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In compiler construction, name mangling (also called name decoration) is a technique used to solve various problems caused by the need to resolve unique names for programming entities in many modern programming languages. It provides a way of encoding additional information in the name of a function, structure, class or another datatype in order to pass more semantic information from the compilers to linkers. The need arises where the language allows different entities to be named with the same identifier as long as they occupy a different namespace (where a namespace is typically defined by a module, class, or explicit ''namespace'' directive) or have different signatures (such as function overloading). Any object code produced by compilers is usually linked with other pieces of object code (produced by the same or another compiler) by a type of program called a linker. The linker needs a great deal of information on each program entity. For example, to correctly link a function it needs its name, the number of arguments and their types, and so on. ==C name decoration in Microsoft Windows== Although name mangling is not generally required or used by languages that do not support function overloading (such as C and classic Pascal), they use it in some cases to provide additional information about a function. For example, compilers targeted at Microsoft Windows platforms support a variety of calling conventions, which determine the manner in which parameters are sent to subroutines and results returned. Because the different calling conventions are not compatible with one another, compilers mangle symbols with codes detailing which convention should be used to call the specific routine. The mangling scheme was established by Microsoft, and has been informally followed by other compilers including Digital Mars, Borland, and GNU GCC, when compiling code for the Windows platforms. The scheme even applies to other languages, such as Pascal, D, Delphi, Fortran, and C#. This allows subroutines written in those languages to call, or be called by, existing Windows libraries using a calling convention different from their default. When compiling the following C examples: int _cdecl f (int x) int _stdcall g (int y) int _fastcall h (int z) 32 bit compilers emit, respectively: _f _g@4 @h@4 In the stdcall and fastcall mangling schemes, the function is encoded as _name@X and @name@X respectively, where X is the number of bytes, in decimal, of the argument(s) in the parameter list (including those passed in registers, for fastcall). In the case of cdecl, the function name is merely prefixed by an underscore. Note that the 64-bit convention on Windows (Microsoft C) has no leading underscore. This difference may in some rare cases lead to unresolved externals when porting such code to 64 bits. For example, Fortran code can use 'alias' to link against a C method by name as follows: SUBROUTINE f() !DEC$ ATTRIBUTES C, ALIAS:'_f' :: f END SUBROUTINE This will compile and link fine under 32 bits, but generate an unresolved external '_f' under 64 bits. One work around for this is to not use 'alias' at all (in which the method names typically need to be capitalized in C and Fortran), or to use the BIND option: SUBROUTINE f() BIND(C,NAME="f") END SUBROUTINE 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Name mangling」の詳細全文を読む スポンサード リンク
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