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[Ada] Compiler crash with Initialize_Scalars

Message ID 20101026110331.GA23871@adacore.com
State New
Headers show

Commit Message

Arnaud Charlet Oct. 26, 2010, 11:03 a.m. UTC 
If pragma Initialize_Scalars applies, then in certain obscure cases the
compiler would crash. In particular, a private type whose full type is an
array, and then another private type whose full type is derived from the first
private type, and then an object declared of that second private type.
This patch fixes the bug.

The following test should compile quietly.

gcc -c q.adb -gnatws

with Interrupt_Management;

procedure Q is

  Mask : Interrupt_Management.Interrupt_Mask;

begin
  null;
end;
package OS_Interface is

   type sigset_t is private;

private

   type unsigned_char is mod 256;
   type sigset_t is array (0 .. 127) of unsigned_char;

end OS_Interface;
with OS_Interface;

package Interrupt_Management is

   type Interrupt_Mask is private;

private
   type Interrupt_Mask is new OS_Interface.sigset_t;

end Interrupt_Management;

Tested on x86_64-pc-linux-gnu, committed on trunk

2010-10-26  Bob Duff  <duff@adacore.com>

	* sem_res.adb (Resolve_Actuals): In case of certain
	internally-generated type conversions (created by OK_Convert_To, so the
	Conversion_OK flag is set), avoid fetching the component type when it's
	not really an array type, but a private type completed by an array type.
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Patch

Index: sem_res.adb
===================================================================
--- sem_res.adb	(revision 165944)
+++ sem_res.adb	(working copy)
@@ -3334,45 +3334,55 @@  package body Sem_Res is
                if Ekind (F) = E_In_Out_Parameter
                  and then Is_Array_Type (Etype (F))
                then
-                  if Has_Aliased_Components (Etype (Expression (A)))
-                    /= Has_Aliased_Components (Etype (F))
-                  then
-
-                     --  In a view conversion, the conversion must be legal in
-                     --  both directions, and thus both component types must be
-                     --  aliased, or neither (4.6 (8)).
-
-                     --  The additional rule 4.6 (24.9.2) seems unduly
-                     --  restrictive: the privacy requirement should not apply
-                     --  to generic types, and should be checked in an
-                     --  instance. ARG query is in order ???
+                  --  In a view conversion, the conversion must be legal in
+                  --  both directions, and thus both component types must be
+                  --  aliased, or neither (4.6 (8)).
+
+                  --  The extra rule in 4.6 (24.9.2) seems unduly restrictive:
+                  --  the privacy requirement should not apply to generic
+                  --  types, and should be checked in an instance. ARG query
+                  --  is in order ???
 
+                  if Has_Aliased_Components (Etype (Expression (A))) /=
+                     Has_Aliased_Components (Etype (F))
+                  then
                      Error_Msg_N
                        ("both component types in a view conversion must be"
                          & " aliased, or neither", A);
 
+                  --  Comment here??? what set of cases???
+
                   elsif
                      not Same_Ancestor (Etype (F), Etype (Expression (A)))
                   then
+                     --  Check view conv between unrelated by ref array types
+
                      if Is_By_Reference_Type (Etype (F))
                         or else Is_By_Reference_Type (Etype (Expression (A)))
                      then
                         Error_Msg_N
                           ("view conversion between unrelated by reference " &
                            "array types not allowed (\'A'I-00246)", A);
-                     else
+
+                     --  In Ada 2005 mode, check view conversion component
+                     --  type cannot be private, tagged, or volatile. Note
+                     --  that we only apply this to source conversions. The
+                     --  generated code can contain conversions which are
+                     --  not subject to this test, and we cannot extract the
+                     --  component type in such cases since it is not present.
+
+                     elsif Comes_From_Source (A)
+                       and then Ada_Version >= Ada_2005
+                     then
                         declare
                            Comp_Type : constant Entity_Id :=
                                          Component_Type
                                            (Etype (Expression (A)));
                         begin
-                           if Comes_From_Source (A)
-                             and then Ada_Version >= Ada_2005
-                             and then
-                               ((Is_Private_Type (Comp_Type)
-                                   and then not Is_Generic_Type (Comp_Type))
-                                 or else Is_Tagged_Type (Comp_Type)
-                                 or else Is_Volatile (Comp_Type))
+                           if (Is_Private_Type (Comp_Type)
+                                 and then not Is_Generic_Type (Comp_Type))
+                             or else Is_Tagged_Type (Comp_Type)
+                             or else Is_Volatile (Comp_Type)
                            then
                               Error_Msg_N
                                 ("component type of a view conversion cannot"
@@ -3385,8 +3395,10 @@  package body Sem_Res is
                   end if;
                end if;
 
+               --  Resolve expression if conversion is all OK
+
                if (Conversion_OK (A)
-                     or else Valid_Conversion (A, Etype (A), Expression (A)))
+                    or else Valid_Conversion (A, Etype (A), Expression (A)))
                  and then not Is_Ref_To_Bit_Packed_Array (Expression (A))
                then
                   Resolve (Expression (A));