commit 83a5b1df3da2d6c50efabdbf4767a32e80f0cab1
author Gary Dismukes <dismukes@adacore.com> Wed Mar 10 18:35:58 2021 -0500
committer Pierre-Marie de Rodat <derodat@adacore.com> Thu Jun 17 10:32:14 2021 -0400
tree c818deead6432edd42dd41fd6d3da23e86bcb133
parent cad7431bd64325e1a30f868615aa04d01a472b01

[Ada] Error in instance on incomplete actual passed to formal incomplete type

gcc/ada/

	* sem_ch12.adb (Instantiate_Type): If the actual type for an
	incomplete formal type is also incomplete, but has a Full_View,
	use the Full_View of the actual type rather than the incomplete
	view.

gcc/ada/sem_ch12.adb

diff --git a/gcc/ada/sem_ch12.adb b/gcc/ada/sem_ch12.adb
index 2cd4689..06947e2 100644
--- a/gcc/ada/sem_ch12.adb
+++ b/gcc/ada/sem_ch12.adb
@@ -14022,9 +14022,12 @@
                      and then Ekind (Root_Type (Act_T)) = E_Incomplete_Type)
          then
             --  If the formal is an incomplete type, the actual can be
-            --  incomplete as well.
+            --  incomplete as well, but if an actual incomplete type has
+            --  a full view, then we'll retrieve that.
 
-            if Ekind (A_Gen_T) = E_Incomplete_Type then
+            if Ekind (A_Gen_T) = E_Incomplete_Type
+              and then not Present (Full_View (Act_T))
+            then
                null;
 
             elsif Is_Class_Wide_Type (Act_T)
@@ -14032,6 +14035,7 @@
             then
                Error_Msg_N ("premature use of incomplete type", Actual);
                Abandon_Instantiation (Actual);
+
             else
                Act_T := Full_View (Act_T);
                Set_Entity (Actual, Act_T);