Implement #129347: inline attributes on async fn and async closures affect the poll impl

Author: xacrimon

compiler/rustc_codegen_ssa/src/codegen_attrs.rs

@@ -6,7 +6,10 @@ use rustc_ast::{LitKind, MetaItem, MetaItemInner, attr};
 use rustc_hir::attrs::{AttributeKind, InlineAttr, InstructionSetAttr, RtsanSetting, UsedBy};
 use rustc_hir::def::DefKind;
 use rustc_hir::def_id::{DefId, LOCAL_CRATE, LocalDefId};
-use rustc_hir::{self as hir, Attribute, LangItem, find_attr, lang_items};
+use rustc_hir::{
+    self as hir, Attribute, CoroutineDesugaring, CoroutineKind, CoroutineSource, LangItem,
+    find_attr, lang_items,
+};
 use rustc_middle::middle::codegen_fn_attrs::{
     CodegenFnAttrFlags, CodegenFnAttrs, PatchableFunctionEntry, SanitizerFnAttrs,
 };
@@ -386,6 +389,35 @@ fn apply_overrides(tcx: TyCtxt<'_>, did: LocalDefId, codegen_fn_attrs: &mut Code
         }
     }
 
+    // #129347: desugared async coutines inherit inline attrs from the async fn/closure
+    // Must not be reordered with the below override.
+    if let Some(parent) = async_poll_inherit_inline(tcx, did.to_def_id()) {
+        let parent_attrs = tcx.codegen_fn_attrs(parent);
+        if matches!(parent_attrs.inline, InlineAttr::Never | InlineAttr::Hint | InlineAttr::Always)
+        {
+            codegen_fn_attrs.inline = parent_attrs.inline;
+        }
+    }
+
+    // #129347: the inline attributes should not be applied to the fn that creates the coroutine
+    // Must not be reordered with the above override.
+    {
+        let def_kind = tcx.def_kind(did);
+        let is_fn_with_possible_attribs =
+            matches!(def_kind, DefKind::Fn | DefKind::AssocFn) && tcx.asyncness(did).is_async();
+
+        let is_async_closure = tcx.is_closure_like(did.into())
+            && matches!(
+                tcx.hir_node_by_def_id(did).expect_closure().kind,
+                rustc_hir::ClosureKind::CoroutineClosure(CoroutineDesugaring::Async)
+            )
+            && tcx.asyncness(did).is_async();
+
+        if is_fn_with_possible_attribs || is_async_closure {
+            codegen_fn_attrs.inline = InlineAttr::None;
+        }
+    }
+
     // When `no_builtins` is applied at the crate level, we should add the
     // `no-builtins` attribute to each function to ensure it takes effect in LTO.
     let crate_attrs = tcx.hir_attrs(rustc_hir::CRATE_HIR_ID);
@@ -647,6 +679,23 @@ fn inherited_align<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Option<Align> {
     tcx.codegen_fn_attrs(tcx.trait_item_of(def_id)?).alignment
 }
 
+// Checks if the given DefId is a desugared async couroutine that should inherit inline attrs.
+fn async_poll_inherit_inline(tcx: TyCtxt<'_>, def_id: DefId) -> Option<DefId> {
+    let Some(kind) = tcx.coroutine_kind(def_id) else {
+        return None;
+    };
+
+    if matches!(
+        kind,
+        CoroutineKind::Desugared(CoroutineDesugaring::Async, CoroutineSource::Fn)
+            | CoroutineKind::Desugared(CoroutineDesugaring::Async, CoroutineSource::Closure)
+    ) {
+        Some(tcx.parent(def_id))
+    } else {
+        None
+    }
+}
+
 /// We now check the #\[rustc_autodiff\] attributes which we generated from the #[autodiff(...)]
 /// macros. There are two forms. The pure one without args to mark primal functions (the functions
 /// being differentiated). The other form is #[rustc_autodiff(Mode, ActivityList)] on top of the