refactor(tvix/eval/io): use io::Error instead of tvix_eval errors

We didn't return anything useful other than ErrorKind::IO anyways.

We can use io::ErrorKind::Unsupported for DummyIO.

Fixes b/271.

Change-Id: Icb231e9b38168e8b6fa473bfa405d160357b317f
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8602
Autosubmit: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Reviewed-by: tazjin <tazjin@tvl.su>

tvix/cli/src/nix_compat.rs

@@ -11,7 +11,7 @@ use std::process::Command;
 use std::{io, path::PathBuf};
 
 use smol_str::SmolStr;
-use tvix_eval::{ErrorKind, EvalIO, FileType, StdIO};
+use tvix_eval::{EvalIO, FileType, StdIO};
 
 /// Compatibility implementation of [`EvalIO`] that uses C++ Nix to
 /// write files to the Nix store.
@@ -33,16 +33,13 @@ impl EvalIO for NixCompatIO {
     }
 
     // Pass path imports through to `nix-store --add`
-    fn import_path(&mut self, path: &Path) -> Result<PathBuf, ErrorKind> {
+    fn import_path(&mut self, path: &Path) -> Result<PathBuf, io::Error> {
         let path = path.to_owned();
         if let Some(path) = self.import_cache.get(&path) {
             return Ok(path.to_path_buf());
         }
 
-        let store_path = self.add_to_store(&path).map_err(|error| ErrorKind::IO {
-            error: std::rc::Rc::new(error),
-            path: Some(path.to_path_buf()),
-        })?;
+        let store_path = self.add_to_store(&path)?;
 
         self.import_cache.insert(path, store_path.clone());
 
@@ -50,7 +47,7 @@ impl EvalIO for NixCompatIO {
     }
 
     // Pass the rest of the functions through to `Self::underlying`
-    fn path_exists(&mut self, path: PathBuf) -> Result<bool, ErrorKind> {
+    fn path_exists(&mut self, path: PathBuf) -> Result<bool, io::Error> {
         if path.starts_with("/__corepkgs__") {
             return Ok(true);
         }
@@ -58,7 +55,7 @@ impl EvalIO for NixCompatIO {
         self.underlying.path_exists(path)
     }
 
-    fn read_to_string(&mut self, path: PathBuf) -> Result<String, ErrorKind> {
+    fn read_to_string(&mut self, path: PathBuf) -> Result<String, io::Error> {
         // Bundled version of corepkgs/fetchurl.nix. This workaround
         // is similar to what cppnix does for passing the path
         // through.
@@ -72,7 +69,7 @@ impl EvalIO for NixCompatIO {
         self.underlying.read_to_string(path)
     }
 
-    fn read_dir(&mut self, path: PathBuf) -> Result<Vec<(SmolStr, FileType)>, ErrorKind> {
+    fn read_dir(&mut self, path: PathBuf) -> Result<Vec<(SmolStr, FileType)>, io::Error> {
         self.underlying.read_dir(path)
     }
 }

tvix/cli/src/tvix_io.rs

@@ -11,9 +11,10 @@
 use crate::KnownPaths;
 use smol_str::SmolStr;
 use std::cell::RefCell;
+use std::io;
 use std::path::{Path, PathBuf};
 use std::rc::Rc;
-use tvix_eval::{ErrorKind, EvalIO, FileType};
+use tvix_eval::{EvalIO, FileType};
 
 pub(crate) struct TvixIO<T: EvalIO> {
     /// Ingested paths must be reported to this known paths tracker
@@ -38,7 +39,7 @@ impl<T: EvalIO> EvalIO for TvixIO<T> {
         self.actual.store_dir()
     }
 
-    fn import_path(&mut self, path: &Path) -> Result<PathBuf, ErrorKind> {
+    fn import_path(&mut self, path: &Path) -> Result<PathBuf, io::Error> {
         let imported_path = self.actual.import_path(path)?;
         self.known_paths
             .borrow_mut()
@@ -47,7 +48,7 @@ impl<T: EvalIO> EvalIO for TvixIO<T> {
         Ok(imported_path)
     }
 
-    fn path_exists(&mut self, path: PathBuf) -> Result<bool, ErrorKind> {
+    fn path_exists(&mut self, path: PathBuf) -> Result<bool, io::Error> {
         if path.starts_with("/__corepkgs__") {
             return Ok(true);
         }
@@ -55,7 +56,7 @@ impl<T: EvalIO> EvalIO for TvixIO<T> {
         self.actual.path_exists(path)
     }
 
-    fn read_to_string(&mut self, path: PathBuf) -> Result<String, ErrorKind> {
+    fn read_to_string(&mut self, path: PathBuf) -> Result<String, io::Error> {
         // Bundled version of corepkgs/fetchurl.nix. The counterpart
         // of this happens in `main`, where the `nix_path` of the
         // evaluation has `nix=/__corepkgs__` added to it.
@@ -72,7 +73,7 @@ impl<T: EvalIO> EvalIO for TvixIO<T> {
         self.actual.read_to_string(path)
     }
 
-    fn read_dir(&mut self, path: PathBuf) -> Result<Vec<(SmolStr, FileType)>, ErrorKind> {
+    fn read_dir(&mut self, path: PathBuf) -> Result<Vec<(SmolStr, FileType)>, io::Error> {
         self.actual.read_dir(path)
     }
 }