| use proc_macro::TokenStream; |
| use proc_macro2::Span; |
| use quote::quote; |
| |
| pub(crate) fn current_version(_input: TokenStream) -> TokenStream { |
| let env_var = "CFG_RELEASE"; |
| TokenStream::from(match RustcVersion::parse_cfg_release(env_var) { |
| Ok(RustcVersion { major, minor, patch }) => quote!( |
| // The produced literal has type `rustc_session::RustcVersion`. |
| Self { major: #major, minor: #minor, patch: #patch } |
| ), |
| Err(err) => syn::Error::new(Span::call_site(), format!("{env_var} env var: {err}")) |
| .into_compile_error(), |
| }) |
| } |
| |
| struct RustcVersion { |
| major: u16, |
| minor: u16, |
| patch: u16, |
| } |
| |
| impl RustcVersion { |
| fn parse_cfg_release(env_var: &str) -> Result<Self, Box<dyn std::error::Error>> { |
| let value = proc_macro::tracked_env::var(env_var)?; |
| Self::parse_str(&value) |
| .ok_or_else(|| format!("failed to parse rustc version: {:?}", value).into()) |
| } |
| |
| fn parse_str(value: &str) -> Option<Self> { |
| // Ignore any suffixes such as "-dev" or "-nightly". |
| let mut components = value.split('-').next().unwrap().splitn(3, '.'); |
| let major = components.next()?.parse().ok()?; |
| let minor = components.next()?.parse().ok()?; |
| let patch = components.next().unwrap_or("0").parse().ok()?; |
| Some(RustcVersion { major, minor, patch }) |
| } |
| } |