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49908b4d90
It currently has the syntax
`current_rustc_version!(env!("CFG_RELEASE"))` where the
`env!("CFG_RELEASE")` part looks like a normal expression but it is
actually parsed and processed by the `current_rustc_version` macro.
The documented rationale for this is that you'll find it if you grep for
`env!("CFG_RELEASE")`. But I think that's of very little use -- I would
personally grep for just "CFG_RELEASE" -- and it complicates the macro,
requiring the use of `syn`.
This commit simplifies the macro.
39 lines
1.3 KiB
Rust
39 lines
1.3 KiB
Rust
use proc_macro::TokenStream;
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use proc_macro2::Span;
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use quote::quote;
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pub(crate) fn current_version(_input: TokenStream) -> TokenStream {
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let env_var = "CFG_RELEASE";
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TokenStream::from(match RustcVersion::parse_cfg_release(env_var) {
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Ok(RustcVersion { major, minor, patch }) => quote!(
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// The produced literal has type `rustc_session::RustcVersion`.
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Self { major: #major, minor: #minor, patch: #patch }
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),
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Err(err) => syn::Error::new(Span::call_site(), format!("{env_var} env var: {err}"))
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.into_compile_error(),
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})
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}
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struct RustcVersion {
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major: u16,
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minor: u16,
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patch: u16,
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}
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impl RustcVersion {
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fn parse_cfg_release(env_var: &str) -> Result<Self, Box<dyn std::error::Error>> {
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let value = proc_macro::tracked_env::var(env_var)?;
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Self::parse_str(&value)
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.ok_or_else(|| format!("failed to parse rustc version: {:?}", value).into())
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}
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fn parse_str(value: &str) -> Option<Self> {
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// Ignore any suffixes such as "-dev" or "-nightly".
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let mut components = value.split('-').next().unwrap().splitn(3, '.');
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let major = components.next()?.parse().ok()?;
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let minor = components.next()?.parse().ok()?;
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let patch = components.next().unwrap_or("0").parse().ok()?;
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Some(RustcVersion { major, minor, patch })
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}
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}
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