siso.py: check ninja marker

If out dir was built by Ninja, don't build by Siso.

(still allow `siso query` etc)

Bug: b/338414465
Change-Id: I48f8fbb5e83714fd3d27ff3a2bfffe929e4ef121
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5518396
Reviewed-by: Junji Watanabe <jwata@google.com>
Commit-Queue: Junji Watanabe <jwata@google.com>
Auto-Submit: Fumitoshi Ukai <ukai@google.com>
Commit-Queue: Fumitoshi Ukai <ukai@google.com>

siso.py

@@ -15,6 +15,29 @@ import sys
 import gclient_paths
 
 
+def checkOutdir(args):
+    subcmd = ''
+    out_dir = "."
+    for i, arg in enumerate(ninja_args):
+        if not arg.startswith("-") and not subcmd:
+            subcmd = arg
+            continue
+        if arg == "-C":
+            out_dir = ninja_args[i + 1]
+        elif arg.startswith("-C"):
+            out_dir = arg[2:]
+    if subcmd != "ninja":
+        return
+    ninja_marker = os.path.join(out_dir, ".ninja_deps")
+    if os.path.exists(ninja_marker):
+        print("depot_tools/siso.py: %s contains Ninja state file.\n"
+              "Use `autoninja` to use reclient,\n"
+              "or run `gn clean %s` to switch from ninja to siso\n" %
+              (out_dir, out_dir),
+              file=sys.stderr)
+        sys.exit(1)
+
+
 def main(args):
     # Propagate signals to siso process so that it can run cleanup steps.
     # Siso will be terminated immediately after the second Ctrl-C.
@@ -78,6 +101,7 @@ def main(args):
             base_path, 'third_party', 'siso',
             'siso' + gclient_paths.GetExeSuffix())
         if os.path.isfile(siso_path):
+            checkOutdir(args[1:])
             return subprocess.call([siso_path] + args[1:], env=env)
 
     print(