Detect and allow older nightlies

embassy-executor/Cargo.toml

@@ -57,6 +57,9 @@ avr-device = { version = "0.5.3", optional = true }
 critical-section = { version = "1.1", features = ["std"] }
 trybuild = "1.0"
 
+[build-dependencies]
+rustc_version = "0.4.1"
+
 [features]
 
 ## Enable nightly-only features

embassy-executor/build.rs

@@ -96,4 +96,15 @@ fn main() {
 
     let mut rustc_cfgs = common::CfgSet::new();
     common::set_target_cfgs(&mut rustc_cfgs);
+
+    // Waker API changed on 2024-09-06
+    rustc_cfgs.declare("at_least_2024_09_06");
+    let Some(compiler) = common::compiler_info() else {
+        return;
+    };
+    if compiler.channel == rustc_version::Channel::Nightly
+        && compiler.commit_date.map(|d| d >= "2024-09-06").unwrap_or(false)
+    {
+        rustc_cfgs.enable("at_least_2024_09_06");
+    }
 }

embassy-executor/build_common.rs

@@ -92,3 +92,54 @@ pub fn set_target_cfgs(cfgs: &mut CfgSet) {
 
     cfgs.set("has_fpu", target.ends_with("-eabihf"));
 }
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
+pub struct CompilerDate {
+    year: u16,
+    month: u8,
+    day: u8,
+}
+
+impl CompilerDate {
+    fn parse(date: &str) -> Option<Self> {
+        let mut parts = date.split('-');
+        let year = parts.next()?.parse().ok()?;
+        let month = parts.next()?.parse().ok()?;
+        let day = parts.next()?.parse().ok()?;
+        Some(Self { year, month, day })
+    }
+}
+
+impl PartialEq<&str> for CompilerDate {
+    fn eq(&self, other: &&str) -> bool {
+        let Some(other) = Self::parse(other) else {
+            return false;
+        };
+        self.eq(&other)
+    }
+}
+
+impl PartialOrd<&str> for CompilerDate {
+    fn partial_cmp(&self, other: &&str) -> Option<std::cmp::Ordering> {
+        Self::parse(other).map(|other| self.cmp(&other))
+    }
+}
+
+pub struct CompilerInfo {
+    #[allow(unused)]
+    pub version: rustc_version::Version,
+    pub channel: rustc_version::Channel,
+    pub commit_date: Option<CompilerDate>,
+}
+
+pub fn compiler_info() -> Option<CompilerInfo> {
+    let Ok(meta) = rustc_version::version_meta() else {
+        return None;
+    };
+
+    Some(CompilerInfo {
+        version: meta.semver,
+        channel: meta.channel,
+        commit_date: meta.commit_date.as_deref().and_then(CompilerDate::parse),
+    })
+}

embassy-executor/src/lib.rs

@@ -1,4 +1,5 @@
 #![cfg_attr(not(any(feature = "arch-std", feature = "arch-wasm")), no_std)]
+#![cfg_attr(all(feature = "nightly", not(at_least_2024_09_06)), feature(waker_getters))]
 #![allow(clippy::new_without_default)]
 #![doc = include_str!("../README.md")]
 #![warn(missing_docs)]

embassy-executor/src/raw/waker.rs

@@ -49,9 +49,18 @@ pub fn task_from_waker(waker: &Waker) -> TaskRef {
         }
 
         #[cfg(feature = "nightly")]
+        {
+            #[cfg(not(at_least_2024_09_06))]
+            {
+                let raw_waker = waker.as_raw();
+                (raw_waker.vtable(), raw_waker.data())
+            }
+
+            #[cfg(at_least_2024_09_06)]
             {
                 (waker.vtable(), waker.data())
             }
+        }
     };
 
     if vtable != &VTABLE {