executor: fix unsoundness due to `impl Trait`, improve macro error handling. (#3425)

* executor-macros: don't parse function bodies.

* executor-macros: refactor for better recovery and ide-friendliness on errors.

* executor-macros: disallow `impl Trait` in task arguments.

Fixes #3420

* Fix example using `impl Trait` in tasks.

2 files changed, 0 insertions, 73 deletions

diff --git a/embassy-executor-macros/src/util/ctxt.rs b/embassy-executor-macros/src/util/ctxt.rs
deleted file mode 100644
index 9c78cda01..000000000
--- a/embassy-executor-macros/src/util/ctxt.rs
+++ /dev/null
@@ -1,72 +0,0 @@
-// nifty utility borrowed from serde :)
-// https://github.com/serde-rs/serde/blob/master/serde_derive/src/internals/ctxt.rs
-
-use std::cell::RefCell;
-use std::fmt::Display;
-use std::thread;
-
-use proc_macro2::TokenStream;
-use quote::{quote, ToTokens};
-
-/// A type to collect errors together and format them.
-///
-/// Dropping this object will cause a panic. It must be consumed using `check`.
-///
-/// References can be shared since this type uses run-time exclusive mut checking.
-#[derive(Default)]
-pub struct Ctxt {
-    // The contents will be set to `None` during checking. This is so that checking can be
-    // enforced.
-    errors: RefCell<Option<Vec<syn::Error>>>,
-}
-
-impl Ctxt {
-    /// Create a new context object.
-    ///
-    /// This object contains no errors, but will still trigger a panic if it is not `check`ed.
-    pub fn new() -> Self {
-        Ctxt {
-            errors: RefCell::new(Some(Vec::new())),
-        }
-    }
-
-    /// Add an error to the context object with a tokenenizable object.
-    ///
-    /// The object is used for spanning in error messages.
-    pub fn error_spanned_by<A: ToTokens, T: Display>(&self, obj: A, msg: T) {
-        self.errors
-            .borrow_mut()
-            .as_mut()
-            .unwrap()
-            // Curb monomorphization from generating too many identical methods.
-            .push(syn::Error::new_spanned(obj.into_token_stream(), msg));
-    }
-
-    /// Add one of Syn's parse errors.
-    #[allow(unused)]
-    pub fn syn_error(&self, err: syn::Error) {
-        self.errors.borrow_mut().as_mut().unwrap().push(err);
-    }
-
-    /// Consume this object, producing a formatted error string if there are errors.
-    pub fn check(self) -> Result<(), TokenStream> {
-        let errors = self.errors.borrow_mut().take().unwrap();
-        match errors.len() {
-            0 => Ok(()),
-            _ => Err(to_compile_errors(errors)),
-        }
-    }
-}
-
-fn to_compile_errors(errors: Vec<syn::Error>) -> proc_macro2::TokenStream {
-    let compile_errors = errors.iter().map(syn::Error::to_compile_error);
-    quote!(#(#compile_errors)*)
-}
-
-impl Drop for Ctxt {
-    fn drop(&mut self) {
-        if !thread::panicking() && self.errors.borrow().is_some() {
-            panic!("forgot to check for errors");
-        }
-    }
-}
diff --git a/embassy-executor-macros/src/util/mod.rs b/embassy-executor-macros/src/util/mod.rs
deleted file mode 100644
index 28702809e..000000000
--- a/embassy-executor-macros/src/util/mod.rs
+++ /dev/null
@@ -1 +0,0 @@
-pub mod ctxt;