feat: Support Verus verification (microsoft#759)

Support for Verus verification. Also add a verus github workflow.

Signed-off-by: Jay Lorch <jaylorch@gmail.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: jaylorch

.dir-locals.el

@@ -0,0 +1,12 @@
+;;; Directory Local Variables            -*- no-byte-compile: t; -*-
+;;; For more information see (info "(emacs) Directory Variables")
+
+;; Regorus is a cargo-verus project (package.metadata.verus.verify = true), so
+;; verus-mode.el runs `cargo verus verify' rather than the raw `verus' binary.
+;; The cargo-verus path ignores `package.metadata.verus.ide.extra_args' and
+;; instead reads `verus-cargo-verus-arguments'. We set it here so that Verus is
+;; invoked with the `verus' Cargo feature enabled.
+;;
+;; Everything before `--' is passed to cargo-verus; everything after `--' is
+;; forwarded to the Verus binary. The `--' is required by verus-mode.el.
+((verus-mode . ((verus-cargo-verus-arguments . ("--features" "verus" "--")))))

.github/workflows/verus.yml

@@ -0,0 +1,80 @@
+# Copyright (c) Microsoft Corporation. All rights reserved.
+#
+name: verus
+
+on:
+  push:
+    branches: [ "main" ]
+  pull_request:
+    branches: [ "main" ]
+
+env:
+  CARGO_TERM_COLOR: always
+
+# This workflow only checks out code, downloads a pinned Verus release asset,
+# and runs verification. It never writes to the repository, so restrict the
+# GITHUB_TOKEN to read-only access to repository contents.
+permissions:
+  contents: read
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+    - name: Setup Rust toolchain
+      uses: ./.github/actions/toolchains/rust
+      with:
+        components: ""
+    - name: Cache cargo
+      uses: Swatinem/rust-cache@c19371144df3bb44fab255c43d04cbc2ab54d1c4 # v2.9.1
+      with:
+        shared-key: ${{ runner.os }}-regorus-verus
+    - name: Install Verus and run verification
+      shell: bash
+      run: |
+        set -euxo pipefail
+        asset_url=https://github.com/verus-lang/verus/releases/download/release%2F0.2026.07.12.0b42f4c/verus-0.2026.07.12.0b42f4c-x86-linux.zip
+        asset_sha256=f6f4f5d08e07d3e1ad721d775bda5ba96b9dd0c73b48fc17f2e071866fbd01c0
+        test -n "$asset_url"
+        curl -fsSL "$asset_url" -o verus.zip
+
+        # Verify the download integrity before trusting/executing its contents.
+        echo "${asset_sha256}  verus.zip" | sha256sum --check --strict
+
+        unzip -q verus.zip -d verus-dist
+
+        # Search under an absolute path so that `find` yields absolute paths;
+        # this keeps the PATH entries below valid regardless of the working
+        # directory.
+        verus_bin="$(find "$PWD/verus-dist" -type f -name verus -perm -u+x | head -n1)"
+        cargo_verus_bin="$(find "$PWD/verus-dist" -type f -name cargo-verus -perm -u+x | head -n1)"
+        version_json="$(find "$PWD/verus-dist" -type f -name version.json | head -n1)"
+        test -n "$verus_bin"
+        test -n "$cargo_verus_bin"
+        test -n "$version_json"
+
+        # Verus is built against a specific Rust toolchain and refuses to run
+        # against any other version. Read the required toolchain from the
+        # release metadata so we track it automatically instead of hardcoding.
+        required_toolchain="$(sed -n 's/.*"toolchain"[[:space:]]*:[[:space:]]*"\([^"]*\)".*/\1/p' "$version_json")"
+        test -n "$required_toolchain"
+        echo "Verus requires Rust toolchain: $required_toolchain"
+
+        # Install the exact toolchain Verus expects, including the extra
+        # components (rustc-dev, llvm-tools) that Verus links against and that
+        # are not part of the default rustup profile.
+        rustup toolchain install "$required_toolchain" \
+          --profile minimal \
+          --component rustc-dev --component llvm-tools --component rustfmt
+
+        # Force cargo/rustc to resolve to the Verus toolchain for the commands
+        # below, overriding any repository/directory toolchain override.
+        export RUSTUP_TOOLCHAIN="$required_toolchain"
+
+        # Put cargo-verus on PATH for the commands below.
+        export PATH="$(dirname "$cargo_verus_bin"):$(dirname "$verus_bin"):$PATH"
+        cargo verus --help
+        cargo fetch --locked
+        cargo verus verify --locked --features verus

Cargo.lock

@@ -14,13 +14,19 @@ license = "MIT AND Apache-2.0 AND BSD-3-Clause"
 repository = "https://github.com/microsoft/regorus"
 keywords = ["interpreter", "no_std", "opa", "policy-as-code", "rego"]
 
+# Support verification with Verus, a Rust verifier (https://github.com/verus-lang/verus)
+
+[package.metadata.verus]
+verify = true
+
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [lib]
 doctest = false
 
 [features]
 default = ["full-opa", "arc", "rvm"]
+verus = ["dep:vstd"]
 
 arc = []
 ast = []
@@ -43,7 +49,7 @@ cache = ["dep:lru"]
 rvm = ["dep:postcard", "dep:indexmap"]
 semver = ["dep:semver"]
 allocator-memory-limits = ["std", "mimalloc", "mimalloc/allocator-memory-limits"]
-std = ["rand/std", "rand/std_rng", "serde_json/std", "indexmap?/std", "msvc_spectre_libs", "dep:parking_lot" ]
+std = ["rand/std", "rand/std_rng", "serde_json/std", "indexmap?/std", "msvc_spectre_libs", "dep:parking_lot", "vstd?/std" ]
 time = ["dep:chrono", "dep:chrono-tz"]
 uuid = ["dep:uuid"]
 urlquery = ["dep:url"]
@@ -134,6 +140,11 @@ mimalloc = { package = "regorus-mimalloc", path = "mimalloc", version = "2.2.7",
 indexmap = { version = "2.13.1", default-features = false, features = ["serde"], optional = true }
 postcard = { version = "1.1.3", default-features = false, features = ["alloc"], optional = true }
 
+# Verus-related dependencies.
+# vstd is enabled via the `verus` feature. In no_std builds only the `alloc` feature is used;
+# the crate's `std` feature additionally enables `vstd/std` (matching vstd's default features).
+vstd = { version = "=0.0.0-2026-07-12-0122", optional = true, default-features = false, features = ["alloc"] }
+
 [dev-dependencies]
 anyhow = "1.0.102"
 cfg-if = "1.0.0"
@@ -214,3 +225,7 @@ doctest=false
 # RUSTDOCFLAGS="--cfg docsrs" cargo +nightly doc --all-features --no-deps
 all-features = true
 rustdoc-args = ["--cfg", "docsrs"]
+
+[lints.rust]
+# Allow `verus_keep_ghost` configuration flag (used by Verus)
+unexpected_cfgs = { level = "warn", check-cfg = ['cfg(verus_keep_ghost)'] }

Cargo.toml

@@ -115,6 +115,10 @@ public void Engine_create_eval_dispose_does_not_grow_working_set()
 
                 if (i % LogEvery == 0)
                 {
+                    // Collect transient managed garbage so the working-set delta reflects
+                    // retained (leaked) memory rather than uncollected allocations. A real
+                    // native leak from a missed Dispose() would survive GC and still be caught.
+                    ForceFullGc();
                     process.Refresh();
                     var workingSet = process.WorkingSet64;
                     var managed = GC.GetTotalMemory(false);
@@ -228,6 +232,10 @@ public void Rvm_rehydrate_execute_dispose_does_not_grow_working_set()
 
                 if (i % LogEvery == 0)
                 {
+                    // Collect transient managed garbage so the working-set delta reflects
+                    // retained (leaked) memory rather than uncollected allocations. A real
+                    // native leak from a missed Dispose() would survive GC and still be caught.
+                    ForceFullGc();
                     process.Refresh();
                     var workingSet = process.WorkingSet64;
                     var managed = GC.GetTotalMemory(false);