Use more precise wording for errors specifying requirements for types that can be used in a using statement.

src/Analyzers/CSharp/CodeFixes/MakeStatementAsynchronous/CSharpMakeStatementAsynchronousCodeFixProvider.cs

@@ -32,7 +32,7 @@ public CSharpMakeStatementAsynchronousCodeFixProvider()
     }
 
     // error CS8414: foreach statement cannot operate on variables of type 'IAsyncEnumerable<int>' because 'IAsyncEnumerable<int>' does not contain a public instance definition for 'GetEnumerator'. Did you mean 'await foreach'?
-    // error CS8418: 'IAsyncDisposable': type used in a using statement must be implicitly convertible to 'System.IDisposable'. Did you mean 'await using' rather than 'using'?
+    // error CS8418: 'IAsyncDisposable': type used in a using statement must implement 'System.IDisposable'. Did you mean 'await using' rather than 'using'?
     public sealed override ImmutableArray<string> FixableDiagnosticIds => ["CS8414", "CS8418"];
 
     public override async Task RegisterCodeFixesAsync(CodeFixContext context)

src/Analyzers/CSharp/Tests/MakeMethodSynchronous/MakeMethodSynchronousTests.cs

@@ -883,7 +883,7 @@ async System.Threading.Tasks.Task MAsync()
             TestCode = source,
             ExpectedDiagnostics =
             {
-                // /0/Test0.cs(5,22): error CS8410: 'object': type used in an asynchronous using statement must be implicitly convertible to 'System.IAsyncDisposable' or implement a suitable 'DisposeAsync' method.
+                // /0/Test0.cs(5,22): error CS8410: 'object': type used in an asynchronous using statement must implement 'System.IAsyncDisposable' or implement a suitable 'DisposeAsync' method.
                 DiagnosticResult.CompilerError("CS8410").WithLocation(0).WithArguments("object"),
             },
             FixedCode = source,
@@ -905,7 +905,7 @@ class C
                 }
             }
             """,
-            // /0/Test0.cs(5,16): error CS1674: 'object': type used in a using statement must be implicitly convertible to 'System.IDisposable'.
+            // /0/Test0.cs(5,16): error CS1674: 'object': type used in a using statement must implement 'System.IDisposable'.
             DiagnosticResult.CompilerError("CS1674").WithLocation(0).WithArguments("object"),
             """
             class C

src/Compilers/CSharp/Portable/CSharpResources.resx

@@ -3119,16 +3119,16 @@ A catch() block after a catch (System.Exception e) block can catch non-CLS excep
     <value>Anonymous methods, lambda expressions, query expressions, and local functions inside structs cannot access instance members of 'this'. Consider copying 'this' to a local variable outside the anonymous method, lambda expression, query expression, or local function and using the local instead.</value>
   </data>
   <data name="ERR_NoConvToIDisp" xml:space="preserve">
-    <value>'{0}': type used in a using statement must be implicitly convertible to 'System.IDisposable'.</value>
+    <value>'{0}': type used in a using statement must implement 'System.IDisposable'.</value>
   </data>
   <data name="ERR_NoConvToIDispWrongAsync" xml:space="preserve">
-    <value>'{0}': type used in a using statement must be implicitly convertible to 'System.IDisposable'. Did you mean 'await using' rather than 'using'?</value>
+    <value>'{0}': type used in a using statement must implement 'System.IDisposable'. Did you mean 'await using' rather than 'using'?</value>
   </data>
   <data name="ERR_NoConvToIAsyncDisp" xml:space="preserve">
-    <value>'{0}': type used in an asynchronous using statement must be implicitly convertible to 'System.IAsyncDisposable' or implement a suitable 'DisposeAsync' method.</value>
+    <value>'{0}': type used in an asynchronous using statement must implement 'System.IAsyncDisposable' or implement a suitable 'DisposeAsync' method.</value>
   </data>
   <data name="ERR_NoConvToIAsyncDispWrongAsync" xml:space="preserve">
-    <value>'{0}': type used in an asynchronous using statement must be implicitly convertible to 'System.IAsyncDisposable' or implement a suitable 'DisposeAsync' method. Did you mean 'using' rather than 'await using'?</value>
+    <value>'{0}': type used in an asynchronous using statement must implement 'System.IAsyncDisposable' or implement a suitable 'DisposeAsync' method. Did you mean 'using' rather than 'await using'?</value>
   </data>
   <data name="ERR_BadParamRef" xml:space="preserve">
     <value>Parameter {0} must be declared with the '{1}' keyword</value>