Build backend: Support data files (#9197)

Allow including data files in wheels, configured through
`pyproject.toml`. This configuration is currently only read in the build
backend. We'd only start using it in the frontend when we're adding a
fast path.

Each data entry is a directory, whose contents are copied to the
matching directory in the wheel in
`<name>-<version>.data/(purelib|platlib|headers|scripts|data)`. Upon
installation, this data is moved to its target location, as defined by
<https://docs.python.org/3.12/library/sysconfig.html#installation-paths>:
- `data`: Installed over the virtualenv environment root. Warning: This
may override existing files!
- `scripts`: Installed to the directory for executables, `<venv>/bin` on
Unix or `<venv>\Scripts` on Windows. This directory is added to PATH
when the virtual environment is activated or when using `uv run`, so
this data type can be used to install additional binaries. Consider
using `project.scripts` instead for starting Python code.
- `headers`: Installed to the include directory, where compilers
building Python packages with this package as built requirement will
search for header files.
- `purelib` and `platlib`: Installed to the `site-packages` directory.
It is not recommended to uses these two options.

For simplicity, for now we're just defining a directory to be copied for
each data directory, while using the glob based include mechanism in the
background. We thereby introduce a third mechanism next to the main
includes and the PEP 639 mechanism, which is not what we should finalize
on.

scripts/packages/built-by-uv/assets/data.csv

@@ -0,0 +1,10 @@
+sepal_length,sepal_width,petal_length,petal_width,species
+5.1,3.5,1.4,0.2,setosa
+4.9,3.0,1.4,0.2,setosa
+4.7,3.2,1.3,0.2,setosa
+4.6,3.1,1.5,0.2,setosa
+5.0,3.6,1.4,0.2,setosa
+5.4,3.9,1.7,0.4,setosa
+4.6,3.4,1.4,0.3,setosa
+5.0,3.4,1.5,0.2,setosa
+4.4,2.9,1.4,0.2,setosa

scripts/packages/built-by-uv/header/built_by_uv.h

@@ -0,0 +1,8 @@
+#ifndef BUILT_BY_UV_H
+#define BUILT_BY_UV_H
+
+static inline const char* hello_world() {
+    return "Hello World!";
+}
+
+#endif /* HELLO_WORLD_H */

scripts/packages/built-by-uv/pyproject.toml

@@ -7,6 +7,11 @@ requires-python = ">=3.12"
 dependencies = ["anyio>=4,<5"]
 license-files = ["LICENSE*", "third-party-licenses/*"]
 
+[tool.uv.wheel.data]
+scripts = "scripts"
+data = "assets"
+headers = "header"
+
 [build-system]
 requires = ["uv>=0.4.15,<5"]
 build-backend = "uv"

scripts/packages/built-by-uv/scripts/whoami.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+
+whoami