[Ada] AI12-0407: Fixups on Big_Integers and Big_Reals

[Pierre-Marie de Rodat]

This AI updates among other things some declarations in big number
packages.

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

gcc/ada/

        * libgnat/a-nbnbin.ads (From_Universal_Image): New.
        (Big_Integer): Update definition.
        * libgnat/a-nbnbre.ads, libgnat/a-nbnbre.adb
        (From_Universal_Image): New.
        (From_String): Remove alternate body, replaced by
        From_Universal_Image.
        (Big_Real): Update definition.
diff --git a/gcc/ada/libgnat/a-nbnbin.ads b/gcc/ada/libgnat/a-nbnbin.ads
--- a/gcc/ada/libgnat/a-nbnbin.ads
+++ b/gcc/ada/libgnat/a-nbnbin.ads
@@ -22,7 +22,7 @@ package Ada.Numerics.Big_Numbers.Big_Integers
   with Preelaborate
 is
    type Big_Integer is private
-     with Integer_Literal => From_String,
+     with Integer_Literal => From_Universal_Image,
           Put_Image       => Put_Image;
 
    function Is_Valid (Arg : Big_Integer) return Boolean
@@ -116,6 +116,9 @@ is
    function From_String (Arg : String) return Valid_Big_Integer
      with Global => null;
 
+   function From_Universal_Image (Arg : String) return Valid_Big_Integer
+     renames From_String;
+
    procedure Put_Image (S : in out Sink'Class; V : Big_Integer);
 
    function "+" (L : Valid_Big_Integer) return Valid_Big_Integer


diff --git a/gcc/ada/libgnat/a-nbnbre.adb b/gcc/ada/libgnat/a-nbnbre.adb
--- a/gcc/ada/libgnat/a-nbnbre.adb
+++ b/gcc/ada/libgnat/a-nbnbre.adb
@@ -593,13 +593,6 @@ package body Ada.Numerics.Big_Numbers.Big_Reals is
       end;
    end From_String;
 
-   function From_String
-     (Numerator, Denominator : String) return Valid_Big_Real is
-   begin
-      return Big_Integers.From_String (Numerator) /
-        Big_Integers.From_String (Denominator);
-   end From_String;
-
    --------------------------
    -- From_Quotient_String --
    --------------------------


diff --git a/gcc/ada/libgnat/a-nbnbre.ads b/gcc/ada/libgnat/a-nbnbre.ads
--- a/gcc/ada/libgnat/a-nbnbre.ads
+++ b/gcc/ada/libgnat/a-nbnbre.ads
@@ -21,7 +21,7 @@ package Ada.Numerics.Big_Numbers.Big_Reals
   with Preelaborate
 is
    type Big_Real is private with
-     Real_Literal => From_String,
+     Real_Literal => From_Universal_Image,
      Put_Image    => Put_Image;
 
    function Is_Valid (Arg : Big_Real) return Boolean
@@ -122,8 +122,13 @@ is
 
    function From_String (Arg : String) return Valid_Big_Real
      with Global => null;
-   function From_String (Numerator, Denominator : String) return Valid_Big_Real
-     with Global => null;
+
+   function From_Universal_Image (Arg : String) return Valid_Big_Real
+     renames From_String;
+   function From_Universal_Image (Num, Den : String) return Valid_Big_Real is
+     (Big_Integers.From_Universal_Image (Num) /
+      Big_Integers.From_Universal_Image (Den))
+      with Global => null;
 
    function To_Quotient_String (Arg : Big_Real) return String is
      (Big_Integers.To_String (Numerator (Arg)) & " / "