We initially added these fingerprint checks as a tool to use whenĭeveloping rustc itself, back in 2017. In some cases, due to bugs in the compiler's implementation,
#Rust update verification
Newly enabled verification checks that the value is indeed as expected, rather That the output is the same as from a prior incremental compilation session. Sometimes the compiler is forced to rerun a query, and expects The fingerprint stability check is a safeguard asserting internal consistency of (More details about this are available in the relevant chapter of the rustc dev guide.) Fingerprints are used to validate that a newly computed result is unchanged from the cached result. Some compiler-internal results are stored on disk ("cached") between runs. More specifically, a fingerprint (along with some other state to establish context) is a 128-bit value intended to uniquely identify internal values used within the compiler. Then, when the inputs change, it detects this and reuses artifacts from previous builds, striving to expend effort solely on building the parts that need to respond to the changes to the input source code.įingerprints are part of our architecture for detecting when inputs change. When incremental compilation is turned on, the compiler breaks the input source into pieces, and tracks how those input pieces influence the final build product. The Rust compiler has support for "incremental compilation", which has been described in a 2016 blog post. What are fingerprints? Why are we checking them? In this case, the ICE is revealing a bug in incremental compilation that predates the 1.52.0 release and could result in miscompilation if it had not been caught. In other words, it represents a bug in the internals of the Rust compiler itself. This is the error caused by the internal consistency check, and as stated in the diagnostic, it yields an "Internal Compiler Error" (or ICE). Note: the compiler unexpectedly panicked. thread 'rustc' panicked at 'assertion failed: `(left = right)` The error message looks something like this, with the key piece being the "found Describe our plans for how the Rust project will address the problems discussed here.Tell you what you should do if you see an unstable fingerprint on your project,.Explain how the check is presenting itself in the Rust 1.52.0 release,.
#Rust update code
Miscompilations that can arise from the bugs in incremental compilation generate incorrect code in finalĪrtifacts, essentially producing malformed binaries, which means that in theoryĪny behavior is possible. Production builds should be affected (only for users who have opted in). Incremental compilation is off by default for release builds, so few
#Rust update upgrade
Users are encouraged to upgrade to 1.52.1 or disable incremental in their localĮnvironment if on a prior version: please see the what you should do
Versions 1, and can trigger miscompilations in incremental builds, so downgrading The bugs this verification detects are present in all Rust This release works around broken builds on 1.52.0, which are caused by newlyĪdded verification. If you don't have it already, you can get rustupįrom the appropriate page on our website.
#Rust update update
If you have a previous version of Rust installed via rustup, getting Rustġ.52.1 is as easy as: rustup update stable To 1.52.0, upgrade to 1.52.1 or disable incremental compilation. Recommend all Rust users, including those currently using stable versions prior Incremental compilation which was made into a compiler error in 1.52.0. The Rust team has prepared a new release, 1.52.1, working around a bug in
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