only use env!(CARGO) for development run

Author: Carolyn Zech

kani-driver/src/call_cargo.rs

@@ -4,7 +4,9 @@
 use crate::args::VerificationArgs;
 use crate::call_single_file::{LibConfig, to_rustc_arg};
 use crate::project::Artifact;
-use crate::session::{KaniSession, lib_folder, lib_no_core_folder, setup_cargo_command};
+use crate::session::{
+    KaniSession, get_cargo_path, lib_folder, lib_no_core_folder, setup_cargo_command,
+};
 use crate::util;
 use anyhow::{Context, Result, bail};
 use cargo_metadata::diagnostic::{Diagnostic, DiagnosticLevel};
@@ -248,7 +250,8 @@ crate-type = ["lib"]
         let mut cmd = MetadataCommand::new();
 
         // Use Kani's toolchain when running `cargo metadata`
-        cmd.cargo_path(env!("CARGO"));
+        let cargo_path = get_cargo_path().unwrap();
+        cmd.cargo_path(cargo_path);
 
         // restrict metadata command to host platform. References:
         // https://github.com/rust-lang/rust-analyzer/issues/6908

kani-driver/src/session.rs

@@ -439,3 +439,17 @@ pub fn setup_cargo_command() -> Result<Command> {
 
     Ok(cmd)
 }
+
+// Get the cargo path corresponding to the toolchain version in rust-toolchain.toml.
+// If kani is being run in developer mode, then we use the compile-time toolchain, i.e. the one used during cargo build-dev.
+// For release versions of Kani, we use a version of cargo that's in the toolchain that's been symlinked during `cargo-kani` setup.
+pub fn get_cargo_path() -> Result<PathBuf> {
+    let install_type = InstallType::new()?;
+
+    let cargo_path = match install_type {
+        InstallType::DevRepo(_) => env!("CARGO").into(),
+        InstallType::Release(kani_dir) => kani_dir.join("toolchain").join("bin").join("cargo"),
+    };
+
+    Ok(cargo_path)
+}