Add option to compile bytecode during installation (similar to default behavior of old installer)

docs/cli.md

@@ -225,6 +225,21 @@ If you want to skip this installation, use the `--no-root` option.
 poetry install --no-root
 ```
 
+By default `poetry` does not compile Python source files to bytecode during installation.
+This speeds up the installation process, but the first execution may take a little more
+time because Python then compiles source files to bytecode automatically.
+If you want to compile source files to bytecode during installation,
+you can use the `--compile` option:
+
+```bash
+poetry install --compile
+```
+
+{{% note %}}
+The `--compile` option has no effect if `installer.modern-installation`
+is set to `false` because the old installer always compiles source files to bytecode.
+{{% /note %}}
+
 ### Options
 
 * `--without`: The dependency groups to ignore.
@@ -236,6 +251,7 @@ poetry install --no-root
 * `--dry-run`: Output the operations but do not execute anything (implicitly enables --verbose).
 * `--extras (-E)`: Features to install (multiple values allowed).
 * `--all-extras`: Install all extra features (conflicts with --extras).
+* `--compile`: Compile Python source files to bytecode.
 * `--no-dev`: Do not install dev dependencies. (**Deprecated**, use `--without dev` or `--only main` instead)
 * `--remove-untracked`: Remove dependencies not presented in the lock file. (**Deprecated**, use `--sync` instead)
 

src/poetry/console/commands/install.py

@@ -54,12 +54,15 @@ class InstallCommand(InstallerCommand):
             multiple=True,
         ),
         option("all-extras", None, "Install all extra dependencies."),
+        option("only-root", None, "Exclude all dependencies."),
         option(
-            "only-root",
+            "compile",
             None,
-            "Exclude all dependencies.",
-            flag=True,
-            multiple=False,
+            (
+                "Compile Python source files to bytecode."
+                " (This option has no effect if modern-installation is disabled"
+                " because the old installer always compiles.)"
+            ),
         ),
     ]
 
@@ -146,6 +149,7 @@ dependencies and not including the current project, run the command with the
         self.installer.only_groups(self.activated_groups)
         self.installer.dry_run(self.option("dry-run"))
         self.installer.requires_synchronization(with_synchronization)
+        self.installer.executor.enable_bytecode_compilation(self.option("compile"))
         self.installer.verbose(self.io.is_verbose())
 
         return_code = self.installer.run()

src/poetry/installation/executor.py

@@ -123,6 +123,9 @@ class Executor:
 
         return self
 
+    def enable_bytecode_compilation(self, enable: bool = True) -> None:
+        self._wheel_installer.enable_bytecode_compilation(enable)
+
     def pip_install(
         self, req: Path, upgrade: bool = False, editable: bool = False
     ) -> int:

src/poetry/installation/wheel_installer.py

@@ -66,7 +66,10 @@ class WheelDestination(SchemeDictionaryDestination):
         scheme_dict["headers"] = str(Path(scheme_dict["headers"]) / source.distribution)
 
         return self.__class__(
-            scheme_dict, interpreter=self.interpreter, script_kind=self.script_kind
+            scheme_dict,
+            interpreter=self.interpreter,
+            script_kind=self.script_kind,
+            bytecode_optimization_levels=self.bytecode_optimization_levels,
         )
 
 
@@ -90,6 +93,9 @@ class WheelInstaller:
             schemes, interpreter=self._env.python, script_kind=script_kind
         )
 
+    def enable_bytecode_compilation(self, enable: bool = True) -> None:
+        self._destination.bytecode_optimization_levels = (1,) if enable else ()
+
     def install(self, wheel: Path) -> None:
         with WheelFile.open(Path(wheel.as_posix())) as source:
             install(

tests/console/commands/test_install.py

@@ -162,6 +162,24 @@ def test_sync_option_is_passed_to_the_installer(
     assert tester.command.installer._requires_synchronization
 
 
+@pytest.mark.parametrize("compile", [False, True])
+def test_compile_option_is_passed_to_the_installer(
+    tester: CommandTester, mocker: MockerFixture, compile: bool
+):
+    """
+    The --compile option is passed properly to the installer.
+    """
+    mocker.patch.object(tester.command.installer, "run", return_value=1)
+    enable_bytecode_compilation_mock = mocker.patch.object(
+        tester.command.installer.executor._wheel_installer,
+        "enable_bytecode_compilation",
+    )
+
+    tester.execute("--compile" if compile else "")
+
+    enable_bytecode_compilation_mock.assert_called_once_with(compile)
+
+
 def test_no_all_extras_doesnt_populate_installer(
     tester: CommandTester, mocker: MockerFixture
 ):

tests/installation/test_wheel_installer.py

@@ -59,3 +59,23 @@ def test_installer_file_contains_valid_version(default_installation: Path) -> No
     match = re.match(r"Poetry (?P<version>.*)", installer_content)
     assert match
     parse_constraint(match.group("version"))  # must not raise an error
+
+
+def test_default_installation_no_bytecode(default_installation: Path) -> None:
+    cache_dir = default_installation / "demo" / "__pycache__"
+    assert not cache_dir.exists()
+
+
+@pytest.mark.parametrize("compile", [True, False])
+def test_enable_bytecode_compilation(
+    env: MockEnv, demo_wheel: Path, compile: bool
+) -> None:
+    installer = WheelInstaller(env)
+    installer.enable_bytecode_compilation(compile)
+    installer.install(demo_wheel)
+    cache_dir = Path(env.paths["purelib"]) / "demo" / "__pycache__"
+    if compile:
+        assert cache_dir.exists()
+        assert list(cache_dir.glob("*.pyc"))
+    else:
+        assert not cache_dir.exists()