ada: Nested use_type_clause with "all" cancels use_type_clause with wider scope

The compiler mishandles nested use_type_clauses in the case where the
outer one is a normal use_type_clause and the inner one has "all".
Upon leaving the scope of the inner use_type_clause, the outer one
is effectively disabled, because it's not considered redundant (and
in fact it's only partially redundant). This is fixed by testing for
the presence of a use_type_clause for the same type that has a wider
scope when ending the inner use_type_clause.

gcc/ada/ChangeLog:

	* sem_ch8.adb (End_Use_Type): Add a test for there not being an earlier
	use_type_clause for the same type as an additional criterion for turning
	off In_Use and Current_Use_Clause.

diff --git a/gcc/ada/sem_ch8.adb b/gcc/ada/sem_ch8.adb
index 54066b4f23eadde4c9ced63986194ea50a9be516..e6ef65860d630f58bd15b4cfea6f3a7c1c36ce43 100644 (file)
--- a/gcc/ada/sem_ch8.adb
+++ b/gcc/ada/sem_ch8.adb
@@ -5444,7 +5444,15 @@ package body Sem_Ch8 is
          elsif In_Open_Scopes (Scope (Base_Type (T))) then
             null;
 
-         elsif not Redundant_Use (Id) then
+         --  Turn off the use_type_clause on the type unless the clause is
+         --  redundant, or there's a previous use_type_clause. (The case where
+         --  a use_type_clause without "all" is followed by one with "all" in
+         --  a more nested scope is not considered redundant, necessitating
+         --  the test for a previous clause. One might expect the latter test
+         --  to suffice, but it turns out there are cases where Redundant_Use
+         --  is set, but Prev_Use_Clause is not set. ???)
+
+         elsif not Redundant_Use (Id) and then No (Prev_Use_Clause (N)) then
             Set_In_Use (T, False);
             Set_In_Use (Base_Type (T), False);
             Set_Current_Use_Clause (T, Empty);