Make rustup a requirement and switch to `rust-toolchain.toml` (#30056)

This change makes rustup a requirement for building Servo with `./mach`
and switches to the newer `rust-toolchain.toml` format. The goal here is
to make mach builds more similar to non-mach builds.

- The new format allows listing the required components, removing some of
  the complexity from our mach scripts.
- This means we must raise the required version of rustup to 1.23. The
  current version is 1.26.
- We no longer wrap every call to cargo and rustc in "rustup run" calls
  as both cargo and rustc will take care of installing and using all
  necessary components specified in `rust-toolchain.toml` when run
  inside the project directory.

1 files changed, 13 insertions, 9 deletions

diff --git a/python/servo/devenv_commands.py b/python/servo/devenv_commands.py
index b09086a8ed4..9e7527d6fd8 100644
--- a/python/servo/devenv_commands.py
+++ b/python/servo/devenv_commands.py
@@ -97,7 +97,7 @@ class MachCommands(CommandBase):
 
         self.ensure_bootstrapped()
         with cd(self.context.topdir):
-            self.call_rustup_run(["cargo", "update"] + params, env=self.build_env())
+            call(["cargo", "update"] + params, env=self.build_env())
 
     @Command('rustc',
              description='Run the Rust compiler',
@@ -110,7 +110,7 @@ class MachCommands(CommandBase):
             params = []
 
         self.ensure_bootstrapped()
-        return self.call_rustup_run(["rustc"] + params, env=self.build_env())
+        return call(["rustc"] + params, env=self.build_env())
 
     @Command('cargo-fix',
              description='Run "cargo fix"',
@@ -173,10 +173,16 @@ class MachCommands(CommandBase):
     def rustup(self):
         nightly_date = urllib.request.urlopen(
             "https://static.rust-lang.org/dist/channel-rust-nightly-date.txt").read()
-        toolchain = b"nightly-" + nightly_date
-        filename = path.join(self.context.topdir, "rust-toolchain")
-        with open(filename, "wb") as f:
-            f.write(toolchain + b"\n")
+        new_toolchain = f"nightly-{nightly_date.decode('utf-8')}"
+        old_toolchain = self.rust_toolchain()
+
+        filename = path.join(self.context.topdir, "rust-toolchain.toml")
+        with open(filename, "r", encoding="utf-8") as file:
+            contents = file.read()
+        contents = contents.replace(old_toolchain, new_toolchain)
+        with open(filename, "w", encoding="utf-8") as file:
+            file.write(contents)
+
         self.ensure_bootstrapped()
 
     @Command('fetch',
@@ -184,9 +190,7 @@ class MachCommands(CommandBase):
              category='devenv')
     def fetch(self):
         self.ensure_bootstrapped()
-
-        with cd(self.context.topdir):
-            return self.call_rustup_run(["cargo", "fetch"], env=self.build_env())
+        return call(["cargo", "fetch"], env=self.build_env())
 
     @Command('ndk-stack',
              description='Invoke the ndk-stack tool with the expected symbol paths',