[Ada] Facilitate proof of Overwrite in bounded strings library

[Ada] Facilitate proof of Overwrite in bounded strings library

[Pierre-Marie de Rodat]

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Consistently use >= operator in both the code and contracts of
function/procedure Overwrite, to facilitate proof, instead of the strict
inequality > sometimes, as only New_Item remains in the result in the
case of equal size too.

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

gcc/ada/

	* libgnat/a-strbou.ads (Overwrite): Switch to >= operator in
	contracts.
	* libgnat/a-strsup.adb (Super_Overwrite): Switch to >= operator
	in code of procedure (function already uses it).
	* libgnat/a-strsup.ads (Super_Overwrite): Switch to >= operator
	in contracts.

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diff --git a/gcc/ada/libgnat/a-strbou.ads b/gcc/ada/libgnat/a-strbou.ads
--- a/gcc/ada/libgnat/a-strbou.ads
+++ b/gcc/ada/libgnat/a-strbou.ads
@@ -1898,7 +1898,7 @@ package Ada.Strings.Bounded with SPARK_Mode is
                --  some characters of Source are remaining at the left.
 
                and then
-                 (if New_Item'Length > Max_Length then
+                 (if New_Item'Length >= Max_Length then
 
                     --  New_Item covers all Max_Length characters
 
@@ -1984,7 +1984,7 @@ package Ada.Strings.Bounded with SPARK_Mode is
                --  some characters of Source are remaining at the left.
 
                and then
-                 (if New_Item'Length > Max_Length then
+                 (if New_Item'Length >= Max_Length then
 
                     --  New_Item covers all Max_Length characters
 


diff --git a/gcc/ada/libgnat/a-strsup.adb b/gcc/ada/libgnat/a-strsup.adb
--- a/gcc/ada/libgnat/a-strsup.adb
+++ b/gcc/ada/libgnat/a-strsup.adb
@@ -1226,7 +1226,7 @@ package body Ada.Strings.Superbounded with SPARK_Mode is
                  (New_Item (New_Item'First .. New_Item'Last - Droplen));
 
             when Strings.Left =>
-               if New_Item'Length > Max_Length then
+               if New_Item'Length >= Max_Length then
                   Source.Data (1 .. Max_Length) := Super_String_Data
                     (New_Item
                       (New_Item'Last - Max_Length + 1 .. New_Item'Last));


diff --git a/gcc/ada/libgnat/a-strsup.ads b/gcc/ada/libgnat/a-strsup.ads
--- a/gcc/ada/libgnat/a-strsup.ads
+++ b/gcc/ada/libgnat/a-strsup.ads
@@ -2000,7 +2000,7 @@ package Ada.Strings.Superbounded with SPARK_Mode is
             --  Source are remaining at the left.
 
             and then
-              (if New_Item'Length > Source.Max_Length then
+              (if New_Item'Length >= Source.Max_Length then
 
                  --  New_Item covers all Max_Length characters
 
@@ -2089,7 +2089,7 @@ package Ada.Strings.Superbounded with SPARK_Mode is
             --  Source are remaining at the left.
 
             and then
-              (if New_Item'Length > Source.Max_Length then
+              (if New_Item'Length >= Source.Max_Length then
 
                  --  New_Item covers all Max_Length characters