From: Javier Miranda <[email protected]>
This patch fixes a spurious error reported by the frontend when
a dispatching primitive of a tagged type has additional formals
with types that have the First_Controlling_Parameter aspect.
gcc/ada/ChangeLog:
* sem_disp.adb (Check_Controlling_Formals): Formals of a type
specifying aspect First_Controlling_Parameter are not candidate
controlling parameters when they are not the first formal of
the dispatching primitive.
Tested on x86_64-pc-linux-gnu, committed on master.
---
gcc/ada/sem_disp.adb | 24 +++++++++++++++++++++++-
1 file changed, 23 insertions(+), 1 deletion(-)
diff --git a/gcc/ada/sem_disp.adb b/gcc/ada/sem_disp.adb
index ff606c7cfa7..160f1a31575 100644
--- a/gcc/ada/sem_disp.adb
+++ b/gcc/ada/sem_disp.adb
@@ -309,7 +309,29 @@ package body Sem_Disp is
-- Common Ada case
if not Has_First_Controlling_Parameter_Aspect (Typ) then
- Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
+
+ -- Formals of a type specifying aspect First_Controlling_Parameter
+ -- are not candidate controlling parameters when they are not
+ -- the first formal of the dispatching primitive. For example:
+ --
+ -- type T1 is tagged ...
+ -- type T2 is tagged ... with First_Controlling_Parameter;
+ -- procedure Prim (X : T1; Y : T2);
+ --
+ -- When T2 does not have the First_Controlling_Parameter aspect
+ -- this example is rejected because a primitive can be dispatching
+ -- in only one type. However, T2 cannot be a candidate controlling
+ -- type for Prim because Y is not its first formal. Therefore,
+ -- this example is accepted.
+
+ if Is_Tagged_Type (Etype (Formal))
+ and then Has_First_Controlling_Parameter_Aspect (Etype (Formal))
+ and then Formal /= First_Formal (Subp)
+ then
+ null;
+ else
+ Ctrl_Type := Check_Controlling_Type (Etype (Formal), Subp);
+ end if;
-- Type with the First_Controlling_Parameter aspect: for overriding
-- primitives of a parent type that lacks this aspect, we cannot be
--
2.53.0
