[Mono-bugs] [Bug 49904][Nor] New - Error CS0136 for compiling program -- scope issue

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Changed by cristian.adam at gmx.net.

http://bugzilla.ximian.com/show_bug.cgi?id=49904

--- shadow/49904	2007-01-10 04:08:52.000000000 -0500
+++ shadow/49904.tmp.24762	2007-01-10 04:08:52.000000000 -0500
@@ -0,0 +1,130 @@
+Bug#: 49904
+Product: Mono: Compilers
+Version: unspecified
+OS: unknown
+OS Details: debian gnu/linux woody 2.4.18
+Status: RESOLVED   
+Resolution: NOTABUG
+Severity: Unknown
+Priority: Normal
+Component: C#
+AssignedTo: mono-bugs at ximian.com                            
+ReportedBy: baskmau at hotmail.com               
+QAContact: mono-bugs at ximian.com
+TargetMilestone: ---
+URL: 
+Cc: 
+Summary: Error CS0136 for compiling program -- scope issue
+
+Description of Problem:
+
+Scopes seem to work differently in Java and C# per mcs and javac -- not
+sure if this is the case:
+
+Compiling C# program with 0.26 mcs gives:
+
+class Scope
+{
+    bool condition;
+
+    Scope()
+    {
+        condition = true;
+
+        if ( condition )
+        {
+            int inner = 0;
+            Console.WriteLine( " .. inside if block .. " );
+        }
+
+        int inner = 0;
+        Console.WriteLine( " .. top level scope .. " );
+    }
+
+    public static void Main()
+    {
+        Scope test = new Scope();
+        Console.WriteLine( " .. fini scope test .. " );
+    }
+}
+
+gives the following error message:
+
+Scope.cs(15) error CS0136: A local variable named `inner' cannot be
+declared in this scope since it would give a different meaning to `inner',
+which is already used in a `child' scope to denote something else
+Compilation failed: 1 error(s), 0 warnings
+
+Expected Results:
+Additional Information:
+
+The corresponding Java program compiles and runs:
+class Scope
+{
+    boolean condition;
+
+    Scope()
+    {
+        condition = true;
+
+        if ( condition )
+        {
+            int inner = 0;
+            System.out.println( " .. inside if block .. " );
+        }
+
+        int inner = 0;
+        System.out.println( " .. top level scope .. " );
+    }
+
+    public static void main( String[] args )
+    {
+        Scope test = new Scope();
+        System.out.println( " .. fini scope test .. " );
+    }
+}
+~/j2sdk142/bin/java Scope
+ .. inside if block .. 
+ .. top level scope .. 
+ .. fini scope test .. 
+
+I thought scopes would work similarly in this case:
+
+------- Additional Comments From bmaurer at users.sf.net  2003-11-18 12:36 -------
+Please see the spec, section 3.7:
+
+"The scope of a local variable declared in a local-variable-
+declaration (Section 8.5.1) is the block in which the declaration 
+occurs."
+
+http://msdn.microsoft.com/library/default.asp?url=/library/en-
+us/csspec/html/vclrfcsharpspec_3_9.asp
+
+------- Additional Comments From cristian.adam at gmx.net  2007-01-10 04:08 -------
+It's a bug! 
+Compiler Error CS0136A local variable named 'var' cannot be declared
+in this scope because it would give a different meaning to 'var',
+which is already used in a 'parent or current' scope to denote
+something else
+A variable declaration hides another declaration that would otherwise
+be in scope. Rename the variable that is declared on the line that
+generated CS0136.
+The following sample generates CS0136:
+// CS0136.cs
+namespace x
+{
+   public class a
+   {
+      public static void Main()
+      {
+         int i = 0;
+         {
+            char i = 'a';   // CS0136, hides int i
+         }
+         i++;
+      }
+   }
+}
+
+This is not the case, inner was in a closed block (the if block) when
+the second inner appeared.