Deprecate --system and --no-system in uv venv

crates/uv-cli/src/lib.rs

@@ -1837,15 +1837,22 @@ pub struct VenvArgs {
  )]
  pub python: Option<String>,
 
- // TODO(zanieb): Hide me, I do nothing.
+ /// Ignore virtual environments when searching for the Python interpreter.
+ ///
+ /// This is the default behavior and has no effect.
  #[arg(
  long,
  env = "UV_SYSTEM_PYTHON",
  value_parser = clap::builder::BoolishValueParser::new(),
- overrides_with("no_system")
+ overrides_with("no_system"),
+ hide = true,
  )]
  pub system: bool,
 
+ /// This flag is included for compatibility only, it has no effect.
+ ///
+ /// uv will never search for interpreters in virtual environments when
+ /// creating a virtual environment.
  #[arg(long, overrides_with("system"), hide = true)]
  pub no_system: bool,
 

crates/uv/src/lib.rs

@@ -24,7 +24,7 @@ use uv_configuration::Concurrency;
 use uv_fs::CWD;
 use uv_requirements::RequirementsSource;
 use uv_settings::{Combine, FilesystemOptions};
-use uv_warnings::warn_user;
+use uv_warnings::{warn_user, warn_user_once};
 use uv_workspace::{DiscoveryOptions, Workspace};
 
 use crate::commands::{ExitStatus, ToolRunCommand};
@@ -627,6 +627,14 @@ async fn run(cli: Cli) -> Result<ExitStatus> {
  Commands::Venv(args) => {
  args.compat_args.validate()?;
 
+ if args.no_system {
+ warn_user_once!("The `--no-system` flag has no effect, a system Python interpreter is always used in `uv venv`");
+ }
+
+ if args.system {
+ warn_user_once!("The `--system` flag has no effect, a system Python interpreter is always used in `uv venv`");
+ }
+
  // Resolve the settings from the command-line arguments and workspace configuration.
  let args = settings::VenvSettings::resolve(args, filesystem);
  show_settings!(args);