Rust 1.100 stops shipping compilers for 32-bit Windows hosts

Serguey Asael Shinder02 October 2026, 17:331 min read

The Rust project has announced that with Rust 1.100.0 its two 32-bit Windows targets lose their host tools. In the post on the Rust Blog on 2 October, i686-pc-windows-msvc moves from Tier 1 with host tools to Tier 1 without host tools, and i686-pc-windows-gnu from Tier 2 with host tools to Tier 2 without them.

In practice, prebuilt standard libraries for both targets continue to be distributed, and i686-pc-windows-msvc as a Tier 1 target still runs through CI testing. What goes away is the compiler and other host tools built to run on 32-bit Windows. After Rust 1.100 it will no longer be possible to install toolchains on 32-bit Windows hosts; to produce 32-bit Windows binaries, developers cross-compile from a supported host, such as a 64-bit Windows toolchain. Other 32-bit platforms are not affected.

The project gives two kinds of reasons. Desktop and server x86 CPUs that are only 32-bit have not been sold for more than 15 years, and, the post notes, general 32-bit Windows support ended in October 2025, so development machines of that kind hardly exist and are rarely capable enough. And building the i686 Windows toolchains has itself been a problem even on modern hardware: the team reports compiler binaries crashing when built with the i686 MSVC target, and the GNU C++ toolchain running out of memory during the LLVM build.

The decisions are recorded in RFC 3999 for the MSVC target and in compiler MCP 1020 for the GNU target.

Why it matters

Anyone still shipping 32-bit Windows binaries is unaffected as long as they build them from a 64-bit host, which most CI setups already do. The change matters for the rare build machine that is itself 32-bit Windows, and for projects that pin a toolchain by host triple in scripts.