Syntax:
pragma Linker_Constructor (procedure_LOCAL_NAME);
procedure_LOCAL_NAME must refer to a parameterless procedure that
is declared at the library level. A procedure to which this pragma is
applied will be treated as an initialization routine by the linker.
It is equivalent to __attribute__((constructor)) in GNU C and
causes procedure_LOCAL_NAME to be invoked before the entry point
of the executable is called (or immediately after the shared library is
loaded if the procedure is linked in a shared library), in particular
before the Ada run-time environment is set up.
Because of these specific contexts, the set of operations such a procedure can perform is very limited and the type of objects it can manipulate is essentially restricted to the elementary types. In particular, it must only contain code to which pragma Restrictions (No_Elaboration_Code) applies.
This pragma is used by GNAT to implement auto-initialization of shared Stand Alone Libraries, which provides a related capability without the restrictions listed above. Where possible, the use of Stand Alone Libraries is preferable to the use of this pragma.