doc/gnat_ugn/elaboration_order_handling_in_gnat.rst

30 its run-time effect. This process is also referred to as **elaboration** for
31 declarations and *evaluation* for expressions.
33 The execution model in Ada allows for certain sections of an Ada program to be
41 * The execution of a partition involves running the environment task for that
44 * The environment task executes all elaboration code (if available) for all
48 * The environment task executes the Ada program (if available) for that
233 vein as index or null exclusion checks. A failed ABE check raises exception
272   A failed run-time check raises exception ``Program_Error``. The following
298   Pragmas are provided for the programmer to specify the desired elaboration
406 ``Elaborate_Body`` are not applicable. Ada provides another set of pragmas for
534   Note that there are several allowable suborders for the specs and bodies of
558 Elaborate_All for the server unit.*
616   effect, GNAT performs extensive diagnostics on a unit-by-unit basis for all
618   run-time checks for all external targets and for all scenarios that may
620   ``Elaborate_All`` pragmas for server units based on the dependencies of
658   GNAT installs run-time checks for each primitive subprogram of each tagged
717 elaboration code. As a result, run-time checks are installed for each scenario
733       <check that the body of Server.Gen is elaborated>
739       <check that the body of Server.Task_Type is elaborated>
741       <check that the body of Server.Proc is elaborated>
753 missing ``Elaborate`` and ``Elaborate_All`` pragmas for library-level
764       >>> info: missing pragma "Elaborate_All" for unit "Server"
843            <check that the body of Server.Func is elaborated>
856   external target, GNAT installs a run-time check to verify that its body has
881          >>> info: implicit pragma "Elaborate_All" generated for unit "Server"
900   external target, GNAT installs an implicit ``Elaborate_All`` pragma for unit
922       >>> unit "SPARK_Model" requires pragma "Elaborate_All" for "Server"
931 The legacy elaboration model is provided for compatibility with code bases
955   - The client unit has an explicit ``Elaborate_All`` pragma for the server
974 diagnostics describing an **elaboration circularity**.
1006    error: elaboration circularity detected
1009    info:       recompile "client (spec)" with -gnatel for full details
1020 static model generates an implicit ``Elaborate_All`` pragma for ``Server``. The
1025 ``Client``, and this leads to a circularity.
1032 When faced with an elaboration circularity, a programmer has several options
1120     ``Suppress`` pragmas with arguments naming specific entities for which
1253 circularity arises:
1257    error: elaboration circularity detected
1260    info:       recompile "decls (body)" with -gnatel for full details
1273 for ``Units`` due to the call to ``Utils.Put_Val``. The pragma implies that
1278 leads to a circularity.
1281 When the body of task ``Lib_Task`` is activated, execution will wait for entry
1289 When faced with a task elaboration circularity, a programmer has several
1303   dependencies that would otherwise cause an elaboration circularity. The
1369   The original example uses a single task declaration for ``Lib_Task``. An
1371   the dependencies that would otherwise cause an elaboration circularity. The
1480     GNAT will indicate missing ``Elaborate`` and ``Elaborate_All`` pragmas for
1501           >>> info: "Elaborate_All" requirement for unit "Server" met by pragma at line 1
1525   Turn on warnings for suspicious Subp'Access
1556   Turn on warnings for elaboration problems
1564   Turn off warnings for elaboration problems
1596 Summary of Procedures for Elaboration Control
1604 If it is important for the program to be portable to compilers other than GNAT,
1609 If the binder reports an elaboration circularity, the programmer has several
1625 * If none of the steps outlined above resolve the circularity, use a more