[Ada] Fix expansion of operations on nonbinary modular types

2018-10-09  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* exp_ch4.adb (Expand_Modular_Op): When expanding an operation
	on nonbinary modular types, convert the opersnds to an integer
	type that is large enough to hold the modulus of the type, which
	may be larger than Integer'Last.

From-SVN: r264973

gcc/ada/ChangeLog

 2018-10-09  Ed Schonberg  <schonberg@adacore.com>
 
+	* exp_ch4.adb (Expand_Modular_Op): When expanding an operation
+	on nonbinary modular types, convert the opersnds to an integer
+	type that is large enough to hold the modulus of the type, which
+	may be larger than Integer'Last.
+
+2018-10-09  Ed Schonberg  <schonberg@adacore.com>
+
 	* exp_unst.adb (Unnest_Subprogram):  When an uplevel reference
 	is to an unconstrained formal, the 'Access reference that is
 	created to initialize the corresponding component of the

gcc/ada/exp_ch4.adb

@@ -4067,6 +4067,8 @@ package body Exp_Ch4 is
          Op_Expr  : constant Node_Id := New_Op_Node (Nkind (N), Loc);
          Mod_Expr : constant Node_Id := New_Op_Node (N_Op_Mod, Loc);
 
+         Target_Type   : Entity_Id;
+
       begin
          --  Convert nonbinary modular type operands into integer values. Thus
          --  we avoid never-ending loops expanding them, and we also ensure
@@ -4083,11 +4085,21 @@ package body Exp_Ch4 is
               Unchecked_Convert_To (Standard_Integer, Op_Expr));
 
          else
+            --  If the modulus of the type is larger than Integer'Last
+            --  use a larger type for the operands, to prevent spurious
+            --  constraint errors on large legal literals of the type.
+
+            if Modulus (Etype (N)) > UI_From_Int (Int (Integer'Last)) then
+               Target_Type := Standard_Long_Integer;
+            else
+               Target_Type := Standard_Integer;
+            end if;
+
             Set_Left_Opnd (Op_Expr,
-              Unchecked_Convert_To (Standard_Integer,
+              Unchecked_Convert_To (Target_Type,
                 New_Copy_Tree (Left_Opnd (N))));
             Set_Right_Opnd (Op_Expr,
-              Unchecked_Convert_To (Standard_Integer,
+              Unchecked_Convert_To (Target_Type,
                 New_Copy_Tree (Right_Opnd (N))));
 
             --  Link this node to the tree to analyze it