR}/${VCPKG_TRIPLET} to set for the BOOST_ROOT variable, I'd be more than happy to add it. But when I tried those they were empty and it was working regardless so I stopped caring at that point.

Also, my assumption is that its searching the vcpkg configured include/link directories which aren't system paths.

[teo-tsirpanis]

I will more thoroughly look at it tomorrow.