Watcom C/C++

In 2000, Sybase, who owned Watcom International Corporation halted the commercial sale of the Watcom C/C++ and Fortran compilers. In 2003, SciTech Software Inc, a customer of Sybase, negotiated wth Sybase, to have the code for the compilers released as an open source project under a new name, Open Watcom. The Watcom C/C++ compiler and the Watcom Fortran compiler were made available free of charge as the Open Watcom package. The last stable version endorsed by the original openwatcom.org team was 1.9, released in June 2010. A community-based forked version 2.0 (with continuous updates under the same version moniker) was released after the original codebase was seemingly no longer developed by the original team. It includes miscellaneous bugfixes, supports 64-bit hosts (Windows and Linux), built-in text editor, 2-phase build system, and has a DOS version that supports long filenames (LFN). Release history The Open Watcom Wiki has a comprehensive history. ==License==

The Open Source Initiative has approved the license as open source, but Debian, Fedora and the Free Software Foundation have rejected it because "It requires you to publish the source code publicly whenever you “Deploy” the covered software, and “Deploy” is defined to include many kinds of private use." ==Design==

The compiler can be operated from, and generate executable code for, the DOS, OS/2, Windows, Linux operating systems. It also supports NLM targets for Novell NetWare. There is ongoing work to extend the targeting to Linux and modern BSD (e.g., FreeBSD) operating systems, running on x86, PowerPC, and other processors. The code is portable and, like many other open source compiler projects such as GCC or LCC the compiler backend (code generator) is retargetable. ==Uses==

In the mid-1990s some of the most technically ambitious DOS computer games such as Doom, Descent, and Tomb Raider were built using Watcom C/C++ using the DOS/4GW protected mode extender with the Watcom compiler. It was used to port the game Retro City Rampage to DOS in 2015. It was used by VirtualBox to compile the BIOS. Current development for FreeDOS requires that all C source code must be compilable by Open Watcom C. Open Watcom is the recommended compiler for application and driver development for the OS/2-based ArcaOS operating system. ==Compatibility==

Open Watcom's syntax supports many conventions introduced by other compilers, such as Microsoft's and Borland's, including differing conventions regarding (for instance) the number of leading underscores on the "asm" tag. Code written specifically for another compiler rather than standard-compliant C or C++ will often compile with the Watcom compiler. The C compiler supports ANSI C (C89, C90, ISO C) standard by default. Open Watcom supports partial compatibility with the C99 standard. It implements the most commonly used parts of the standard, including inline variable declaration. However, they are enabled only through the undocumented command-line switch "-za99" (which needs to be added to the "Other options" field in "4. Miscellaneous Switches" panel in the GUI). In a more recent version of Open Watcom 2.0, a check box was added for C99 in the "2. Diagnostics Switches" panel in the GUI. Three C99 features have been bundled as C90 Extension since pre-v1.0: C++ style comments (//), flexible array members, trailing comma allowed in enum declaration. The compiler currently doesn't support any new major C11 features, though the C library does include "Safe C" functions. It is specified in ISO/IEC TR 24731-1 and known as "Bounds-checking interfaces (Annex K)" in C11. Some function name examples are strcpy_s(), memcpy_s(), printf_s(). This library was released along with Open Watcom 1.5 in April 2006. ==Reception==

In a February 1989 overview of optimizing C compilers, BYTE praised Watcom C 6.5's "unmatched execution speed" and noted that it was the most ANSI C-compliant. The magazine advised, "If speed is absolutely critical and OS/2 compatibility isn't, choose Watcom". ==See also==