The compiler gave a wrong error about "must override" in the following
case. A private type is completed with a derived type that inherits a
must-override function. Outside that package, a type extension of the
private type is declared. The function on that type extension is not
visible, and is not must-override, so should not be in error. Indeed, it
cannot be overridden. This patch fixes the bug, suppressing that error
message.
Tested on x86_64-pc-linux-gnu, committed on trunk
2019-12-18 Bob Duff <d...@adacore.com>
gcc/ada/
* sem_ch3.adb (Derive_Subprogram): Do not set the
Requires_Overriding flag in the above-mentioned case.--- gcc/ada/sem_ch3.adb
+++ gcc/ada/sem_ch3.adb
@@ -15606,7 +15606,8 @@ package body Sem_Ch3 is
Set_Derived_Name;
-- Otherwise, the type is inheriting a private operation, so enter it
- -- with a special name so it can't be overridden.
+ -- with a special name so it can't be overridden. See also below, where
+ -- we check for this case, and if so avoid setting Requires_Overriding.
else
Set_Chars (New_Subp, New_External_Name (Chars (Parent_Subp), 'P'));
@@ -15786,7 +15787,15 @@ package body Sem_Ch3 is
or else Is_Abstract_Subprogram (Alias (New_Subp))
then
Set_Is_Abstract_Subprogram (New_Subp);
- else
+
+ -- If the Chars of the new subprogram is different from that of the
+ -- parent's one, it means that we entered it with a special name so
+ -- it can't be overridden (see above). In that case we had better not
+ -- *require* it to be overridden. This is the case where the parent
+ -- type inherited the operation privately, so there's no danger of
+ -- dangling dispatching.
+
+ elsif Chars (New_Subp) = Chars (Alias (New_Subp)) then
Set_Requires_Overriding (New_Subp);
end if;
