Auto merge of rust-lang#138525 - cuviper:beta-next, r=cuviper

[beta] backports

- Windows: Fix error in `fs::rename` on Windows 1607 rust-lang#137528
- rustdoc: when merging target features, keep the highest stability rust-lang#137632
- doctests: fix merging on stable rust-lang#137899
- Revert wf sized check on beta rust-lang#138122

r? cuviper

Author: bors

compiler/rustc_codegen_ssa/src/target_features.rs

@@ -10,7 +10,7 @@ use rustc_middle::query::Providers;
 use rustc_middle::ty::TyCtxt;
 use rustc_session::parse::feature_err;
 use rustc_span::{Span, Symbol, sym};
-use rustc_target::target_features;
+use rustc_target::target_features::{self, Stability};
 
 use crate::errors;
 
@@ -87,12 +87,17 @@ pub(crate) fn from_target_feature_attr(
                     // But ensure the ABI does not forbid enabling this.
                     // Here we do assume that LLVM doesn't add even more implied features
                     // we don't know about, at least no features that would have ABI effects!
-                    if abi_feature_constraints.incompatible.contains(&name.as_str()) {
-                        tcx.dcx().emit_err(errors::ForbiddenTargetFeatureAttr {
-                            span: item.span(),
-                            feature: name.as_str(),
-                            reason: "this feature is incompatible with the target ABI",
-                        });
+                    // We skip this logic in rustdoc, where we want to allow all target features of
+                    // all targets, so we can't check their ABI compatibility and anyway we are not
+                    // generating code so "it's fine".
+                    if !tcx.sess.opts.actually_rustdoc {
+                        if abi_feature_constraints.incompatible.contains(&name.as_str()) {
+                            tcx.dcx().emit_err(errors::ForbiddenTargetFeatureAttr {
+                                span: item.span(),
+                                feature: name.as_str(),
+                                reason: "this feature is incompatible with the target ABI",
+                            });
+                        }
                     }
                     target_features.push(TargetFeature { name, implied: name != feature_sym })
                 }
@@ -142,11 +147,38 @@ pub(crate) fn provide(providers: &mut Providers) {
         rust_target_features: |tcx, cnum| {
             assert_eq!(cnum, LOCAL_CRATE);
             if tcx.sess.opts.actually_rustdoc {
-                // rustdoc needs to be able to document functions that use all the features, so
-                // whitelist them all
-                rustc_target::target_features::all_rust_features()
-                    .map(|(a, b)| (a.to_string(), b))
-                    .collect()
+                // HACK: rustdoc would like to pretend that we have all the target features, so we
+                // have to merge all the lists into one. To ensure an unstable target never prevents
+                // a stable one from working, we merge the stability info of all instances of the
+                // same target feature name, with the "most stable" taking precedence. And then we
+                // hope that this doesn't cause issues anywhere else in the compiler...
+                let mut result: UnordMap<String, Stability> = Default::default();
+                for (name, stability) in rustc_target::target_features::all_rust_features() {
+                    use std::collections::hash_map::Entry;
+                    match result.entry(name.to_owned()) {
+                        Entry::Vacant(vacant_entry) => {
+                            vacant_entry.insert(stability);
+                        }
+                        Entry::Occupied(mut occupied_entry) => {
+                            // Merge the two stabilities, "more stable" taking precedence.
+                            match (occupied_entry.get(), stability) {
+                                (Stability::Stable, _)
+                                | (
+                                    Stability::Unstable { .. },
+                                    Stability::Unstable { .. } | Stability::Forbidden { .. },
+                                )
+                                | (Stability::Forbidden { .. }, Stability::Forbidden { .. }) => {
+                                    // The stability in the entry is at least as good as the new one, just keep it.
+                                }
+                                _ => {
+                                    // Overwrite stabilite.
+                                    occupied_entry.insert(stability);
+                                }
+                            }
+                        }
+                    }
+                }
+                result
             } else {
                 tcx.sess
                     .target

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -1110,7 +1110,6 @@ fn check_associated_item(
                 let ty = tcx.type_of(item.def_id).instantiate_identity();
                 let ty = wfcx.normalize(span, Some(WellFormedLoc::Ty(item_id)), ty);
                 wfcx.register_wf_obligation(span, loc, ty.into());
-                check_sized_if_body(wfcx, item.def_id.expect_local(), ty, Some(span));
                 Ok(())
             }
             ty::AssocKind::Fn => {
@@ -1235,7 +1234,7 @@ fn check_type_defn<'tcx>(
                     ),
                     wfcx.param_env,
                     ty,
-                    tcx.require_lang_item(LangItem::Sized, Some(hir_ty.span)),
+                    tcx.require_lang_item(LangItem::Sized, None),
                 );
             }
 
@@ -1360,7 +1359,7 @@ fn check_item_type(
                 ),
                 wfcx.param_env,
                 item_ty,
-                tcx.require_lang_item(LangItem::Sized, Some(ty_span)),
+                tcx.require_lang_item(LangItem::Sized, None),
             );
         }
 
@@ -1690,36 +1689,6 @@ fn check_fn_or_method<'tcx>(
             );
         }
     }
-
-    // If the function has a body, additionally require that the return type is sized.
-    check_sized_if_body(
-        wfcx,
-        def_id,
-        sig.output(),
-        match hir_decl.output {
-            hir::FnRetTy::Return(ty) => Some(ty.span),
-            hir::FnRetTy::DefaultReturn(_) => None,
-        },
-    );
-}
-
-fn check_sized_if_body<'tcx>(
-    wfcx: &WfCheckingCtxt<'_, 'tcx>,
-    def_id: LocalDefId,
-    ty: Ty<'tcx>,
-    maybe_span: Option<Span>,
-) {
-    let tcx = wfcx.tcx();
-    if let Some(body) = tcx.hir().maybe_body_owned_by(def_id) {
-        let span = maybe_span.unwrap_or(body.value.span);
-
-        wfcx.register_bound(
-            ObligationCause::new(span, def_id, traits::ObligationCauseCode::SizedReturnType),
-            wfcx.param_env,
-            ty,
-            tcx.require_lang_item(LangItem::Sized, Some(span)),
-        );
-    }
 }
 
 /// The `arbitrary_self_types_pointers` feature implies `arbitrary_self_types`.