Rollup of 9 pull requests

compiler/rustc_expand/src/expand.rs

@@ -301,6 +301,8 @@ pub enum InvocationKind {
     },
     Attr {
         attr: ast::Attribute,
+        // Re-insertion position for inert attributes.
+        pos: usize,
         item: Annotatable,
         // Required for resolving derive helper attributes.
         derives: Vec<Path>,
@@ -690,7 +692,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                 }
                 _ => unreachable!(),
             },
-            InvocationKind::Attr { attr, mut item, derives } => match ext {
+            InvocationKind::Attr { attr, pos, mut item, derives } => match ext {
                 SyntaxExtensionKind::Attr(expander) => {
                     self.gate_proc_macro_input(&item);
                     self.gate_proc_macro_attr_item(span, &item);
@@ -721,7 +723,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                                 ExpandResult::Retry(item) => {
                                     // Reassemble the original invocation for retrying.
                                     return ExpandResult::Retry(Invocation {
-                                        kind: InvocationKind::Attr { attr, item, derives },
+                                        kind: InvocationKind::Attr { attr, pos, item, derives },
                                         ..invoc
                                     });
                                 }
@@ -739,7 +741,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                     if *mark_used {
                         self.cx.sess.mark_attr_used(&attr);
                     }
-                    item.visit_attrs(|attrs| attrs.push(attr));
+                    item.visit_attrs(|attrs| attrs.insert(pos, attr));
                     fragment_kind.expect_from_annotatables(iter::once(item))
                 }
                 _ => unreachable!(),
@@ -1000,17 +1002,20 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
 
     fn collect_attr(
         &mut self,
-        (attr, derives): (ast::Attribute, Vec<Path>),
+        (attr, pos, derives): (ast::Attribute, usize, Vec<Path>),
         item: Annotatable,
         kind: AstFragmentKind,
     ) -> AstFragment {
-        self.collect(kind, InvocationKind::Attr { attr, item, derives })
+        self.collect(kind, InvocationKind::Attr { attr, pos, item, derives })
     }
 
     /// If `item` is an attribute invocation, remove the attribute and return it together with
-    /// derives following it. We have to collect the derives in order to resolve legacy derive
-    /// helpers (helpers written before derives that introduce them).
-    fn take_first_attr(&mut self, item: &mut impl HasAttrs) -> Option<(ast::Attribute, Vec<Path>)> {
+    /// its position and derives following it. We have to collect the derives in order to resolve
+    /// legacy derive helpers (helpers written before derives that introduce them).
+    fn take_first_attr(
+        &mut self,
+        item: &mut impl HasAttrs,
+    ) -> Option<(ast::Attribute, usize, Vec<Path>)> {
         let mut attr = None;
 
         item.visit_attrs(|attrs| {
@@ -1033,7 +1038,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                         })
                         .collect();
 
-                    (attr, following_derives)
+                    (attr, attr_pos, following_derives)
                 })
         });
 

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -50,6 +50,7 @@ use super::region_constraints::GenericKind;
 use super::{InferCtxt, RegionVariableOrigin, SubregionOrigin, TypeTrace, ValuePairs};
 
 use crate::infer;
+use crate::infer::error_reporting::nice_region_error::find_anon_type::find_anon_type;
 use crate::traits::error_reporting::report_object_safety_error;
 use crate::traits::{
     IfExpressionCause, MatchExpressionArmCause, ObligationCause, ObligationCauseCode,
@@ -179,7 +180,14 @@ fn msg_span_from_early_bound_and_free_regions(
         }
         ty::ReFree(ref fr) => match fr.bound_region {
             ty::BrAnon(idx) => {
-                (format!("the anonymous lifetime #{} defined on", idx + 1), tcx.hir().span(node))
+                if let Some((ty, _)) = find_anon_type(tcx, region, &fr.bound_region) {
+                    ("the anonymous lifetime defined on".to_string(), ty.span)
+                } else {
+                    (
+                        format!("the anonymous lifetime #{} defined on", idx + 1),
+                        tcx.hir().span(node),
+                    )
+                }
             }
             _ => (
                 format!("the lifetime `{}` as defined on", region),
@@ -1484,13 +1492,16 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 for (key, values) in types.iter() {
                     let count = values.len();
                     let kind = key.descr();
+                    let mut returned_async_output_error = false;
                     for sp in values {
                         err.span_label(
                             *sp,
                             format!(
                                 "{}{}{} {}{}",
-                                if sp.is_desugaring(DesugaringKind::Async) {
-                                    "the `Output` of this `async fn`'s "
+                                if sp.is_desugaring(DesugaringKind::Async)
+                                    && !returned_async_output_error
+                                {
+                                    "checked the `Output` of this `async fn`, "
                                 } else if count == 1 {
                                     "the "
                                 } else {
@@ -1502,6 +1513,12 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                                 pluralize!(count),
                             ),
                         );
+                        if sp.is_desugaring(DesugaringKind::Async)
+                            && returned_async_output_error == false
+                        {
+                            err.note("while checking the return type of the `async fn`");
+                            returned_async_output_error = true;
+                        }
                     }
                 }
             }

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/different_lifetimes.rs

@@ -1,6 +1,7 @@
 //! Error Reporting for Anonymous Region Lifetime Errors
 //! where both the regions are anonymous.
 
+use crate::infer::error_reporting::nice_region_error::find_anon_type::find_anon_type;
 use crate::infer::error_reporting::nice_region_error::util::AnonymousParamInfo;
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use crate::infer::lexical_region_resolve::RegionResolutionError;
@@ -66,9 +67,9 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
         let scope_def_id_sub = anon_reg_sub.def_id;
         let bregion_sub = anon_reg_sub.boundregion;
 
-        let ty_sup = self.find_anon_type(sup, &bregion_sup)?;
+        let ty_sup = find_anon_type(self.tcx(), sup, &bregion_sup)?;
 
-        let ty_sub = self.find_anon_type(sub, &bregion_sub)?;
+        let ty_sub = find_anon_type(self.tcx(), sub, &bregion_sub)?;
 
         debug!(
             "try_report_anon_anon_conflict: found_param1={:?} sup={:?} br1={:?}",

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/find_anon_type.rs

@@ -1,72 +1,68 @@
-use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use rustc_hir as hir;
 use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
 use rustc_hir::Node;
 use rustc_middle::hir::map::Map;
 use rustc_middle::middle::resolve_lifetime as rl;
 use rustc_middle::ty::{self, Region, TyCtxt};
 
-impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
-    /// This function calls the `visit_ty` method for the parameters
-    /// corresponding to the anonymous regions. The `nested_visitor.found_type`
-    /// contains the anonymous type.
-    ///
-    /// # Arguments
-    /// region - the anonymous region corresponding to the anon_anon conflict
-    /// br - the bound region corresponding to the above region which is of type `BrAnon(_)`
-    ///
-    /// # Example
-    /// ```
-    /// fn foo(x: &mut Vec<&u8>, y: &u8)
-    ///    { x.push(y); }
-    /// ```
-    /// The function returns the nested type corresponding to the anonymous region
-    /// for e.g., `&u8` and Vec<`&u8`.
-    pub(super) fn find_anon_type(
-        &self,
-        region: Region<'tcx>,
-        br: &ty::BoundRegionKind,
-    ) -> Option<(&hir::Ty<'tcx>, &hir::FnDecl<'tcx>)> {
-        if let Some(anon_reg) = self.tcx().is_suitable_region(region) {
-            let hir_id = self.tcx().hir().local_def_id_to_hir_id(anon_reg.def_id);
-            let fndecl = match self.tcx().hir().get(hir_id) {
-                Node::Item(&hir::Item { kind: hir::ItemKind::Fn(ref m, ..), .. })
-                | Node::TraitItem(&hir::TraitItem {
-                    kind: hir::TraitItemKind::Fn(ref m, ..),
-                    ..
-                })
-                | Node::ImplItem(&hir::ImplItem {
-                    kind: hir::ImplItemKind::Fn(ref m, ..), ..
-                }) => &m.decl,
-                _ => return None,
-            };
+/// This function calls the `visit_ty` method for the parameters
+/// corresponding to the anonymous regions. The `nested_visitor.found_type`
+/// contains the anonymous type.
+///
+/// # Arguments
+/// region - the anonymous region corresponding to the anon_anon conflict
+/// br - the bound region corresponding to the above region which is of type `BrAnon(_)`
+///
+/// # Example
+/// ```
+/// fn foo(x: &mut Vec<&u8>, y: &u8)
+///    { x.push(y); }
+/// ```
+/// The function returns the nested type corresponding to the anonymous region
+/// for e.g., `&u8` and Vec<`&u8`.
+pub(crate) fn find_anon_type(
+    tcx: TyCtxt<'tcx>,
+    region: Region<'tcx>,
+    br: &ty::BoundRegionKind,
+) -> Option<(&'tcx hir::Ty<'tcx>, &'tcx hir::FnDecl<'tcx>)> {
+    if let Some(anon_reg) = tcx.is_suitable_region(region) {
+        let hir_id = tcx.hir().local_def_id_to_hir_id(anon_reg.def_id);
+        let fndecl = match tcx.hir().get(hir_id) {
+            Node::Item(&hir::Item { kind: hir::ItemKind::Fn(ref m, ..), .. })
+            | Node::TraitItem(&hir::TraitItem {
+                kind: hir::TraitItemKind::Fn(ref m, ..), ..
+            })
+            | Node::ImplItem(&hir::ImplItem { kind: hir::ImplItemKind::Fn(ref m, ..), .. }) => {
+                &m.decl
+            }
+            _ => return None,
+        };
 
-            fndecl
-                .inputs
-                .iter()
-                .find_map(|arg| self.find_component_for_bound_region(arg, br))
-                .map(|ty| (ty, &**fndecl))
-        } else {
-            None
-        }
+        fndecl
+            .inputs
+            .iter()
+            .find_map(|arg| find_component_for_bound_region(tcx, arg, br))
+            .map(|ty| (ty, &**fndecl))
+    } else {
+        None
     }
+}
 
-    // This method creates a FindNestedTypeVisitor which returns the type corresponding
-    // to the anonymous region.
-    fn find_component_for_bound_region(
-        &self,
-        arg: &'tcx hir::Ty<'tcx>,
-        br: &ty::BoundRegionKind,
-    ) -> Option<&'tcx hir::Ty<'tcx>> {
-        let mut nested_visitor = FindNestedTypeVisitor {
-            tcx: self.tcx(),
-            bound_region: *br,
-            found_type: None,
-            current_index: ty::INNERMOST,
-        };
-        nested_visitor.visit_ty(arg);
-        nested_visitor.found_type
-    }
+// This method creates a FindNestedTypeVisitor which returns the type corresponding
+// to the anonymous region.
+fn find_component_for_bound_region(
+    tcx: TyCtxt<'tcx>,
+    arg: &'tcx hir::Ty<'tcx>,
+    br: &ty::BoundRegionKind,
+) -> Option<&'tcx hir::Ty<'tcx>> {
+    let mut nested_visitor = FindNestedTypeVisitor {
+        tcx,
+        bound_region: *br,
+        found_type: None,
+        current_index: ty::INNERMOST,
+    };
+    nested_visitor.visit_ty(arg);
+    nested_visitor.found_type
 }
 
 // The FindNestedTypeVisitor captures the corresponding `hir::Ty` of the

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/mod.rs

@@ -6,7 +6,7 @@ use rustc_middle::ty::{self, TyCtxt};
 use rustc_span::source_map::Span;
 
 mod different_lifetimes;
-mod find_anon_type;
+pub mod find_anon_type;
 mod named_anon_conflict;
 mod placeholder_error;
 mod static_impl_trait;

compiler/rustc_infer/src/infer/error_reporting/nice_region_error/named_anon_conflict.rs

@@ -1,5 +1,6 @@
 //! Error Reporting for Anonymous Region Lifetime Errors
 //! where one region is named and the other is anonymous.
+use crate::infer::error_reporting::nice_region_error::find_anon_type::find_anon_type;
 use crate::infer::error_reporting::nice_region_error::NiceRegionError;
 use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
 use rustc_hir::intravisit::Visitor;
@@ -74,7 +75,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             return None;
         }
 
-        if let Some((_, fndecl)) = self.find_anon_type(anon, &br) {
+        if let Some((_, fndecl)) = find_anon_type(self.tcx(), anon, &br) {
             if self.is_self_anon(is_first, scope_def_id) {
                 return None;
             }

compiler/rustc_interface/src/tests.rs

@@ -557,8 +557,9 @@ fn test_debugging_options_tracking_hash() {
     tracked!(function_sections, Some(false));
     tracked!(human_readable_cgu_names, true);
     tracked!(inline_in_all_cgus, Some(true));
-    tracked!(inline_mir_threshold, 123);
-    tracked!(inline_mir_hint_threshold, 123);
+    tracked!(inline_mir, Some(true));
+    tracked!(inline_mir_threshold, Some(123));
+    tracked!(inline_mir_hint_threshold, Some(123));
     tracked!(insert_sideeffect, true);
     tracked!(instrument_coverage, true);
     tracked!(instrument_mcount, true);

compiler/rustc_mir/src/transform/inline.rs

@@ -37,21 +37,27 @@ struct CallSite<'tcx> {
     source_info: SourceInfo,
 }
 
+/// Returns true if MIR inlining is enabled in the current compilation session.
+crate fn is_enabled(tcx: TyCtxt<'_>) -> bool {
+    if tcx.sess.opts.debugging_opts.instrument_coverage {
+        // Since `Inline` happens after `InstrumentCoverage`, the function-specific coverage
+        // counters can be invalidated, such as by merging coverage counter statements from
+        // a pre-inlined function into a different function. This kind of change is invalid,
+        // so inlining must be skipped. Note: This check is performed here so inlining can
+        // be disabled without preventing other optimizations (regardless of `mir_opt_level`).
+        return false;
+    }
+
+    if let Some(enabled) = tcx.sess.opts.debugging_opts.inline_mir {
+        return enabled;
+    }
+
+    tcx.sess.opts.debugging_opts.mir_opt_level >= 2
+}
+
 impl<'tcx> MirPass<'tcx> for Inline {
     fn run_pass(&self, tcx: TyCtxt<'tcx>, body: &mut Body<'tcx>) {
-        // If you change this optimization level, also change the level in
-        // `mir_drops_elaborated_and_const_checked` for the call to `mir_inliner_callees`.
-        // Otherwise you will get an ICE about stolen MIR.
-        if tcx.sess.opts.debugging_opts.mir_opt_level < 2 {
-            return;
-        }
-
-        if tcx.sess.opts.debugging_opts.instrument_coverage {
-            // Since `Inline` happens after `InstrumentCoverage`, the function-specific coverage
-            // counters can be invalidated, such as by merging coverage counter statements from
-            // a pre-inlined function into a different function. This kind of change is invalid,
-            // so inlining must be skipped. Note: This check is performed here so inlining can
-            // be disabled without preventing other optimizations (regardless of `mir_opt_level`).
+        if !is_enabled(tcx) {
             return;
         }
 
@@ -310,9 +316,9 @@ impl Inliner<'tcx> {
         }
 
         let mut threshold = if hinted {
-            self.tcx.sess.opts.debugging_opts.inline_mir_hint_threshold
+            self.tcx.sess.opts.debugging_opts.inline_mir_hint_threshold.unwrap_or(100)
         } else {
-            self.tcx.sess.opts.debugging_opts.inline_mir_threshold
+            self.tcx.sess.opts.debugging_opts.inline_mir_threshold.unwrap_or(50)
         };
 
         if codegen_fn_attrs.flags.contains(CodegenFnAttrFlags::NAKED) {

compiler/rustc_mir/src/transform/mod.rs

@@ -429,8 +429,7 @@ fn mir_drops_elaborated_and_const_checked<'tcx>(
         let def = ty::WithOptConstParam::unknown(did);
 
         // Do not compute the mir call graph without said call graph actually being used.
-        // Keep this in sync with the mir inliner's optimization level.
-        if tcx.sess.opts.debugging_opts.mir_opt_level >= 2 {
+        if inline::is_enabled(tcx) {
             let _ = tcx.mir_inliner_callees(ty::InstanceDef::Item(def));
         }
     }

compiler/rustc_session/src/options.rs

@@ -957,9 +957,11 @@ options! {DebuggingOptions, DebuggingSetter, basic_debugging_options,
         (default: no)"),
     incremental_verify_ich: bool = (false, parse_bool, [UNTRACKED],
         "verify incr. comp. hashes of green query instances (default: no)"),
-    inline_mir_threshold: usize = (50, parse_uint, [TRACKED],
+    inline_mir: Option<bool> = (None, parse_opt_bool, [TRACKED],
+        "enable MIR inlining (default: no)"),
+    inline_mir_threshold: Option<usize> = (None, parse_opt_uint, [TRACKED],
         "a default MIR inlining threshold (default: 50)"),
-    inline_mir_hint_threshold: usize = (100, parse_uint, [TRACKED],
+    inline_mir_hint_threshold: Option<usize> = (None, parse_opt_uint, [TRACKED],
         "inlining threshold for functions with inline hint (default: 100)"),
     inline_in_all_cgus: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "control whether `#[inline]` functions are in all CGUs"),