[Ada] Robust detection of access-to-subprogram and access-to-object types

Message ID 20210507093823.GA140847@adacore.com
State New
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  • [Ada] Robust detection of access-to-subprogram and access-to-object types
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Commit Message

Pierre-Marie de Rodat May 7, 2021, 9:38 a.m.
Routines Is_Access_Object_Type and Is_Access_Subprogram_Type were
arbitrarily categorizing E_Access_Subtype as an access-to-object, even
though it could represent an access-to-subprogram.

Now those routines examine not just the Ekind, but also the
Designated_Type of an access (sub)type, which is more reliable.

Only the handling of Can_Use_Internal_Rep and Convention flags need to
be adjusted, because they are set before the Designated_Type. However,
those flags are only set at base type anyway, so there is no problem
with E_Access_Subtype being wrongly recognized and we can safely rely on
the Ekind to detect access-to-subprograms.

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


	* einfo-utils.adb (Is_Access_Object_Type): Use
	(Is_Access_Subprogram_Type): Use Directly_Designated_Type.
	(Set_Convention): Use plain Ekind.
	* gen_il-gen-gen_entities.adb (Type_Kind): Use plain Ekind.
	* sem_ch3.adb (Access_Type_Declaration): When seeing an illegal
	completion with an access type don't attempt to decorate the
	completion entity; previously the entity had its Ekind set to
	E_General_Access_Type or E_Access_Type, but its Designated_Type
	was empty, which caused a crash in freezing. (Actually, the
	error recovery in the surrounding context is still incomplete,
	e.g. we will crash when the illegal completion is an access to
	an unknown identifier).


diff --git a/gcc/ada/einfo-utils.adb b/gcc/ada/einfo-utils.adb
--- a/gcc/ada/einfo-utils.adb
+++ b/gcc/ada/einfo-utils.adb
@@ -101,7 +101,8 @@  package body Einfo.Utils is
    function Is_Access_Object_Type               (Id : E) return B is
-      return Is_Access_Type (Id) and then not Is_Access_Subprogram_Type (Id);
+      return Is_Access_Type (Id)
+        and then Ekind (Directly_Designated_Type (Id)) /= E_Subprogram_Type;
    end Is_Access_Object_Type;
    function Is_Access_Type                      (Id : E) return B is
@@ -116,7 +117,8 @@  package body Einfo.Utils is
    function Is_Access_Subprogram_Type           (Id : E) return B is
-      return Ekind (Id) in Access_Subprogram_Kind;
+      return Is_Access_Type (Id)
+        and then Ekind (Directly_Designated_Type (Id)) = E_Subprogram_Type;
    end Is_Access_Subprogram_Type;
    function Is_Aggregate_Type                   (Id : E) return B is
@@ -2672,8 +2674,7 @@  package body Einfo.Utils is
       Set_Basic_Convention (E, Val);
-      if Is_Type (E)
-        and then Is_Access_Subprogram_Type (Base_Type (E))
+      if Ekind (E) in Access_Subprogram_Kind
         and then Has_Foreign_Convention (E)
          Set_Can_Use_Internal_Rep (E, False);

diff --git a/gcc/ada/gen_il-gen-gen_entities.adb b/gcc/ada/gen_il-gen-gen_entities.adb
--- a/gcc/ada/gen_il-gen-gen_entities.adb
+++ b/gcc/ada/gen_il-gen-gen_entities.adb
@@ -480,7 +480,7 @@  begin -- Gen_IL.Gen.Gen_Entities
        (Sm (Alignment, Uint),
         Sm (Associated_Node_For_Itype, Node_Id),
         Sm (Can_Use_Internal_Rep, Flag, Base_Type_Only,
-            Pre => "Is_Access_Subprogram_Type (Base_Type (N))"),
+            Pre => "Ekind (Base_Type (N)) in Access_Subprogram_Kind"),
         Sm (Class_Wide_Type, Node_Id),
         Sm (Contract, Node_Id),
         Sm (Current_Use_Clause, Node_Id),

diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -1354,6 +1354,7 @@  package body Sem_Ch3 is
                pragma Assert (Error_Posted (T));
+               return;
             end if;
             --  If the designated type is a limited view, we cannot tell if
@@ -6725,7 +6726,9 @@  package body Sem_Ch3 is
                               Has_Private_Component (Derived_Type));
       Conditional_Delay      (Derived_Type, Subt);
-      if Is_Access_Subprogram_Type (Derived_Type) then
+      if Is_Access_Subprogram_Type (Derived_Type)
+        and then Is_Base_Type (Derived_Type)
+      then
            (Derived_Type, Can_Use_Internal_Rep (Parent_Type));
       end if;