[COMMITTED] ada: Compiler crash on container aggregate with loop_parameter_specifications

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

From: Gary Dismukes <dismukes@adacore.com>

The compiler crashes on a container aggregate with more than one
iterated_element_association given by a loop_parameter_specification.
In such a case, the tree contains N_Iterated_Component_Association
nodes rather than N_Iterated_Element_Association nodes, and the code
for handling those needs to obtain the bounds from the Discrete_Choices
field of each N_Iterated_Component_Association rather than assuming
that the association has a normal list of choices.

gcc/ada/

	* sem_aggr.adb (Resolve_Container_Aggregate): In the case where Comp
	is an N_Iterated_Component_Association, pick up Discrete_Choices rather
	than Choices.

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

---
 gcc/ada/sem_aggr.adb | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/gcc/ada/sem_aggr.adb b/gcc/ada/sem_aggr.adb
index d3f9a773191..bc03a079f5a 100644
--- a/gcc/ada/sem_aggr.adb
+++ b/gcc/ada/sem_aggr.adb
@@ -3575,7 +3575,23 @@ package body Sem_Aggr is
                               end if;
                            end if;
                         else
-                           Choice := First (Choices (Comp));
+
+                           --  If Nkind is N_Iterated_Component_Association,
+                           --  this corresponds to an iterator_specification
+                           --  with a loop_parameter_specification, and we
+                           --  have to pick up Discrete_Choices. In this case
+                           --  there will be just one "choice", which will
+                           --  typically be a range.
+
+                           if Nkind (Comp) = N_Iterated_Component_Association
+                           then
+                              Choice := First (Discrete_Choices (Comp));
+
+                           --  Case where there's a list of choices
+
+                           else
+                              Choice := First (Choices (Comp));
+                           end if;
 
                            while Present (Choice) loop
                               Get_Index_Bounds (Choice, Lo, Hi);
-- 
2.42.0