Fix eigen build

[elcerdo]

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PR Description

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Checklist

• Unit-test of your feature with Catch.
• Doxygen documentation of the code completed (classes, methods, types, members...)
• Documentation module page added or updated.
• New entry in the ChangeLog.md added.
• No warning raised in Debug cmake mode (otherwise, Travis C.I. will fail).
• All continuous integration tests pass (Travis & appveyor)

[rolanddenis]

I confirm that it solves the compilation issue with Eigen 3.3 (Ubuntu 16.04) but I was wondering if it is better to replace SparseMatrix::Index by SparseMatrix::StorageIndex (line 109 ) instead of modifying default index for SparseMatrix typedef, following instructions in http://eigen.tuxfamily.org/index.php?title=3.3#Index_typedef .

Finally, it seems that this modification (replacing Index by StorageIndex) doesn't work for previous Eigen versions (even previous 3.x releases, as pointed out in https://forum.kde.org/viewtopic.php?f=74&t=132256#p355171 ) so OK for your solution.

There is still warnings about variables shadowing class members (-Wshadow) but I think we can merge this PR ... are you ready ?

PS: sorry for the closed PR, it was a mistake...

[dcoeurjo]

Before the merge, @elcerdo would have to add an entry to the change log. This bug fix might be critical for compatibility with Eigen.

[dcoeurjo]

@elcerdo can you please add a changelog entry?

[dcoeurjo]

Ping @elcerdo

[elcerdo]

added changelog entry.
@rolanddenis i didn't experience the -Wshadow warnings. which version of eigen are you using?
i am using eigen 3.2.8 under archlinux.

[elcerdo]

warnings can be ignored by adding a line here.

[rolanddenis]

I get those warnings with Eigen 3.3-beta1 (shipped with Ubuntu 16.04, shown as 3.2.92) and Eigen 3.3-beta2 (shown as 3.2.93) with g++ (test with 5.4.0 and 4.9.3) in Debug mode and only WITH_EIGEN set (see https://gist.github.com/rolanddenis/65ecc38045e4fff22c54b4a12bf760e5 ).

No warnings when adding

#pragma GCC diagnostic ignored "-Wshadow"

or when using clang.

It's maybe related to this bug report http://eigen.tuxfamily.org/bz/show_bug.cgi?id=640 that also links to a gcc bug https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66472

[dcoeurjo]

Okay.. Let's merge this one and check later the warnings. (I'll add a more recent gcc in the buildbot to keep track of such issues).

[dcoeurjo]

thanks ;)