Rollup merge of rust-lang#48569 - Phlosioneer:x-py-help-optimization,…

… r=petrochenkov

Fixes rust-lang#47311.
r? @nrc

src/bootstrap/bootstrap.py

@@ -314,7 +314,6 @@ def __init__(self):
  self.build_dir = os.path.join(os.getcwd(), "build")
  self.clean = False
  self.config_toml = ''
- self.printed = False
  self.rust_root = os.path.abspath(os.path.join(__file__, '../../..'))
  self.use_locked_deps = ''
  self.use_vendored_sources = ''
@@ -336,7 +335,6 @@ def download_stage0(self):
  if self.rustc().startswith(self.bin_root()) and \
  (not os.path.exists(self.rustc()) or
  self.program_out_of_date(self.rustc_stamp())):
- self.print_what_bootstrap_means()
  if os.path.exists(self.bin_root()):
  shutil.rmtree(self.bin_root())
  filename = "rust-std-{}-{}.tar.gz".format(
@@ -362,7 +360,6 @@ def download_stage0(self):
  if self.cargo().startswith(self.bin_root()) and \
  (not os.path.exists(self.cargo()) or
  self.program_out_of_date(self.cargo_stamp())):
- self.print_what_bootstrap_means()
  filename = "cargo-{}-{}.tar.gz".format(cargo_channel, self.build)
  self._download_stage0_helper(filename, "cargo")
  self.fix_executable("{}/bin/cargo".format(self.bin_root()))
@@ -563,23 +560,6 @@ def exe_suffix():
  return '.exe'
  return ''
 
- def print_what_bootstrap_means(self):
- """Prints more information about the build system"""
- if hasattr(self, 'printed'):
- return
- self.printed = True
- if os.path.exists(self.bootstrap_binary()):
- return
- if '--help' not in sys.argv or len(sys.argv) == 1:
- return
-
- print('info: the build system for Rust is written in Rust, so this')
- print(' script is now going to download a stage0 rust compiler')
- print(' and then compile the build system itself')
- print('')
- print('info: in the meantime you can read more about rustbuild at')
- print(' src/bootstrap/README.md before the download finishes')
-
  def bootstrap_binary(self):
  """Return the path of the boostrap binary
 
@@ -593,7 +573,6 @@ def bootstrap_binary(self):
 
  def build_bootstrap(self):
  """Build bootstrap"""
- self.print_what_bootstrap_means()
  build_dir = os.path.join(self.build_dir, "bootstrap")
  if self.clean and os.path.exists(build_dir):
  shutil.rmtree(build_dir)
@@ -678,8 +657,16 @@ def set_dev_environment(self):
  self._download_url = 'https://dev-static.rust-lang.org'
 
 
-def bootstrap():
+def bootstrap(help_triggered):
  """Configure, fetch, build and run the initial bootstrap"""
+
+ # If the user is asking for help, let them know that the whole download-and-build
+ # process has to happen before anything is printed out.
+ if help_triggered:
+ print("info: Downloading and building bootstrap before processing --help")
+ print(" command. See src/bootstrap/README.md for help with common")
+ print(" commands.")
+
  parser = argparse.ArgumentParser(description='Build rust')
  parser.add_argument('--config')
  parser.add_argument('--build')
@@ -716,7 +703,7 @@ def bootstrap():
  print(' and so in order to preserve your $HOME this will now')
  print(' use vendored sources by default. Note that if this')
  print(' does not work you should run a normal build first')
- print(' before running a command like `sudo make install`')
+ print(' before running a command like `sudo ./x.py install`')
 
  if build.use_vendored_sources:
  if not os.path.exists('.cargo'):
@@ -742,7 +729,10 @@ def bootstrap():
  if 'dev' in data:
  build.set_dev_environment()
 
- build.update_submodules()
+ # No help text depends on submodules. This check saves ~1 minute of git commands, even if
+ # all the submodules are present and downloaded!
+ if not help_triggered:
+ build.update_submodules()
 
  # Fetch/build the bootstrap
  build.build = args.build or build.build_triple()
@@ -768,7 +758,7 @@ def main():
  help_triggered = (
  '-h' in sys.argv) or ('--help' in sys.argv) or (len(sys.argv) == 1)
  try:
- bootstrap()
+ bootstrap(help_triggered)
  if not help_triggered:
  print("Build completed successfully in {}".format(
  format_build_time(time() - start_time)))