[COMMITTED] ada: Fix crash on concurrent type aggregate

["Marc Poulhiès" <poulhies@adacore.com>]

From: Ronan Desplanques <desplanques@adacore.com>

Before this patch, the compiler would fail to examine the corresponding
record types of concurrent types when building aggregate components.
This patch fixes this, and adds a precondition and additional documentation
on the subprogram that triggered the crash, as it never makes sense
to call it with a concurrent type.

gcc/ada/

	* exp_aggr.adb (Initialize_Component): Use corresponding record
	types of concurrent types.
	* exp_util.ads (Make_Tag_Assignment_From_Type): Add precondition
	and extend documentation.

Co-authored-by: Javier Miranda <miranda@adacore.com>

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/exp_aggr.adb | 15 ++++++++++++---
 gcc/ada/exp_util.ads |  8 ++++++--
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/gcc/ada/exp_aggr.adb b/gcc/ada/exp_aggr.adb
index d61fbbc8c73..50063ed819e 100644
--- a/gcc/ada/exp_aggr.adb
+++ b/gcc/ada/exp_aggr.adb
@@ -8509,9 +8509,18 @@ package body Exp_Aggr is
          Set_No_Ctrl_Actions (Init_Stmt);
 
          if Tagged_Type_Expansion and then Is_Tagged_Type (Comp_Typ) then
-            Append_To (Blk_Stmts,
-              Make_Tag_Assignment_From_Type
-                (Loc, New_Copy_Tree (Comp), Underlying_Type (Comp_Typ)));
+            declare
+               Typ : Entity_Id := Underlying_Type (Comp_Typ);
+
+            begin
+               if Is_Concurrent_Type (Typ) then
+                  Typ := Corresponding_Record_Type (Typ);
+               end if;
+
+               Append_To (Blk_Stmts,
+                 Make_Tag_Assignment_From_Type
+                   (Loc, New_Copy_Tree (Comp), Typ));
+            end;
          end if;
       end if;
 
diff --git a/gcc/ada/exp_util.ads b/gcc/ada/exp_util.ads
index 267a127ec5e..d15e4f90865 100644
--- a/gcc/ada/exp_util.ads
+++ b/gcc/ada/exp_util.ads
@@ -941,9 +941,13 @@ package Exp_Util is
    function Make_Tag_Assignment_From_Type
      (Loc    : Source_Ptr;
       Target : Node_Id;
-      Typ    : Entity_Id) return Node_Id;
+      Typ    : Entity_Id) return Node_Id
+   with
+     Pre => (not Is_Concurrent_Type (Typ));
    --  Return an assignment of the tag of tagged type Typ to prefix Target,
-   --  which must be a record object of a descendant of Typ.
+   --  which must be a record object of a descendant of Typ. Typ cannot be a
+   --  concurrent type; for concurrent types, the corresponding record types
+   --  should be passed to this function instead.
 
    function Make_Variant_Comparison
      (Loc      : Source_Ptr;
-- 
2.43.0