Leading newline in description causes silent failures

[meejah]

If you have a leading \n character in the description, then installing the resulting built wheel "succeeds" but doesn't completely install things.

One way to see this is to set at least one dependency -- installing the wheel says it was successful, but the dependencies are not installed.

I didn't track down precisely what is going on beyond this. I don't know if the correct behavior should be an error or to (always) strip leading newlines.

My pyproject.toml file came from running hatch new --init in an existing project.

(This might not really be a hatch problem, but I only saw it when using the hatchling.build build-system).

[ischaojie]

I tried to follow the steps you mentioned, adding \n to the description and then using flask as a dependency, but didn't find an error. Would you mind posting the detailed steps for error generation?

[meejah]

Here's a minimal pyproject.toml that repeats the issue for me (on Debian bookworm if that matters).

Note that there's no "error": what happens is that the package successfully installs, but just doesn't install any of the dependencies.

[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"

[project]
name = "abc"
version = "1.0.0"
description = "\nthis is a description."
license.text = "MIT"
authors = [
    { name = "meejah", email = "meejah@meejah.ca" },
]
requires-python = ">=3.8"
classifiers = [
    "Programming Language :: Python :: 3",
]
dependencies = [
    "click",
]

With the above in an empty directory, I create a venv, install hatch and run hatch build. This results in a .whl file in dist/.

In a fresh virtualenv (I used one in /tmp):

$ pip install ~/src/abc/dist/abc-1.0.0-py3-none-any.whl                          
Processing /home/meejah/src/abc/dist/abc-1.0.0-py3-none-any.whl                                          Installing collected packages: abc
Successfully installed abc-1.0.0

However, a pip freeze reveals that click (the dependency I declared) didn't get installed. If you remove the \n from the start of description= and repeat the steps, then click does get installed.

I believe the problem comes from the fact that a wheel METADATA file uses an HTTP-header sort of line-based format, and the (extra) newline causes ... something to stop parsing..?

[ischaojie]

METADATA file for wheel already contains click requires:

Metadata-Version: 2.1
Name: abc
Version: 1.0.0
Summary: 
this is a description.
Author-email: meejah <meejah@meejah.ca>
License: MIT
Classifier: Programming Language :: Python :: 3
Requires-Python: >=3.8
Requires-Dist: click

https://packaging.python.org/en/latest/specifications/core-metadata/#summary, The metadata document describes the summary field as follows：

A one-line summary of what the distribution does.

So, the summary field should not contain any \n. Maybe hatch should preprocess and remove all \n.

[ofek]

#794