Merge pull request #260 from Microsoft/cr-new-error

Fix two error messages

Author: mikeblome

docs/error-messages/compiler-errors-1/compiler-error-c2280.md

@@ -82,7 +82,7 @@ struct A {
 
 ## Example: Reference and const data members  
 
-A `const` or reference type data member causes the compiler to declare a `deleted` copy assignment operator. Once initialized, these members can't be assigned to. To fix this issue, we recommend you change your logic to remove the assignment operations that cause the error.  
+A `const` or reference type data member causes the compiler to declare a `deleted` copy assignment operator. Once initialized, these members can't be assigned to, so a simple copy or move can't work. To fix this issue, we recommend you change your logic to remove the assignment operations that cause the error.  
 
 ```cpp  
 // C2280_ref.cpp

docs/error-messages/compiler-errors-2/compiler-error-c2872.md

@@ -35,28 +35,31 @@ translation.priority.ht:
   - "zh-tw"
 ---
 # Compiler Error C2872
-'symbol' : ambiguous symbol  
+'*symbol*' : ambiguous symbol  
 
-The compiler cannot determine which symbol you are referring to.  
+The compiler cannot determine which symbol you are referring to. More than one symbol with the specified name is in scope. See the notes following the error message for the file locations and declarations the compiler found for the ambiguous symbol. To fix this issue, you can fully qualify the ambiguous symbol by using its namespace, for example, `std::byte` or `::byte`. You can also use a [namespace alias](../../cpp/namespaces-cpp.md#namespace_aliases) to give an included namespace a convenient short name for use when disambiguating symbols in your source code.  
 
-C2872 can occur if a header file includes a [using directive](../../cpp/namespaces-cpp.md#using_directives), and a subsequent header file is included and it contains a type that is also in the namespace specified in the `using` directive. Specify a `using` directive only after all your header files are specified with `#include`.  
+C2872 can occur if a header file includes a [using directive](../../cpp/namespaces-cpp.md#using_directives), and a subsequent header file is included that contains a type that is also in the namespace specified in the `using` directive. Specify a `using` directive only after all your header files are specified with `#include`.  
 
  For more information about C2872, see Knowledge Base articles [PRB: Compiler Errors When You Use #import with XML in Visual C++ .NET](http://support.microsoft.com/kb/316317) and ["Error C2872: 'Platform' : ambiguous symbol" error message when you use the Windows::Foundation::Metadata namespace in Visual Studio 2013](https://support.microsoft.com/kb/2890859).  
 
 ## Example  
- The following sample generates C2872:  
+ The following sample generates C2872, because an ambiguous reference is made to a variable named `i`; two variables with the same name are in scope:  
 
 ```cpp  
 // C2872.cpp  
+// compile with: cl /EHsc C2872.cpp  
 namespace A {  
    int i;  
 }  
 
 using namespace A;  
 int i;  
 int main() {  
-   ::i++;   // ok  
-   A::i++;   // ok  
-   i++;   // C2872 ::i or A::i?  
+   ::i++;   // ok, uses i from global namespace  
+   A::i++;   // ok, uses i from namespace A  
+   i++;   // C2872 ambiguous: ::i or A::i? 
+   // To fix this issue, use the fully qualified name
+   // for the intended variable. 
 }  
 ```