[gcc r12-5035] [Ada] Initialize Current_Source_Unit

[Pierre-Marie de Rodat <pmderodat@gcc.gnu.org>]

https://gcc.gnu.org/g:80d52cbe59b19577fa215a4357c327e707890e9b

commit r12-5035-g80d52cbe59b19577fa215a4357c327e707890e9b
Author: Etienne Servais <servais@adacore.com>
Date:   Fri Oct 29 12:32:11 2021 +0200

    [Ada] Initialize Current_Source_Unit
    
    gcc/ada/
    
            * sinput.ads: Initialize Current_Source_Unit to No_Unit.

Diff:
---
 gcc/ada/sinput.ads | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/gcc/ada/sinput.ads b/gcc/ada/sinput.ads
index 2926b85acff..881e7750634 100644
--- a/gcc/ada/sinput.ads
+++ b/gcc/ada/sinput.ads
@@ -412,10 +412,10 @@ package Sinput is
    --  Initialized so that some tools (such as gprbuild) can be built with
    --  -gnatVa and pragma Initialize_Scalars without problems.
 
-   Current_Source_Unit : Unit_Number_Type;
-   --  Unit number of source file currently being scanned. The special value
-   --  of No_Unit indicates that the configuration pragma file is currently
-   --  being scanned (this has no entry in the unit table).
+   Current_Source_Unit : Unit_Number_Type := No_Unit;
+   --  Unit number of source file currently being scanned. Initialized to
+   --  No_Unit for pre-processing and the configuration pragma file scanning,
+   --  since both stages have no corresponding entry in the unit table.
 
    Source_gnat_adc : Source_File_Index := No_Source_File;
    --  This is set if a gnat.adc file is present to reference this file