CMake static-library build is broken on Linux

[steven-johnson]

On Linux, configure a build with HALIDE_SHARED_LIBRARY=OFF, then "make all -k". You'll fail a fair number of targets with "cannot find -lxml2"

[steven-johnson]

tagging @shoaibkamil as it may be related to the Makefile LLVM issue you are investigating (ie, I think the xml2 dep is coming in from LLVM but the CMake build doesn't try to detect the necessary system libs in the way that Make does)

[steven-johnson]

(Doesn't seem to replicate on OSX for me. Haven't tried WIndows or Mingw)

[shoaibkamil]

Hmm, with HALIDE_SHARED_LIBRARY=ON, do we get a static library? Sorry, I'm confused given the title.

[steven-johnson]

Hmm, with HALIDE_SHARED_LIBRARY=ON, do we get a static library? Sorry, I'm confused given the title.

Sorry, typo in my description, fixed now

[shoaibkamil]

Got it. This definitely looks related, I'll take a look after #4576 is merged.

[alexreinking]

On cmake-modern, the command to build static libs is:

dev@host:~/Halide-build$ cmake -G Ninja -DBUILD_SHARED_LIBS=OFF -DCMAKE_BUILD_TYPE=Release ../Halide

You can omit -G Ninja if you don't have ninja-build installed.

[alexreinking]

I ran a static build on Linux with cmake-modern and didn't encounter this issue. However, did run into problems with the autoschedulers that I need to iron out.