[gcc r12-1897] [Ada] Crash on limited array object with address clause

[Pierre-Marie de Rodat]

https://gcc.gnu.org/g:a671959b7640b1b02c924292959f2cbe1574536a

commit r12-1897-ga671959b7640b1b02c924292959f2cbe1574536a
Author: Ed Schonberg <schonberg@adacore.com>
Date:   Fri Apr 16 12:52:50 2021 -0400

    [Ada] Crash on limited array object with address clause
    
    gcc/ada/
    
            * exp_aggr.adb (Convert_Aggr_In_Object_Decl): After expansion of
            the aggregate, the expression can be removed from the
            declaration, except if the object is class-wide, in which case
            the aggregate provides the actual type. In other cases the
            presence of the expression may lead to spurious freezing issue.
            * exp_ch3.adb (Expand_N_Object_Declaration): If the expression
            in the declaration is an aggregate with delayed expansion (as is
            the case for objects of a limited type, or a subsequent address
            specification) the aggregate must be resolved at this point.
            This resolution must not include expansion, because the
            expansion of the enclosing declaration will construct the
            necessary aggregate expansion.

Diff:
---
 gcc/ada/exp_aggr.adb | 9 +++++++++
 gcc/ada/exp_ch3.adb  | 7 ++++++-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/gcc/ada/exp_aggr.adb b/gcc/ada/exp_aggr.adb
index 85e2abb0732..56ec1be5d7f 100644
--- a/gcc/ada/exp_aggr.adb
+++ b/gcc/ada/exp_aggr.adb
@@ -4437,6 +4437,15 @@ package body Exp_Aggr is
       end;
 
       Set_No_Initialization (N);
+
+      --  After expansion the expression can be removed from the declaration
+      --  except if the object is class-wide, in which case the aggregate
+      --  provides the actual type.
+
+      if not Is_Class_Wide_Type (Etype (Obj)) then
+         Set_Expression (N, Empty);
+      end if;
+
       Initialize_Discriminants (N, Typ);
    end Convert_Aggr_In_Object_Decl;
 
diff --git a/gcc/ada/exp_ch3.adb b/gcc/ada/exp_ch3.adb
index 6a8b33073cf..4dbaadd637d 100644
--- a/gcc/ada/exp_ch3.adb
+++ b/gcc/ada/exp_ch3.adb
@@ -30,6 +30,7 @@ with Einfo;          use Einfo;
 with Einfo.Entities; use Einfo.Entities;
 with Einfo.Utils;    use Einfo.Utils;
 with Errout;         use Errout;
+with Expander;       use Expander;
 with Exp_Aggr;       use Exp_Aggr;
 with Exp_Atag;       use Exp_Atag;
 with Exp_Ch4;        use Exp_Ch4;
@@ -6985,12 +6986,16 @@ package body Exp_Ch3 is
             --  happen when the aggregate is limited and the declared object
             --  has a following address clause; it happens also when generating
             --  C code for an aggregate that has an alignment or address clause
-            --  (see Analyze_Object_Declaration).
+            --  (see Analyze_Object_Declaration). Resolution is done without
+            --  expansion because it will take place when the declaration
+            --  itself is expanded.
 
             if (Is_Limited_Type (Typ) or else Modify_Tree_For_C)
               and then not Analyzed (Expr)
             then
+               Expander_Mode_Save_And_Set (False);
                Resolve (Expr, Typ);
+               Expander_Mode_Restore;
             end if;
 
             Convert_Aggr_In_Object_Decl (N);