Bug 1944955 - Have action.zip dump dependencies if asked to r=glandium

This avoids unnecessary command execution upon nop build

Differential Revision: https://phabricator.services.mozilla.com/D237269

config/rules.mk

@@ -890,9 +890,13 @@ endif
 # When you move this out of the tools tier, please remove the corresponding
 # hacks in recursivemake.py that check if Makefile.in sets the variable.
 ifneq ($(XPI_PKGNAME),)
-tools realchrome::
+tools realchrome::$(FINAL_TARGET)/../$(XPI_PKGNAME).xpi
+
+XPI_PKGNAME_DEPS=$(MDDEPDIR)/$(XPI_PKGNAME).d
+EXTRA_MDDEPEND_FILES += $(XPI_PKGNAME_DEPS)
+$(FINAL_TARGET)/../$(XPI_PKGNAME).xpi:
 	@echo 'Packaging $(XPI_PKGNAME).xpi...'
-	$(call py_action,zip $(XPI_PKGNAME).xpi,-C $(FINAL_TARGET) ../$(XPI_PKGNAME).xpi '*')
+	$(call py_action,zip $(XPI_PKGNAME).xpi,-C $(FINAL_TARGET) ../$(XPI_PKGNAME).xpi '*' --dep-target $(FINAL_TARGET)/../$(XPI_PKGNAME).xpi --dep-file $(XPI_PKGNAME_DEPS))
 endif
 
 #############################################################################

python/mozbuild/mozbuild/action/zip.py

@@ -6,6 +6,7 @@
 # it finds before adding them to the zip.
 
 import argparse
+import os
 import sys
 
 import mozpack.path as mozpath
@@ -14,6 +15,9 @@
 from mozpack.files import FileFinder
 from mozpack.path import match
 
+from mozbuild.makeutil import Makefile
+from mozbuild.util import FileAvoidWrite
+
 
 def main(args):
     parser = argparse.ArgumentParser()
@@ -33,18 +37,37 @@ def main(args):
     )
     parser.add_argument("zip", help="Path to zip file to write")
     parser.add_argument("input", nargs="+", help="Path to files to add to zip")
+    parser.add_argument(
+        "--dep-file",
+        help="File to write any additional make dependencies to",
+    )
+    parser.add_argument(
+        "--dep-target",
+        help="Make target to use in the dependencies file",
+    )
     args = parser.parse_args(args)
 
     jarrer = Jarrer()
 
+    deps = []
     with errors.accumulate():
         finder = FileFinder(args.C, find_executables=args.strip)
         for path in args.input:
             for p, f in finder.find(path):
                 if not any([match(p, exclude) for exclude in args.x]):
                     jarrer.add(p, f)
+                    deps.append(f.path)
         jarrer.copy(mozpath.join(args.C, args.zip))
 
+    if args.dep_target and args.dep_file:
+        mk = Makefile()
+        mk.create_rule([args.dep_target]).add_dependencies(deps)
+        mk.create_rule(deps)  # empty rule to avoid error if a file gets removed
+
+        os.makedirs(mozpath.dirname(args.dep_file), exist_ok=True)
+        with FileAvoidWrite(args.dep_file) as dep_file:
+            mk.dump(dep_file)
+
 
 if __name__ == "__main__":
     main(sys.argv[1:])