Watcom C/C++

Watcom C/C++ (currently Open Watcom C/C++) is an integrated development environment (IDE) product from Watcom International Corporation for the C, C++, and Fortran programming languages. Watcom C/C++ was a commercial product until it was discontinued, then released under the Sybase Open Watcom Public License as Open Watcom C/C++. It features tools for developing and debugging code for DOS, OS/2, Windows, and Linux operating systems, which are based upon 16-bit x86, 32-bit IA-32, or 64-bit x86-64 compatible processors.

History 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).Open Watcom v2 Fork

Release history The Open Watcom Wiki has a comprehensive history.

Date Product Notes 1984 1985 Work on current code generator codebase started 1988 DOS host and target only Included a debugger and full set of runtime libraries Generated better code than other compilers at the time Watcom C Version 6.5 contained Graphics Library similar to Microsoft Graphics Library Real mode support only 1989 1989 First 32-bit version, DOS host and target only Supported Phar Lap DOS extender Did not come with a linker or debugger 1990 1990 Added linker, librarian, debugger, and profiler 1991 1991 Shipped with DOS/4GW Windows 3.0 supported (Win386 extender) Unicode support OS/2 hosted executables added 1992 1992 OS/2 2.0 host and target support 486 optimizations Based pointer support Windows 3.1 support 1993 1993 C++ compiler added Pentium optimizations Windows NT host and target support 1994 MFC included Precompiled header support 16-bit and 32-bit tools merged into single package Redesigned debugger C++ class browser added Windows resource editors added Graphical IDE for Windows and OS/2 1995 Native C++ exception handling on OS/2 and Win32 Windows 95 and NT 3.5 support TCP/IP remote debugging 1996 Structured exception handling in C Improved compatibility with Microsoft compilers 1997 Q1SYBASE INC. ANNOUNCES WATCOM C/C++ VERSION 11.0 Includes New Support For MMX Technology and Improved C++ language Support Namespace, RTTI, and new style cast support in C++ compiler 64-bit integer support Multi-byte character support in libraries Incremental linking support COFF and ELF object file support in linker and librarian Microsoft clone tools added DLL based tools for better IDE integration MMX support, including debugging Pentium Pro optimizations, including branch prediction Novell NLM support 1998 1999-06-30 Sybase issues end-of-life notice for Watcom C/C++ 11.0End of Life Notice for Watcom C/C++ Version 11.0 2000-08-22 Sybase announces open sourcing of Watcom toolsSybase to Open Source Watcom C/C++ and Fortran Compilers - SciTech Software Selected as Official Maintainer for the Open Watcom Project 2001-09-27 2002-12-21 2003-01-28 2003-08-12 2004-01-07 2004-08-03 2005-12-14 2006-04-26 2006-12-15 2007-08-18 2007-10-23 2009-02-21 2010-06-02 Last version released via https://www.openwatcom.org initial release: 2015-04-02(continuous updates later on, up until at least 2025) GitHub v2 fork, numerous fixes Open Watcom ported to 64-bit hosts (Windows and Linux) Resource compiler and Resource editor support WIN64 executables built-in text editor two-phase build system DOS version of tools support long filenames (LFN) add check box for C99 in the "2. Diagnostics Switches" panel of the GUI

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 LinuxInstalling Open Watcom on Linux - Open Watcom. OpenWatcom.org wiki. 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,History - Open Watcom. OpenWatcom.com wiki. Descent, Duke Nukem 3D, Rise of the Triad, 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.

The Embeddable Linux Kernel Subset also supports using Open Watcom C.

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 24731-1ISO/IEC TR 24731-1; Extension to the C Library, Part 1: Bounds-checking interfaces.WG14 N1969 — "Updated Field Experience With Annex K — Bounds Checking Interfaces", Carlos O'Donell, Martin Sebor 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".

Watcom C/C++

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