Generating hashes from files for incompatible wheels isn't working

[RazerM]

Environment Versions

1. OS Type: macOS
2. Python version: 3.9.6
3. pip version: 21.3.1
4. pip-tools version: 6.4.0

Steps to replicate

(These replication steps require that you run this on a machine not compatible with the manylinux wheels provided in the demo repository used in the following commands)

1. Create a requirements file using the project I prepared

   echo regex > requirements.in
   pip-compile --index-url https://gitlab.com/api/v4/projects/31206336/packages/pypi/simple --no-header --generate-hashes -o normal.txt

2. Patch the installed pip to remove this line.

3. Generate a new requirements file:

   pip-compile --index-url https://gitlab.com/api/v4/projects/31206336/packages/pypi/simple --no-header --generate-hashes -o patched.txt

4. Compare the files

   git diff --no-index normal.txt patched.txt

Expected result

Both files should include all hashes

Actual result

diff --git a/normal.txt b/patched.txt
index da086ab..23bc894 100644
--- a/normal.txt
+++ b/patched.txt
@@ -1,5 +1,10 @@
 --index-url https://gitlab.com/api/v4/projects/31206336/packages/pypi/simple

 regex==2021.11.10 \
+    --hash=sha256:05b7d6d7e64efe309972adab77fc2af8907bb93217ec60aa9fe12a0dad35874f \
+    --hash=sha256:30ab804ea73972049b7a2a5c62d97687d69b5a60a67adca07eb73a0ddbc9e29f \
+    --hash=sha256:85bfa6a5413be0ee6c5c4a663668a2cad2cbecdee367630d097d7823041bdeec \
+    --hash=sha256:962b9a917dd7ceacbe5cd424556914cb0d636001e393b43dc886ba31d2a1e449 \
+    --hash=sha256:ca5f18a75e1256ce07494e245cdb146f5a9267d3c702ebf9b65c7f8bd843431e \
     --hash=sha256:f341ee2df0999bfdf7a95e448075effe0db212a59387de1a70690e4acb03d4c6
     # via -r requirements.in

Only hashes compatible with my system are generated.

The easy solution I see would be to call self.finder.find_all_candidates.cache_clear() in PyPIRepository.allow_all_wheels, but as maintainers of the library you'll probably have more insight. Maybe even creating a new finder instance rather than rely on this implementation detail?

[RazerM]

This is still an issue on pip-tools 6.5.1 with pip 22.0.4