// SPDX-License-Identifier: Apache-2.0 OR MIT use std::fmt::Display; use proc_macro2::TokenStream; use quote::quote_spanned; use syn::{spanned::Spanned, Error}; pub(crate) struct DiagCtxt(TokenStream); pub(crate) struct ErrorGuaranteed(()); impl DiagCtxt { pub(crate) fn error(&mut self, span: impl Spanned, msg: impl Display) -> ErrorGuaranteed { let error = Error::new(span.span(), msg); self.0.extend(error.into_compile_error()); ErrorGuaranteed(()) } pub(crate) fn warn(&mut self, span: impl Spanned, msg: impl Display) { // Have the message start on a new line for visual clarity. let msg = format!("\n{}", msg); self.0.extend(quote_spanned!(span.span() => // Approximate using deprecated warning while `proc_macro_diagnostic` is unstable. const _: () = { #[deprecated = #msg] const fn warn() {} warn(); }; )); } pub(crate) fn with( fun: impl FnOnce(&mut DiagCtxt) -> Result<TokenStream, ErrorGuaranteed>, ) -> TokenStream { let mut dcx = Self(TokenStream::new()); match fun(&mut dcx) { Ok(mut stream) => { stream.extend(dcx.0); stream } Err(ErrorGuaranteed(())) => dcx.0, } } }