makeutl.adb (Executable_Prefix_Path): If Locate_Exec_On_Path fails...

2008-07-31  Vincent Celier  <celier@adacore.com>

	* makeutl.adb (Executable_Prefix_Path): If Locate_Exec_On_Path fails,
	return the empty string, instead of raising Constraint_Error.

From-SVN: r138398

gcc/ada/makeutl.adb

@@ -246,7 +246,17 @@ package body Makeutl is
       --  If we get here, the user has typed the executable name with no
       --  directory prefix.
 
-      return Get_Install_Dir (Locate_Exec_On_Path (Exec_Name).all);
+      declare
+         Path : constant String_Access := Locate_Exec_On_Path (Exec_Name);
+
+      begin
+         if Path = null then
+            return "";
+
+         else
+            return Get_Install_Dir (Path.all);
+         end if;
+      end;
    end Executable_Prefix_Path;
 
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