9.16 Summary of Procedures for Elaboration Control

A programmer should first compile the program with the default options, using none of the binder or compiler switches. If the binder succeeds in finding an elaboration order, then apart from possible cases involing dispatching calls and access-to-subprogram types, the program is free of elaboration errors.

If it is important for the program to be portable to compilers other than GNAT, then the programmer should use compiler switch -gnatel and consider the messages about missing or implicitly created Elaborate and Elaborate_All pragmas.

If the binder reports an elaboration circularity, the programmer has several options:

• * Ensure that elaboration warnings are enabled. This will allow the static model to output trace information of elaboration issues. The trace information could shed light on previously unforeseen dependencies, as well as their origins. Elaboration warnings are enabled with compiler switch -gnatwl.
• * Use switch -gnatel to obtain messages on generated implicit Elaborate and Elaborate_All pragmas. The trace information could indicate why a server unit must be elaborated prior to a client unit.
• * If the warnings produced by the static model indicate that a task is involved, consider the options in section Resolving Task Issues.
• * If none of the steps outlined above resolve the circularity, use a more permissive elaboration model, in the following order:
  • - Use the dynamic elaboration model, with compiler switch -gnatE.
  • - Use the legacy static elaboration model, with compiler switch -gnatH.
  • - Use the legacy dynamic elaboration model, with compiler switches -gnatH -gnatE.
  • - Use the relaxed legacy static elaboration model, with compiler switches -gnatH -gnatJ.
  • - Use the relaxed legacy dynamic elaboration model, with compiler switches -gnatH -gnatJ -gnatE.