The parameter type for Shift_Left (etc.) intrinsics is required to have 'Size =
8, 16, 32, or 64 bits, but the compiler failed to check this rule. This patch
checks the rule.
The following test should get a compile-time error.
gnatmake -f -q shift_test.adb
shift_test.adb:4:27: first argument for shift must have size 8, 16, 32 or 64
shift_test.adb:5:29: incorrect intrinsic subprogram, see spec
gnatmake: "shift_test.adb" compilation error
with Text_IO; use Text_IO;
procedure Shift_Test is
type M is mod 2**12; -- Illegal!
function Shift_Left(X: M; Amount: Natural) return M;
pragma Import(Intrinsic, Shift_Left);
X : M := M'Last;
begin
Put_Line(M'Size'Img);
for Amount in Natural range 0..100 loop
Put_Line(Shift_Left(X, Amount)'Img);
end loop;
end Shift_Test;
Tested on x86_64-pc-linux-gnu, committed on trunk
2012-01-10 Bob Duff <d...@adacore.com>
* sem_intr.adb (Check_Shift): Use RM_Size instead of Esize, when
checking that the 'Size is correct. If the type is "mod 2**12",
for example, it's illegal, but Esize is the 'Object_Size, which
will be something like 16 or 32, so the error ('Size = 12) was
not detected.
* gnat_rm.texi: Improve documentation of shift
and rotate intrinsics.
Index: gnat_rm.texi
===================================================================
--- gnat_rm.texi (revision 183051)
+++ gnat_rm.texi (working copy)
@@ -10385,11 +10385,7 @@
* Exception_Name::
* File::
* Line::
-* Rotate_Left::
-* Rotate_Right::
-* Shift_Left::
-* Shift_Right::
-* Shift_Right_Arithmetic::
+* Shifts and Rotates::
* Source_Location::
@end menu
@@ -10506,62 +10502,36 @@
@code{GNAT.Source_Info.Line} to obtain the number of the current
source line.
-@node Rotate_Left
-@section Rotate_Left
+@node Shifts and Rotates
+@section Shifts and Rotates
+@cindex Shift_Left
+@cindex Shift_Right
+@cindex Shift_Right_Arithmetic
@cindex Rotate_Left
+@cindex Rotate_Right
@noindent
-In standard Ada, the @code{Rotate_Left} function is available only
+In standard Ada, the shift and rotate functions are available only
for the predefined modular types in package @code{Interfaces}. However, in
-GNAT it is possible to define a Rotate_Left function for a user
-defined modular type or any signed integer type as in this example:
+GNAT it is possible to define these functions for any integer
+type (signed or modular), as in this example:
@smallexample @c ada
function Shift_Left
- (Value : My_Modular_Type;
+ (Value : T;
Amount : Natural)
- return My_Modular_Type;
+ return T;
@end smallexample
@noindent
-The requirements are that the profile be exactly as in the example
-above. The only modifications allowed are in the formal parameter
-names, and in the type of @code{Value} and the return type, which
-must be the same, and must be either a signed integer type, or
-a modular integer type with a binary modulus, and the size must
-be 8. 16, 32 or 64 bits.
+The function name must be one of
+Shift_Left, Shift_Right, Shift_Right_Arithmetic, Rotate_Left, or
+Rotate_Right. T must be an integer type. T'Size must be
+8, 16, 32 or 64 bits; if T is modular, the modulus
+must be 2**8, 2**16, 2**32 or 2**64.
+The result type must be the same as the type of @code{Value}.
+The shift amount must be Natural.
+The formal parameter names can be anything.
-@node Rotate_Right
-@section Rotate_Right
-@cindex Rotate_Right
-@noindent
-A @code{Rotate_Right} function can be defined for any user defined
-binary modular integer type, or signed integer type, as described
-above for @code{Rotate_Left}.
-
-@node Shift_Left
-@section Shift_Left
-@cindex Shift_Left
-@noindent
-A @code{Shift_Left} function can be defined for any user defined
-binary modular integer type, or signed integer type, as described
-above for @code{Rotate_Left}.
-
-@node Shift_Right
-@section Shift_Right
-@cindex Shift_Right
-@noindent
-A @code{Shift_Right} function can be defined for any user defined
-binary modular integer type, or signed integer type, as described
-above for @code{Rotate_Left}.
-
-@node Shift_Right_Arithmetic
-@section Shift_Right_Arithmetic
-@cindex Shift_Right_Arithmetic
-@noindent
-A @code{Shift_Right_Arithmetic} function can be defined for any user
-defined binary modular integer type, or signed integer type, as described
-above for @code{Rotate_Left}.
-
@node Source_Location
@section Source_Location
@cindex Source_Location
Index: sem_intr.adb
===================================================================
--- sem_intr.adb (revision 183051)
+++ sem_intr.adb (working copy)
@@ -455,12 +455,14 @@
return;
end if;
- Size := UI_To_Int (Esize (Typ1));
+ -- type'Size (not 'Object_Size!) must be one of the allowed values
- if Size /= 8
- and then Size /= 16
- and then Size /= 32
- and then Size /= 64
+ Size := UI_To_Int (RM_Size (Typ1));
+
+ if Size /= 8 and then
+ Size /= 16 and then
+ Size /= 32 and then
+ Size /= 64
then
Errint
("first argument for shift must have size 8, 16, 32 or 64",
@@ -469,8 +471,7 @@
elsif Non_Binary_Modulus (Typ1) then
Errint
- ("shifts not allowed for non-binary modular types",
- Ptyp1, N);
+ ("shifts not allowed for non-binary modular types", Ptyp1, N);
elsif Etype (Arg1) /= Etype (E) then
Errint
