Bug 1766045 - Adding mach command to generate UniFFI files r=glandium

Added `mach uniffi generate` which executes `uniffi-bindgen-gecko-js` to
generate UniFFI bindings. It's unfortunate that we need to check these
files in, but I couldn't figure out a way to auto-generate them as part
of the build process.

Adding `#include "nsIContent.h"` to dom/base/nsINodeList.h.  I think
that should have been present before, but things built okay because of
the way things got combined in the uniffied .cpp files. Adding these new
webIDL files bumped `NodeListBinding.cpp` to a new uniffied .cpp file
which caused the build to fail.

Differential Revision: https://phabricator.services.mozilla.com/D144468

build/mach_initialize.py

@@ -363,6 +363,9 @@ def initialize(topsrcdir):
         ),
         "esmify": MachCommandReference("tools/esmify/mach_commands.py"),
         "xpcshell": MachCommandReference("js/xpconnect/mach_commands.py"),
+        "uniffi": MachCommandReference(
+            "toolkit/components/uniffi-bindgen-gecko-js/mach_commands.py"
+        ),
     }
 
     # Set a reasonable limit to the number of open files.

dom/base/nsINodeList.h

@@ -9,6 +9,7 @@
 
 #include "nsWrapperCache.h"
 #include "nsISupports.h"
+#include "nsIContent.h"
 
 // IID for the nsINodeList interface
 #define NS_INODELIST_IID                             \

toolkit/components/moz.build

@@ -143,3 +143,6 @@ if CONFIG["COMPILE_ENVIRONMENT"]:
     EXPORTS.mozilla += [
         "!regex_ffi_generated.h",
     ]
+
+if CONFIG["MOZ_UNIFFI_FIXTURES"]:
+    DIRS += ["uniffi-bindgen-gecko-js/fixtures"]

toolkit/components/uniffi-bindgen-gecko-js/fixtures/README.md

@@ -0,0 +1,36 @@
+This directory contains generated code for the UniFFI examples/fixtures and JS
+unit tests for it.
+
+This is only built if the `--enable-uniffi-fixtures` flag is present in
+`mozconfig`.  There's no benefit to including this in a release build.
+
+To add additional examples/fixtures:
+  - For most of these steps, find the code for existing fixtures and use it as a template for the new code.
+  - Edit `toolkit/components/uniffi-bindgen-gecko-js/mach_commands.py`
+    - Add an entry to `FIXTURE_UDL_FILES`
+  - Edit `toolkit/library/rust/shared/Cargo.toml`
+    - Add an optional dependency for the fixture.
+    - Add the feature to the list of features enabled by `uniffi_fixtures`.
+  - Edit `toolkit/library/rust/shared/lib.rs`:
+     - Add an `extern crate [name]` to the `uniffi_fixtures` mod
+       - Note: [name] is the name from the `[lib]` section in the Cargo.toml
+         for the example/fixture crate.  This does not always match the package
+         name for the crate.
+     - Add `[name]::reexport_uniffi_scaffolding` to the `uniffi_fixtures` mod
+  - Edit `toolkit/components/uniffi-bindgen-gecko-js/fixtures/moz.build` and add the fixture name to the `components`
+    list.
+  - Add a test module to the `toolkit/components/uniffi-bindgen-gecko-js/fixtures/tests/` directory and an entry for it
+    in `toolkit/components/uniffi-bindgen-gecko-js/fixtures/tests/xpcshell.ini`
+  - Run `mach vendor rust` to vendor in the Rust code.
+  - Run `mach uniffi generate` to generate the scaffolding code.
+  - Check in any new files
+
+To run the tests:
+  - Make sure you have a `mozconfig` file containing the line `ac_add_options --enable-uniffi-fixtures`
+  - Run `mach uniffi generate` if:
+    - You've added or updated a fixture
+    - You've made changes to `uniffi-bindgen-gecko-js`
+  - Run `mach build`
+  - Run `mach xpcshell-test toolkit/components/uniffi-bindgen-gecko-js/fixtures/tests/`
+    - You can also use a path to specific test file
+    - For subsequent runs, if you only modify the test files, then you can re-run this step directly