On 17 September 2010 10:07, Gustavo Sverzut Barbieri
<[email protected]> wrote:
> changeset: 3753:62e52f105bc0
> tag: tip
> user: Gustavo Sverzut Barbieri <[email protected]>
> date: Fri Sep 17 09:42:57 2010 -0300
> files: Cython/Compiler/ModuleNode.py
> description:
> Force GCC>=4 to export module initialization function.
>
> With GCC's -fvisibility=hidden (both CFLAGS and LDFLAGS) it is
> possible to have the compiler to produce binaries where all symbols
> are hidden (local to the binary). To force a symbol to be visible one
> must specify __attribute__ ((visibility("default"))).
>
Why do you need to force -fvisibility=hidden ? In general, Cython
emits 'static' storage specifier, unless 'public' or 'api' keywords
are involved.
> This patch introduces pre-processor code to always force module
> symbols to be visible.
>
> NOTE: in theory pyport.h from Python would do the right thing, but it
> does not define any special cases for GCC, just Windows. As Python is
> not changing that easily and even if it does is just for future releases,
> it's better to have those in Cython.
>
Did you bug Python?
>
> diff --git a/Cython/Compiler/ModuleNode.py b/Cython/Compiler/ModuleNode.py
> --- a/Cython/Compiler/ModuleNode.py
> +++ b/Cython/Compiler/ModuleNode.py
> @@ -1671,9 +1671,15 @@
> header2 = "PyMODINIT_FUNC init%s(void)" % env.module_name
> header3 = "PyMODINIT_FUNC PyInit_%s(void)" % env.module_name
> code.putln("#if PY_MAJOR_VERSION < 3")
> + code.putln("# if defined(__GNUC__) && (__GNUC__ >= 4)")
> + code.putln("__attribute__ ((visibility(\"default\")))")
> + code.putln("# endif")
> code.putln("%s; /*proto*/" % header2)
> code.putln(header2)
> code.putln("#else")
> + code.putln("# if defined(__GNUC__) && (__GNUC__ >= 4)")
> + code.putln("__attribute__ ((visibility(\"default\")))")
> + code.putln("# endif")
> code.putln("%s; /*proto*/" % header3)
> code.putln(header3)
> code.putln("#endif")
>
It looks good, I support the patch. However,
1) Do you know how this would work in Windows with MinGW? I would
MinGW to do the right thing, but we have to be sure...
2) Do you know if this could affect full static Python builds? (I
mean, when you build a Python interpreter with all ext modules
'built-in' in the python binary) ? I cannot think of any problem, but
perhaps you do?
--
Lisandro Dalcin
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