Avoid ignore crate finding cache gitignore (#2615)

We put a `.gitignore` with `*` at the top of our cache. When maturin was
building a source distribution inside the cache, it would walk up the
tree to find a gitignore, see that and ignore all python files. We now
add an (empty) `.git` directory one directory below, in the root of
built-wheels cache. This prevents ignore walking further up (it marks
the top level a git repository).

Deptry (from #2490) is a mid sized rust package with additional python
packages, so instead of using it in the test i've replaced it with a
small (44KB total) reproducer that uses cffi for faster building, the
entire test taking <2s on my machine.

Fixes #2490

crates/uv-cache/src/lib.rs

@@ -251,15 +251,6 @@ impl Cache {
             Err(err) => return Err(err),
         }
 
-        // Add a phony .git, if it doesn't exist, to ensure that the cache isn't considered to be
-        // part of a Git repository. (Some packages will include Git metadata (like a hash) in the
-        // built version if they're in a Git repository, but the cache should be viewed as an
-        // isolated store.)
-        fs::OpenOptions::new()
-            .create(true)
-            .write(true)
-            .open(root.join(".git"))?;
-
         // Add an empty .gitignore to the build bucket, to ensure that the cache's own .gitignore
         // doesn't interfere with source distribution builds. Build backends (like hatchling) will
         // traverse upwards to look for .gitignore files.
@@ -273,6 +264,18 @@ impl Cache {
             Err(err) => return Err(err),
         }
 
+        // Add a phony .git, if it doesn't exist, to ensure that the cache isn't considered to be
+        // part of a Git repository. (Some packages will include Git metadata (like a hash) in the
+        // built version if they're in a Git repository, but the cache should be viewed as an
+        // isolated store.).
+        // We have to put this below the gitignore. Otherwise, if the build backend uses the rust
+        // ignore crate it will walk up to the top level .gitignore and ignore its python source
+        // files.
+        fs::OpenOptions::new()
+            .create(true)
+            .write(true)
+            .open(root.join(CacheBucket::BuiltWheels.to_str()).join(".git"))?;
+
         fs::canonicalize(root)
     }
 

crates/uv/tests/pip_install.rs

@@ -6,10 +6,12 @@ use assert_fs::prelude::*;
 use base64::{prelude::BASE64_STANDARD as base64, Engine};
 use indoc::indoc;
 use itertools::Itertools;
+use std::env::current_dir;
 use std::process::Command;
 use url::Url;
 
 use common::{uv_snapshot, TestContext, EXCLUDE_NEWER, INSTA_FILTERS};
+use uv_fs::Simplified;
 
 use crate::common::get_bin;
 
@@ -2952,3 +2954,57 @@ fn install_site_packages_mtime_updated() -> Result<()> {
 
     Ok(())
 }
+
+/// We had a bug where maturin would walk up to the top level gitignore of the cache with a `*`
+/// entry (because we want to ignore the entire cache from outside), ignoring all python source
+/// files.
+#[test]
+fn deptry_gitignore() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let project_root = current_dir()?
+        .parent()
+        .unwrap()
+        .parent()
+        .unwrap()
+        .to_path_buf();
+    let source_dist_dir = project_root
+        .join("scripts")
+        .join("packages")
+        .join("deptry_reproducer");
+    let filter_path = regex::escape(
+        Url::from_directory_path(source_dist_dir.simplified_display().to_string())
+            .unwrap()
+            .to_string()
+            .trim_end_matches('/'),
+    );
+    let filters: Vec<_> = [(filter_path.as_str(), "[SOURCE_DIST_DIR]")]
+        .into_iter()
+        .chain(INSTA_FILTERS.to_vec())
+        .collect();
+
+    uv_snapshot!(filters, command(&context)
+        .arg(format!("deptry_reproducer @ {}/deptry_reproducer-0.1.0.tar.gz", source_dist_dir.simplified_display()))
+        .arg("--strict")
+        .current_dir(source_dist_dir), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 3 packages in [TIME]
+    Downloaded 3 packages in [TIME]
+    Installed 3 packages in [TIME]
+     + cffi==1.16.0
+     + deptry-reproducer==0.1.0 (from [SOURCE_DIST_DIR]/deptry_reproducer-0.1.0.tar.gz)
+     + pycparser==2.21
+    "###
+    );
+
+    // Check that we packed the python source files
+    context
+        .assert_command("import deptry_reproducer.foo")
+        .success();
+
+    Ok(())
+}

scripts/packages/deptry_reproducer/.gitignore

@@ -0,0 +1 @@
+/target

scripts/packages/deptry_reproducer/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "deptry_reproducer"
+version = "0.1.0"

scripts/packages/deptry_reproducer/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "deptry_reproducer"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[lib]
+name = "deptry_reproducer"
+crate-type = ["cdylib"]
+
+[dependencies]

scripts/packages/deptry_reproducer/pyproject.toml

@@ -0,0 +1,21 @@
+[build-system]
+requires = ["maturin>=1,<2.0"]
+build-backend = "maturin"
+
+[project]
+name = "deptry_reproducer"
+requires-python = ">=3.8"
+classifiers = [
+  "Programming Language :: Rust",
+  "Programming Language :: Python :: Implementation :: CPython",
+  "Programming Language :: Python :: Implementation :: PyPy",
+]
+dependencies = ["cffi"]
+dynamic = ["version"]
+[project.optional-dependencies]
+tests = [
+  "pytest",
+]
+[tool.maturin]
+bindings = "cffi"
+python-source = "python"

scripts/packages/deptry_reproducer/python/deptry_reproducer/__init__.py

@@ -0,0 +1,6 @@
+from .deptry_reproducer import *
+
+
+__doc__ = deptry_reproducer.__doc__
+if hasattr(deptry_reproducer, "__all__"):
+    __all__ = deptry_reproducer.__all__

scripts/packages/deptry_reproducer/src/lib.rs

@@ -0,0 +1 @@
+