Poetry allows multiline descriptions which causes problems with pip installing extras

• I am on the latest Poetry version.
• I have searched the issues of this repo and believe that this is not a duplicate.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• Poetry version: 1.0.0b1
• Link to pyproject.toml file: https://github.com/undp/MsGraphExporter/blob/e75b59102d31225b12f6181ea3118ad65cfb22b9/pyproject.toml

Issue

The issue was discovered while publishing docs from undp/MsGraphExporter on ReadTheDocs. When pyproject.toml option description has a multi-line string enclosed in """ (which is perfectly legit for a string in TOML), it causes poetry to build the package with multi-line Summary in info/METADATA which does not seem to be valid according to https://github.com/pypa/pip/issues/7010#issuecomment-531068027

Perhaps poetry could just truncate the multi-line description, make it a single-lined one or flag the issue with poetry check.

_Originally posted by @OK-UNDP in https://github.com/readthedocs/readthedocs.org/issues/6151#issuecomment-531048562_

[bmoeskau]

I also ran into this today, and spent multiple hours trying to figure out why my package deps were not installing. Funny enough, I accidentally fixed it at one point just through the course of generally editing the file, then reverted that and broke it again – never once understanding cause and effect. Amazingly frustrating!

I really, really appreciate the work on this project, and know what it’s like to maintain OSS. Not complaining (too loudly) – but consider this a vote to fix this to help the next person avoid hours of pain 😃

[rrei]

@sdispater thank you very much for creating poetry! I am absolutely in love with this tool ❤️

Any news on this topic? I just spent way too much time banging my head against the wall because of this… 😭

According to this link (https://packaging.python.org/specifications/core-metadata/#summary) and what @OK-UNDP said, I believe poetry should enforce a single-line description field (during poetry build and poetry check). Also, it would be nice if this restriction was mentioned in the documentation (https://python-poetry.org/docs/pyproject/#description).

As it stands now, no error occurs when building, poetry check says everything is okay, and pip only installs my library and none of its dependencies, but it doesn’t display any errors either, which makes it extremely hard to find the source of the error. Worse still, pip installing the sdist does install dependencies!

A simple example that breaks without any useful feedback (I am using Poetry 1.0.5):

[build-system]
requires = ["poetry>=0.12"]
build-backend = "poetry.masonry.api"

[tool.poetry]
name = "example-lib"
version = "0.1.0"
description = """
First line
Second line (BOOOOOM)"""
authors = ["John Doe <[e-mail]>"]
packages = [{ include = "example", from = "src" }]

[tool.poetry.dependencies]
python = "^3.8"
addict = "^2.2.1"
loguru = "^0.5.0"
typer = {extras = ["all"], version = "^0.2.1"}
wcmatch = "^6.0.1"

@sdispater if you agree with my suggestion to enforce the single-line description field, I’d be happy to give it a try and submit a PR 😃