[Ada] Warning on out-of-range value for default-initialized scalar object

[Ada] Warning on out-of-range value for default-initialized scalar object

[Pierre-Marie de Rodat]

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When an object of a type with a specified Default_Value aspect is
declared without an explicit initial value and the default value is
out of range of the objects subtype, the compiler now issues a warning
that Constraint_Error will be raised due to an out-of-range value.

The test below must output a compiler warning as follows:

$ gcc -c -gnatj70 default_warning.adb
default_warning.adb:7:08: warning: value not in range of type
                          "Subint" defined at line 5,
                          "Constraint_Error" will be raised at run
                          time

procedure Default_Warning is

   type Int_With_Default is new Integer with Default_Value => 0;

   subtype Subint is Int_With_Default range 1 .. 100;

   S : Subint;

begin
   null;
end Default_Warning;

Tested on x86_64-pc-linux-gnu, committed on trunk

2018-01-11  Gary Dismukes  <dismukes@adacore.com>

gcc/ada/

	* exp_ch3.adb (Default_Initialize_Object): Call New_Copy_Tree on the
	result of Get_Simple_Init_Value and pass the source location of the
	object declaration's object_definition.

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--- gcc/ada/exp_ch3.adb
+++ gcc/ada/exp_ch3.adb
@@ -6052,7 +6052,10 @@ package body Exp_Ch3 is
            and then not Has_Init_Expression (N)
          then
             Set_No_Initialization (N, False);
-            Set_Expression (N, Get_Simple_Init_Val (Typ, N, Esize (Def_Id)));
+            Set_Expression
+              (N, New_Copy_Tree
+                    (Get_Simple_Init_Val (Typ, N, Esize (Def_Id)),
+                     New_Sloc => Sloc (Obj_Def)));
             Analyze_And_Resolve (Expression (N), Typ);
          end if;