Rollup of 6 pull requests

Cargo.lock

@@ -2652,9 +2652,9 @@ checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
 
 [[package]]
 name = "pkg-config"
-version = "0.3.18"
+version = "0.3.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d36492546b6af1463394d46f0c834346f31548646f6ba10849802c9c9a27ac33"
+checksum = "1df8c4ec4b0627e53bdf214615ad287367e482558cf84b109250b37464dc03ae"
 
 [[package]]
 name = "polonius-engine"

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -1,8 +1,5 @@
 //! Print diagnostics to explain why values are borrowed.
 
-use std::collections::VecDeque;
-
-use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::{Applicability, Diagnostic};
 use rustc_index::vec::IndexVec;
 use rustc_infer::infer::NllRegionVariableOrigin;
@@ -359,19 +356,37 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         let borrow_region_vid = borrow.region;
         debug!(?borrow_region_vid);
 
-        let region_sub = self.regioncx.find_sub_region_live_at(borrow_region_vid, location);
+        let mut region_sub = self.regioncx.find_sub_region_live_at(borrow_region_vid, location);
         debug!(?region_sub);
 
-        match find_use::find(body, regioncx, tcx, region_sub, location) {
+        let mut use_location = location;
+        let mut use_in_later_iteration_of_loop = false;
+
+        if region_sub == borrow_region_vid {
+            // When `region_sub` is the same as `borrow_region_vid` (the location where the borrow is
+            // issued is the same location that invalidates the reference), this is likely a loop iteration
+            // - in this case, try using the loop terminator location in `find_sub_region_live_at`.
+            if let Some(loop_terminator_location) =
+                regioncx.find_loop_terminator_location(borrow.region, body)
+            {
+                region_sub = self
+                    .regioncx
+                    .find_sub_region_live_at(borrow_region_vid, loop_terminator_location);
+                debug!("explain_why_borrow_contains_point: region_sub in loop={:?}", region_sub);
+                use_location = loop_terminator_location;
+                use_in_later_iteration_of_loop = true;
+            }
+        }
+
+        match find_use::find(body, regioncx, tcx, region_sub, use_location) {
             Some(Cause::LiveVar(local, location)) => {
                 let span = body.source_info(location).span;
                 let spans = self
                     .move_spans(Place::from(local).as_ref(), location)
                     .or_else(|| self.borrow_spans(span, location));
 
-                let borrow_location = location;
-                if self.is_use_in_later_iteration_of_loop(borrow_location, location) {
-                    let later_use = self.later_use_kind(borrow, spans, location);
+                if use_in_later_iteration_of_loop {
+                    let later_use = self.later_use_kind(borrow, spans, use_location);
                     BorrowExplanation::UsedLaterInLoop(later_use.0, later_use.1, later_use.2)
                 } else {
                     // Check if the location represents a `FakeRead`, and adapt the error
@@ -425,131 +440,6 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
         }
     }
 
-    /// true if `borrow_location` can reach `use_location` by going through a loop and
-    /// `use_location` is also inside of that loop
-    fn is_use_in_later_iteration_of_loop(
-        &self,
-        borrow_location: Location,
-        use_location: Location,
-    ) -> bool {
-        let back_edge = self.reach_through_backedge(borrow_location, use_location);
-        back_edge.map_or(false, |back_edge| self.can_reach_head_of_loop(use_location, back_edge))
-    }
-
-    /// Returns the outmost back edge if `from` location can reach `to` location passing through
-    /// that back edge
-    fn reach_through_backedge(&self, from: Location, to: Location) -> Option<Location> {
-        let mut visited_locations = FxHashSet::default();
-        let mut pending_locations = VecDeque::new();
-        visited_locations.insert(from);
-        pending_locations.push_back(from);
-        debug!("reach_through_backedge: from={:?} to={:?}", from, to,);
-
-        let mut outmost_back_edge = None;
-        while let Some(location) = pending_locations.pop_front() {
-            debug!(
-                "reach_through_backedge: location={:?} outmost_back_edge={:?}
-                   pending_locations={:?} visited_locations={:?}",
-                location, outmost_back_edge, pending_locations, visited_locations
-            );
-
-            if location == to && outmost_back_edge.is_some() {
-                // We've managed to reach the use location
-                debug!("reach_through_backedge: found!");
-                return outmost_back_edge;
-            }
-
-            let block = &self.body.basic_blocks[location.block];
-
-            if location.statement_index < block.statements.len() {
-                let successor = location.successor_within_block();
-                if visited_locations.insert(successor) {
-                    pending_locations.push_back(successor);
-                }
-            } else {
-                pending_locations.extend(
-                    block
-                        .terminator()
-                        .successors()
-                        .map(|bb| Location { statement_index: 0, block: bb })
-                        .filter(|s| visited_locations.insert(*s))
-                        .map(|s| {
-                            if self.is_back_edge(location, s) {
-                                match outmost_back_edge {
-                                    None => {
-                                        outmost_back_edge = Some(location);
-                                    }
-
-                                    Some(back_edge)
-                                        if location.dominates(back_edge, &self.dominators) =>
-                                    {
-                                        outmost_back_edge = Some(location);
-                                    }
-
-                                    Some(_) => {}
-                                }
-                            }
-
-                            s
-                        }),
-                );
-            }
-        }
-
-        None
-    }
-
-    /// true if `from` location can reach `loop_head` location and `loop_head` dominates all the
-    /// intermediate nodes
-    fn can_reach_head_of_loop(&self, from: Location, loop_head: Location) -> bool {
-        self.find_loop_head_dfs(from, loop_head, &mut FxHashSet::default())
-    }
-
-    fn find_loop_head_dfs(
-        &self,
-        from: Location,
-        loop_head: Location,
-        visited_locations: &mut FxHashSet<Location>,
-    ) -> bool {
-        visited_locations.insert(from);
-
-        if from == loop_head {
-            return true;
-        }
-
-        if loop_head.dominates(from, &self.dominators) {
-            let block = &self.body.basic_blocks[from.block];
-
-            if from.statement_index < block.statements.len() {
-                let successor = from.successor_within_block();
-
-                if !visited_locations.contains(&successor)
-                    && self.find_loop_head_dfs(successor, loop_head, visited_locations)
-                {
-                    return true;
-                }
-            } else {
-                for bb in block.terminator().successors() {
-                    let successor = Location { statement_index: 0, block: bb };
-
-                    if !visited_locations.contains(&successor)
-                        && self.find_loop_head_dfs(successor, loop_head, visited_locations)
-                    {
-                        return true;
-                    }
-                }
-            }
-        }
-
-        false
-    }
-
-    /// True if an edge `source -> target` is a backedge -- in other words, if the target
-    /// dominates the source.
-    fn is_back_edge(&self, source: Location, target: Location) -> bool {
-        target.dominates(source, &self.dominators)
-    }
-
     /// Determine how the borrow was later used.
     /// First span returned points to the location of the conflicting use
     /// Second span if `Some` is returned in the case of closures and points

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -15,7 +15,7 @@ use rustc_infer::infer::region_constraints::{GenericKind, VarInfos, VerifyBound,
 use rustc_infer::infer::{InferCtxt, NllRegionVariableOrigin, RegionVariableOrigin};
 use rustc_middle::mir::{
     Body, ClosureOutlivesRequirement, ClosureOutlivesSubject, ClosureRegionRequirements,
-    ConstraintCategory, Local, Location, ReturnConstraint,
+    ConstraintCategory, Local, Location, ReturnConstraint, TerminatorKind,
 };
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::traits::ObligationCauseCode;
@@ -2236,6 +2236,27 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     pub(crate) fn universe_info(&self, universe: ty::UniverseIndex) -> UniverseInfo<'tcx> {
         self.universe_causes[&universe].clone()
     }
+
+    /// Tries to find the terminator of the loop in which the region 'r' resides.
+    /// Returns the location of the terminator if found.
+    pub(crate) fn find_loop_terminator_location(
+        &self,
+        r: RegionVid,
+        body: &Body<'_>,
+    ) -> Option<Location> {
+        let scc = self.constraint_sccs.scc(r.to_region_vid());
+        let locations = self.scc_values.locations_outlived_by(scc);
+        for location in locations {
+            let bb = &body[location.block];
+            if let Some(terminator) = &bb.terminator {
+                // terminator of a loop should be TerminatorKind::FalseUnwind
+                if let TerminatorKind::FalseUnwind { .. } = terminator.kind {
+                    return Some(location);
+                }
+            }
+        }
+        None
+    }
 }
 
 impl<'tcx> RegionDefinition<'tcx> {

compiler/rustc_const_eval/src/transform/validate.rs

@@ -284,7 +284,7 @@ impl<'a, 'tcx> Visitor<'tcx> for TypeChecker<'a, 'tcx> {
                         this.fail(
                         location,
                         format!(
-                            "Field projection `{:?}.{:?}` specified type `{:?}`, but actual type is {:?}",
+                            "Field projection `{:?}.{:?}` specified type `{:?}`, but actual type is `{:?}`",
                             parent, f, ty, f_ty
                         )
                     )

compiler/rustc_hir_pretty/src/lib.rs

@@ -1687,7 +1687,11 @@ impl<'a> State<'a> {
 
             let mut nonelided_generic_args: bool = false;
             let elide_lifetimes = generic_args.args.iter().all(|arg| match arg {
-                GenericArg::Lifetime(lt) => lt.is_elided(),
+                GenericArg::Lifetime(lt) if lt.is_elided() => true,
+                GenericArg::Lifetime(_) => {
+                    nonelided_generic_args = true;
+                    false
+                }
                 _ => {
                     nonelided_generic_args = true;
                     true

src/librustdoc/html/markdown.rs

@@ -1433,6 +1433,7 @@ static DEFAULT_ID_MAP: Lazy<FxHashMap<Cow<'static, str>, usize>> = Lazy::new(||
 fn init_id_map() -> FxHashMap<Cow<'static, str>, usize> {
     let mut map = FxHashMap::default();
     // This is the list of IDs used in Javascript.
+    map.insert("help".into(), 1);
     map.insert("settings".into(), 1);
     map.insert("not-displayed".into(), 1);
     map.insert("alternative-display".into(), 1);

src/librustdoc/html/render/context.rs

@@ -581,6 +581,7 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         let crate_name = self.tcx().crate_name(LOCAL_CRATE);
         let final_file = self.dst.join(crate_name.as_str()).join("all.html");
         let settings_file = self.dst.join("settings.html");
+        let help_file = self.dst.join("help.html");
         let scrape_examples_help_file = self.dst.join("scrape-examples-help.html");
 
         let mut root_path = self.dst.to_str().expect("invalid path").to_owned();
@@ -657,6 +658,39 @@ impl<'tcx> FormatRenderer<'tcx> for Context<'tcx> {
         );
         shared.fs.write(settings_file, v)?;
 
+        // Generating help page.
+        page.title = "Rustdoc help";
+        page.description = "Documentation for Rustdoc";
+        page.root_path = "./";
+
+        let sidebar = "<h2 class=\"location\">Help</h2><div class=\"sidebar-elems\"></div>";
+        let v = layout::render(
+            &shared.layout,
+            &page,
+            sidebar,
+            |buf: &mut Buffer| {
+                write!(
+                    buf,
+                    "<div class=\"main-heading\">\
+                     <h1 class=\"fqn\">Rustdoc help</h1>\
+                     <span class=\"out-of-band\">\
+                         <a id=\"back\" href=\"javascript:void(0)\" onclick=\"history.back();\">\
+                            Back\
+                        </a>\
+                     </span>\
+                     </div>\
+                     <noscript>\
+                        <section>\
+                            <p>You need to enable Javascript to use keyboard commands or search.</p>\
+                            <p>For more information, browse the <a href=\"https://doc.rust-lang.org/rustdoc/\">rustdoc handbook</a>.</p>\
+                        </section>\
+                     </noscript>",
+                )
+            },
+            &shared.style_files,
+        );
+        shared.fs.write(help_file, v)?;
+
         if shared.layout.scrape_examples_extension {
             page.title = "About scraped examples";
             page.description = "How the scraped examples feature works in Rustdoc";

src/librustdoc/html/static/css/rustdoc.css

@@ -199,7 +199,7 @@ h1, h2, h3, h4, h5, h6,
 .out-of-band,
 span.since,
 a.srclink,
-#help-button > button,
+#help-button > a,
 details.rustdoc-toggle.top-doc > summary,
 details.rustdoc-toggle.non-exhaustive > summary,
 .scraped-example-title,
@@ -974,32 +974,33 @@ so that we can apply CSS-filters to change the arrow color in themes */
 	color: var(--main-color);
 }
 
-#help-button .popover {
+/* use larger max-width for help popover, but not for help.html */
+#help.popover {
 	max-width: 600px;
 }
 
-#help-button .popover::before {
+#help.popover::before {
 	right: 48px;
 }
 
-#help-button dt {
+#help dt {
 	float: left;
 	clear: left;
 	display: block;
 	margin-right: 0.5rem;
 }
-#help-button span.top, #help-button span.bottom {
+#help span.top, #help span.bottom {
 	text-align: center;
 	display: block;
 	font-size: 1.125rem;
 }
-#help-button span.top {
+#help span.top {
 	margin: 10px 0;
 	border-bottom: 1px solid var(--border-color);
 	padding-bottom: 4px;
 	margin-bottom: 6px;
 }
-#help-button span.bottom {
+#help span.bottom {
 	clear: both;
 	border-top: 1px solid var(--border-color);
 }
@@ -1433,7 +1434,7 @@ h3.variant {
 	outline: none;
 }
 
-#settings-menu > a, #help-button > button, #copy-path {
+#settings-menu > a, #help-button > a, #copy-path {
 	padding: 5px;
 	width: 33px;
 	border: 1px solid var(--border-color);
@@ -1442,7 +1443,7 @@ h3.variant {
 	line-height: 1.5;
 }
 
-#settings-menu > a, #help-button > button {
+#settings-menu > a, #help-button > a {
 	padding: 5px;
 	height: 100%;
 	display: block;
@@ -1490,7 +1491,7 @@ input:checked + .slider {
 	background-color: var(--settings-input-color);
 }
 
-#help-button > button {
+#help-button > a {
 	text-align: center;
 	/* Rare exception to specifying font sizes in rem. Since this is acting
 	   as an icon, it's okay to specify their sizes in pixels. */