Fix GLEW deprecation errors

[bellenot]

• Move TGLWSIncludes.h from the inc to the src directory
• Don't install the GLEW headers

[silverweed]

Thanks

[github-actions]

Test Results

    20 files      20 suites   3d 14h 7m 30s ⏱️
 3 707 tests  3 707 ✅ 0 💤 0 ❌
72 342 runs  72 342 ✅ 0 💤 0 ❌

Results for commit e16b358.

[smuzaffar]

Hi @bellenot , while testing latest root mater changes , we get build errors in CMSSW [a]. The root change set which we are testing in cmssw is 4ee5e77...59b8b01 . I think this error might be a side effect of change here. Any idea why this header is now needed ?

[a]

In file included from src/Fireworks/Core/src/CmsAnnotation.cc:4:
.../lcg/root/6.39.1-f6b681b05d584b7e93413a4cff8a643d/include/TGLIncludes.h:21:10: fatal error: GL/glew.h: No such file or directory
   21 | #include <GL/glew.h>

[smuzaffar]

TGLIncludes.h header in root has not changed in years , so may be something wrong on our side. Let me first check if this still works with previous commit of root

[smuzaffar]

ah previously GL/glew.h header was part of root distribution but it is not any more. So are we suppose to get glew-devel from system ?

[guitargeek]

Yes, I guess you don't build ROOT with builtin_glew on?

[smuzaffar]

we do build ROOT with builtin_glew https://github.com/cms-sw/cmsdist/blob/IB/CMSSW_16_0_X/rootmaster/root.spec#L91

  -Dbuiltin_zlib=OFF \
  -Dbuiltin_lzma=OFF \
  -Dbuiltin_gsl=OFF \
  -Dbuiltin_glew=ON \
  -Dbuiltin_ftgl=ON \
  -Dbuiltin_gl2ps=ON \
  -Dbuiltin_xxhash=ON \

[smuzaffar]

cmake also confirms this
-- Enabled support for: asimage asimage_tiff builtin_clang builtin_cling builtin_civetweb builtin_ftgl builtin_gl2ps builtin_glew builtin_llvm builtin_openui5 builtin_xxhash check_connection clad dataframe davix dcache fftw3 gdml geom http imt mathmore opengl pyroot roofit root7 runtime_cxxmodules shared spectrum ssl thisroot_scripts tmva tmva-cpu tmva-cudnn tmva-pymva tpython use_gsl_cblas webgui x11 xml xrootd

[bellenot]

@smuzaffar Weird, it looks like GLEW_INCLUDE_DIR (or GLEW_INCLUDE_DIRS) is missing, somehow. I'll check

[guitargeek]

Wait, isn't it just because this PR removed installing of the glew headers in builtins/glew/CMakeLists.txt?

So no matter what the include path is, the headers won't be found because ROOT doesn't ship them anymore.

[guitargeek]

This PR did two things in one commit that seem unrelated to me:

• Move TGLWSIncludes.h from the inc to the src directory

  • Don't install the GLEW headers

The TGLWSIncludes.h header was properly deprecated with an entry in the 6.38 release notes:
https://github.com/root-project/root/blob/master/README/ReleaseNotes/v638/index.md?plain=1#L44

Installing the builtin glew headers was not deprecated yet, so this change comes at a surprise. But I agree it's a good change, because we want to replace glew with glad anyway! But I think we are missing a few things in the release notes:

• deprecate the installed glew headers in 6.38 with announcement in the release notes
• mention in the 6.40 release notes that the builtin glew headers were removed (as done in this PR)

As a consequence, we also need to deprecate the TGLIncludes.h header, because this was a wrapper for the builtin <GL/glew.h>. I can take care of that stuff, because I started the whole chain with the deprecation of TGLWSIncludes.h 🙂

On the CMSSW side, glew is not used anyway, so I'll remove some includes there to make it compile. I'll open a PR to CMSSW.

[bellenot]

@smuzaffar @guitargeek See #20323

[guitargeek]

@smuzaffar, I think this PR should fix the situation for CMSSW:

• Don't use GLEW in Fireworks cms-sw/cmssw#49341

That gives us more time to think calmly what to do on the ROOT side.