uniffi_macros: Force-include the Cargo.toml to read

uniffi_macros/src/lib.rs

@@ -186,9 +186,31 @@ pub fn include_scaffolding(component_name: TokenStream) -> TokenStream {
  },
  None,
  );
+
+ let toml_path = match util::manifest_path() {
+ Ok(path) => path.display().to_string(),
+ Err(_) => {
+ return quote! {
+ compile_error!("This macro assumes the crate has a build.rs script, but $OUT_DIR is not present");
+ }.into();
+ }
+ };
+
  quote! {
  #metadata
 
+ // FIXME(HACK):
+ // Include the `Cargo.toml` file into the build.
+ // That way cargo tracks the file and other tools relying on file
+ // tracking see it as well.
+ // See https://bugzilla.mozilla.org/show_bug.cgi?id=1846223
+ // In the future we should handle that by using the `track_path::path` API,
+ // see https://github.com/rust-lang/rust/pull/84029
+ #[allow(dead_code)]
+ mod __unused {
+ const _: &[u8] = include_bytes!(#toml_path);
+ }
+
  include!(concat!(env!("OUT_DIR"), "/", #name, ".uniffi.rs"));
  }
  }.into()

uniffi_macros/src/util.rs

@@ -4,18 +4,24 @@
 
 use proc_macro2::{Ident, Span, TokenStream};
 use quote::{format_ident, quote, ToTokens};
+use std::path::{Path as StdPath, PathBuf};
 use syn::{
  ext::IdentExt,
  parse::{Parse, ParseStream},
  Attribute, Path, Token,
 };
 
+pub fn manifest_path() -> Result<PathBuf, String> {
+ let manifest_dir =
+ std::env::var_os("CARGO_MANIFEST_DIR").ok_or("`CARGO_MANIFEST_DIR` is not set")?;
+
+ Ok(StdPath::new(&manifest_dir).join("Cargo.toml"))
+}
+
 #[cfg(not(feature = "nightly"))]
 pub fn mod_path() -> syn::Result<String> {
  // Without the nightly feature and TokenStream::expand_expr, just return the crate name
 
- use std::path::Path;
-
  use fs_err as fs;
  use once_cell::sync::Lazy;
  use serde::Deserialize;
@@ -38,11 +44,9 @@ pub fn mod_path() -> syn::Result<String> {
  }
 
  static LIB_CRATE_MOD_PATH: Lazy<Result<String, String>> = Lazy::new(|| {
- let manifest_dir =
-  std::env::var_os("CARGO_MANIFEST_DIR").ok_or("`CARGO_MANIFEST_DIR` is not set")?;
+ let file = manifest_path()?;
+ let cargo_toml_bytes = fs::read(file).map_err(|e| e.to_string())?;
 
- let cargo_toml_bytes =
- fs::read(Path::new(&manifest_dir).join("Cargo.toml")).map_err(|e| e.to_string())?;
  let cargo_toml = toml::from_slice::<CargoToml>(&cargo_toml_bytes)
  .map_err(|e| format!("Failed to parse `Cargo.toml`: {e}"))?;