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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - -fvisibility=hidden and -fvisibility-ms-compat are order dependent"
href="https://llvm.org/bugs/show_bug.cgi?id=24918">24918</a>
</td>
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<tr>
<th>Summary</th>
<td>-fvisibility=hidden and -fvisibility-ms-compat are order dependent
</td>
</tr>
<tr>
<th>Product</th>
<td>clang
</td>
</tr>
<tr>
<th>Version</th>
<td>unspecified
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Macintosh
</td>
</tr>
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<th>OS</th>
<td>MacOS X
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>C++
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>jinxcat2008@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>dgregor@apple.com, llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=14928" name="attach_14928" title="The Makefile and source files to reproduce the issue.">attachment 14928</a> <a href="attachment.cgi?id=14928&action=edit" title="The Makefile and source files to reproduce the issue.">[details]</a></span>
The Makefile and source files to reproduce the issue.
The order of the -fvisibility=hidden and -fvisibility-ms-compat flags affects
the resulting binaries and the symbols which are visible in a dynamic library
created from them. This seems to specifically affect templated functions which
contain declarations in a header file and definitions in a source file. The
fact that the template was specialized in the source file also seems necessary
to reproduce the issue. In the larger program where I first noticed the
problem, explicit instantiations, not specializations, also seemed to show
behavior differences.
Here are the files used:
% cat foo.h
class Bar
{
};
class ChildBar : public Bar
{
};
class __attribute__((visibility("default"))) Foo
{
public:
template< class Bar >
void bar( const Bar & );
};
% cat foo.cpp
#include "foo.h"
template< class Bar >
void Foo::bar( const Bar & )
{
}
template<>
void Foo::bar( const ChildBar & )
{
}
% cat Makefile
foo.o: foo.cpp
@clang++ -fvisibility=hidden -fvisibility-ms-compat -c foo.cpp -o foo.o
libfoo.dylib: foo.o
@clang++ -dynamiclib -o libfoo.dylib foo.o
foo_missing.o: foo.cpp
@clang++ -fvisibility-ms-compat -fvisibility=hidden -c foo.cpp -o
foo_missing.o
libfoo_missing.dylib: foo_missing.o
@clang++ -dynamiclib -o libfoo_missing.dylib foo_missing.o
symbols: libfoo.dylib
@echo Symbols present:
@nm -g libfoo.dylib
symbols_missing: libfoo_missing.dylib
@echo Symbols missing:
@nm -g libfoo_missing.dylib
all: symbols symbols_missing
clean:
@rm foo.o libfoo.dylib foo_missing.o libfoo_missing.dylib
Run 'make all' from the command line and it will produce the following output:
Symbols present:
0000000000000f90 T __ZN3Foo3barI8ChildBarEEvRKT_
U dyld_stub_binder
Symbols missing:
U dyld_stub_binder
The exported symbols from the two dylibs should match.
I used these two versions of clang on Mac OSX.
(Mac OSX 10.9.5 - Mavericks)
Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin13.4.0
Thread model: posix
(Mac OSX 10.11 Developer Preview - El Capitan GM Seed)
Apple LLVM version 7.0.0 (clang-700.0.72)
Target: x86_64-apple-darwin15.0.0
Thread model: posix</pre>
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