[gcc r12-967] Fix internal error on locally derived bit-packed array type

[Eric Botcazou <ebotcazou@gcc.gnu.org>]

https://gcc.gnu.org/g:dd9a8fff14eda90fcaa3ac4b6b68ceded72a6af5

commit r12-967-gdd9a8fff14eda90fcaa3ac4b6b68ceded72a6af5
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Fri May 21 10:57:02 2021 +0200

    Fix internal error on locally derived bit-packed array type
    
    This is a regression present on the mainline, 11 and 10 branches,
    in the form of an ICE on a locally derived bit-packed array type.
    
    gcc/ada/
            * gcc-interface/decl.c (gnat_to_gnu_entity) <E_Array_Type>: Process
            the implementation type of a packed type implemented specially.
    gcc/testsuite/
            * gnat.dg/derived_type7.adb, gnat.dg/derived_type7.ads: New test.

Diff:
---
 gcc/ada/gcc-interface/decl.c            | 14 +++++++++-----
 gcc/testsuite/gnat.dg/derived_type7.adb |  9 +++++++++
 gcc/testsuite/gnat.dg/derived_type7.ads | 13 +++++++++++++
 3 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/gcc/ada/gcc-interface/decl.c b/gcc/ada/gcc-interface/decl.c
index 19e851ff712..8d3c16c624b 100644
--- a/gcc/ada/gcc-interface/decl.c
+++ b/gcc/ada/gcc-interface/decl.c
@@ -2345,11 +2345,15 @@ gnat_to_gnu_entity (Entity_Id gnat_entity, tree gnu_expr, bool definition)
 	      set_nonaliased_component_on_array_type (tem);
 	  }
 
-	/* If an alignment is specified, use it if valid.  But ignore it
-	   for the original type of packed array types.  If the alignment
-	   was requested with an explicit alignment clause, state so.  */
-	if (No (Packed_Array_Impl_Type (gnat_entity))
-	    && Known_Alignment (gnat_entity))
+	/* If this is a packed type implemented specially, then process the
+	   implementation type so it is elaborated in the proper scope.  */
+	if (Present (Packed_Array_Impl_Type (gnat_entity)))
+	  gnat_to_gnu_entity (Packed_Array_Impl_Type (gnat_entity), NULL_TREE,
+			      false);
+
+	/* Otherwise, if an alignment is specified, use it if valid and, if
+	   the alignment was requested with an explicit clause, state so.  */
+	else if (Known_Alignment (gnat_entity))
 	  {
 	    SET_TYPE_ALIGN (tem,
 			    validate_alignment (Alignment (gnat_entity),
diff --git a/gcc/testsuite/gnat.dg/derived_type7.adb b/gcc/testsuite/gnat.dg/derived_type7.adb
new file mode 100644
index 00000000000..61e7abaa1d7
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/derived_type7.adb
@@ -0,0 +1,9 @@
+package body Derived_Type7 is
+
+  procedure Proc (Size : Natural) is
+    type Sar_Six_Bit_Arr is new Six_Bit_Data_Array_Type (1 .. Size);
+  begin
+    null;
+  end;
+
+end Derived_Type7;
diff --git a/gcc/testsuite/gnat.dg/derived_type7.ads b/gcc/testsuite/gnat.dg/derived_type7.ads
new file mode 100644
index 00000000000..2b1427af3c6
--- /dev/null
+++ b/gcc/testsuite/gnat.dg/derived_type7.ads
@@ -0,0 +1,13 @@
+-- { dg-do compile }
+
+package Derived_Type7 is
+
+  type Six_Bit_Data_Type is range 0 .. 63;
+  for Six_Bit_Data_Type'Size use 6;
+
+  type Six_Bit_Data_Array_Type is array (Integer range <>) of Six_Bit_Data_Type;
+  for Six_Bit_Data_Array_Type'Component_Size use 6;
+
+  procedure Proc (Size : Natural);
+
+end Derived_Type7;