Linker script vs. visibility patch

[Karl Vogel]

Karl Vogel wrote:

> kdemacros.h :
> -#define KDE_EXPORT __attribute__ ((visibility("visible")))
> +#define KDE_EXPORT __attribute__ ((visibility("default")))

Note: this looks like an error in KDE.. as GCC doesn't know a visibility of
"visible" !

==== GCC Info page:

 `visibility ("VISIBILITY_TYPE")'
      The `visibility' attribute on ELF targets causes the declaration
      to be emitted with default, hidden, protected or internal
      visibility.
 
           void __attribute__ ((visibility ("protected")))
           f () { /* Do something. */; }
           int i __attribute__ ((visibility ("hidden")));
 
      See the ELF gABI for complete details, but the short story is:
 
     "default"
           Default visibility is the normal case for ELF.  This value is
           available for the visibility attribute to override other
           options that may change the assumed visibility of symbols.
 
     "hidden"
           Hidden visibility indicates that the symbol will not be
           placed into the dynamic symbol table, so no other "module"
           (executable or shared library) can reference it directly.
 
     "protected"
           Protected visibility indicates that the symbol will be placed
           in the dynamic symbol table, but that references within the
           defining module will bind to the local symbol.  That is, the
           symbol cannot be overridden by another module.
 
     "internal"
           Internal visibility is like hidden visibility, but with
           additional processor specific semantics.  Unless otherwise
           specified by the psABI, gcc defines internal visibility to
           mean that the function is never called from another module.
           Note that hidden symbols, while they cannot be referenced
           directly by other modules, can be referenced indirectly via
           function pointers.  By indicating that a symbol cannot be
           called from outside the module, gcc may for instance omit the
           load of a PIC register since it is known that the calling
           function loaded the correct value.
 
      Not all ELF targets support this attribute.
====

Also.. I noticed that the Intel C++ Compiler for Linux already supports the
-fvisibility option to set the default to hidden:

 http://www.intel.com/software/products/compilers/clin/docs/ug/lin1005.htm