Rewrite diff workflow to make it compare properly (#1405)

* change workflow

* simplify return values

* exit properly oops

* Update .github/workflows/build.yml

* Fix result check

* Run `black`

---------

Co-authored-by: Robin Avery <[email protected]>

.github/workflows/build.yml

@@ -120,6 +120,7 @@ jobs:
             expected="$root/expected-report.json"
             actual="$root/actual-report.json"
             changes="$root/changes-report.json"
+            head=$(git rev-parse HEAD)
 
             ninja all_source
             objdiff-cli report generate -o "$actual"
@@ -134,24 +135,14 @@ jobs:
               ;;
               *) exit 1 ;;
             esac
+
             ninja all_source
             objdiff-cli report generate -o "$expected"
 
+            git checkout "$head"
             objdiff-cli report changes -o "$changes" "$expected" "$actual"
-            results="$(jq '
-              .units[]
-              | select(.functions[]
-                | { from: .from.fuzzy_match_percent,
-                    to: .to.fuzzy_match_percent }
-                | .from == 100 and .to < .from)
-              | { (.name): ([.functions[] | .name]) }' \
-              "$changes")"
-            status="$(echo "$results" | jq -s 'if . == [] then 0 else 1 end')"
-
-            if [ "$status" -ne 0 ]; then
-              echo "::error::One or more functions were broken!"
-              echo "$results"
-            fi
+            python tools/diff_changes.py "$changes"
+            status="$?"
             exit "$status"
           ;;
           *) exit 1 ;;

tools/diff_changes.py

@@ -0,0 +1,59 @@
+import argparse
+import json
+import sys
+from typing import Optional
+
+
+def process_json(data):
+    result = {}
+    for unit in data.get("units", []):
+        matching_functions = []
+        for function in unit.get("functions", []):
+            from_fuzzy = function.get("from", {}).get("fuzzy_match_percent")
+            to_fuzzy = function.get("to", {}).get("fuzzy_match_percent")
+            if from_fuzzy == 100 and to_fuzzy < from_fuzzy:
+                func_name = function.get("name")
+                matching_functions.append(f"{func_name} ({from_fuzzy}% -> {to_fuzzy})")
+
+        if matching_functions:
+            result[unit.get("name")] = matching_functions
+
+    return result
+
+
+def process_input(input_file: Optional[str]) -> None:
+    content = ""
+    if input_file == "-" or not input_file:
+        content = json.load(sys.stdin)
+    else:
+        with open(input_file, "r") as f:
+            content = json.load(f)
+
+    result = process_json(content)
+    if not result:
+        print("No functions broken.")
+        sys.exit(0)
+    else:
+        print("::error::One or more functions were broken!")
+        sys.stdout.write(json.dumps(result, indent=2))
+        sys.exit(1)
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        description="List broken functions from the output of objdiff's `changes` command."
+    )
+    parser.add_argument(
+        "input_file",
+        metavar="INPUT_FILE",
+        nargs="?",
+        default="",
+        help='input file to process (use "-" for stdin)',
+    )
+    args = parser.parse_args()
+
+    if args.input_file != "":
+        process_input(args.input_file)
+    else:
+        print("No argument provided to diff_changes.py.")
+        sys.exit(1)