When generating code, subunits are inserted into the tree of the parent unit,
and their context is added to the context of the parent. This makes it hard
to determine whether any with_clause on the proper body is superfluous. This
patch adds circuitry to detect these superfluous with_clauses when the subunit
is compiled by itself, in -gnatc mode.
Executing:
gcc -c -gnatc -gnatwu pkg-proc.adb
must yield:
pkg-proc.adb:1:06: warning: unit "Unused_Pkg" is not referenced
pkg-proc.adb:2:06: warning: unit "Unused_Pkg_2" is not referenced
pkg.adb:3:03: warning: variable "Variable" is never read and never assigned
---
with Unused_Pkg;
with Unused_Pkg_2;
with Ada.Text_Io;
separate (Pkg)
procedure Proc is
begin
Ada.Text_Io.Put_Line ("Hello");
end Proc;
---
with Unused_Pkg;
package body pkg is
Variable : Unused_Pkg.T;
procedure Proc is separate;
end Pkg;
---
package Pkg is
procedure Proc;
end Pkg;
---
package body Unused_Pkg is
procedure Empty is
begin
null;
end Empty;
end Unused_Pkg;
--
package Unused_Pkg is
type T is (Tbd);
procedure Empty;
end Unused_Pkg;
--
package Unused_Pkg_2 is
type T is (Tbd);
end Unused_Pkg_2;
Tested on x86_64-pc-linux-gnu, committed on trunk
2013-10-17 Ed Schonberg <schonb...@adacore.com>
* sem_warn.adb (Check_Unused_Withs): If the main unit is a
subunit, apply the check to the units mentioned in its context
only. This provides additional warnings on with_clauses that
are superfluous.
Index: sem_warn.adb
===================================================================
--- sem_warn.adb (revision 203763)
+++ sem_warn.adb (working copy)
@@ -2545,13 +2545,16 @@
return;
end if;
- -- Flag any unused with clauses, but skip this step if we are compiling
- -- a subunit on its own, since we do not have enough information to
- -- determine whether with's are used. We will get the relevant warnings
- -- when we compile the parent. This is the normal style of GNAT
- -- compilation in any case.
+ -- Flag any unused with clauses. For a subunit, check only the units
+ -- in its context, not those of the parent, which may be needed by other
+ -- subunits. We will get the full warnings when we compile the parent,
+ -- but the following is helpful when compiling a subunit by itself.
if Nkind (Unit (Cunit (Main_Unit))) = N_Subunit then
+ if Current_Sem_Unit = Main_Unit then
+ Check_One_Unit (Main_Unit);
+ end if;
+
return;
end if;
