user0/rust
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Merge pull request #4767 from RalfJung/shim-scope

Browse source 
document guidelines for which shims have a place in Miri
This commit is contained in:
Ralf Jung 2026-01-25 19:00:51 +00:00 • committed by GitHub
commit be79f4711d
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
1 changed files with 17 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

17
src/tools/miri/CONTRIBUTING.md
View file

@ -66,6 +66,23 @@ process for such contributions:
This process is largely informal, and its primary goal is to more clearly communicate expectations.
Please get in touch with us if you have any questions!
## Scope of Miri shims
Miri has "shims" to implement functionality that is usually implemented in C libraries which are
invoked from Rust code, such as opening files or spawning threads, as well as for
CPU-vendor-provided SIMD intrinsics. However, the set of C functions that Rust code invokes this way
is enormous, and for obvious reasons we have no intention of implementing every C API ever written
in Miri.
At the moment, the general guideline for "could this function have a shim in Miri" is: we will
generally only add shims for functions that can be implemented in a portable way using just what is
provided by the Rust standard library. The function should also be reasonably widely-used in Rust
code to justify the review and maintenance effort (i.e. the easier the function is to implement, the
lower the barrier). Other than that, we might make exceptions for certain cases if (a) there is a
good case for why Miri should support those APIs, and (b) robust and widely-used portable libraries
exist in the Rust ecosystem. We will generally not add shims to Miri that would require Miri to
directly interact with platform-specific APIs (such as `libc` or `windows-sys`).
## Preparing the build environment
Miri heavily relies on internal and unstable rustc interfaces to execute MIR,