Auto merge of #113120 - Dylan-DPC:rollup-cz4qr3o, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - #111571 (Implement proposed API for `proc_macro_span`)
 - #112236 (Simplify computation of killed borrows)
 - #112867 (More `ImplSource` nits)
 - #113019 (add note for non-exhaustive matches with guards)
 - #113094 (Fix invalid HTML DIV tag used in HEAD)
 - #113111 (add myself to review for t-types stuff)

r? `@ghost`
`@rustbot` modify labels: rollup

Cargo.lock

@@ -2580,9 +2580,9 @@ checksum = "dbf0c48bc1d91375ae5c3cd81e3722dff1abcf81a30960240640d223f59fe0e5"
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.56"
+version = "1.0.60"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2b63bdb0cd06f1f4dedf69b254734f9b45af66e4a031e42a7480257d9898b435"
+checksum = "dec2b086b7a862cf4de201096214fa870344cf922b2b30c167badb3af3195406"
 dependencies = [
  "unicode-ident",
 ]

compiler/rustc_borrowck/src/dataflow.rs

@@ -125,15 +125,9 @@ pub struct Borrows<'a, 'tcx> {
     borrows_out_of_scope_at_location: FxIndexMap<Location, Vec<BorrowIndex>>,
 }
 
-struct StackEntry {
-    bb: mir::BasicBlock,
-    lo: usize,
-    hi: usize,
-}
-
 struct OutOfScopePrecomputer<'a, 'tcx> {
     visited: BitSet<mir::BasicBlock>,
-    visit_stack: Vec<StackEntry>,
+    visit_stack: Vec<mir::BasicBlock>,
     body: &'a Body<'tcx>,
     regioncx: &'a RegionInferenceContext<'tcx>,
     borrows_out_of_scope_at_location: FxIndexMap<Location, Vec<BorrowIndex>>,
@@ -158,68 +152,66 @@ impl<'tcx> OutOfScopePrecomputer<'_, 'tcx> {
         borrow_region: RegionVid,
         first_location: Location,
     ) {
-        // We visit one BB at a time. The complication is that we may start in the
-        // middle of the first BB visited (the one containing `first_location`), in which
-        // case we may have to later on process the first part of that BB if there
-        // is a path back to its start.
-
-        // For visited BBs, we record the index of the first statement processed.
-        // (In fully processed BBs this index is 0.) Note also that we add BBs to
-        // `visited` once they are added to `stack`, before they are actually
-        // processed, because this avoids the need to look them up again on
-        // completion.
-        self.visited.insert(first_location.block);
-
         let first_block = first_location.block;
-        let mut first_lo = first_location.statement_index;
-        let first_hi = self.body[first_block].statements.len();
+        let first_bb_data = &self.body.basic_blocks[first_block];
+
+        // This is the first block, we only want to visit it from the creation of the borrow at
+        // `first_location`.
+        let first_lo = first_location.statement_index;
+        let first_hi = first_bb_data.statements.len();
+
+        if let Some(kill_stmt) = self.regioncx.first_non_contained_inclusive(
+            borrow_region,
+            first_block,
+            first_lo,
+            first_hi,
+        ) {
+            let kill_location = Location { block: first_block, statement_index: kill_stmt };
+            // If region does not contain a point at the location, then add to list and skip
+            // successor locations.
+            debug!("borrow {:?} gets killed at {:?}", borrow_index, kill_location);
+            self.borrows_out_of_scope_at_location
+                .entry(kill_location)
+                .or_default()
+                .push(borrow_index);
+
+            // The borrow is already dead, there is no need to visit other blocks.
+            return;
+        }
 
-        self.visit_stack.push(StackEntry { bb: first_block, lo: first_lo, hi: first_hi });
+        // The borrow is not dead. Add successor BBs to the work list, if necessary.
+        for succ_bb in first_bb_data.terminator().successors() {
+            if self.visited.insert(succ_bb) {
+                self.visit_stack.push(succ_bb);
+            }
+        }
 
-        'preorder: while let Some(StackEntry { bb, lo, hi }) = self.visit_stack.pop() {
+        // We may end up visiting `first_block` again. This is not an issue: we know at this point
+        // that it does not kill the borrow in the `first_lo..=first_hi` range, so checking the
+        // `0..first_lo` range and the `0..first_hi` range give the same result.
+        while let Some(block) = self.visit_stack.pop() {
+            let bb_data = &self.body[block];
+            let num_stmts = bb_data.statements.len();
             if let Some(kill_stmt) =
-                self.regioncx.first_non_contained_inclusive(borrow_region, bb, lo, hi)
+                self.regioncx.first_non_contained_inclusive(borrow_region, block, 0, num_stmts)
             {
-                let kill_location = Location { block: bb, statement_index: kill_stmt };
+                let kill_location = Location { block, statement_index: kill_stmt };
                 // If region does not contain a point at the location, then add to list and skip
                 // successor locations.
                 debug!("borrow {:?} gets killed at {:?}", borrow_index, kill_location);
                 self.borrows_out_of_scope_at_location
                     .entry(kill_location)
                     .or_default()
                     .push(borrow_index);
-                continue 'preorder;
-            }
 
-            // If we process the first part of the first basic block (i.e. we encounter that block
-            // for the second time), we no longer have to visit its successors again.
-            if bb == first_block && hi != first_hi {
+                // We killed the borrow, so we do not visit this block's successors.
                 continue;
             }
 
             // Add successor BBs to the work list, if necessary.
-            let bb_data = &self.body[bb];
-            debug_assert!(hi == bb_data.statements.len());
             for succ_bb in bb_data.terminator().successors() {
-                if !self.visited.insert(succ_bb) {
-                    if succ_bb == first_block && first_lo > 0 {
-                        // `succ_bb` has been seen before. If it wasn't
-                        // fully processed, add its first part to `stack`
-                        // for processing.
-                        self.visit_stack.push(StackEntry { bb: succ_bb, lo: 0, hi: first_lo - 1 });
-
-                        // And update this entry with 0, to represent the
-                        // whole BB being processed.
-                        first_lo = 0;
-                    }
-                } else {
-                    // succ_bb hasn't been seen before. Add it to
-                    // `stack` for processing.
-                    self.visit_stack.push(StackEntry {
-                        bb: succ_bb,
-                        lo: 0,
-                        hi: self.body[succ_bb].statements.len(),
-                    });
+                if self.visited.insert(succ_bb) {
+                    self.visit_stack.push(succ_bb);
                 }
             }
         }

compiler/rustc_expand/src/proc_macro_server.rs

@@ -2,7 +2,7 @@ use crate::base::ExtCtxt;
 use pm::bridge::{
     server, DelimSpan, Diagnostic, ExpnGlobals, Group, Ident, LitKind, Literal, Punct, TokenTree,
 };
-use pm::{Delimiter, Level, LineColumn};
+use pm::{Delimiter, Level};
 use rustc_ast as ast;
 use rustc_ast::token;
 use rustc_ast::tokenstream::{self, Spacing::*, TokenStream};
@@ -648,23 +648,22 @@ impl server::Span for Rustc<'_, '_> {
 
         Range { start: relative_start_pos.0 as usize, end: relative_end_pos.0 as usize }
     }
-
-    fn start(&mut self, span: Self::Span) -> LineColumn {
-        let loc = self.sess().source_map().lookup_char_pos(span.lo());
-        LineColumn { line: loc.line, column: loc.col.to_usize() }
+    fn start(&mut self, span: Self::Span) -> Self::Span {
+        span.shrink_to_lo()
     }
 
-    fn end(&mut self, span: Self::Span) -> LineColumn {
-        let loc = self.sess().source_map().lookup_char_pos(span.hi());
-        LineColumn { line: loc.line, column: loc.col.to_usize() }
+    fn end(&mut self, span: Self::Span) -> Self::Span {
+        span.shrink_to_hi()
     }
 
-    fn before(&mut self, span: Self::Span) -> Self::Span {
-        span.shrink_to_lo()
+    fn line(&mut self, span: Self::Span) -> usize {
+        let loc = self.sess().source_map().lookup_char_pos(span.lo());
+        loc.line
     }
 
-    fn after(&mut self, span: Self::Span) -> Self::Span {
-        span.shrink_to_hi()
+    fn column(&mut self, span: Self::Span) -> usize {
+        let loc = self.sess().source_map().lookup_char_pos(span.lo());
+        loc.col.to_usize() + 1
     }
 
     fn join(&mut self, first: Self::Span, second: Self::Span) -> Option<Self::Span> {

compiler/rustc_middle/src/traits/mod.rs

@@ -660,9 +660,6 @@ pub enum ImplSource<'tcx, N> {
 
     /// ImplSource for trait upcasting coercion
     TraitUpcasting(ImplSourceTraitUpcastingData<N>),
-
-    /// ImplSource for a trait alias.
-    TraitAlias(ImplSourceTraitAliasData<'tcx, N>),
 }
 
 impl<'tcx, N> ImplSource<'tcx, N> {
@@ -671,7 +668,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             ImplSource::UserDefined(i) => i.nested,
             ImplSource::Param(n, _) | ImplSource::Builtin(n) => n,
             ImplSource::Object(d) => d.nested,
-            ImplSource::TraitAlias(d) => d.nested,
             ImplSource::TraitUpcasting(d) => d.nested,
         }
     }
@@ -681,7 +677,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             ImplSource::UserDefined(i) => &i.nested,
             ImplSource::Param(n, _) | ImplSource::Builtin(n) => &n,
             ImplSource::Object(d) => &d.nested,
-            ImplSource::TraitAlias(d) => &d.nested,
             ImplSource::TraitUpcasting(d) => &d.nested,
         }
     }
@@ -691,7 +686,6 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             ImplSource::UserDefined(i) => &mut i.nested,
             ImplSource::Param(n, _) | ImplSource::Builtin(n) => n,
             ImplSource::Object(d) => &mut d.nested,
-            ImplSource::TraitAlias(d) => &mut d.nested,
             ImplSource::TraitUpcasting(d) => &mut d.nested,
         }
     }
@@ -709,15 +703,9 @@ impl<'tcx, N> ImplSource<'tcx, N> {
             ImplSource::Param(n, ct) => ImplSource::Param(n.into_iter().map(f).collect(), ct),
             ImplSource::Builtin(n) => ImplSource::Builtin(n.into_iter().map(f).collect()),
             ImplSource::Object(o) => ImplSource::Object(ImplSourceObjectData {
-                upcast_trait_def_id: o.upcast_trait_def_id,
                 vtable_base: o.vtable_base,
                 nested: o.nested.into_iter().map(f).collect(),
             }),
-            ImplSource::TraitAlias(d) => ImplSource::TraitAlias(ImplSourceTraitAliasData {
-                alias_def_id: d.alias_def_id,
-                substs: d.substs,
-                nested: d.nested.into_iter().map(f).collect(),
-            }),
             ImplSource::TraitUpcasting(d) => {
                 ImplSource::TraitUpcasting(ImplSourceTraitUpcastingData {
                     vtable_vptr_slot: d.vtable_vptr_slot,
@@ -761,9 +749,6 @@ pub struct ImplSourceTraitUpcastingData<N> {
 #[derive(PartialEq, Eq, Clone, TyEncodable, TyDecodable, HashStable, Lift)]
 #[derive(TypeFoldable, TypeVisitable)]
 pub struct ImplSourceObjectData<N> {
-    /// `Foo` upcast to the obligation trait. This will be some supertrait of `Foo`.
-    pub upcast_trait_def_id: DefId,
-
     /// The vtable is formed by concatenating together the method lists of
     /// the base object trait and all supertraits, pointers to supertrait vtable will
     /// be provided when necessary; this is the start of `upcast_trait_ref`'s methods
@@ -773,14 +758,6 @@ pub struct ImplSourceObjectData<N> {
     pub nested: Vec<N>,
 }
 
-#[derive(Clone, PartialEq, Eq, TyEncodable, TyDecodable, HashStable, Lift)]
-#[derive(TypeFoldable, TypeVisitable)]
-pub struct ImplSourceTraitAliasData<'tcx, N> {
-    pub alias_def_id: DefId,
-    pub substs: SubstsRef<'tcx>,
-    pub nested: Vec<N>,
-}
-
 #[derive(Clone, Debug, PartialEq, Eq, Hash, HashStable, PartialOrd, Ord)]
 pub enum ObjectSafetyViolation {
     /// `Self: Sized` declared on the trait.

compiler/rustc_middle/src/traits/structural_impls.rs

@@ -17,8 +17,6 @@ impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSource<'tcx, N> {
                 write!(f, "ImplSourceParamData({:?}, {:?})", n, ct)
             }
 
-            super::ImplSource::TraitAlias(ref d) => write!(f, "{:?}", d),
-
             super::ImplSource::TraitUpcasting(ref d) => write!(f, "{:?}", d),
         }
     }
@@ -48,18 +46,8 @@ impl<N: fmt::Debug> fmt::Debug for traits::ImplSourceObjectData<N> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
             f,
-            "ImplSourceObjectData(upcast={:?}, vtable_base={}, nested={:?})",
-            self.upcast_trait_def_id, self.vtable_base, self.nested
-        )
-    }
-}
-
-impl<'tcx, N: fmt::Debug> fmt::Debug for traits::ImplSourceTraitAliasData<'tcx, N> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(
-            f,
-            "ImplSourceTraitAliasData(alias_def_id={:?}, substs={:?}, nested={:?})",
-            self.alias_def_id, self.substs, self.nested
+            "ImplSourceObjectData(vtable_base={}, nested={:?})",
+            self.vtable_base, self.nested
         )
     }
 }

compiler/rustc_mir_build/messages.ftl

@@ -214,6 +214,9 @@ mir_build_mutation_of_layout_constrained_field_requires_unsafe_unsafe_op_in_unsa
 
 mir_build_non_const_path = runtime values cannot be referenced in patterns
 
+mir_build_non_exhaustive_match_all_arms_guarded =
+    match arms with guards don't count towards exhaustivity
+
 mir_build_non_exhaustive_omitted_pattern = some variants are not matched explicitly
     .help = ensure that all variants are matched explicitly by adding the suggested match arms
     .note = the matched value is of type `{$scrut_ty}` and the `non_exhaustive_omitted_patterns` attribute was found

compiler/rustc_mir_build/src/errors.rs

@@ -432,6 +432,10 @@ impl<'a> IntoDiagnostic<'a> for NonExhaustivePatternsTypeNotEmpty<'_, '_, '_> {
     }
 }
 
+#[derive(Subdiagnostic)]
+#[note(mir_build_non_exhaustive_match_all_arms_guarded)]
+pub struct NonExhaustiveMatchAllArmsGuarded;
+
 #[derive(Diagnostic)]
 #[diag(mir_build_static_in_pattern, code = "E0158")]
 pub struct StaticInPattern {

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -830,6 +830,11 @@ fn non_exhaustive_match<'p, 'tcx>(
             _ => " or multiple match arms",
         },
     );
+
+    let all_arms_have_guards = arms.iter().all(|arm_id| thir[*arm_id].guard.is_some());
+    if !is_empty_match && all_arms_have_guards {
+        err.subdiagnostic(NonExhaustiveMatchAllArmsGuarded);
+    }
     if let Some((span, sugg)) = suggestion {
         err.span_suggestion_verbose(span, msg, sugg, Applicability::HasPlaceholders);
     } else {