fix(async): #256 spec-compliant microtask ordering for plain async functions

Cargo.toml

@@ -113,7 +113,7 @@ opt-level = "s"       # Optimize for size in stdlib
 opt-level = 3
 
 [workspace.package]
-version = "0.5.370"
+version = "0.5.371"
 edition = "2021"
 license = "MIT"
 repository = "https://github.com/PerryTS/perry"

crates/perry-codegen/src/codegen.rs

@@ -469,6 +469,7 @@ pub fn compile_module(hir: &HirModule, opts: CompileOptions) -> Result<Vec<u8>>
                 body: Vec::new(),
                 is_async: false,
                 is_generator: false,
+                was_plain_async: false,
                 is_exported: false,
                 captures: Vec::new(),
                 decorators: Vec::new(),
@@ -1389,6 +1390,7 @@ pub fn compile_module(hir: &HirModule, opts: CompileOptions) -> Result<Vec<u8>>
                 body: ctor_body.1,
                 is_async: false,
                 is_generator: false,
+                was_plain_async: false,
                 is_exported: false,
                 captures: ctor_body.2,
                 decorators: Vec::new(),

crates/perry-hir/src/ir.rs

@@ -677,6 +677,12 @@ pub struct Function {
     pub captures: Vec<LocalId>,
     /// Decorators applied to this function/method
     pub decorators: Vec<Decorator>,
+    /// Issue #256: true if this function was originally a plain async function
+    /// that the async_to_generator pre-pass rewrote into a generator. The
+    /// generator state-machine transform reads this flag and wraps the
+    /// resulting iterator in an async-step driver so the function returns
+    /// a Promise that respects spec microtask ordering.
+    pub was_plain_async: bool,
 }
 
 /// A function parameter

crates/perry-hir/src/lower.rs

@@ -742,6 +742,7 @@ impl LoweringContext {
             body: ctor_body,
             is_async: false,
             is_generator: false,
+            was_plain_async: false,
             is_exported: false,
             captures: Vec::new(),
             decorators: Vec::new(),

crates/perry-hir/src/lower/expr_object.rs

@@ -355,6 +355,7 @@ pub(super) fn lower_object(ctx: &mut LoweringContext, obj: &ast::ObjectLit) -> R
                                         body,
                                         is_async: method.function.is_async,
                                         is_generator: false,
+                                        was_plain_async: false,
                                         is_exported: false,
                                         captures: Vec::new(),
                                         decorators: Vec::new(),