`--use-deprecated=html5lib` does not parse links, even though they're present

Description

When using Pip 22.0 with --use-deprecated=html5lib with JFrog as the Index packages pip throws the error: ERROR: No matching distribution found for requests

Tested with the “requests” package on Windows 10 using pip 22.0 (fails) and pip 21.3.1 (works)

Expected behavior

--use-deprecated=html5lib should allow JFrog indexes to work.

pip version

22.0

Python version

3.10

OS

Windows

How to Reproduce

Install package from JFrog index using pip 22.0

Output

C:\>python -m pip install -vvv requests --use-deprecated=html5lib
Using pip 22.0 from <corporate_local_path>\lib\site-packages\pip (python 3.10)
Non-user install by explicit request
Created temporary directory: <corporate_user_path>\AppData\Local\Temp\pip-ephem-wheel-cache-4a5e6ucc
Created temporary directory: <corporate_user_path>\AppData\Local\Temp\pip-req-tracker-p0zhtye3
Initialized build tracking at <corporate_user_path>\AppData\Local\Temp\pip-req-tracker-p0zhtye3
Created build tracker: <corporate_user_path>\AppData\Local\Temp\pip-req-tracker-p0zhtye3
Entered build tracker: <corporate_user_path>\AppData\Local\Temp\pip-req-tracker-p0zhtye3
Created temporary directory: <corporate_user_path>\AppData\Local\Temp\pip-install-_cnfjhxu
Looking in indexes: http://<corporate_domain>/artifactory/api/pypi/pypi-release/simple
1 location(s) to search for versions of requests:
* http://<corporate_domain>/artifactory/api/pypi/pypi-release/simple/requests/
Fetching project page and analyzing links: http://<corporate_domain>/artifactory/api/pypi/pypi-release/simple/requests/
Getting page http://<corporate_domain>/artifactory/api/pypi/pypi-release/simple/requests/
Found index url http://<corporate_domain>/artifactory/api/pypi/pypi-release/simple
Looking up http://<corporate_domain>/artifactory/api/pypi/pypi-release/simple/requests/ in the cache
Request header has "max_age" as 0, cache bypassed
Starting new HTTP connection (1): <corporate_domain>:80
http://<corporate_domain>:80 "GET /artifactory/api/pypi/pypi-release/simple/requests/ HTTP/1.1" 200 None
Updating cache with response from http://<corporate_domain>/artifactory/api/pypi/pypi-release/simple/requests/
Skipping link: not a file: http://<corporate_domain>/artifactory/api/pypi/pypi-release/simple/requests/
Given no hashes to check 0 links for project 'requests': discarding no candidates
ERROR: Could not find a version that satisfies the requirement requests (from versions: none)
ERROR: No matching distribution found for requests
Exception information:
Traceback (most recent call last):
  File "<corporate_local_path>\lib\site-packages\pip\_vendor\resolvelib\resolvers.py", line 348, in resolve
    self._add_to_criteria(self.state.criteria, r, parent=None)
  File "<corporate_local_path>\lib\site-packages\pip\_vendor\resolvelib\resolvers.py", line 173, in _add_to_criteria
    raise RequirementsConflicted(criterion)
pip._vendor.resolvelib.resolvers.RequirementsConflicted: Requirements conflict: SpecifierRequirement('requests')
 
During handling of the above exception, another exception occurred:
 
Traceback (most recent call last):
  File "<corporate_local_path>\lib\site-packages\pip\_internal\resolution\resolvelib\resolver.py", line 94, in resolve
    result = self._result = resolver.resolve(
  File "<corporate_local_path>\lib\site-packages\pip\_vendor\resolvelib\resolvers.py", line 481, in resolve
    state = resolution.resolve(requirements, max_rounds=max_rounds)
  File "<corporate_local_path>\lib\site-packages\pip\_vendor\resolvelib\resolvers.py", line 350, in resolve
    raise ResolutionImpossible(e.criterion.information)
pip._vendor.resolvelib.resolvers.ResolutionImpossible: [RequirementInformation(requirement=SpecifierRequirement('requests'), parent=None)]
 
The above exception was the direct cause of the following exception:
 
Traceback (most recent call last):
  File "<corporate_local_path>\lib\site-packages\pip\_internal\cli\base_command.py", line 165, in exc_logging_wrapper
    status = run_func(*args)
  File "<corporate_local_path>\lib\site-packages\pip\_internal\cli\req_command.py", line 205, in wrapper
    return func(self, options, args)
  File "<corporate_local_path>\lib\site-packages\pip\_internal\commands\install.py", line 339, in run
    requirement_set = resolver.resolve(
  File "<corporate_local_path>\lib\site-packages\pip\_internal\resolution\resolvelib\resolver.py", line 103, in resolve
    raise error from e
pip._internal.exceptions.DistributionNotFound: No matching distribution found for requests

Removed build tracker: '<corporate_user_path>\\AppData\\Local\\Temp\\pip-req-tracker-p0zhtye3'

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[pfmoore]

The issue seems to be simply that the HTML doesn’t include a doctype (which seems to be required by PEP 503 and the HTML5 spec)

I’m unsure whether this is something where we should be lenient in what we accept.

Edit: Never mind, I missed that this was about the old parsing using html5lib.

[pradyunsg]

I’m able to reproduce this, with just pip’s parsing logic:

from pathlib import Path

from pip._internal.index.collector import HTMLPage, parse_links

content = Path("/tmp/page.html").read_bytes()
page = HTMLPage(content, "utf-8", "https://private.domain.example.com/index")

try:
    print("new", len(list(parse_links(page, use_deprecated_html5lib=True))))
except TypeError:
    print("old", len(list(parse_links(page))))

21.3.1

❯ python /tmp/foo.py
old 208

22.0

❯ python /tmp/foo.py
new 0