Auto merge of #63043 - Centril:rollup-f4baee4, r=Centril

Rollup of 6 pull requests

Successful merges:

 - #62423 (Fix cycle error with existential types)
 - #62979 (Cleanup save-analysis JsonDumper)
 - #62982 (Don't access a static just for its size and alignment)
 - #63013 (add `repr(transparent)` to `IoSliceMut` where missing)
 - #63014 (Stop bare trait lint applying to macro call sites)
 - #63036 (Add lib section to rustc_lexer's Cargo.toml)

Failed merges:

r? @ghost

Author: bors

Diff for: src/librustc/hir/lowering.rs

@@ -5753,13 +5753,21 @@ impl<'a> LoweringContext<'a> {
     }
 
     fn maybe_lint_bare_trait(&self, span: Span, id: NodeId, is_global: bool) {
-        self.sess.buffer_lint_with_diagnostic(
-            builtin::BARE_TRAIT_OBJECTS,
-            id,
-            span,
-            "trait objects without an explicit `dyn` are deprecated",
-            builtin::BuiltinLintDiagnostics::BareTraitObject(span, is_global),
-        )
+        // FIXME(davidtwco): This is a hack to detect macros which produce spans of the
+        // call site which do not have a macro backtrace. See #61963.
+        let is_macro_callsite = self.sess.source_map()
+            .span_to_snippet(span)
+            .map(|snippet| snippet.starts_with("#["))
+            .unwrap_or(true);
+        if !is_macro_callsite {
+            self.sess.buffer_lint_with_diagnostic(
+                builtin::BARE_TRAIT_OBJECTS,
+                id,
+                span,
+                "trait objects without an explicit `dyn` are deprecated",
+                builtin::BuiltinLintDiagnostics::BareTraitObject(span, is_global),
+            )
+        }
     }
 
     fn wrap_in_try_constructor(

Diff for: src/librustc_lexer/Cargo.toml

@@ -7,3 +7,9 @@ edition = "2018"
 # Note that this crate purposefully does not depend on other rustc crates
 [dependencies]
 unicode-xid = { version = "0.1.0", optional = true }
+
+# Note: do not remove this blank `[lib]` section.
+# This will be used when publishing this crate as `rustc-ap-rustc_lexer`.
+[lib]
+doctest = false
+name = "rustc_lexer"

Diff for: src/librustc_mir/borrow_check/nll/type_check/mod.rs

@@ -1281,15 +1281,43 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
                         let opaque_defn_ty = tcx.type_of(opaque_def_id);
                         let opaque_defn_ty = opaque_defn_ty.subst(tcx, opaque_decl.substs);
                         let opaque_defn_ty = renumber::renumber_regions(infcx, &opaque_defn_ty);
+                        let concrete_is_opaque = infcx
+                            .resolve_vars_if_possible(&opaque_decl.concrete_ty).is_impl_trait();
+
                         debug!(
-                            "eq_opaque_type_and_type: concrete_ty={:?}={:?} opaque_defn_ty={:?}",
+                            "eq_opaque_type_and_type: concrete_ty={:?}={:?} opaque_defn_ty={:?} \
+                            concrete_is_opaque={}",
                             opaque_decl.concrete_ty,
                             infcx.resolve_vars_if_possible(&opaque_decl.concrete_ty),
-                            opaque_defn_ty
+                            opaque_defn_ty,
+                            concrete_is_opaque
                         );
-                        obligations.add(infcx
-                            .at(&ObligationCause::dummy(), param_env)
-                            .eq(opaque_decl.concrete_ty, opaque_defn_ty)?);
+
+                        // concrete_is_opaque is `true` when we're using an existential
+                        // type without 'revealing' it. For example, code like this:
+                        //
+                        // existential type Foo: Debug;
+                        // fn foo1() -> Foo { ... }
+                        // fn foo2() -> Foo { foo1() }
+                        //
+                        // In `foo2`, we're not revealing the type of `Foo` - we're
+                        // just treating it as the opaque type.
+                        //
+                        // When this occurs, we do *not* want to try to equate
+                        // the concrete type with the underlying defining type
+                        // of the existential type - this will always fail, since
+                        // the defining type of an existential type is always
+                        // some other type (e.g. not itself)
+                        // Essentially, none of the normal obligations apply here -
+                        // we're just passing around some unknown opaque type,
+                        // without actually looking at the underlying type it
+                        // gets 'revealed' into
+
+                        if !concrete_is_opaque {
+                            obligations.add(infcx
+                                .at(&ObligationCause::dummy(), param_env)
+                                .eq(opaque_decl.concrete_ty, opaque_defn_ty)?);
+                        }
                     }
 
                     debug!("eq_opaque_type_and_type: equated");

Diff for: src/librustc_mir/interpret/memory.rs

@@ -535,41 +535,48 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         id: AllocId,
         liveness: AllocCheck,
     ) -> InterpResult<'static, (Size, Align)> {
-        // Regular allocations.
-        if let Ok(alloc) = self.get(id) {
-            return Ok((Size::from_bytes(alloc.bytes.len() as u64), alloc.align));
-        }
-        // Function pointers.
-        if let Ok(_) = self.get_fn_alloc(id) {
-            return if let AllocCheck::Dereferencable = liveness {
-                // The caller requested no function pointers.
-                err!(DerefFunctionPointer)
-            } else {
-                Ok((Size::ZERO, Align::from_bytes(1).unwrap()))
-            };
-        }
-        // Foreign statics.
-        // Can't do this in the match argument, we may get cycle errors since the lock would
-        // be held throughout the match.
-        let alloc = self.tcx.alloc_map.lock().get(id);
-        match alloc {
-            Some(GlobalAlloc::Static(did)) => {
-                assert!(self.tcx.is_foreign_item(did));
-                // Use size and align of the type
-                let ty = self.tcx.type_of(did);
-                let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap();
-                return Ok((layout.size, layout.align.abi));
+        // Don't use `self.get` here as that will
+        // a) cause cycles in case `id` refers to a static
+        // b) duplicate a static's allocation in miri
+        match self.alloc_map.get_or(id, || Err(())) {
+            Ok((_, alloc)) => Ok((Size::from_bytes(alloc.bytes.len() as u64), alloc.align)),
+            Err(()) => {
+                // Not a local allocation, check the global `tcx.alloc_map`.
+
+                // Can't do this in the match argument, we may get cycle errors since the lock would
+                // be held throughout the match.
+                let alloc = self.tcx.alloc_map.lock().get(id);
+                match alloc {
+                    Some(GlobalAlloc::Static(did)) => {
+                        // Use size and align of the type.
+                        let ty = self.tcx.type_of(did);
+                        let layout = self.tcx.layout_of(ParamEnv::empty().and(ty)).unwrap();
+                        Ok((layout.size, layout.align.abi))
+                    },
+                    Some(GlobalAlloc::Memory(alloc)) =>
+                        // Need to duplicate the logic here, because the global allocations have
+                        // different associated types than the interpreter-local ones.
+                        Ok((Size::from_bytes(alloc.bytes.len() as u64), alloc.align)),
+                    Some(GlobalAlloc::Function(_)) => {
+                        if let AllocCheck::Dereferencable = liveness {
+                            // The caller requested no function pointers.
+                            err!(DerefFunctionPointer)
+                        } else {
+                            Ok((Size::ZERO, Align::from_bytes(1).unwrap()))
+                        }
+                    },
+                    // The rest must be dead.
+                    None => if let AllocCheck::MaybeDead = liveness {
+                        // Deallocated pointers are allowed, we should be able to find
+                        // them in the map.
+                        Ok(*self.dead_alloc_map.get(&id)
+                            .expect("deallocated pointers should all be recorded in \
+                                    `dead_alloc_map`"))
+                    } else {
+                        err!(DanglingPointerDeref)
+                    },
+                }
             }
-            _ => {}
-        }
-        // The rest must be dead.
-        if let AllocCheck::MaybeDead = liveness {
-            // Deallocated pointers are allowed, we should be able to find
-            // them in the map.
-            Ok(*self.dead_alloc_map.get(&id)
-                .expect("deallocated pointers should all be recorded in `dead_alloc_map`"))
-        } else {
-            err!(DanglingPointerDeref)
         }
     }
 

Diff for: src/librustc_save_analysis/dump_visitor.rs

@@ -10,7 +10,7 @@
 //!
 //! SpanUtils is used to manipulate spans. In particular, to extract sub-spans
 //! from spans (e.g., the span for `bar` from the above example path).
-//! DumpVisitor walks the AST and processes it, and JsonDumper is used for
+//! DumpVisitor walks the AST and processes it, and Dumper is used for
 //! recording the output.
 
 use rustc::hir::def::{Res, DefKind as HirDefKind};
@@ -38,7 +38,7 @@ use syntax_pos::*;
 
 use crate::{escape, generated_code, id_from_def_id, id_from_node_id, lower_attributes,
             PathCollector, SaveContext};
-use crate::json_dumper::{Access, DumpOutput, JsonDumper};
+use crate::dumper::{Access, Dumper};
 use crate::span_utils::SpanUtils;
 use crate::sig;
 
@@ -75,10 +75,10 @@ macro_rules! access_from_vis {
     };
 }
 
-pub struct DumpVisitor<'l, 'tcx, 'll, O: DumpOutput> {
+pub struct DumpVisitor<'l, 'tcx, 'll> {
     save_ctxt: SaveContext<'l, 'tcx>,
     tcx: TyCtxt<'tcx>,
-    dumper: &'ll mut JsonDumper<O>,
+    dumper: &'ll mut Dumper,
 
     span: SpanUtils<'l>,
 
@@ -92,11 +92,11 @@ pub struct DumpVisitor<'l, 'tcx, 'll, O: DumpOutput> {
     // macro_calls: FxHashSet<Span>,
 }
 
-impl<'l, 'tcx, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
+impl<'l, 'tcx, 'll> DumpVisitor<'l, 'tcx, 'll> {
     pub fn new(
         save_ctxt: SaveContext<'l, 'tcx>,
-        dumper: &'ll mut JsonDumper<O>,
-    ) -> DumpVisitor<'l, 'tcx, 'll, O> {
+        dumper: &'ll mut Dumper,
+    ) -> DumpVisitor<'l, 'tcx, 'll> {
         let span_utils = SpanUtils::new(&save_ctxt.tcx.sess);
         DumpVisitor {
             tcx: save_ctxt.tcx,
@@ -111,7 +111,7 @@ impl<'l, 'tcx, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
 
     fn nest_scope<F>(&mut self, scope_id: NodeId, f: F)
     where
-        F: FnOnce(&mut DumpVisitor<'l, 'tcx, 'll, O>),
+        F: FnOnce(&mut DumpVisitor<'l, 'tcx, 'll>),
     {
         let parent_scope = self.cur_scope;
         self.cur_scope = scope_id;
@@ -121,7 +121,7 @@ impl<'l, 'tcx, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
 
     fn nest_tables<F>(&mut self, item_id: NodeId, f: F)
     where
-        F: FnOnce(&mut DumpVisitor<'l, 'tcx, 'll, O>),
+        F: FnOnce(&mut DumpVisitor<'l, 'tcx, 'll>),
     {
         let item_def_id = self.tcx.hir().local_def_id_from_node_id(item_id);
         if self.tcx.has_typeck_tables(item_def_id) {
@@ -1311,7 +1311,7 @@ impl<'l, 'tcx, 'll, O: DumpOutput + 'll> DumpVisitor<'l, 'tcx, 'll, O> {
     }
 }
 
-impl<'l, 'tcx, 'll, O: DumpOutput + 'll> Visitor<'l> for DumpVisitor<'l, 'tcx, 'll, O> {
+impl<'l, 'tcx, 'll> Visitor<'l> for DumpVisitor<'l, 'tcx, 'll> {
     fn visit_mod(&mut self, m: &'l ast::Mod, span: Span, attrs: &[ast::Attribute], id: NodeId) {
         // Since we handle explicit modules ourselves in visit_item, this should
         // only get called for the root module of a crate.

Diff for: src/librustc_save_analysis/json_dumper.rs renamed to src/librustc_save_analysis/dumper.rs

@@ -1,80 +1,33 @@
-use std::io::Write;
-
 use rls_data::config::Config;
 use rls_data::{self, Analysis, CompilationOptions, CratePreludeData, Def, DefKind, Impl, Import,
                MacroRef, Ref, RefKind, Relation};
 use rls_span::{Column, Row};
 
-use log::error;
-
 #[derive(Debug)]
 pub struct Access {
     pub reachable: bool,
     pub public: bool,
 }
 
-pub struct JsonDumper<O: DumpOutput> {
+pub struct Dumper {
     result: Analysis,
     config: Config,
-    output: O,
-}
-
-pub trait DumpOutput {
-    fn dump(&mut self, result: &Analysis);
-}
-
-pub struct WriteOutput<'b, W: Write> {
-    output: &'b mut W,
-}
-
-impl<'b, W: Write> DumpOutput for WriteOutput<'b, W> {
-    fn dump(&mut self, result: &Analysis) {
-        if let Err(e) = serde_json::to_writer(self.output.by_ref(), result) {
-            error!("Can't serialize save-analysis: {:?}", e);
-        }
-    }
-}
-
-pub struct CallbackOutput<'b> {
-    callback: &'b mut dyn FnMut(&Analysis),
-}
-
-impl<'b> DumpOutput for CallbackOutput<'b> {
-    fn dump(&mut self, result: &Analysis) {
-        (self.callback)(result)
-    }
 }
 
-impl<'b, W: Write> JsonDumper<WriteOutput<'b, W>> {
-    pub fn new(writer: &'b mut W, config: Config) -> JsonDumper<WriteOutput<'b, W>> {
-        JsonDumper {
-            output: WriteOutput { output: writer },
+impl Dumper {
+    pub fn new(config: Config) -> Dumper {
+        Dumper {
             config: config.clone(),
             result: Analysis::new(config),
         }
     }
-}
-
-impl<'b> JsonDumper<CallbackOutput<'b>> {
-    pub fn with_callback(
-        callback: &'b mut dyn FnMut(&Analysis),
-        config: Config,
-    ) -> JsonDumper<CallbackOutput<'b>> {
-        JsonDumper {
-            output: CallbackOutput { callback },
-            config: config.clone(),
-            result: Analysis::new(config),
-        }
-    }
-}
 
-impl<O: DumpOutput> Drop for JsonDumper<O> {
-    fn drop(&mut self) {
-        self.output.dump(&self.result);
+    pub fn to_output(self, f: impl FnOnce(&Analysis)) {
+        f(&self.result)
     }
 }
 
-impl<'b, O: DumpOutput + 'b> JsonDumper<O> {
+impl Dumper {
     pub fn crate_prelude(&mut self, data: CratePreludeData) {
         self.result.prelude = Some(data)
     }