[llvm-bugs] [Bug 35446] New: Please backport r319105 to 5.0.1: [cmake] Pass -Wl, -z, nodelete on Linux to prevent unloading

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=35446

            Bug ID: 35446
           Summary: Please backport r319105 to 5.0.1: [cmake] Pass
                    -Wl,-z,nodelete on Linux to prevent unloading
           Product: new-bugs
           Version: 5.0
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: mgorny at gentoo.org
                CC: llvm-bugs at lists.llvm.org
            Blocks: 34492

This has no effect on most of LLVM installs (static & dylib) but it's very
important for BUILD_SHARED_LIBS=ON installs as it unbreaks mesa plugins.


commit 937b23b5fffa59deb1dc342cc5602d387d84a762
Author: Michal Gorny <mgorny at gentoo.org>
Date:   Mon Nov 27 23:23:09 2017

    [cmake] Pass -Wl,-z,nodelete on Linux to prevent unloading

    Prevent unloading shared libraries on Linux when dlclose() is called.
    This is necessary since command-line option parsing API relies on
    registering the global option instances in the option parser instance
    which can be loaded in a different shared library.

    Given that we can't reliably remove those options when a library is
    unloaded, the parser ends up containing dangling references. Since glibc
    has relatively complex library unloading rules, some of the LLVM
    libraries can be unloaded while others (including the Support library)
    stay loaded causing quite a mayhem. To reliably prevent that, just
    forbid unloading all libraries -- it's a very bad idea anyway.

    While the issue arguably happens only with BUILD_SHARED_LIBS, it may
    affect any library reusing llvm::cl interface.

    Based on patch provided Ross Hayward on https://bugs.gentoo.org/617154.
    Previously hit by Fedora back in Feb 2016:
    https://lists.freedesktop.org/archives/mesa-dev/2016-February/107242.html

    Differential Revision: https://reviews.llvm.org/D40459

    git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@319105
91177308-0d34-0410-b5e6-96231b3b80d8


Referenced Bugs:

https://bugs.llvm.org/show_bug.cgi?id=34492
[Bug 34492] [meta] 5.0.1 Release Blockers
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