Portable C, C++, and Fortran Development Kit for x64 and x86 Windows

w64devkit is a Dockerfile that builds from source a small, portable development suite for creating C and C++ applications on and for x86 and x64 Windows. See "Releases" for pre-built, ready-to-use kits.

Included tools:

• Mingw-w64 GCC : compilers, linker, assembler
• GDB : debugger
• GNU Make : standard build tool
• busybox-w32 : standard unix utilities, including sh
• Vim : powerful text editor
• Universal Ctags : source navigation

It is an MSVCRT toolchain with pthreads, C++11 threads, and OpenMP. All included runtime components are static. Docker/Podman is not required to use the development kit. It's merely a reliable, clean environment for building the kit itself.

Build

Build the image, then run it to produce a self-extracting 7z archive:

docker build -t w64devkit .
docker run --rm w64devkit >w64devkit-x64.exe

This takes about 15 minutes on modern systems. You will need an internet connection during the first few minutes of the build. Note: Do not use PowerShell because it lacks file redirection.

Usage

The self-extracting 7z archive contains tools in a typical unix-like configuration. Extract wherever is convenient. Inside is w64devkit.exe, which launches a console window with the environment configured and ready to go. It is the easiest way to enter the development environment, and requires no system changes. It also sets two extra environment variables: W64DEVKIT_HOME to the installation root and W64DEVKIT to the version.

Alternatively, add the bin/ directory to your path. For example, inside a cmd.exe console or batch script:

set PATH=c:\path\to\w64devkit\bin;%PATH%

Then to start an interactive unix shell:

sh -l

Main features

• No installation required. Run it anywhere as any user. Simply delete when no longer needed.

• Fully offline. No internet access is ever required or attempted.

• A focus on static linking all runtime components. The runtime is optimized for size.

• Trivial to build from source, meaning it's easy to tweak and adjust any part of the kit for your own requirements.

• Complements Go for cgo and bootstrapping.

Operating system support

The x64 kit requires Windows 7 or later, though some tools only support Unicode ("wide") paths, inputs, and outputs on Windows 10 or later. The toolchain targets Windows 7 by default.

The x86 kit requires Windows XP or later and an SSE2-capable processor (e.g. at least Pentium 4); limited Unicode support. The toolchain targets the same by default. Runtimes contain SSE2 instructions, so GCC -march will not reliably target less capable processors when runtimes are linked (exceptions: -lmemory, -lchkstk).

Optimized for size

Runtime components are optimized for size, leading to smaller application executables. Unique to w64devkit, libmemory.a is a library of memset, memcpy, memmove, memcmp, and strlen implemented as x86 string instructions. When not linking a CRT, linking -lmemory provides tiny definitions, particularly when GCC requires them.

Also unique to w64devkit, libchkstk.a has a leaner, faster definition of ___chkstk_ms than GCC (-lgcc), as well as __chkstk, sometimes needed when linking MSVC artifacts. Both are in the public domain and so, unlike default implementations, do not involve complex licensing. When required in a -nostdlib build, link -lchkstk.

Unlike traditional toolchains, import tables are not populated with junk ordinal hints. If an explicit hint is not provided (i.e. via a DEF file), then the hint is zeroed: "no data." Eliminating this random data makes binaries more compressible and theoretically faster loading. See also: peports.

Recommended downloadable, offline documentation

With a few exceptions, such as Vim's built-in documentation (:help), w64devkit does not include documentation. However, you need not forgo offline documentation alongside your offline development tools. This is a list of recommended, no-cost, downloadable documentation complementing w64devkit's capabilities. In rough order of importance:

• cppreference (HTML), friendly documentation for the C and C++ standard libraries.

• GCC manuals (PDF, HTML), to reference GCC features, especially built-ins, intrinsics, and command line switches.

• Win32 Help File (CHM) is old, but official, Windows API documentation. Unfortunately much is missing, such as Winsock. (Offline Windows documentation has always been very hard to come by.)

• C and C++ Standards (drafts) (PDF), for figuring out how corner cases are intended to work.

• Intel Intrinsics Guide (interactive HTML), a great resource when working with SIMD intrinsics. (Search for "Download" on the left.)

• GNU Make manual (PDF, HTML)

• GNU Binutils manuals (PDF, HTML), particularly ld and as.

• GDB manual (PDF)

• BusyBox man pages (TXT), though everything here is also available via -h option inside w64devkit.

• Intel Software Developer Manuals (PDF), for referencing x86 instructions, when either studying compiler output with objdump or writing assembly.

Library installation

Except for the standard libraries and Win32 import libraries, w64devkit does not include libraries, but you can install additional libraries such that the toolchain can find them naturally. There are three options:

1. Install it under the sysroot at w64devkit/$ARCH/. The easiest option, but will require re-installation after upgrading w64devkit. If it defines .pc files, the pkg-config command will automatically find and use them.

2. Append its installation directory to your CPATH and LIBRARY_PATH environment variables. Use ; to delimit directories. You would likely do this in your .profile.

3. If it exists, append its pkgconfig directory to the PKG_CONFIG_PATH environment variable, then use the pkg-config command as usual. Use ; to delimit directories

Both (1) and (3) are designed to work correctly even if w64devkit or the libraries have paths containing spaces.

Unique command-line programs

• peports: displays export and import tables of EXEs and DLLs. Like MSVC dumpbin options /exports and /imports; narrower and more precise than Binutils objdump -p. Useful for checking if exports and imports match your expectations. Complemented by c++filt and vc++filt, i.e. in a pipeline. Pronounced like purports.

• vc++filt: a c++filt for Visual C++ name decorations. Used to examine GCC-incompatible binaries, potentially to make some use of them anyway.

• debugbreak: causes all debugee processes to break in the debugger, like using Windows' F12 debugger hotkey. Especially useful for console subsystem programs.

Notes

$HOME can be set through the adjacent w64devkit.ini configuration, and may even be relative to the w64devkit/ directory. This is useful for encapsulating the entire development environment, with home directory, on removable, even read-only, media. Use a .profile in the home directory to configure the environment further.

Neither Address Sanitizer (ASan) nor Thread Sanitizer (TSan) has been ported to Mingw-w64 (also), but Undefined Behavior Sanitizer (UBSan) works perfectly under GDB. With both -fsanitize=undefined and -fsanitize-trap, GDB will break precisely on undefined behavior, and it does not require linking with libsanitizer.

GCC does not fully support AVX on Windows and may use aligned moves on unaligned addresses. When targeting AVX, consider disabling all aligned moves in the assembler: -Wa,-muse-unaligned-vector-move.

Licenses

When distributing binaries built using w64devkit, your .exe will include parts of this distribution. For the GCC runtime, including OpenMP, you're covered by the GCC Runtime Library Exception so you do not need to do anything. However the Mingw-w64 runtime has the usual software license headaches and you may need to comply with various BSD-style licenses depending on the functionality used by your program: MinGW-w64 runtime licensing and winpthreads license. To make this easy, w64devkit includes the concatenated set of all licenses in the file COPYING.MinGW-w64-runtime.txt, which should be distributed with your binaries.