refactor(tvix/eval): Don't double-box Path values r/7461

PathBuf internally contains a heap pointer (an OsString), so we were in
effect double-boxing here. Removing the extra layer by making
Tvix::Value represented by a Box<Path> rather than a Box<PathBuf> saves
us an indirection, while still avoiding the extra memory overhead of the
capacity which was the reason we were boxing PathBuf in the first place.

Change-Id: I8c185b9d4646161d1921917f83e87421496a3e24
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10725
Reviewed-by: sterni <sternenseemann@systemli.org>
Autosubmit: aspen <root@gws.fyi>
Tested-by: BuildkiteCI

3 files changed, 10 insertions, 10 deletions

diff --git a/tvix/eval/src/value/arbitrary.rs b/tvix/eval/src/value/arbitrary.rs
index bf53f4fcb28a..d894aa3fe937 100644
--- a/tvix/eval/src/value/arbitrary.rs
+++ b/tvix/eval/src/value/arbitrary.rs
@@ -2,7 +2,7 @@
 
 use imbl::proptest::{ord_map, vector};
 use proptest::{prelude::*, strategy::BoxedStrategy};
-use std::ffi::OsString;
+use std::{ffi::OsString, path::PathBuf};
 
 use super::{attrs::AttrsRep, NixAttrs, NixList, NixString, Value};
 
@@ -92,7 +92,7 @@ fn leaf_value() -> impl Strategy<Value = Value> {
         any::<i64>().prop_map(Integer),
         any::<f64>().prop_map(Float),
         any::<NixString>().prop_map(String),
-        any::<OsString>().prop_map(|s| Path(Box::new(s.into()))),
+        any::<OsString>().prop_map(|s| Path(PathBuf::from(s).into_boxed_path())),
     ]
 }
 
diff --git a/tvix/eval/src/value/json.rs b/tvix/eval/src/value/json.rs
index 4e915a36e55a..c2f8b2c2b1ef 100644
--- a/tvix/eval/src/value/json.rs
+++ b/tvix/eval/src/value/json.rs
@@ -27,7 +27,7 @@ impl Value {
             Value::String(s) => Json::String(s.to_str()?.to_owned()),
 
             Value::Path(p) => {
-                let imported = generators::request_path_import(co, *p).await;
+                let imported = generators::request_path_import(co, p.into_path_buf()).await;
                 Json::String(imported.to_string_lossy().to_string())
             }
 
diff --git a/tvix/eval/src/value/mod.rs b/tvix/eval/src/value/mod.rs
index e181b3a2da4e..df663dd34c06 100644
--- a/tvix/eval/src/value/mod.rs
+++ b/tvix/eval/src/value/mod.rs
@@ -3,7 +3,7 @@
 use std::cmp::Ordering;
 use std::fmt::Display;
 use std::num::{NonZeroI32, NonZeroUsize};
-use std::path::PathBuf;
+use std::path::{Path, PathBuf};
 use std::rc::Rc;
 
 use bstr::{BString, ByteVec};
@@ -50,7 +50,7 @@ pub enum Value {
     String(NixString),
 
     #[serde(skip)]
-    Path(Box<PathBuf>),
+    Path(Box<Path>),
     Attrs(Box<NixAttrs>),
     List(NixList),
 
@@ -76,7 +76,7 @@ pub enum Value {
     #[serde(skip)]
     DeferredUpvalue(StackIdx),
     #[serde(skip)]
-    UnresolvedPath(Box<PathBuf>),
+    UnresolvedPath(Box<Path>),
     #[serde(skip)]
     Json(serde_json::Value),
 
@@ -349,7 +349,7 @@ impl Value {
                         import_paths: true, ..
                     },
                 ) => {
-                    let imported = generators::request_path_import(co, *p).await;
+                    let imported = generators::request_path_import(co, p.to_path_buf()).await;
                     // When we import a path from the evaluator, we must attach
                     // its original path as its context.
                     context = context.append(NixContextElement::Plain(
@@ -363,7 +363,7 @@ impl Value {
                         import_paths: false,
                         ..
                     },
-                ) => Ok(p.into_os_string().into_encoded_bytes().into()),
+                ) => Ok((*p).as_os_str().as_encoded_bytes().into()),
 
                 // Attribute sets can be converted to strings if they either have an
                 // `__toString` attribute which holds a function that receives the
@@ -705,7 +705,7 @@ impl Value {
         Value::String(s),
         s.clone()
     );
-    gen_cast!(to_path, Box<PathBuf>, "path", Value::Path(p), p.clone());
+    gen_cast!(to_path, Box<Path>, "path", Value::Path(p), p.clone());
     gen_cast!(to_attrs, Box<NixAttrs>, "set", Value::Attrs(a), a.clone());
     gen_cast!(to_list, NixList, "list", Value::List(l), l.clone());
     gen_cast!(
@@ -1009,7 +1009,7 @@ impl From<f64> for Value {
 
 impl From<PathBuf> for Value {
     fn from(path: PathBuf) -> Self {
-        Self::Path(Box::new(path))
+        Self::Path(path.into_boxed_path())
     }
 }