This variable attribute affects the visibility of ELF symbols.
Note
This attribute is a GNU compiler extension supported by the ARM compiler.
Syntax
__attribute__((visibility("visibility_type")))
Where visibility_type
defaultThe assumed visibility of symbols can be changed by other options. Default visibility overrides such changes. Default visibility corresponds to external linkage.
hiddenThe symbol is not placed into the dynamic symbol table, so no other executable or shared library can directly reference it. Indirect references are possible using function pointers.
internalUnless otherwise specified by the processor-specific Application Binary Interface (psABI), internal visibility means that the function is never called from another module.
protectedThe symbol is placed into the dynamic symbol table, but references within the defining module bind to the local symbol. That is, the symbol cannot be overridden by another module.
Except when specifying default visibility,
this attribute is intended for use with declarations that would
otherwise have external linkage.
You can apply this attribute to functions and variables in C and C++. In C++, you can also apply it to class, struct, union, and enum types, and namespace declarations.
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