From: "Brian" <brian.ngc@gmail.com>
Subject: GNAT Unchecked_Union and multiple components
Date: 18 Apr 2005 07:58:00 -0700
Date: 2005-04-18T07:58:00-07:00 [thread overview]
Message-ID: <1113836280.439166.180090@f14g2000cwb.googlegroups.com> (raw)
Hi,
I've started to use GNAT 3.15p and noticed it handles the pragma
Unchecked_Union differently from other compilers. According to the
GNAT Reference Manual "Each variant has a component list with a single
component.", if you violate this rule the compiler will generate the
error "Unchecked_Union variant can have only one component". Other
compilers allow multiple components per variant. Is there a GNAT
compiler switch I can use to loosen this restriction? My current
workaround is to create a new record type containing the multiple
components and use it as the type for one of the variants (see code
snippet below). Thanks.
Regards,
Brian
<snip>
type Msg_Type is (Msg_A, Msg_B);
-- This is what I want as my variant record type definition.
type Data_Type1(Msg : Msg_Type := Msg_A) is
record
case Msg is
when Msg_A =>
A1 : Integer;
A2 : Integer;
when Msg_B =>
B : Float;
end case;
end record;
-- This is my current workaround.
type Msg_A_Variant is
record
A1 : Integer;
A2 : Integer;
end record;
type Data_Type1(Msg : Msg_Type := Msg_A) is
record
case Msg is
when Msg_A =>
A : Msg_A_Variant;
when Msg_B =>
B : Float;
end case;
end record;
-- end workaround
pragma Unchecked_Union(Data_Type1);
<snip>
next reply other threads:[~2005-04-18 14:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-18 14:58 Brian [this message]
2005-04-20 21:03 ` GNAT Unchecked_Union and multiple components Randy Brukardt
replies disabled
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox