show: include a list of dependency cycles

This gives all cycles in the queue right now, ignoring the build
status of the packages.

If one part of the cycle is already built then it will not matter.

autobuild.py

@@ -30,7 +30,7 @@ import io
 from datetime import datetime, timezone
 from enum import Enum
 from hashlib import sha256
-from typing import Generator, Union, AnyStr, List, Any, Dict, Tuple, Set, Optional, Sequence, Literal
+from typing import Generator, Union, AnyStr, List, Any, Dict, Tuple, Set, Optional, Sequence, Literal, cast
 
 
 ArchType = Literal["mingw32", "mingw64", "ucrt64", "clang64", "clang32", "clangarm64", "msys"]
@@ -906,6 +906,21 @@ def get_buildqueue_with_status(full_details: bool = False) -> List[Package]:
     return pkgs
 
 
+def get_cycles(pkgs: List[Package]) -> Set[Tuple[Package, Package]]:
+    cycles: Set[Tuple[Package, Package]] = set()
+    for pkg in pkgs:
+        for build_type in pkg.get_build_types():
+            if build_type_is_src(build_type):
+                continue
+            build_type = cast(ArchType, build_type)
+            for dep_type, deps in pkg.get_depends(build_type).items():
+                for dep in deps:
+                    dep_deps = dep.get_depends(dep_type)
+                    if pkg in dep_deps.get(build_type, set()):
+                        cycles.add(tuple(sorted([pkg, dep], key=lambda p: p["name"])))  # type: ignore
+    return cycles
+
+
 BuildFrom = Literal["start", "middle", "end"]
 
 
@@ -1139,7 +1154,15 @@ def show_build(args: Any) -> None:
     done = []
     failed = []
 
-    for pkg in get_buildqueue_with_status(full_details=True):
+    pkgs = get_buildqueue_with_status(full_details=True)
+
+    cycles = get_cycles(pkgs)
+    if cycles:
+        with gha_group(f"Dependency Cycles ({len(cycles)})"):
+            print(tabulate([(a["name"], b["name"]) for (a, b) in cycles],
+                           headers=["Package", "Package"]))
+
+    for pkg in pkgs:
         for build_type in pkg.get_build_types():
             status = pkg.get_status(build_type)
             details = pkg.get_status_details(build_type)