2.55 Pragma Eliminate


pragma Eliminate (
            [  Unit_Name       => ] IDENTIFIER | SELECTED_COMPONENT ,
            [  Entity          => ] IDENTIFIER |
                                    SELECTED_COMPONENT |
            [, Source_Location =>   SOURCE_TRACE ] );


This pragma indicates that the given entity is not used in the program to be compiled and built, thus allowing the compiler to eliminate the code or data associated with the named entity. Any reference to an eliminated entity causes a compile-time or link-time error.

The pragma has the following semantics, where U is the unit specified by the Unit_Name argument and E is the entity specified by the Entity argument:

Pragma Eliminate allows a program to be compiled in a system-independent manner, so that unused entities are eliminated but without needing to modify the source text. Normally the required set of Eliminate pragmas is constructed automatically using the gnatelim tool.

Any source file change that removes, splits, or adds lines may make the set of Eliminate pragmas invalid because their Source_Location argument values may get out of date.

Pragma Eliminate may be used where the referenced entity is a dispatching operation. In this case all the subprograms to which the given operation can dispatch are considered to be unused (are never called as a result of a direct or a dispatching call).

The string literal given for the source location specifies the line number of the declaration of the entity, using the following syntax for SOURCE_TRACE:


LBRACKET         ::= '['
RBRACKET         ::= ']'



Spaces around the colon in a SOURCE_REFERENCE are optional.

The source trace that is given as the Source_Location must obey the following rules (or else the pragma is ignored), where U is the unit U specified by the Unit_Name argument and E is the subprogram specified by the Entity argument:


pragma Eliminate (Pkg0, Proc);
-- Eliminate (all overloadings of) Proc in Pkg0

pragma Eliminate (Pkg1, Proc,
                  Source_Location => "pkg1.ads:8");
-- Eliminate overloading of Proc at line 8 in pkg1.ads

-- Assume the following file contents:
--   gen_pkg.ads
--   1: generic
--   2:   type T is private;
--   3: package Gen_Pkg is
--   4:   procedure Proc(N : T);
--  ...   ...
--  ... end Gen_Pkg;
--    q.adb
--   1: with Gen_Pkg;
--   2: procedure Q is
--   3:   package Inst_Pkg is new Gen_Pkg(Integer);
--  ...   -- No calls on Inst_Pkg.Proc
--  ... end Q;

-- The following pragma eliminates Inst_Pkg.Proc from Q
pragma Eliminate (Q, Proc,
                  Source_Location => "gen_pkg.ads:4[q.adb:3]");