[Bug ld/16715] New: -Bsymbolic breaks PMF comparison under ARM

[giuseppe.dangelo at kdab dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=16715

            Bug ID: 16715
           Summary: -Bsymbolic breaks PMF comparison under ARM
           Product: binutils
           Version: 2.22
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: giuseppe.dangelo at kdab dot com

Created attachment 7474
  --> https://sourceware.org/bugzilla/attachment.cgi?id=7474&action=edit
testcase

The attached program changes the output from "true" to "false" when the
-Bsymbolic / -Bsymbolic-functions options are passed to GCC. This happens on
ARM -- on x86-64 output is always "true".

The program involves a comparison, within a shared library, of a PMF defined
inside the shared library itself with the same PMF passed by the application.

Compile with:

 > g++ -fPIC -shared -Wall -o libshared.so -Wl,-Bsymbolic shared.cpp
 > g++ -fPIE -Wall -o main main.cpp -L. -lshared

(The long story is that Qt 5 is taking PMFs in its public API, and the
comparison failing inside of Qt shared libraries is breaking code on ARM, as
-Bsymbolic is set by default there.)

The bug has been acknowledged, and tentative patch has been kindly provided by
W. Newton here:

> https://sourceware.org/ml/binutils/2014-01/msg00172.html

but there hasn't been any activity from what I can see, so I'm opening this bug
report to keep track of the issue.

References:

> http://lists.linaro.org/pipermail/linaro-toolchain/2014-January/003942.html
> https://bugreports.qt-project.org/browse/QTBUG-36129

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