The compiler incorrectly allows overriding_indicators to be applied
to protected subprogram bodies (and flags a style error with -gnatyO
when they're missing), but those are disallowed by the Ada RM (see
RM-8.3.1(3-6) and AC95-00213 for confirmation of intent). This is
fixed, but the error can be changed to a warning with -gnatd.E to
ease transition for programs that were using such overriding_indicators.
The test below must report the following style warning and error
when compiled with:
$ gcc -c -gnatyO -gnatj60 prot_subp_indicator_bug.adb
prot_subp_indicator_bug.adb:17:07: (style) missing
"overriding" indicator
in declaration of "P"
prot_subp_indicator_bug.adb:32:07: overriding indicator not
allowed for protected
subprogram body
and the following warnings when compiled with:
$ gcc -c -gnatyO -gnatd.E -gnatj60 prot_subp_indicator_bug.adb
prot_subp_indicator_bug.adb:17:07: (style) missing
"overriding" indicator
in declaration of "P"
prot_subp_indicator_bug.adb:32:07: warning: overriding
indicator not allowed
for protected subprogram
body
procedure Prot_Subp_Indicator_Bug is
package Synch_Pkg is
type Synch_Interface is synchronized interface;
procedure P (X : out Synch_Interface) is abstract;
procedure Q (X : in out Synch_Interface) is abstract;
end Synch_Pkg;
use Synch_Pkg;
protected type Prot_Type is new Synch_Interface with
procedure P; -- Warning "missing overriding indicator" OK with -gnatyO
overriding -- OK
procedure Q;
end Prot_Type;
protected body Prot_Type is
procedure P is -- Shouldn't get warning about adding overriding indicator
begin
null;
end P;
overriding -- Illegal (but only give a warning when using -gnatd.E)
procedure Q is
begin
null;
end Q;
end Prot_Type;
begin
null;
end Prot_Subp_Indicator_Bug;
Tested on x86_64-pc-linux-gnu, committed on trunk
2014-05-21 Gary Dismukes <dismu...@adacore.com>
* debug.adb: Add case of illegal overriding_indicator for a
protected subprogram body to description of -gnatd.E switch.
* sem_ch6.adb (Verify_Overriding_Indicator): Issue error message
for cases of giving overriding_indicators on protected subprogram
bodies, but change this to a warning if -gnatd.E is enabled. No
longer give a style warning about missing indicators on protected
subprogram bodies.
Index: debug.adb
===================================================================
--- debug.adb (revision 210697)
+++ debug.adb (working copy)
@@ -614,6 +614,11 @@
--
-- Errors relating to the new rules about not defining equality
-- too late so that composition of equality can be assured.
+ --
+ -- Errors relating to overriding indicators on protected subprogram
+ -- bodies (not an Ada 2012 incompatibility, but might cause errors
+ -- for existing programs assuming they were legal because GNAT
+ -- formerly allowed them).
-- d.F Sets GNATprove_Mode to True. This allows debugging the frontend in
-- the special mode used by GNATprove.
Index: sem_ch6.adb
===================================================================
--- sem_ch6.adb (revision 210697)
+++ sem_ch6.adb (working copy)
@@ -2782,6 +2782,16 @@
elsif not Present (Overridden_Operation (Spec_Id)) then
Error_Msg_NE
("subprogram& is not overriding", Body_Spec, Spec_Id);
+
+ -- Overriding indicators aren't allowed for protected subprogram
+ -- bodies (see the Confirmation in Ada Comment AC95-00213). Change
+ -- this to a warning if -gnatd.E is enabled.
+
+ elsif Ekind (Scope (Spec_Id)) = E_Protected_Type then
+ Error_Msg_Warn := Error_To_Warning;
+ Error_Msg_N
+ ("<overriding indicator not allowed for protected "
+ & "subprogram body", Body_Spec);
end if;
elsif Must_Not_Override (Body_Spec) then
@@ -2797,20 +2807,37 @@
("subprogram & overrides predefined operator ",
Body_Spec, Spec_Id);
- -- If this is not a primitive operation or protected subprogram,
- -- then the overriding indicator is altogether illegal.
+ -- Overriding indicators aren't allowed for protected subprogram
+ -- bodies (see the Confirmation in Ada Comment AC95-00213). Change
+ -- this to a warning if -gnatd.E is enabled.
- elsif not Is_Primitive (Spec_Id)
- and then Ekind (Scope (Spec_Id)) /= E_Protected_Type
- then
+ elsif Ekind (Scope (Spec_Id)) = E_Protected_Type then
+ Error_Msg_Warn := Error_To_Warning;
+
Error_Msg_N
+ ("<overriding indicator not allowed " &
+ "for protected subprogram body",
+ Body_Spec);
+
+ -- If this is not a primitive operation, then the overriding
+ -- indicator is altogether illegal.
+
+ elsif not Is_Primitive (Spec_Id) then
+ Error_Msg_N
("overriding indicator only allowed " &
"if subprogram is primitive",
Body_Spec);
end if;
+ -- If checking the style rule and the operation overrides, then
+ -- issue a warning about a missing overriding_indicator. Protected
+ -- subprogram bodies are excluded from this style checking, since
+ -- they aren't primitives (even though their declarations can
+ -- override) and aren't allowed to have an overriding_indicator.
+
elsif Style_Check
and then Present (Overridden_Operation (Spec_Id))
+ and then Ekind (Scope (Spec_Id)) /= E_Protected_Type
then
pragma Assert (Unit_Declaration_Node (Body_Id) = N);
Style.Missing_Overriding (N, Body_Id);
