Bug 35827 - -fvisibility only works for C/C++/Objective-C/Objective-C++
Summary: -fvisibility only works for C/C++/Objective-C/Objective-C++
Alias: None
Product: gcc
Classification: Unclassified
Component: middle-end (show other bugs)
Version: 4.4.0
: P3 enhancement
Target Milestone: ---
Assignee: Not yet assigned to anyone
Depends on:
Reported: 2008-04-04 18:08 UTC by Ed Smith-Rowland
Modified: 2011-06-10 10:20 UTC (History)
2 users (show)

See Also:
Host: x86_64-redhat-linux
Target: x86_64-redhat-linux
Build: x86_64-redhat-linux
Known to work:
Known to fail:
Last reconfirmed:


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Description Ed Smith-Rowland 2008-04-04 18:08:27 UTC
I am having trouble with symbol visibility with gfortran on Linux x86_64.
It looks like -fvisibility=hidden doesn't work.

[ed@alion7 tirem-3.2]$ gfortran -v
Using built-in specs.
Target: x86_64-redhat-linux
Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --enable-checking=release --with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions --enable-libgcj-multifile --enable-languages=c,c++,objc,obj-c++,java,fortran,ada --enable-java-awt=gtk --disable-dssi --enable-plugin --with-java-home=/usr/lib/jvm/java-1.4.2-gcj- --with-cpu=generic --host=x86_64-redhat-linux
Thread model: posix
gcc version 4.1.2 20070626 (Red Hat 4.1.2-14)

So I copied and translated a gcc.dg/visibility-9.c to Fortran for a small test case.

I compiled with gfortran to a shared library (x86_64 ELF Linux etc.).

! Test that -fvisibility works.
! { dg-do compile }
! { dg-require-visibility "" }
! { dg-options "-fvisibility=hidden" }
! { dg-final { scan-hidden "foo" } }

subroutine foo
end subroutine

[ed@alion7 ~]$ gfortran -shared  -fvisibility=default -fPIC -o visibility-1.so visibility-1.f90
[ed@alion7 ~]$ nm -C -D visibility-1.so
                 w _Jv_RegisterClasses
00000000002007c8 A __bss_start
                 w __cxa_finalize
                 w __gmon_start__
00000000002007c8 A _edata
00000000002007d8 A _end
0000000000000548 T _fini
00000000000003f0 T _init
00000000000004fc T foo_

The "foo_" at the end is teh bad thing.

I haven't checked a gfortran less than 4.1 but g77 as of gcc-3.4 supports visibility.
I've checked with an almost release gcc-4.3 and visibility still didn't work.

Is anyone else seeing a problem?

I'll check PPC MacOS and i32 Cygwin when I get home.

Ed Smith-Rowland


I just verified this on PPC MacOSX:

MacOSX:~ ed$ bin-4.3/bin/gfortran -v
Using built-in specs.
Target: powerpc-apple-darwin7.9.0
Configured with: ../gcc/configure --prefix=/Users/ed/bin-4.3 --enable-languages=c,c++,objc,obj-c++,fortran,treelang
Thread model: posix
gcc version 4.3.0 20071116 (experimental) (GCC)

The results of nm:

MacOSX:~ ed$ bin-4.3/bin/gfortran -dynamiclib  -fvisibility=default -fPIC -o visibility-1.dylib visibility-1.f90
MacOSX:~ ed$ nm visibility-1.dylib

00001db0 T _foo_

So foo is visible on PPC MacOSX too.
Comment 1 Andrew Pinski 2008-04-04 18:12:49 UTC
-fvisibility should be only a C/C++ option as you cannot change the visibility in any other language.  Also it is only implemented for C/C++/Objective-C/Objective-C++:
[dhcp-10-98-10-23:local/gcc/gcc] apinski% grep default_visibility */*.c
cp/decl.c:    default_visibility = VISIBILITY_HIDDEN;
cp/decl2.c:       DECL_VISIBILITY (decl) = default_visibility;
[dhcp-10-98-10-23:local/gcc/gcc] apinski% grep default_visibility *.c
c-common.c:      DECL_VISIBILITY (decl) = default_visibility;
c-pragma.c:              default_visibility);
c-pragma.c:    default_visibility = VISIBILITY_DEFAULT;
c-pragma.c:    default_visibility = VISIBILITY_INTERNAL;
c-pragma.c:    default_visibility = VISIBILITY_HIDDEN;
c-pragma.c:    default_visibility = VISIBILITY_PROTECTED;
c-pragma.c:  default_visibility = VEC_pop (visibility, visstack);
opts.c:enum symbol_visibility default_visibility = VISIBILITY_DEFAULT;
opts.c:          default_visibility = VISIBILITY_DEFAULT;
opts.c:          default_visibility = VISIBILITY_INTERNAL;
opts.c:          default_visibility = VISIBILITY_HIDDEN;
opts.c:          default_visibility = VISIBILITY_PROTECTED;

Comment 2 Bastien ROUCARIES 2011-06-10 10:20:15 UTC
Dear andrew,

You have miss that visibility is supported by intel fortran, and is therefore quite useful for fortran dso. See http://software.intel.com/sites/products/documentation/hpc/compilerpro/en-us/fortran/lin/compiler_f/optaps/common/optaps_cmp_visib.htm

BTW could you mark that this bug is blocked by 41209 ? http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41209