CI: Only check the latest GHC release per major version

Testing all releases is getting too cumbersome to deal with, and
ensuring the latest release works should be good enough.

Author: avdv

.github/extract_from_ghc_bindist.py

@@ -1,28 +1,36 @@
 import json
 import os
 import sys
+from packaging import version
 
-current_dir = os.path.dirname(__file__)
-haskell_dir = os.path.join(current_dir, "..", "haskell")
 
+def get_latest_versions(version_list):
+    # Create a dictionary to store the latest version for each major.minor pair
+    latest_versions = {}
+
+    for ver in version_list:
+        # Split the version into major, minor, and patch
+        major, minor, patch = map(int, ver.split('.'))
+
+        # Create a key for the major.minor pair
+        key = f"{major}.{minor}"
+
+        # If the key is not in the dictionary or the current version is greater than the stored version
+        if key not in latest_versions or version.parse(ver) > version.parse(latest_versions[key]):
+            # Update the dictionary with the latest version
+            latest_versions[key] = ver
 
-def unexpected(unexpected, l, error_message):
-    for a in unexpected:
-        if a in l:
-            print(error_message, file=sys.stderr)
-            list.remove(a)
+    # Return the latest versions
+    return list(latest_versions.values())
 
 
+current_dir = os.path.dirname(__file__)
+haskell_dir = os.path.join(current_dir, "..", "haskell")
+
 with open(
     os.path.join(haskell_dir, "private", "ghc_bindist_generated.json"), mode="rb"
 ) as f:
-    version_numbers = list(json.load(f).keys())
-
-unexpected(
-    ["8.10.1", "8.10.2"],
-    version_numbers,
-    "GHC 8.10.1 and 8.10.2 not supported. Upgrade to 8.10.3 or later.",
-)
+    version_numbers = get_latest_versions(json.load(f).keys())
 
 with open(os.environ["GITHUB_OUTPUT"], mode="a", encoding="utf-8") as output:
     output.write("ghc-matrix={}\n".format(version_numbers))