Merge pull request MicrosoftDocs#3552 from MicrosoftDocs/master

5/4 Publishing

Author: v-alje

docs/build/reference/experimental-module.md

@@ -5,7 +5,7 @@ ms.date: "04/13/2021"
 f1_keywords: ["module", "/experimental:module"]
 helpviewer_keywords: ["module", "/experimental:module", "Enable module support"]
 ---
-# /experimental:module (Enable module support)
+# `/experimental:module` (Enable module support)
 
 Enables experimental compiler support for Standard Template Library named modules.
 

docs/error-messages/compiler-errors-1/compiler-error-c2139.md

@@ -1,17 +1,18 @@
 ---
 description: "Learn more about: Compiler Error C2139"
 title: "Compiler Error C2139"
-ms.date: "11/04/2016"
+ms.date: 05/03/2021
 f1_keywords: ["C2139"]
 helpviewer_keywords: ["C2139"]
-ms.assetid: 31e047c0-5bf9-46c2-b6de-b627ea6a5768
 ---
 # Compiler Error C2139
 
-'type' : an undefined class is not allowed as an argument to compiler intrinsic type trait 'trait'
+> '*type*' : an undefined class is not allowed as an argument to compiler intrinsic type trait '*trait*'
 
 An invalid argument was passed to a type trait.
 
+## Remarks
+
 For more information, see [Compiler Support for Type Traits](../../extensions/compiler-support-for-type-traits-cpp-component-extensions.md).
 
 ## Example

docs/error-messages/compiler-errors-1/compiler-error-c2201.md

@@ -1,18 +1,19 @@
 ---
 description: "Learn more about: Compiler Error C2201"
 title: "Compiler Error C2201"
-ms.date: "11/04/2016"
+ms.date: 05/03/2021
 f1_keywords: ["C2201"]
 helpviewer_keywords: ["C2201"]
-ms.assetid: ed927659-6e9c-447d-9963-19969ae1e957
 ---
 # Compiler Error C2201
 
-'identifier' : must have external linkage in order to be exported/imported
+> '*identifier*' : must have external linkage in order to be exported/imported
 
 The exported identifier is **`static`**.
 
-The following sample generates C2286:
+## Example
+
+The following sample generates C2286, and shows how to fix it:
 
 ```cpp
 // C2201.cpp

docs/error-messages/compiler-errors-2/compiler-error-c2668.md

@@ -1,18 +1,18 @@
 ---
 description: "Learn more about: Compiler Error C2668"
 title: "Compiler Error C2668"
-ms.date: "03/28/2017"
+ms.date: 05/03/2021
 f1_keywords: ["C2668"]
 helpviewer_keywords: ["C2668"]
 ms.assetid: 041e9627-1c76-420e-a653-cfc83f933bd3
 ---
 # Compiler Error C2668
 
-'function' : ambiguous call to overloaded function
+> 'function' : ambiguous call to overloaded function
 
-The specified overloaded function call could not be resolved. You may want to explicitly cast one or more of the actual parameters.
+The specified overloaded function call couldn't be resolved. You may want to explicitly cast one or more of the actual parameters.
 
-You can also get this error through template use. If, in the same class, you have a regular member function and a templated member function with the same signature, the templated one must come first. This is a limitation of the current implementation of Visual C++.
+You can also get this error through template use. If, in the same class, you have a regular member function and a templated member function with the same signature, the templated one must come first. This limitation remains in the current implementation of Visual C++.
 
 ## Examples
 
@@ -34,7 +34,7 @@ int main() {
 }
 ```
 
-Another way to resolve this error is with a [using declaration](../../cpp/using-declaration.md):
+Another way to resolve this error is with a [`using` declaration](../../cpp/using-declaration.md):
 
 ```cpp
 // C2668b.cpp
@@ -75,9 +75,7 @@ class MyTestCase : public AppTestCase {
 };
 ```
 
-This error can also be generated as a result of compiler conformance work that was done for Visual Studio .NET 2003: ambiguous conversion on cast of constant 0.
-
-Conversion on a cast using constant 0 is ambiguous since int requires a conversion both to long and to void*. To resolve this error, cast 0 to the exact type of the function parameter it is being used for so that no conversions need to take place (this code will be valid in the Visual Studio .NET 2003 and Visual Studio .NET versions of Visual C++).
+Conversion on a cast using constant 0 is ambiguous since **`int`** requires a conversion both to **`long`** and to `void*`. To resolve this error, cast 0 to the exact type of the function parameter it's being used for. Then no conversions need to take place.
 
 ```cpp
 // C2668c.cpp
@@ -97,7 +95,7 @@ int main() {
 }
 ```
 
-This error can occur because the CRT now has float and double forms of all math functions.
+This error can occur because the CRT now has **`float`** and **`double`** forms of all math functions.
 
 ```cpp
 // C2668d.cpp
@@ -110,7 +108,7 @@ int main() {
 }
 ```
 
-This error can occur because the pow(int, int) was removed from math.h in the CRT.
+This error can occur because the `pow(int, int)` was removed from *`math.h`* in the CRT.
 
 ```cpp
 // C2668e.cpp
@@ -121,7 +119,7 @@ int main() {
 }
 ```
 
-This code succeeds in Visual Studio 2015 but fails in Visual Studio 2017 and later with C2668. In Visual Studio 2015, the compiler erroneously treated copy-list-initialization in the same way as regular copy-initialization; it considered only converting constructors for overload resolution.
+This code succeeds in Visual Studio 2015 but fails in Visual Studio 2017 and later with C2668. In Visual Studio 2015, the compiler erroneously treated copy-list-initialization in the same way as regular copy-initialization. It considered only converting constructors for overload resolution.
 
 ```cpp
 struct A {

docs/error-messages/compiler-errors-2/compiler-error-c7536.md

@@ -0,0 +1,19 @@
+---
+description: "Learn about the causes of Compiler error C7536 and how to fix it."
+title: "Compiler Error C7536"
+ms.date: 05/03/2021
+f1_keywords: ["C7536"]
+helpviewer_keywords: ["C7536"]
+---
+# Compiler Error C7536
+
+> ifc failed integrity checks.  Expected SHA2: '*hash-value*'
+
+The compiler raises C7536 whenever the *`.ifc`* file has been tampered with. The header of the module interface contains an SHA2 hash of the contents below it. On import, the *`.ifc`* file is hashed, then checked against the hash provided in the header. If these don't match, error C7536 is raised:
+
+```Output
+error C7536: ifc failed integrity checks.
+Expected SHA2: '66d5c8154df0c71d4cab7665bab4a125c7ce5cb9a401a4d8b461b706ddd771c6'
+```
+
+This error is new in Visual Studio 2017 version 15.9. It's only generated when creating or consuming modules, specified by the `/experimental:module` compiler option.

docs/error-messages/compiler-errors-2/compiler-errors-c7500-through-c7999.md

@@ -2,8 +2,8 @@
 description: "Learn more about: Compiler errors C7500 through C7999"
 title: "Compiler errors C7500 through C7999"
 ms.date: 04/18/2021
-f1_keywords: ["C7500", "C7501", "C7502", "C7503", "C7504", "C7505", "C7506", "C7507", "C7508", "C7509", "C7511", "C7512", "C7513", "C7514", "C7515", "C7516", "C7517", "C7518", "C7519", "C7520", "C7521", "C7522", "C7523", "C7524", "C7525", "C7526", "C7527", "C7528", "C7529", "C7530", "C7531", "C7532", "C7533", "C7534", "C7535", "C7536", "C7537", "C7538", "C7539", "C7540", "C7541", "C7542", "C7543", "C7544", "C7545", "C7546", "C7547", "C7548", "C7549", "C7550", "C7551", "C7552", "C7553", "C7554", "C7555", "C7556", "C7557", "C7558", "C7559", "C7560", "C7561", "C7562", "C7563", "C7564", "C7565", "C7566", "C7567", "C7568", "C7569", "C7570", "C7571", "C7572", "C7573", "C7574", "C7575", "C7576", "C7577", "C7578", "C7579", "C7580", "C7581", "C7582", "C7583", "C7584", "C7585", "C7586", "C7587", "C7588", "C7589", "C7590", "C7591", "C7592", "C7593", "C7594", "C7595", "C7596", "C7597", "C7599", "C7600", "C7601", "C7602", "C7603", "C7604", "C7605", "C7606", "C7607", "C7608", "C7609", "C7610", "C7611", "C7612", "C7613", "C7614", "C7615", "C7616", "C7617", "C7618", "C7619", "C7620", "C7621", "C7622", "C7623", "C7624", "C7625", "C7627", "C7628", "C7629", "C7630", "C7631", "C7632", "C7633", "C7634", "C7635", "C7636", "C7637", "C7638", "C7639", "C7640", "C7641", "C7642", "C7643", "C7644", "C7645", "C7646", "C7647", "C7648", "C7649", "C7650", "C7651", "C7652", "C7653", "C7654", "C7655", "C7656", "C7657", "C7658", "C7659", "C7660", "C7661", "C7662", "C7700", "C7701", "C7702", "C7703", "C7704"]
-helpviewer_keywords: ["C7500", "C7501", "C7502", "C7503", "C7504", "C7505", "C7506", "C7507", "C7508", "C7509", "C7511", "C7512", "C7513", "C7514", "C7515", "C7516", "C7517", "C7518", "C7519", "C7520", "C7521", "C7522", "C7523", "C7524", "C7525", "C7526", "C7527", "C7528", "C7529", "C7530", "C7531", "C7532", "C7533", "C7534", "C7535", "C7536", "C7537", "C7538", "C7539", "C7540", "C7541", "C7542", "C7543", "C7544", "C7545", "C7546", "C7547", "C7548", "C7549", "C7550", "C7551", "C7552", "C7553", "C7554", "C7555", "C7556", "C7557", "C7558", "C7559", "C7560", "C7561", "C7562", "C7563", "C7564", "C7565", "C7566", "C7567", "C7568", "C7569", "C7570", "C7571", "C7572", "C7573", "C7574", "C7575", "C7576", "C7577", "C7578", "C7579", "C7580", "C7581", "C7582", "C7583", "C7584", "C7585", "C7586", "C7587", "C7588", "C7589", "C7590", "C7591", "C7592", "C7593", "C7594", "C7595", "C7596", "C7597", "C7599", "C7600", "C7601", "C7602", "C7603", "C7604", "C7605", "C7606", "C7607", "C7608", "C7609", "C7610", "C7611", "C7612", "C7613", "C7614", "C7615", "C7616", "C7617", "C7618", "C7619", "C7620", "C7621", "C7622", "C7623", "C7624", "C7625", "C7627", "C7628", "C7629", "C7630", "C7631", "C7632", "C7633", "C7634", "C7635", "C7636", "C7637", "C7638", "C7639", "C7640", "C7641", "C7642", "C7643", "C7644", "C7645", "C7646", "C7647", "C7648", "C7649", "C7650", "C7651", "C7652", "C7653", "C7654", "C7655", "C7656", "C7657", "C7658", "C7659", "C7660", "C7661", "C7662", "C7700", "C7701", "C7702", "C7703", "C7704"]
+f1_keywords: ["C7500", "C7501", "C7502", "C7503", "C7504", "C7505", "C7506", "C7507", "C7508", "C7509", "C7511", "C7512", "C7513", "C7514", "C7515", "C7516", "C7517", "C7518", "C7519", "C7520", "C7521", "C7522", "C7523", "C7524", "C7525", "C7526", "C7527", "C7528", "C7529", "C7530", "C7531", "C7532", "C7533", "C7534", "C7535", "C7537", "C7538", "C7539", "C7540", "C7541", "C7542", "C7543", "C7544", "C7545", "C7546", "C7547", "C7548", "C7549", "C7550", "C7551", "C7552", "C7553", "C7554", "C7555", "C7556", "C7557", "C7558", "C7559", "C7560", "C7561", "C7562", "C7563", "C7564", "C7565", "C7566", "C7567", "C7568", "C7569", "C7570", "C7571", "C7572", "C7573", "C7574", "C7575", "C7576", "C7577", "C7578", "C7579", "C7580", "C7581", "C7582", "C7583", "C7584", "C7585", "C7586", "C7587", "C7588", "C7589", "C7590", "C7591", "C7592", "C7593", "C7594", "C7595", "C7596", "C7597", "C7599", "C7600", "C7601", "C7602", "C7603", "C7604", "C7605", "C7606", "C7607", "C7608", "C7609", "C7610", "C7611", "C7612", "C7613", "C7614", "C7615", "C7616", "C7617", "C7618", "C7619", "C7620", "C7621", "C7622", "C7623", "C7624", "C7625", "C7627", "C7628", "C7629", "C7630", "C7631", "C7632", "C7633", "C7634", "C7635", "C7636", "C7637", "C7638", "C7639", "C7640", "C7641", "C7642", "C7643", "C7644", "C7645", "C7646", "C7647", "C7648", "C7649", "C7650", "C7651", "C7652", "C7653", "C7654", "C7655", "C7656", "C7657", "C7658", "C7659", "C7660", "C7661", "C7662", "C7700", "C7701", "C7702", "C7703", "C7704"]
+helpviewer_keywords: ["C7500", "C7501", "C7502", "C7503", "C7504", "C7505", "C7506", "C7507", "C7508", "C7509", "C7511", "C7512", "C7513", "C7514", "C7515", "C7516", "C7517", "C7518", "C7519", "C7520", "C7521", "C7522", "C7523", "C7524", "C7525", "C7526", "C7527", "C7528", "C7529", "C7530", "C7531", "C7532", "C7533", "C7534", "C7535", "C7537", "C7538", "C7539", "C7540", "C7541", "C7542", "C7543", "C7544", "C7545", "C7546", "C7547", "C7548", "C7549", "C7550", "C7551", "C7552", "C7553", "C7554", "C7555", "C7556", "C7557", "C7558", "C7559", "C7560", "C7561", "C7562", "C7563", "C7564", "C7565", "C7566", "C7567", "C7568", "C7569", "C7570", "C7571", "C7572", "C7573", "C7574", "C7575", "C7576", "C7577", "C7578", "C7579", "C7580", "C7581", "C7582", "C7583", "C7584", "C7585", "C7586", "C7587", "C7588", "C7589", "C7590", "C7591", "C7592", "C7593", "C7594", "C7595", "C7596", "C7597", "C7599", "C7600", "C7601", "C7602", "C7603", "C7604", "C7605", "C7606", "C7607", "C7608", "C7609", "C7610", "C7611", "C7612", "C7613", "C7614", "C7615", "C7616", "C7617", "C7618", "C7619", "C7620", "C7621", "C7622", "C7623", "C7624", "C7625", "C7627", "C7628", "C7629", "C7630", "C7631", "C7632", "C7633", "C7634", "C7635", "C7636", "C7637", "C7638", "C7639", "C7640", "C7641", "C7642", "C7643", "C7644", "C7645", "C7646", "C7647", "C7648", "C7649", "C7650", "C7651", "C7652", "C7653", "C7654", "C7655", "C7656", "C7657", "C7658", "C7659", "C7660", "C7661", "C7662", "C7700", "C7701", "C7702", "C7703", "C7704"]
 ---
 # Compiler errors C7500 through C7999
 
@@ -51,7 +51,7 @@ The articles in this section of the documentation explain a subset of the error
 | Compiler error C7533 | '%$S': template arguments not allowed in this context |
 | Compiler error C7534 | syntax error: '%$L': expected class definition to end with '}' |
 | Compiler error C7535 | '%$S': delegating constructor calls itself |
-| Compiler error C7536 | ifc failed integrity checks.  Expected SHA2: '%s' |
+| [Compiler error C7536](compiler-error-c7536.md) | ifc failed integrity checks.  Expected SHA2: '*hash-value*' |
 | Compiler error C7537 | failed to properly compute SHA2 hash: '%s' |
 | Compiler error C7538 | '%$I' is not a variable template |
 | Compiler error C7539 | '%1$I': a class with user-declared constructors cannot have a member with the same name as the class |

docs/error-messages/compiler-warnings/c4597.md

@@ -0,0 +1,34 @@
+---
+description: "Learn more about: Compiler Warning (error) C4597"
+title: "Compiler Warning (error) C4597"
+ms.date: 05/03/2021
+f1_keywords: ["C4597"]
+helpviewer_keywords: ["C4597"]
+---
+# Compiler Warning (error) C4597
+
+> undefined behavior: `offsetof` applied to a member of a virtual base
+
+Using `offsetof(T, m)` where *`m`* refers to a static data member or a member function results in C4597.
+
+## Remarks
+
+This warning is new in Visual Studio 2017 version 15.3. It's reported as an error by default. For information on how to disable warnings by compiler version, see [Compiler warnings by compiler version](compiler-warnings-by-compiler-version.md).
+
+## Example
+
+The following code produces error C4597:
+
+```cpp
+#include <cstddef>
+
+struct A {
+   int ten() { return 10; }
+   static constexpr int two = 2;
+};
+
+constexpr auto off = offsetof(A, ten);  // C4597: undefined behavior: offsetof applied to member function 'A::ten'
+constexpr auto off2 = offsetof(A, two); // C4597: undefined behavior: offsetof applied to static data member 'A::two'
+```
+
+This code is ill-formed and could potentially cause a crash at runtime. To fix the error, change the code: don't invoke `offsetof` on member functions or static data members. It's non-portable code that's disallowed by the C++ standard.

docs/error-messages/compiler-warnings/c4768.md

@@ -0,0 +1,30 @@
+---
+description: "Learn more about: Compiler Warning (level 3) C4768"
+title: "Compiler Warning (level 3) C4768"
+ms.date: 05/03/2021
+f1_keywords: ["C4768"]
+helpviewer_keywords: ["C4768"]
+---
+# Compiler Warning (level 3) C4768
+
+> `__declspec` attributes before linkage specification are ignored
+
+The compiler warns if `__declspec(...)` is applied before the `extern "C"` linkage specification. Previously, the compiler would ignore the attribute, which could have runtime implications.
+
+## Remarks
+
+This warning is new in Visual Studio 2017 version 15.3, which left it off by default. It's enabled by default as a level 3 warning starting in Visual Studio 2017 version 15.5. For information on how to disable warnings by compiler version, see [Compiler warnings by compiler version](compiler-warnings-by-compiler-version.md).
+
+## Example
+
+The following code produces warning C4768:
+
+```cpp
+__declspec(noinline) extern "C" HRESULT __stdcall // C4768: __declspec attributes before linkage specification are ignored
+```
+
+To fix the warning, put `extern "C"` first:
+
+```cpp
+extern "C" __declspec(noinline) HRESULT __stdcall
+```

docs/error-messages/compiler-warnings/c4841.md

@@ -0,0 +1,31 @@
+---
+description: "Learn more about: Compiler Warning (level 4) C4841"
+title: "Compiler Warning (level 4) C4841"
+ms.date: 05/03/2021
+f1_keywords: ["C4841"]
+helpviewer_keywords: ["C4841"]
+---
+# Compiler Warning (level 4) C4841
+
+> non-standard extension used: compound member designator used in `offsetof`
+
+## Remarks
+
+If you use `offsetof(T, m)`, where *`m`* is a compound member designator, the compiler generates a warning when you compile with the **`/Wall`** option.
+
+This warning is new in Visual Studio 2017 version 15.3, and is off by default. Use [`/Wall`](../../build/reference/compiler-option-warning-level.md) to enable all warnings that are off by default, or **`/w14841`** to enable C4841 as a level 1 warning. For more information, see [Compiler warnings that are off by default](../../preprocessor/compiler-warnings-that-are-off-by-default.md). For information on how to disable warnings by compiler version, see [Compiler warnings by compiler version](compiler-warnings-by-compiler-version.md).
+
+## Example
+
+The following code is ill-formed and could potentially cause a crash at runtime:
+
+```cpp
+struct A {
+   int arr[10];
+};
+
+// warning C4841: non-standard extension used: compound member designator in offsetof
+constexpr auto off = offsetof(A, arr[2]);
+```
+
+To fix the issue, change the code to not use `offsetof` with a compound member designator.

docs/error-messages/compiler-warnings/c4843.md

@@ -0,0 +1,55 @@
+---
+description: "Learn more about: Compiler Warning (level 4) C4843"
+title: "Compiler Warning (level 4) C4843"
+ms.date: 05/03/2021
+f1_keywords: ["C4843"]
+helpviewer_keywords: ["C4843"]
+---
+# Compiler Warning (level 4) C4843
+
+> '*type1*': An exception handler of reference to array or function type is unreachable, use '*type2*' instead
+
+## Remarks
+
+Handlers of reference to array or function type are never a match for any exception object. Starting in Visual Studio 2017 version 15.5, the compiler honors this rule and raises a level 4 warning. It also no longer matches a handler of `char*` or `wchar_t*` to a string literal when **`/Zc:strictStrings`** is used.
+
+This warning is new in Visual Studio 2017 version 15.5. For information on how to disable warnings by compiler version, see [Compiler warnings by compiler version](compiler-warnings-by-compiler-version.md).
+
+## Example
+
+This sample shows several **`catch`** statements that cause C4843:
+
+```cpp
+// C4843_warning.cpp
+// compile by using: cl /EHsc /W4 C4843_warning.cpp
+int main()
+{
+    try {
+        throw "";
+    }
+    catch (int (&)[1]) {} // C4843 (This should always be dead code.)
+    catch (void (&)()) {} // C4843 (This should always be dead code.)
+    catch (char*) {} // This should not be a match under /Zc:strictStrings
+}
+```
+
+The compiler generates these warnings:
+
+```cmd
+warning C4843: 'int (&)[1]': An exception handler of reference to array or function type is unreachable, use 'int*' instead
+warning C4843: 'void (__cdecl &)(void)': An exception handler of reference to array or function type is unreachable, use 'void (__cdecl*)(void)' instead
+```
+
+The following code avoids the error:
+
+```cpp
+// C4843_fixed.cpp
+// compile by using: cl /EHsc /W4 C4843_fixed.cpp
+int main()
+{
+    try {
+        throw "";
+    }
+    catch (int (*)[1]) {}
+}
+```