feat: lockfile path implies --locked on cargo install

Author: ifropc

src/cargo/core/workspace.rs

@@ -662,6 +662,10 @@ impl<'gctx> Workspace<'gctx> {
         self.requested_lockfile_path = path;
     }
 
+    pub fn get_requested_lockfile_path(&mut self) -> Option<&PathBuf> {
+        self.requested_lockfile_path.as_ref()
+    }
+
     /// Get the lowest-common denominator `package.rust-version` within the workspace, if specified
     /// anywhere
     pub fn rust_version(&self) -> Option<&RustVersion> {

src/cargo/ops/cargo_install.rs

@@ -825,6 +825,10 @@ fn make_ws_rustc_target<'gctx>(
         ws
     };
     ws.set_ignore_lock(gctx.lock_update_allowed());
+    // if --lockfile-path is set, imply --locked
+    if ws.get_requested_lockfile_path().is_some() {
+        ws.set_ignore_lock(false);
+    }
     ws.set_require_optional_deps(false);
 
     let rustc = gctx.load_global_rustc(Some(&ws))?;