Rust: Pass --ignore-rust-version to Cargo

rust/extractor/src/config.rs

@@ -189,6 +189,16 @@ impl Config {
 
     pub fn to_cargo_config(&self, dir: &AbsPath) -> (CargoConfig, LoadCargoConfig) {
         let sysroot = self.sysroot(dir);
+        let mut extra_args = self.cargo_extra_args.clone();
+        // The fixed toolchain may be older than the project's declared minimum.
+        // If that's the case `cargo` will error. Passing the flag below ensures
+        // that the project's speified Rust version is ignored. With this
+        // failures will only occur if the project actually uses Rust features
+        // that rust-analyzer and/or the fixed toolchain is incompatible with
+        // (which is the best we can hope for).
+        if !extra_args.iter().any(|arg| arg == "--ignore-rust-version") {
+            extra_args.push("--ignore-rust-version".to_owned());
+        }
         (
             CargoConfig {
                 all_targets: self.cargo_all_targets,
@@ -205,7 +215,7 @@ impl Config {
                     .map(RustLibSource::Path),
 
                 extra_env: self.get_extra_env(),
-                extra_args: self.cargo_extra_args.clone(),
+                extra_args,
                 extra_includes: self
                     .extra_includes
                     .iter()

rust/ql/integration-tests/rust-version/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "rust-version"
+version = "0.1.0"
+edition = "2024"
+rust-version = "1.999.0"
+
+[dependencies]
+macros = { path = "macros" }
+
+[workspace]
+members = ["macros"]

rust/ql/integration-tests/rust-version/build.rs

@@ -0,0 +1,9 @@
+fn main() {
+    let out_dir = std::env::var("OUT_DIR").unwrap();
+    std::fs::write(
+        std::path::Path::new(&out_dir).join("generated.rs"),
+        "pub fn from_build_script() -> u32 { 42 }\n",
+    )
+    .unwrap();
+    println!("cargo:rerun-if-changed=build.rs");
+}

rust/ql/integration-tests/rust-version/functions.expected

@@ -0,0 +1,2 @@
+| from_build_script |
+| from_proc_macro |

rust/ql/integration-tests/rust-version/functions.ql

@@ -0,0 +1,5 @@
+import rust
+
+from Function f
+where f.fromSource() and f.getName().getText() = ["from_build_script", "from_proc_macro"]
+select f.getName().getText()

rust/ql/integration-tests/rust-version/macros/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "macros"
+version = "0.1.0"
+edition = "2024"
+
+[lib]
+proc-macro = true

rust/ql/integration-tests/rust-version/macros/src/lib.rs

@@ -0,0 +1,6 @@
+extern crate proc_macro;
+
+#[proc_macro]
+pub fn generate(_: proc_macro::TokenStream) -> proc_macro::TokenStream {
+    "pub fn from_proc_macro() -> u32 { 43 }".parse().unwrap()
+}

rust/ql/integration-tests/rust-version/src/main.rs

@@ -0,0 +1,7 @@
+include!(concat!(env!("OUT_DIR"), "/generated.rs"));
+
+macros::generate!();
+
+fn main() {
+    println!("{} {}", from_build_script(), from_proc_macro());
+}

rust/ql/integration-tests/rust-version/test_rust_version.py

@@ -0,0 +1,10 @@
+import pytest
+
+
+@pytest.mark.parametrize("rust_edition", [2024])
+@pytest.mark.parametrize("extra_args", [None, "--offline", "--ignore-rust-version"])
+def test_rust_version(codeql, rust, cargo, extra_args):
+    env = {}
+    if extra_args is not None:
+        env["CODEQL_EXTRACTOR_RUST_OPTION_CARGO_EXTRA_ARGS"] = extra_args
+    codeql.database.create(_env=env)