In full warning mode, when an unchecked conversion is applied to types of
different sizes, the compiler issues a warning describing the effects of
the conversion on the additional or missing bits.
When the source is smaller than the target, it was issuing a specific warning
if the target is of a discrete type but, when the source is larger than the
target, it wasn't doing the same if the source is of a discrete type.
The compiler must issue the following warnings with -gnatf:
ucw.ads:12:03: warning: types for unchecked conversion have different sizes
ucw.ads:12:03: warning: size of "REC" is 16, size of "INTEGER" is 32
ucw.ads:12:03: warning: target value will include 16 undefined high order bits
ucw.ads:13:03: warning: types for unchecked conversion have different sizes
ucw.ads:13:03: warning: size of "INTEGER" is 32, size of "REC" is 16
ucw.ads:13:03: warning: 16 high order bits of source will be ignored
on
with Unchecked_Conversion;
package UCW is
type Int8_t is mod 2**8;
type Rec is record
I1 : Int8_t;
I2 : Int8_t;
end record;
function C1 is new Unchecked_Conversion (Source => Rec, Target => Integer);
function C2 is new Unchecked_Conversion (Source => Integer, Target => Rec);
end UCW;
Tested on x86_64-pc-linux-gnu, committed on trunk
2015-05-22 Eric Botcazou <[email protected]>
* sem_ch13.adb (Validate_Unchecked_Conversions): Also issue
specific warning for discrete types when the source is larger
than the target.
Index: sem_ch13.adb
===================================================================
--- sem_ch13.adb (revision 223534)
+++ sem_ch13.adb (working copy)
@@ -13483,9 +13483,22 @@
end if;
else pragma Assert (Source_Siz > Target_Siz);
- Error_Msg
- ("\?z?^ trailing bits of source will be ignored!",
- Eloc);
+ if Is_Discrete_Type (Source) then
+ if Bytes_Big_Endian then
+ Error_Msg
+ ("\?z?^ low order bits of source will be "
+ & "ignored!", Eloc);
+ else
+ Error_Msg
+ ("\?z?^ high order bits of source will be "
+ & "ignored!", Eloc);
+ end if;
+
+ else
+ Error_Msg
+ ("\?z?^ trailing bits of source will be "
+ & "ignored!", Eloc);
+ end if;
end if;
end if;
end if;
