Merge pull request MicrosoftDocs#5071 from MicrosoftDocs/main

PhilKang0704 · web-flow · commit 3aa134c2297e · 2023-10-19T01:43:01.000+08:00
10/18/2023 AM Publish
diff --git a/docs/error-messages/compiler-errors-1/compiler-error-c2397.md b/docs/error-messages/compiler-errors-1/compiler-error-c2397.md
@@ -15,26 +15,22 @@ The C language allows implicit narrowing conversions in assignments and initiali
 
 A narrowing conversion can be okay when you know the possible range of converted values can fit in the target. In this case, you know more than the compiler does. If you make a narrowing conversion intentionally, make your intentions explicit by using a static cast. Otherwise, this error message almost always indicates you have a bug in your code. You can fix it by making sure the objects you initialize have types that are large enough to handle the inputs.
 
-The following sample generates C2397 and shows one way to fix it:
-
-```
-// C2397.cpp -- C++ narrowing conversion diagnostics
-// Compile by using: cl /EHsc C2397.cpp
-#include <vector>
-
-struct S1 {
-    int m1;
-    double m2, m3;
+The following sample generates C2397:
+
+```cpp
+// C2397.cpp
+// compile with: /c
+struct S {
+   int m1;
+   double m2, m3;
 };
 
-void function_C2397(double d1) {
-    char c1 { 127 };          // OK
-    char c2 { 513 };          // error C2397
-
-    std::vector<S1> vS1;
-    vS1.push_back({ d1, 2, 3 }); // error C2397
-
-    // Possible fix if you know d1 always fits in an int
-    vS1.push_back({ static_cast<int>(d1), 2, 3 });
+void func(double d1) {
+   char c1 { 127 };   // OK
+   char c2 { 513 };   // C2397
+   
+   S arr[2]{};
+   arr[0] = { d1, 2.0, 3.0 };   // C2397
+   arr[1] = { static_cast<int>(d1), 2.0, 3.0 };   // OK
 }
 ```
diff --git a/docs/error-messages/compiler-errors-2/compiler-error-c2510.md b/docs/error-messages/compiler-errors-2/compiler-error-c2510.md
@@ -11,3 +11,18 @@ ms.assetid: bf6d28db-f2f4-48f8-8f4e-7d662ed278fe
 'identifier' : left of '::' must be a class/struct/union
 
 A class, structure, or union name must appear on the left side of the scope-resolution operator (`::`) operator.
+
+The following sample generates C2510:
+
+```cpp
+// C2510.cpp
+struct S {
+   static const int x = 1;
+};
+
+int main() {
+   S s;
+   int num1 = s::x;   // C2510
+   int num2 = S::x;   // OK
+}
+```
diff --git a/docs/error-messages/compiler-errors-2/compiler-error-c3551.md b/docs/error-messages/compiler-errors-2/compiler-error-c3551.md
@@ -1,21 +1,25 @@
 ---
 description: "Learn more about: Compiler Error C3551"
 title: "Compiler Error C3551"
-ms.date: "11/04/2016"
+ms.date: "10/07/2023"
 f1_keywords: ["C3551"]
 helpviewer_keywords: ["C3551"]
 ms.assetid: c8ee23da-6568-40db-93a6-3ddb7ac47712
 ---
 # Compiler Error C3551
 
-"expected a late specified return type"
+if a trailing return type is used then the leading return type shall be the single type-specifier 'auto' (not 'type')
 
-If you use the **`auto`** keyword as a placeholder for the return type of a function, you must provide a late-specified return type. In the following example, the late-specified return type of function `myFunction` is a pointer to an array of four elements of type **`int`**.
+The leading return type in [trailing return type](../../cpp/functions-cpp.md#trailing-return-types) syntax must contain only `auto`.
 
-```
-auto myFunction()->int(*)[4];
-```
+```cpp
+// C3551.cpp
+// compile with: /c
+const auto func1() -> const int;   // C3551
+auto* func2() -> int*;   // C3551
+auto& func3() -> int&;   // C3551
+auto&& func4() -> int&&;   // C3551
+decltype(auto) func5() -> int;   // C3551
 
-## See also
-
-[auto](../../cpp/auto-cpp.md)
+auto func6() -> int;   // OK
+```
diff --git a/docs/error-messages/compiler-warnings/compiler-warning-level-3-c4310.md b/docs/error-messages/compiler-warnings/compiler-warning-level-3-c4310.md
@@ -1,12 +1,11 @@
 ---
-description: "Learn more about: Compiler Warning (level 3) C4310"
+description: "Learn more about: Compiler Warning (level 4) C4310"
 title: "Compiler Warning (level 3) C4310"
-ms.date: "11/04/2016"
+ms.date: 10/17/2023
 f1_keywords: ["C4310"]
 helpviewer_keywords: ["C4310"]
-ms.assetid: cba3eca1-f1ed-499c-9243-337446bdbdd8
 ---
-# Compiler Warning (level 3) C4310
+# Compiler Warning (level 4) C4310
 
 cast truncates constant value
 
@@ -15,7 +14,8 @@ A constant value is cast to a smaller type. The compiler performs the cast, whic
 ```cpp
 // C4310.cpp
 // compile with: /W4
-int main() {
+int main()
+{
    long int a;
    a = (char) 128;   // C4310, use value 0-127 to resolve
 }
diff --git a/docs/error-messages/toc.yml b/docs/error-messages/toc.yml
@@ -3606,7 +3606,7 @@ items:
           href: compiler-warnings/compiler-warning-level-2-c4308.md
         - name: Compiler warning (level 2) C4309
           href: compiler-warnings/compiler-warning-level-2-c4309.md
-        - name: Compiler warning (level 3) C4310
+        - name: Compiler warning (level 4) C4310
           href: compiler-warnings/compiler-warning-level-3-c4310.md
         - name: Compiler warning (level 1) C4311
           href: compiler-warnings/compiler-warning-level-1-c4311.md
