[Mono-bugs] [Bug 80632][Nor] New - Cannot compile foreach over generic collections

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Fri Jan 26 05:35:48 EST 2007

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Changed by pawel.sakowski at mindbreeze.com.


--- shadow/80632	2007-01-26 05:35:48.000000000 -0500
+++ shadow/80632.tmp.14470	2007-01-26 05:35:48.000000000 -0500
@@ -0,0 +1,78 @@
+Bug#: 80632
+Product: Mono: Compilers
+Version: 1.2
+OS: GNU/Linux [Other]
+OS Details: 
+Status: NEW   
+Priority: Normal
+Component: C#
+AssignedTo: rharinath at novell.com                            
+ReportedBy: pawel.sakowski at mindbreeze.com               
+QAContact: mono-bugs at ximian.com
+TargetMilestone: ---
+Summary: Cannot compile foreach over generic collections
+Description of Problem:
+In certain cases, gmcs isn't able to compile a foreach enumeration over a
+generic collection, emitting confusing messages regarding ambiguity of
+GetEnumerator(). The messages can be both warnings and errors. An example
+of both cases follows (I considered these related, so posting as a single
+bug report).
+Steps to reproduce the problem:
+1. Download and unpack http://www.itu.dk/research/c5/Release1.0/C5.bin.zip
+2. Create ambiguous-enumerable-warning.cs:
+using System.Collections.Generic;
+class X{static void Main(){
+IDictionary<int,int> dict = new Dictionary<int,int>();
+foreach (KeyValuePair<int,int> pair in dict) {
+3. Create ambiguous-enumerable-error.cs:
+public class A: C5.ArrayList<int> {}
+class X{static void Main(){
+A x = new A();
+foreach (int i in x) {
+4. gmcs -warnaserror ambiguous-enumerable-warning.cs
+5. gmcs /r:C5.dll ambiguous-enumerable-error.cs
+Actual Results:
+ambiguous-enumerable-warning.cs(4,1): error CS0278:
+`System.Collections.Generic.IDictionary<int,int>' contains ambiguous
+implementation of `enumerable' pattern. Method
+`System.Collections.IEnumerable.GetEnumerator()' is ambiguous with method
+/usr/lib/mono/2.0/mscorlib.dll (Location of the symbol related to previous
+/usr/lib/mono/2.0/mscorlib.dll (Location of the symbol related to previous
+Compilation failed: 1 error(s), 0 warnings
+ambiguous-enumerable-error.cs(5,1): error CS1640: foreach statement cannot
+operate on variables of type `A' because it contains multiple
+implementation of `C5.ArrayBase<int>.GetEnumerator()'. Try casting to a
+specific implementation
+ambiguous-enumerable-error.cs(1,14): (Location of the symbol related to
+previous error)
+Compilation failed: 1 error(s), 0 warnings
+Expected Results:
+Two successes.
+How often does this happen? 
+Additional Information:
+Reproduces with mono
+The test cases compile fine with both csc and mono

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