Merge pull request #1467 from corob-msft/cr_single_underscore

Fix DevCom issue: single underscore keywords

Author: Colin Robertson

docs/assembler/inline/asm.md

@@ -1,10 +1,10 @@
 ---
 title: "__asm | Microsoft Docs"
 ms.custom: ""
-ms.date: "08/30/2018"
+ms.date: "10/09/2018"
 ms.technology: ["cpp-masm"]
 ms.topic: "conceptual"
-f1_keywords: ["__asm", "__asm_cpp"]
+f1_keywords: ["__asm", "_asm", "__asm_cpp"]
 dev_langs: ["C++"]
 helpviewer_keywords: ["__asm keyword [C++], vs. asm blocks", "__asm keyword [C++]"]
 ms.assetid: 77ff3bc9-a492-4b5e-85e1-fa4e414e79cd
@@ -47,6 +47,8 @@ did not cause native code to be generated when compiled with **/clr**; the compi
 
 `__asm int 3` now results in native code generation for the function. If you want a function to cause a break point in your code and if you want that function compiled to MSIL, use [__debugbreak](../../intrinsics/debugbreak.md).
 
+For compatibility with previous versions, **_asm** is a synonym for **__asm** unless compiler option [/Za \(Disable language extensions)](../../build/reference/za-ze-disable-language-extensions.md) is specified.
+
 ## Example
 
 The following code fragment is a simple `__asm` block enclosed in braces:

docs/build/calling-dll-functions-from-visual-basic-applications.md

@@ -17,7 +17,7 @@ For Visual Basic applications (or applications in other languages such as Pascal
 
 `__stdcall` creates the correct calling convention for the function (the called function cleans up the stack and parameters are passed from right to left) but decorates the function name differently. So, when **__declspec(dllexport)** is used on an exported function in a DLL, the decorated name is exported.
 
-The `__stdcall` name decoration prefixes the symbol name with an underscore (_) and appends the symbol with an at sign (**\@**) character followed by the number of bytes in the argument list (the required stack space). As a result, the function when declared as:
+The `__stdcall` name decoration prefixes the symbol name with an underscore ( **\_** ) and appends the symbol with an at sign (**\@**) character followed by the number of bytes in the argument list (the required stack space). As a result, the function when declared as:
 
 ```C
 int __stdcall func (int a, double b)
@@ -29,7 +29,7 @@ The C calling convention (`__cdecl`) decorates the name as `_func`.
 
 To get the decorated name, use [/MAP](../build/reference/map-generate-mapfile.md). Use of **__declspec(dllexport)** does the following:
 
-- If the function is exported with the C calling convention (**_cdecl**), it strips the leading underscore (_) when the name is exported.
+- If the function is exported with the C calling convention (`__cdecl`), it strips the leading underscore ( **\_** ) when the name is exported.
 
 - If the function being exported does not use the C calling convention (for example, `__stdcall`), it exports the decorated name.
 

docs/build/reference/gh-enable-penter-hook-function.md

@@ -29,7 +29,7 @@ The `_penter` function is not part of any library and it is up to you to provide
 Unless you plan to explicitly call `_penter`, you do not need to provide a prototype. The function must appear as if it had the following prototype, and it must push the content of all registers on entry and pop the unchanged content on exit:
 
 ```
-void __declspec(naked) _cdecl _penter( void );
+void __declspec(naked) __cdecl _penter( void );
 ```
 
 This declaration is not available for 64-bit projects.
@@ -52,7 +52,7 @@ This declaration is not available for 64-bit projects.
 
 The following code, when compiled with **/Gh**, shows how `_penter` is called twice; once when entering function `main` and once when entering function `x`.
 
-```
+```cpp
 // Gh_compiler_option.cpp
 // compile with: /Gh
 // processor: x86
@@ -63,7 +63,7 @@ int main() {
    x();
 }
 
-extern "C" void __declspec(naked) _cdecl _penter( void ) {
+extern "C" void __declspec(naked) __cdecl _penter( void ) {
    _asm {
       push eax
       push ebx

docs/build/reference/gh-enable-pexit-hook-function.md

@@ -29,7 +29,7 @@ The `_pexit` function is not part of any library and it is up to you to provide
 Unless you plan to explicitly call `_pexit`, you do not need to provide a prototype. The function must appear as if it had the following prototype, and it must push the content of all registers on entry and pop the unchanged content on exit:
 
 ```
-void __declspec(naked) _cdecl _pexit( void );
+void __declspec(naked) __cdecl _pexit( void );
 ```
 
 `_pexit` is similar to `_penter`; see [/Gh (Enable _penter Hook Function)](../../build/reference/gh-enable-penter-hook-function.md) for an example of how to write a `_pexit` function.

docs/build/reference/optimization-pragmas-and-keywords.md

@@ -19,7 +19,7 @@ Several keywords and pragmas that you use in your C or C++ code affect optimizat
 
 - [__assume](../../intrinsics/assume.md)
 
-- [inline, _inline, or \__forceinline](../../cpp/inline-functions-cpp.md)
+- [inline, __inline, or \__forceinline](../../cpp/inline-functions-cpp.md)
 
 - [#pragma auto_inline](../../preprocessor/auto-inline.md)
 

docs/c-language/c-keywords.md

@@ -1,7 +1,7 @@
 ---
 title: "C Keywords | Microsoft Docs"
 ms.custom: ""
-ms.date: "11/04/2016"
+ms.date: "10/09/2018"
 ms.technology: ["cpp-language"]
 ms.topic: "language-reference"
 dev_langs: ["C++"]
@@ -36,17 +36,19 @@ The following keywords and special identifiers are recognized by the Microsoft C
 
 |||||
 |-|-|-|-|
-|**__asm**|**dllimport**<sup>2</sup>|**__int8**|**naked**<sup>2</sup>|
-|**__based**<sup>1</sup>|**__except**|**__int16**|**__stdcall**|
-|**__cdecl**|**__fastcall**|**__int32**|**thread**<sup>2</sup>|
-|**__declspec**|**__finally**|**__int64**|**__try**|
-|**dllexport**<sup>2</sup>|**__inline**|**__leave**||
+|**__asm**<sup>3</sup>|**dllimport**<sup>2</sup>|**__int8**<sup>3</sup>|**naked**<sup>2</sup>|
+|**__based**<sup>1, 3</sup>|**__except**<sup>3</sup>|**__int16**<sup>3</sup>|**__stdcall**<sup>3</sup>|
+|**__cdecl**<sup>3</sup>|**__fastcall**|**__int32**<sup>3</sup>|**thread**<sup>2</sup>|
+|**__declspec**<sup>3</sup>|**__finally**<sup>3</sup>|**__int64**<sup>3</sup>|**__try**<sup>3</sup>|
+|**dllexport**<sup>2</sup>|**__inline**<sup>3</sup>|**__leave**<sup>3</sup>||
 
 <sup>1</sup> The **__based** keyword has limited uses for 32-bit and 64-bit target compilations.
 
 <sup>2</sup> These are special identifiers when used with **__declspec**; their use in other contexts is not restricted.
 
-Microsoft extensions are enabled by default. To ensure that your programs are fully portable, you can disable Microsoft extensions by specifying the /Za option (compile for ANSI compatibility) during compilation. When you do this, Microsoft-specific keywords are disabled.
+<sup>3</sup> For compatibility with previous versions, these keywords are available both with two leading underscores and a single leading underscore when Microsoft extensions are enabled.
+
+Microsoft extensions are enabled by default. To ensure that your programs are fully portable, you can disable Microsoft extensions by specifying the [/Za \(Disable language extensions)](../build/reference/za-ze-disable-language-extensions.md) option during compilation. When you do this, some Microsoft-specific keywords are disabled.
 
 When Microsoft extensions are enabled, you can use the keywords listed above in your programs. For ANSI compliance, most of these keywords are prefaced by a double underscore. The four exceptions, **dllexport**, **dllimport**, **naked**, and **thread**, are used only with **__declspec** and therefore do not require a leading double underscore. For backward compatibility, single-underscore versions of the rest of the keywords are supported.
 

docs/cpp/alignof-operator.md

@@ -1,10 +1,10 @@
 ---
 title: "__alignof Operator | Microsoft Docs"
 ms.custom: ""
-ms.date: "11/04/2016"
+ms.date: "10/09/2018"
 ms.technology: ["cpp-language"]
 ms.topic: "language-reference"
-f1_keywords: ["alignas_cpp", "__alignof_cpp", "alignof_cpp"]
+f1_keywords: ["alignas_cpp", "__alignof_cpp", "alignof_cpp", "__alignof", "_alignof"]
 dev_langs: ["C++"]
 helpviewer_keywords: ["alignas [C++]", "alignment of structures", "__alignof keyword [C++]", "alignof [C++]", "types [C++], alignment requirements"]
 ms.assetid: acb1eed7-6398-40bd-b0c5-684ceb64afbc
@@ -65,6 +65,8 @@ int n = 50; // array size
 S* p = (S*)aligned_malloc(n * sizeof(S), __alignof(S));
 ```
 
+For compatibility with previous versions, **_alignof** is a synonym for **__alignof** unless compiler option [/Za \(Disable language extensions)](../build/reference/za-ze-disable-language-extensions.md) is specified.
+
 For more information on modifying alignment, see:
 
 - [pack](../preprocessor/pack.md)

docs/cpp/based-pointers-cpp.md

@@ -1,10 +1,10 @@
 ---
 title: "Based Pointers (C++) | Microsoft Docs"
 ms.custom: ""
-ms.date: "11/04/2016"
+ms.date: "10/09/2018"
 ms.technology: ["cpp-language"]
 ms.topic: "language-reference"
-f1_keywords: ["__based", "__based_cpp"]
+f1_keywords: ["__based", "_based", "__based_cpp"]
 dev_langs: ["C++"]
 helpviewer_keywords: ["__based keyword [C++]", "based pointers", "pointers, based"]
 ms.assetid: 1e5f2e96-c52e-4738-8e14-87278681205e
@@ -48,7 +48,7 @@ The pointer `vpBuffer` is assigned the address of memory allocated at some later
 
 When dereferencing a based pointer, the base must be either explicitly specified or implicitly known through the declaration.
 
-For compatibility with previous versions, **_based** is a synonym for **__based**.
+For compatibility with previous versions, **_based** is a synonym for **__based** unless compiler option [/Za \(Disable language extensions)](../build/reference/za-ze-disable-language-extensions.md) is specified.
 
 ## Example
 

docs/cpp/cdecl.md

@@ -1,10 +1,10 @@
 ---
 title: "__cdecl | Microsoft Docs"
 ms.custom: ""
-ms.date: "11/04/2016"
+ms.date: "10/09/2018"
 ms.technology: ["cpp-language"]
 ms.topic: "language-reference"
-f1_keywords: ["__cdecl_cpp"]
+f1_keywords: ["__cdecl_cpp", "__cdecl", "_cdecl", "cdecl"]
 dev_langs: ["C++"]
 helpviewer_keywords: ["__cdecl keyword [C++]"]
 ms.assetid: 1ff1d03e-fb4e-4562-8be1-74f1ad6427f1
@@ -52,6 +52,8 @@ is equivalent to this:
 void __cdecl CMyClass::mymethod() { return; }
 ```
 
+For compatibility with previous versions, **cdecl** and **_cdecl** are a synonym for **__cdecl** unless compiler option [/Za \(Disable language extensions)](../build/reference/za-ze-disable-language-extensions.md) is specified.
+
 ## Example
 
 In the following example, the compiler is instructed to use C naming and calling conventions for the `system` function.

docs/cpp/declspec.md

@@ -1,10 +1,10 @@
 ---
 title: "__declspec | Microsoft Docs"
 ms.custom: ""
-ms.date: "1/23/2018"
+ms.date: "10/09/2018"
 ms.technology: ["cpp-language"]
 ms.topic: "language-reference"
-f1_keywords: ["__declspec_cpp"]
+f1_keywords: ["__declspec_cpp", "__declspec", "_declspec"]
 dev_langs: ["C++"]
 helpviewer_keywords: ["__declspec keyword [C++]"]
 author: "mikeblome"
@@ -56,6 +56,8 @@ Extended attribute grammar supports these Microsoft-specific storage-class attri
 
 The **code_seg**, **dllexport**, **dllimport**, **naked**, **noalias**, **nothrow**, **property**, **restrict**, **selectany**, **thread**, and **uuid** storage-class attributes are properties only of the declaration of the object or function to which they are applied. The **thread** attribute affects data and objects only. The **naked** and **spectre** attributes affect functions only. The **dllimport** and **dllexport** attributes affect functions, data, and objects. The **property**, **selectany**, and **uuid** attributes affect COM objects.
 
+For compatibility with previous versions, **_declspec** is a synonym for **__declspec** unless compiler option [/Za \(Disable language extensions)](../build/reference/za-ze-disable-language-extensions.md) is specified.
+
 The **__declspec** keywords should be placed at the beginning of a simple declaration. The compiler ignores, without warning, any **__declspec** keywords placed after * or & and in front of the variable identifier in a declaration.
 
 A **__declspec** attribute specified in the beginning of a user-defined type declaration applies to the variable of that type. For example:

docs/cpp/extension-restrict.md

@@ -1,10 +1,10 @@
 ---
 title: "__restrict | Microsoft Docs"
 ms.custom: ""
-ms.date: "11/04/2016"
+ms.date: "10/10/2018"
 ms.technology: ["cpp-language"]
 ms.topic: "language-reference"
-f1_keywords: ["__restrict_cpp"]
+f1_keywords: ["__restrict_cpp", "__restrict", "_restrict"]
 dev_langs: ["C++"]
 helpviewer_keywords: ["__restrict keyword [C++]"]
 ms.assetid: 2d151b4d-f930-49df-bd16-d8757ec7fa83
@@ -24,6 +24,8 @@ Like the **__declspec ( [restrict](../cpp/restrict.md) )** modifier, the **__res
 
 Generally, if you affect the behavior of an entire function, it is better to use `__declspec ( restrict )` than the keyword.
 
+For compatibility with previous versions, **_restrict** is a synonym for **__restrict** unless compiler option [/Za \(Disable language extensions)](../build/reference/za-ze-disable-language-extensions.md) is specified.
+
 In Visual Studio 2015 and later, **__restrict** can be used on C++ references.
 
 > [!NOTE]

docs/cpp/fastcall.md

@@ -1,10 +1,10 @@
 ---
 title: "__fastcall | Microsoft Docs"
 ms.custom: ""
-ms.date: "11/04/2016"
+ms.date: "10/09/2018"
 ms.technology: ["cpp-language"]
 ms.topic: "language-reference"
-f1_keywords: ["__fastcall_cpp"]
+f1_keywords: ["__fastcall_cpp", "__fastcall", "_fastcall"]
 dev_langs: ["C++"]
 helpviewer_keywords: ["__fastcall keyword [C++]"]
 ms.assetid: bb5b9c8a-dfad-450c-9119-0ac2bc59544f
@@ -52,6 +52,8 @@ is equivalent to this:
 void __fastcall CMyClass::mymethod() { return; }
 ```
 
+For compatibility with previous versions, **_fastcall** is a synonym for **__fastcall** unless compiler option [/Za \(Disable language extensions)](../build/reference/za-ze-disable-language-extensions.md) is specified.
+
 ## Example
 
 In the following example, the function `DeleteAggrWrapper` is passed arguments in registers:

docs/cpp/inheritance-keywords.md

@@ -61,6 +61,8 @@ regardless of command-line options or pragmas, pointers to members of `class S`
 > [!NOTE]
 >  The same forward declaration of a class pointer-to-member representation should occur in every translation unit that declares pointers to members of that class, and the declaration should occur before the pointers to members are declared.
 
+For compatibility with previous versions, **_single_inheritance**, **_multiple_inheritance**, and **_virtual_inheritance** are synonyms for **__single_inheritance**, **__multiple_inheritance**, and **__virtual_inheritance** unless compiler option [/Za \(Disable language extensions)](../build/reference/za-ze-disable-language-extensions.md) is specified.
+
 **END Microsoft Specific**
 
 ## See also

docs/cpp/inline-functions-cpp.md

@@ -1,10 +1,10 @@
 ---
 title: "Inline Functions (C++) | Microsoft Docs"
 ms.custom: ""
-ms.date: "11/04/2016"
+ms.date: "10/09/2018"
 ms.technology: ["cpp-language"]
 ms.topic: "language-reference"
-f1_keywords: ["__forceinline_cpp", "__inline_cpp", "inline_cpp"]
+f1_keywords: ["__forceinline_cpp", "__inline_cpp", "inline_cpp", "__inline", "_inline", "__forceinline", "_forceinline"]
 dev_langs: ["C++"]
 helpviewer_keywords: ["inline functions [C++], class members"]
 ms.assetid: 355f120c-2847-4608-ac04-8dda18ffe10c
@@ -71,7 +71,7 @@ Using inline functions can make your program faster because they eliminate the o
 
 The compiler treats the inline expansion options and keywords as suggestions. There is no guarantee that functions will be inlined. You cannot force the compiler to inline a particular function, even with the **__forceinline** keyword. When compiling with **/clr**, the compiler will not inline a function if there are security attributes applied to the function.
 
-The **inline** keyword is available only in C++. The **__inline** and **__forceinline** keywords are available in both C and C++. For compatibility with previous versions, **_inline** is a synonym for **__inline**.
+The **inline** keyword is available only in C++. The **__inline** and **__forceinline** keywords are available in both C and C++. For compatibility with previous versions, **_inline** and **_forceinline** are synonyms for **__inline**, and **__forceinline** unless compiler option [/Za \(Disable language extensions)](../build/reference/za-ze-disable-language-extensions.md) is specified.
 
 The **inline** keyword tells the compiler that inline expansion is preferred. However, the compiler can create a separate instance of the function (instantiate) and create standard calling linkages instead of inserting the code inline. Two cases where this can happen are:
 

docs/cpp/int8-int16-int32-int64.md

@@ -1,10 +1,10 @@
 ---
 title: "__int8, __int16, __int32, __int64 | Microsoft Docs"
 ms.custom: ""
-ms.date: "11/04/2016"
+ms.date: "10/09/2018"
 ms.technology: ["cpp-language"]
 ms.topic: "language-reference"
-f1_keywords: ["__int8_cpp", "__int16_cpp", "__int32_cpp", "__int64_cpp"]
+f1_keywords: ["__int8_cpp", "__int16_cpp", "__int32_cpp", "__int64_cpp", "__int8", "__int16", "__int32", "__int64", "_int8", "_int16", "_int32", "_int64"]
 dev_langs: ["C++"]
 helpviewer_keywords: ["__int16 keyword [C++]", "integer data type [C++], integer types in C++", "__int32 keyword [C++]", "integer types [C++]", "__int8 keyword [C++]", "__int64 keyword [C++]"]
 ms.assetid: 8e384602-2578-4980-8cc8-da63842356b2
@@ -29,6 +29,8 @@ __int64 nHuge;      // Declares 64-bit integer
 
 The types **__int8**, **__int16**, and **__int32** are synonyms for the ANSI types that have the same size, and are useful for writing portable code that behaves identically across multiple platforms. The **__int8** data type is synonymous with type **char**, **__int16** is synonymous with type **short**, and **__int32** is synonymous with type **int**. The **__int64** type is synonymous with type **long long**.
 
+For compatibility with previous versions, **_int8**, **_int16**, **_int32**, and **_int64** are synonyms for **__int8**, **__int16**, **__int32**, and **__int64** unless compiler option [/Za \(Disable language extensions)](../build/reference/za-ze-disable-language-extensions.md) is specified.
+
 ## Example
 
 The following sample shows that an __int*xx* parameter will be promoted to **int**: