Enforce formatting of TOML files (#30128)

* Fmt all toml files

* bootstrap taplo

* enforce toml formatting with taplo

* Install taplo in CI using cargo-install action

2 files changed, 35 insertions, 3 deletions

diff --git a/python/servo/platform/base.py b/python/servo/platform/base.py
index 7fde2b60c97..8af3e2056eb 100644
--- a/python/servo/platform/base.py
+++ b/python/servo/platform/base.py
@@ -8,6 +8,7 @@
 # except according to those terms.
 
 import os
+import shutil
 import subprocess
 from typing import Dict, Optional
 
@@ -96,9 +97,21 @@ class Base:
         )
 
     def bootstrap(self, force: bool):
-        if not self._platform_bootstrap(force):
+        installed_something = self._platform_bootstrap(force)
+        installed_something |= self.install_taplo(force)
+        if not installed_something:
             print("Dependencies were already installed!")
 
+    def install_taplo(self, force: bool) -> bool:
+        if not force and shutil.which("taplo") is not None:
+            return False
+
+        if subprocess.call(["cargo", "install", "taplo-cli", "--locked"],
+                           stdout=subprocess.PIPE, stderr=subprocess.PIPE) != 0:
+            raise EnvironmentError("Installation of taplo failed.")
+
+        return True
+
     def passive_bootstrap(self) -> bool:
         """A bootstrap method that is called without explicitly invoking `./mach bootstrap`
            but that is executed in the process of other `./mach` commands. This should be
diff --git a/python/servo/testing_commands.py b/python/servo/testing_commands.py
index 328a82a7a23..a0e60cb2e72 100644
--- a/python/servo/testing_commands.py
+++ b/python/servo/testing_commands.py
@@ -57,6 +57,20 @@ TEST_SUITES = OrderedDict([
 TEST_SUITES_BY_PREFIX = {path: k for k, v in TEST_SUITES.items() if "paths" in v for path in v["paths"]}
 
 
+def format_toml_files_with_taplo(check_only: bool = True) -> int:
+    taplo = shutil.which("taplo")
+    if taplo is None:
+        print("Taplo is not installed.")
+        print("It should be installed using `./mach bootstrap`, \
+                but it can be installed manually using `cargo install taplo-cli --locked`")
+        return 1
+
+    if check_only:
+        return call([taplo, "fmt", "--check"], env={'RUST_LOG': 'error'})
+    else:
+        return call([taplo, "fmt"], env={'RUST_LOG': 'error'})
+
+
 @CommandProvider
 class MachCommands(CommandBase):
     DEFAULT_RENDER_MODE = "cpu"
@@ -279,7 +293,9 @@ class MachCommands(CommandBase):
         if rustfmt_failed:
             print("Run `./mach fmt` to fix the formatting")
 
-        return tidy_failed or manifest_dirty or rustfmt_failed
+        taplo_failed = format_toml_files_with_taplo()
+
+        return tidy_failed or manifest_dirty or rustfmt_failed or taplo_failed
 
     @Command('test-scripts',
              description='Run tests for all build and support scripts.',
@@ -370,9 +386,12 @@ class MachCommands(CommandBase):
         return wpt.manifestupdate.update(check_clean=False)
 
     @Command('fmt',
-             description='Format the Rust and CPP source files with rustfmt',
+             description='Format Rust and TOML files',
              category='testing')
     def format_code(self):
+        result = format_toml_files_with_taplo(check_only=False)
+        if result != 0:
+            return result
         return call(["cargo", "fmt"])
 
     @Command('update-wpt',