Use a cross-platform representation for relative paths in pip compile (#3804)

## Summary

I haven't tested on Windows yet, but the idea here is that we should use
a portable representation when printing paths.

I decided to limit the scope here to paths that we write to output
files.

Closes https://github.com/astral-sh/uv/issues/3800.

Cargo.lock

@@ -2486,6 +2486,12 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "path-slash"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e91099d4268b0e11973f036e885d652fb0b21fedcf69738c627f94db6a44f42"
+
 [[package]]
 name = "pathdiff"
 version = "0.2.1"
@@ -4665,7 +4671,7 @@ dependencies = [
  "anyhow",
  "clap",
  "distribution-types",
- "itertools 0.13.0",
+ "either",
  "pep508_rs",
  "platform-tags",
  "rustc-hash",
@@ -4811,12 +4817,14 @@ dependencies = [
  "backoff",
  "cachedir",
  "dunce",
+ "either",
  "encoding_rs_io",
  "fs-err",
  "fs2",
  "junction",
  "once_cell",
  "path-absolutize",
+ "path-slash",
  "tempfile",
  "tracing",
  "urlencoding",

Cargo.toml

@@ -73,7 +73,7 @@ derivative = { version = "2.2.0" }
 directories = { version = "5.0.1" }
 dirs-sys = { version = "0.4.1" }
 dunce = { version = "1.0.4" }
-either = { version = "1.9.0" }
+either = { version = "1.12.0" }
 encoding_rs_io = { version = "0.1.7" }
 flate2 = { version = "1.0.28", default-features = false }
 fs-err = { version = "2.11.0" }
@@ -98,6 +98,7 @@ nanoid = { version = "0.4.0" }
 once_cell = { version = "1.19.0" }
 owo-colors = { version = "4.0.0" }
 path-absolutize = { version = "3.1.1" }
+path-slash = { version = "0.2.1" }
 pathdiff = { version = "0.2.1" }
 petgraph = { version = "0.6.4" }
 platform-info = { version = "2.0.2" }

crates/distribution-types/src/annotation.rs

@@ -22,17 +22,17 @@ impl std::fmt::Display for SourceAnnotation {
         match self {
             Self::Requirement(origin) => match origin {
                 RequirementOrigin::File(path) => {
-                    write!(f, "-r {}", path.user_display())
+                    write!(f, "-r {}", path.portable_display())
                 }
                 RequirementOrigin::Project(path, project_name) => {
-                    write!(f, "{project_name} ({})", path.user_display())
+                    write!(f, "{project_name} ({})", path.portable_display())
                 }
             },
             Self::Constraint(origin) => {
-                write!(f, "-c {}", origin.path().user_display())
+                write!(f, "-c {}", origin.path().portable_display())
             }
             Self::Override(origin) => {
-                write!(f, "--override {}", origin.path().user_display())
+                write!(f, "--override {}", origin.path().portable_display())
             }
         }
     }

crates/uv-configuration/Cargo.toml

@@ -20,7 +20,7 @@ uv-auth = { workspace = true }
 uv-normalize = { workspace = true }
 
 clap = { workspace = true, features = ["derive"], optional = true }
-itertools = { workspace = true }
+either = { workspace = true }
 rustc-hash = { workspace = true }
 schemars = { workspace = true, optional = true }
 serde = { workspace = true }

crates/uv-configuration/src/overrides.rs

@@ -1,6 +1,6 @@
 use std::hash::BuildHasherDefault;
 
-use itertools::Either;
+use either::Either;
 use rustc_hash::FxHashMap;
 
 use distribution_types::Requirement;

crates/uv-fs/Cargo.toml

@@ -18,11 +18,13 @@ uv-warnings = { workspace = true }
 backoff = { workspace = true }
 cachedir = { workspace = true }
 dunce = { workspace = true }
+either = { workspace = true }
 encoding_rs_io = { workspace = true }
 fs-err = { workspace = true }
 fs2 = { workspace = true }
 once_cell = { workspace = true }
 path-absolutize = { workspace = true }
+path-slash = { workspace = true }
 tempfile = { workspace = true }
 tracing = { workspace = true }
 urlencoding = { workspace = true }

crates/uv-fs/src/path.rs

@@ -1,7 +1,9 @@
+use either::Either;
 use std::borrow::Cow;
 use std::path::{Component, Path, PathBuf};
 
 use once_cell::sync::Lazy;
+use path_slash::PathExt;
 
 /// The current working directory.
 pub static CWD: Lazy<PathBuf> =
@@ -25,7 +27,7 @@ pub trait Simplified {
     ///
     /// On Windows, this will strip the `\\?\` prefix from paths. On other platforms, it's
     /// equivalent to [`std::path::Display`].
-    fn simplified_display(&self) -> std::path::Display;
+    fn simplified_display(&self) -> impl std::fmt::Display;
 
     /// Canonicalize a path without a `\\?\` prefix on Windows.
     fn simple_canonicalize(&self) -> std::io::Result<PathBuf>;
@@ -33,7 +35,18 @@ pub trait Simplified {
     /// Render a [`Path`] for user-facing display.
     ///
     /// Like [`simplified_display`], but relativizes the path against the current working directory.
-    fn user_display(&self) -> std::path::Display;
+    fn user_display(&self) -> impl std::fmt::Display;
+
+    /// Render a [`Path`] for user-facing display, where the [`Path`] is relative to a base path.
+    ///
+    /// If the [`Path`] is not relative to the base path, will attempt to relativize the path
+    /// against the current working directory.
+    fn user_display_from(&self, base: impl AsRef<Path>) -> impl std::fmt::Display;
+
+    /// Render a [`Path`] for user-facing display using a portable representation.
+    ///
+    /// Like [`user_display`], but uses a portable representation for relative paths.
+    fn portable_display(&self) -> impl std::fmt::Display;
 }
 
 impl<T: AsRef<Path>> Simplified for T {
@@ -41,7 +54,7 @@ impl<T: AsRef<Path>> Simplified for T {
         dunce::simplified(self.as_ref())
     }
 
-    fn simplified_display(&self) -> std::path::Display {
+    fn simplified_display(&self) -> impl std::fmt::Display {
         dunce::simplified(self.as_ref()).display()
     }
 
@@ -49,17 +62,48 @@ impl<T: AsRef<Path>> Simplified for T {
         dunce::canonicalize(self.as_ref())
     }
 
-    fn user_display(&self) -> std::path::Display {
+    fn user_display(&self) -> impl std::fmt::Display {
         let path = dunce::simplified(self.as_ref());
 
         // Attempt to strip the current working directory, then the canonicalized current working
         // directory, in case they differ.
-        path.strip_prefix(CWD.simplified())
+        let path = path.strip_prefix(CWD.simplified()).unwrap_or_else(|_| {
-            .unwrap_or_else(|_| {
+            path.strip_prefix(CANONICAL_CWD.simplified())
+                .unwrap_or(path)
+        });
+
+        path.display()
+    }
+
+    fn user_display_from(&self, base: impl AsRef<Path>) -> impl std::fmt::Display {
+        let path = dunce::simplified(self.as_ref());
+
+        // Attempt to strip the base, then the current working directory, then the canonicalized
+        // current working directory, in case they differ.
+        let path = path.strip_prefix(base.as_ref()).unwrap_or_else(|_| {
+            path.strip_prefix(CWD.simplified()).unwrap_or_else(|_| {
                 path.strip_prefix(CANONICAL_CWD.simplified())
                     .unwrap_or(path)
             })
-            .display()
+        });
+
+        path.display()
+    }
+
+    fn portable_display(&self) -> impl std::fmt::Display {
+        let path = dunce::simplified(self.as_ref());
+
+        // Attempt to strip the current working directory, then the canonicalized current working
+        // directory, in case they differ.
+        let path = path.strip_prefix(CWD.simplified()).unwrap_or_else(|_| {
+            path.strip_prefix(CANONICAL_CWD.simplified())
+                .unwrap_or(path)
+        });
+
+        // Use a portable representation for relative paths.
+        path.to_slash()
+            .map(Either::Left)
+            .unwrap_or_else(|| Either::Right(path.display()))
     }
 }
 

crates/uv-interpreter/src/discovery.rs

@@ -1256,17 +1256,11 @@ impl fmt::Display for InterpreterNotFound {
                 path.user_display()
             ),
             Self::ExecutableNotFoundInDirectory(directory, executable) => {
-                let executable = if let Ok(relative_executable) = executable.strip_prefix(directory)
-                {
-                    relative_executable.display()
-                } else {
-                    executable.user_display()
-                };
                 write!(
                     f,
                     "Interpreter directory `{}` does not contain Python executable at `{}`",
                     directory.user_display(),
-                    executable
+                    executable.user_display_from(directory)
                 )
             }
             Self::ExecutableNotFoundInSearchPath(name) => {

crates/uv/src/commands/pip/compile.rs

@@ -707,7 +707,7 @@ fn cmd(
     }
     let args = env::args_os()
         .skip(1)
-        .map(|arg| arg.user_display().to_string())
+        .map(|arg| arg.to_string_lossy().to_string())
         .scan(None, move |skip_next, arg| {
             if matches!(skip_next, Some(true)) {
                 // Reset state; skip this iteration.

crates/uv/tests/pip_compile.rs

@@ -7511,7 +7511,7 @@ fn local_version_of_remote_package() -> Result<()> {
     exit_code: 0
     ----- stdout -----
     # This file was autogenerated by uv via the following command:
-    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2024-03-25T00:00:00Z requirements.in
+    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2024-03-25T00:00:00Z [TEMP_DIR]/requirements.in
     anyio==4.3.0
         # via -r requirements.in
     idna==3.6
@@ -7548,7 +7548,7 @@ fn local_version_of_remote_package() -> Result<()> {
     exit_code: 0
     ----- stdout -----
     # This file was autogenerated by uv via the following command:
-    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2024-03-25T00:00:00Z requirements.in
+    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2024-03-25T00:00:00Z [TEMP_DIR]/requirements.in
     anyio==4.3.0
         # via -r requirements.in
     idna==3.6
@@ -7580,7 +7580,7 @@ fn local_version_of_remote_package() -> Result<()> {
     exit_code: 0
     ----- stdout -----
     # This file was autogenerated by uv via the following command:
-    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2024-03-25T00:00:00Z requirements.in --output-file requirements.txt
+    #    uv pip compile --cache-dir [CACHE_DIR] --exclude-newer 2024-03-25T00:00:00Z [TEMP_DIR]/requirements.in --output-file [TEMP_DIR]/requirements.txt
     anyio==4.3.0
         # via -r requirements.in
     idna==3.6