mach: Split out post build tasks into their own command (#38853)

The main reason for this change is that this makes working on this part
of the build a lot easier.

Testing: No tests for this change as it just rearranges code in the
build scripts.

Signed-off-by: Martin Robinson <mrobinson@igalia.com>

python/servo/build_commands.py

@@ -154,18 +154,45 @@ class MachCommands(CommandBase):
         status = self.run_cargo_build_like_command("rustc", opts, env=env, verbose=verbose, **kwargs)
 
         if status == 0:
-            built_binary = self.get_binary_path(build_type, sanitizer=sanitizer)
-
             if not no_package and self.target.needs_packaging():
-                rv = Registrar.dispatch(
+                return_value = Registrar.dispatch(
                     "package", context=self.context, build_type=build_type, flavor=flavor, sanitizer=sanitizer
                 )
-                if rv:
-                    return rv
+                if return_value:
+                    return return_value
+
+            return_value = self.run_post_build_tasks(build_type, sanitizer)
+            if return_value:
+                return return_value
+
+        # Print how long the build took
+        elapsed = time() - build_start
+        elapsed_delta = datetime.timedelta(seconds=int(elapsed))
+        build_message = f"{'Succeeded' if status == 0 else 'Failed'} in {elapsed_delta}"
+        print(build_message)
+        assert isinstance(status, int)
+        return status
+
+    @Command("run-post-build-tasks", description="Run only the post-build tasks", category="build")
+    @CommandBase.common_command_arguments(build_configuration=True, build_type=True)
+    def run_post_build_tasks_cmd(
+        self,
+        build_type: BuildType,
+        sanitizer: SanitizerKind = SanitizerKind.NONE,
+        **_kwargs: Any,
+    ) -> int:
+        return self.run_post_build_tasks(build_type, sanitizer)
+
+    def run_post_build_tasks(self, build_type: BuildType, sanitizer: SanitizerKind = SanitizerKind.NONE) -> int:
+        target_triple = self.target.triple()
+
+        built_binary = self.get_binary_path(build_type, sanitizer=sanitizer)
+        binary_dir = os.path.dirname(built_binary)
+        assert os.path.exists(binary_dir)
 
         if "windows" in target_triple:
             if not copy_windows_dlls_to_build_directory(built_binary, self.target):
-                    status = 1
+                return 1
 
         elif "darwin" in target_triple:
             servo_bin_dir = os.path.dirname(built_binary)
@@ -187,14 +214,7 @@ class MachCommands(CommandBase):
                     Cocoa.NSWorkspace.sharedWorkspace().setIcon_forFile_options_(icon, built_binary, 0)
             except ImportError:
                 pass
-
-        # Print how long the build took
-        elapsed = time() - build_start
-        elapsed_delta = datetime.timedelta(seconds=int(elapsed))
-        build_message = f"{'Succeeded' if status == 0 else 'Failed'} in {elapsed_delta}"
-        print(build_message)
-        assert isinstance(status, int)
-        return status
+        return 0
 
     @Command("clean", description="Clean the target/ and Python virtual environment directories", category="build")
     @CommandArgument("--manifest-path", default=None, help="Path to the manifest to the package to clean")