experimental NTL support for cmake

[dimpase]

for more knowledgeable in cmake people to look at. It does build on FreeBSD.

[wbhart]

@peter-frentrup

[isuruf]

I would change this to,

FIND_PATH(NTL_INCLUDE_DIR NTL/RR.h
  HINTS
  $ENV{NTLDIR}
)

[isuruf]

FIND_LIBRARY(NTL_LIBRARY
  NAMES ntl
  HINTS
  $ENV{NTLDIR}
)

[isuruf]

I'd make this optional as NTL with MPIR on windows 64-bit assumes LP64 and doesn't work.
Something like,

option(WITH_NTL "Build with NTL interface" OFF)
if (WITH_NTL)
    find_package(NTL REQUIRED)
endif()

[dimpase]

How does one check this ? Is it cmake -D??? for some value of ???.

[isuruf]

Yes, cmake -DWITH_NTL=yes would enable it.

[isuruf]

This makes it impossible to build static libraries if needed. There's an option cmake -DBUILD_SHARED_LIBS=on which would build a shared library. (You could change the default value of off in BUILD_SHARED_LIBS to on if you like)

[dimpase]

Thanks - today I touched cmake configs for the 1st time - no wonder this is very far from prefect.

[dimpase]

By the way, how do you test flint's cmake build?

[wbhart]

We don't. We had CI for a while, but it wasn't passing anyway, so we switched it off.

[dimpase]

cmake build does not seem to be working on Linux (Ubuntu 18) --- as well as on FreeBSD, in fact - I overlooked this) for me,
as libntl is not getting linked in:

$ ldd lib/libflint.so 
	linux-vdso.so.1 (0x00007ffe56374000)
	libgmp.so.10 => /usr/lib/x86_64-linux-gnu/libgmp.so.10 (0x00007f0e59edf000)
	libmpfr.so.6 => /usr/lib/x86_64-linux-gnu/libmpfr.so.6 (0x00007f0e59c5f000)
	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f0e59ad5000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f0e59948000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f0e5992e000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f0e59744000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f0e5aad2000)

whereas on the system I install libflint using apt and see

$ ldd /usr/lib/libflint.so 
	linux-vdso.so.1 (0x00007ffdbb11b000)
	libmpfr.so.6 => /usr/lib/x86_64-linux-gnu/libmpfr.so.6 (0x00007fb464072000)
	libgmp.so.10 => /usr/lib/x86_64-linux-gnu/libgmp.so.10 (0x00007fb463df1000)
	libntl.so.35 => /usr/lib/libntl.so.35 (0x00007fb4639d7000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fb4639b6000)
	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fb46382c000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fb46369f000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fb463683000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fb463499000)
	/lib64/ld-linux-x86-64.so.2 (0x00007fb464851000)
	libgf2x.so.1 => /usr/lib/x86_64-linux-gnu/libgf2x.so.1 (0x00007fb46328b000)

So there is a linking problem. What is this? A bug in Cmake? (As NTL is a C++ library, it's less obvious for cmake what to do). Same with cmake versions 3.12.1 and 3.13.4.

[isuruf]

dimpase#1

[dimpase]

We don't. We had CI for a while, but it wasn't passing anyway, so we switched it off.

After the update from @isuruf it seems to be possible to build and test with NTL on linux (latest Ubunti 18, and Gentoo) and FreeBSD, however tests get stuck on fmpz_poly_factor-test-t-factor (running for 40 minutes of CPU time). Is it a known problem with this particular test?

[isuruf]

You are probably building in Debug mode. Did you try cmake -DCMAKE_BUILD_TYPE=Release ?

[wbhart]

It tries to factor some huge polynomials. I think @isuruf is right.

I must speed that code up some day.

[dimpase]

You are probably building in Debug mode. Did you try cmake -DCMAKE_BUILD_TYPE=Release ?

OK, this works, thanks.

[dimpase]

I've added 11a4f5d to allow building on Gentoo, where GMP headers have a different layout to what's programmed in FindGMP.cmake. This certainly is far from ideal, but seems to make sense (and work on an instance of Gentoo I tried it on).

[isuruf]

dimpase#2 changes some default options and fixes some things

[dimpase]

We don't. We had CI for a while, but it wasn't passing anyway, so we switched it off.

here is a passing with tests and NTL cmake Travis build: https://travis-ci.com/dimpase/flint2/builds/101585015 from https://github.com/dimpase/flint2/tree/travis_cmake

Would you like this merged into this PR?

[wbhart]

Yes, go ahead and put it into this PR. Thanks for your efforts.

[isuruf]

@dimpase, do you mind adding a cmake job in addition to the other CI jobs?

[dimpase]

@dimpase, do you mind adding a cmake job in addition to the other CI jobs?

yes, that's what I am going to do, add things in my experimental branch to the pull request (naturally, adding them to the other CI things)

[isuruf]

Thanks. I've got a branch that fixes cmake builds on windows CI (except for 4 tests) on top of this branch. I'll send that when this PR is merged.

[dimpase]

OK, I think I'm done with this, please review.

[dimpase]

Probably Travis script may be made more clear by using their "matrix" stuff, but this can be done later.

[wbhart]

Thanks. I'll wait for @isuruf to sign off on it, then I'll merge it. I'm virtually ignorant about CMake.