1 files changed, 23 insertions, 5 deletions

diff --git a/gcc/ada/s-vallli.adb b/gcc/ada/s-vallli.adb
index 203e475b3cf..bf0e15d1234 100644
--- a/gcc/ada/s-vallli.adb
+++ b/gcc/ada/s-vallli.adb
@@ -91,12 +91,30 @@ package body System.Val_LLI is
    -----------------------------
 
    function Value_Long_Long_Integer (Str : String) return Long_Long_Integer is
-      V : Long_Long_Integer;
-      P : aliased Integer := Str'First;
    begin
-      V := Scan_Long_Long_Integer (Str, P'Access, Str'Last);
-      Scan_Trailing_Blanks (Str, P);
-      return V;
+      --  We have to special case Str'Last = Positive'Last because the normal
+      --  circuit ends up setting P to Str'Last + 1 which is out of bounds. We
+      --  deal with this by converting to a subtype which fixes the bounds.
+
+      if Str'Last = Positive'Last then
+         declare
+            subtype NT is String (1 .. Str'Length);
+         begin
+            return Value_Long_Long_Integer (NT (Str));
+         end;
+
+      --  Normal case where Str'Last < Positive'Last
+
+      else
+         declare
+            V : Long_Long_Integer;
+            P : aliased Integer := Str'First;
+         begin
+            V := Scan_Long_Long_Integer (Str, P'Access, Str'Last);
+            Scan_Trailing_Blanks (Str, P);
+            return V;
+         end;
+      end if;
    end Value_Long_Long_Integer;
 
 end System.Val_LLI;