Create warning directive page

docs/preprocessor/hash-error-directive-c-cpp.md

@@ -26,4 +26,5 @@ The error message that this directive emits includes the *token-string* paramete
 
 ## See also
 
-[Preprocessor directives](../preprocessor/preprocessor-directives.md)
+[Preprocessor directives](../preprocessor/preprocessor-directives.md)\
+[#warning directive](../preprocessor/hash-warning-directive-c-cpp.md)

docs/preprocessor/hash-warning-directive-c-cpp.md

@@ -0,0 +1,29 @@
+---
+description: "Learn more about: #warning directive (C/C++)"
+title: "#warning directive (C/C++)"
+ms.date: "11/08/2023"
+f1_keywords: ["#warning"]
+helpviewer_keywords: ["#warning directive", "preprocessor, directives", "warning directive (#warning directive)"]
+---
+# #warning directive (C/C++)
+
+The **#warning** directive emits a user-specified warning message at compile time, and does not stop the compilation. This directive is a standard feature since C23 and C++23.
+
+## Syntax
+
+> **#warning** *token-string*
+
+## Remarks
+
+The warning message that this directive emits includes the *token-string* parameter. The *token-string* parameter is not subject to macro expansion and can be optionally enclosed in quotes. This directive is used to inform the developer of a non-fatal issue that may have occured, or to disseminate important information. The following example shows how the **#warning** directive is used:
+
+```cpp
+#if defined(_LEGACY_FEATURE_FLAG)
+#warning "_LEGACY_FEATURE is deprecated and should not be used."
+#endif
+```
+
+## See also
+
+[Preprocessor directives](../preprocessor/preprocessor-directives.md)\
+[#error directive](../preprocessor/hash-error-directive-c-cpp.md)

docs/preprocessor/preprocessor-directives.md

@@ -29,7 +29,8 @@ The preprocessor recognizes the following directives:
    :::column span="":::
       [`#import`](../preprocessor/hash-import-directive-cpp.md)\
       [`#include`](../preprocessor/hash-include-directive-c-cpp.md)\
-      [`#line`](../preprocessor/hash-line-directive-c-cpp.md)
+      [`#line`](../preprocessor/hash-line-directive-c-cpp.md)\
+      [`#warning`](../preprocessor/hash-warning-directive-c-cpp.md)
    :::column-end:::
    :::column span="":::
       [`#pragma`](../preprocessor/pragma-directives-and-the-pragma-keyword.md)\

docs/preprocessor/toc.yml

@@ -92,6 +92,8 @@ items:
           href: ../preprocessor/hash-undef-directive-c-cpp.md
         - name: "#using directive (C++/CLI)"
           href: ../preprocessor/hash-using-directive-cpp.md
+        - name: "#warning directive (C/C++)"
+          href: ../preprocessor/hash-warning-directive-c-cpp.md
     - name: Preprocessor operators
       expanded: false
       items: