Merge branch 'master' of github.com:rust-lang/rust into issue-83852

Author: eggyal

Cargo.lock

@@ -5308,6 +5308,7 @@ name = "tidy"
 version = "0.1.0"
 dependencies = [
  "cargo_metadata 0.11.1",
+ "crossbeam-utils 0.8.0",
  "lazy_static",
  "regex",
  "walkdir",

compiler/rustc_builtin_macros/src/derive.rs

@@ -1,6 +1,6 @@
 use crate::cfg_eval::cfg_eval;
 
-use rustc_ast::{self as ast, token, ItemKind, MetaItemKind, NestedMetaItem, StmtKind};
+use rustc_ast::{self as ast, attr, token, ItemKind, MetaItemKind, NestedMetaItem, StmtKind};
 use rustc_errors::{struct_span_err, Applicability};
 use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt, Indeterminate, MultiItemModifier};
 use rustc_feature::AttributeTemplate;
@@ -26,32 +26,39 @@ impl MultiItemModifier for Expander {
             return ExpandResult::Ready(vec![item]);
         }
 
-        let template =
-            AttributeTemplate { list: Some("Trait1, Trait2, ..."), ..Default::default() };
-        let attr = ecx.attribute(meta_item.clone());
-        validate_attr::check_builtin_attribute(&sess.parse_sess, &attr, sym::derive, template);
+        let result =
+            ecx.resolver.resolve_derives(ecx.current_expansion.id, ecx.force_mode, &|| {
+                let template =
+                    AttributeTemplate { list: Some("Trait1, Trait2, ..."), ..Default::default() };
+                let attr = attr::mk_attr_outer(meta_item.clone());
+                validate_attr::check_builtin_attribute(
+                    &sess.parse_sess,
+                    &attr,
+                    sym::derive,
+                    template,
+                );
 
-        let derives: Vec<_> = attr
-            .meta_item_list()
-            .unwrap_or_default()
-            .into_iter()
-            .filter_map(|nested_meta| match nested_meta {
-                NestedMetaItem::MetaItem(meta) => Some(meta),
-                NestedMetaItem::Literal(lit) => {
-                    // Reject `#[derive("Debug")]`.
-                    report_unexpected_literal(sess, &lit);
-                    None
-                }
-            })
-            .map(|meta| {
-                // Reject `#[derive(Debug = "value", Debug(abc))]`, but recover the paths.
-                report_path_args(sess, &meta);
-                meta.path
-            })
-            .collect();
+                attr.meta_item_list()
+                    .unwrap_or_default()
+                    .into_iter()
+                    .filter_map(|nested_meta| match nested_meta {
+                        NestedMetaItem::MetaItem(meta) => Some(meta),
+                        NestedMetaItem::Literal(lit) => {
+                            // Reject `#[derive("Debug")]`.
+                            report_unexpected_literal(sess, &lit);
+                            None
+                        }
+                    })
+                    .map(|meta| {
+                        // Reject `#[derive(Debug = "value", Debug(abc))]`, but recover the paths.
+                        report_path_args(sess, &meta);
+                        meta.path
+                    })
+                    .map(|path| (path, None))
+                    .collect()
+            });
 
-        // FIXME: Try to cache intermediate results to avoid collecting same paths multiple times.
-        match ecx.resolver.resolve_derives(ecx.current_expansion.id, derives, ecx.force_mode) {
+        match result {
             Ok(()) => ExpandResult::Ready(cfg_eval(ecx, item)),
             Err(Indeterminate) => ExpandResult::Retry(item),
         }

compiler/rustc_errors/src/emitter.rs

@@ -195,6 +195,9 @@ pub trait Emitter {
 
     fn emit_future_breakage_report(&mut self, _diags: Vec<(FutureBreakage, Diagnostic)>) {}
 
+    /// Emit list of unused externs
+    fn emit_unused_externs(&mut self, _lint_level: &str, _unused_externs: &[&str]) {}
+
     /// Checks if should show explanations about "rustc --explain"
     fn should_show_explain(&self) -> bool {
         true

compiler/rustc_errors/src/json.rs

@@ -159,6 +159,19 @@ impl Emitter for JsonEmitter {
         }
     }
 
+    fn emit_unused_externs(&mut self, lint_level: &str, unused_externs: &[&str]) {
+        let data = UnusedExterns { lint_level, unused_extern_names: unused_externs };
+        let result = if self.pretty {
+            writeln!(&mut self.dst, "{}", as_pretty_json(&data))
+        } else {
+            writeln!(&mut self.dst, "{}", as_json(&data))
+        }
+        .and_then(|_| self.dst.flush());
+        if let Err(e) = result {
+            panic!("failed to print unused externs: {:?}", e);
+        }
+    }
+
     fn source_map(&self) -> Option<&Lrc<SourceMap>> {
         Some(&self.sm)
     }
@@ -322,6 +335,18 @@ struct FutureIncompatReport {
     future_incompat_report: Vec<FutureBreakageItem>,
 }
 
+// NOTE: Keep this in sync with the equivalent structs in rustdoc's
+// doctest component (as well as cargo).
+// We could unify this struct the one in rustdoc but they have different
+// ownership semantics, so doing so would create wasteful allocations.
+#[derive(Encodable)]
+struct UnusedExterns<'a, 'b, 'c> {
+    /// The severity level of the unused dependencies lint
+    lint_level: &'a str,
+    /// List of unused externs by their names.
+    unused_extern_names: &'b [&'c str],
+}
+
 impl Diagnostic {
     fn from_errors_diagnostic(diag: &crate::Diagnostic, je: &JsonEmitter) -> Diagnostic {
         let sugg = diag.suggestions.iter().map(|sugg| Diagnostic {

compiler/rustc_errors/src/lib.rs

@@ -765,6 +765,10 @@ impl Handler {
         self.inner.borrow_mut().emitter.emit_future_breakage_report(diags)
     }
 
+    pub fn emit_unused_externs(&self, lint_level: &str, unused_externs: &[&str]) {
+        self.inner.borrow_mut().emit_unused_externs(lint_level, unused_externs)
+    }
+
     pub fn delay_as_bug(&self, diagnostic: Diagnostic) {
         self.inner.borrow_mut().delay_as_bug(diagnostic)
     }
@@ -839,6 +843,10 @@ impl HandlerInner {
         self.emitter.emit_artifact_notification(path, artifact_type);
     }
 
+    fn emit_unused_externs(&mut self, lint_level: &str, unused_externs: &[&str]) {
+        self.emitter.emit_unused_externs(lint_level, unused_externs);
+    }
+
     fn treat_err_as_bug(&self) -> bool {
         self.flags.treat_err_as_bug.map_or(false, |c| self.err_count() >= c.get())
     }

compiler/rustc_expand/src/base.rs

@@ -868,6 +868,8 @@ impl SyntaxExtension {
 /// Error type that denotes indeterminacy.
 pub struct Indeterminate;
 
+pub type DeriveResolutions = Vec<(ast::Path, Option<Lrc<SyntaxExtension>>)>;
+
 pub trait ResolverExpand {
     fn next_node_id(&mut self) -> NodeId;
 
@@ -904,15 +906,12 @@ pub trait ResolverExpand {
     fn resolve_derives(
         &mut self,
         expn_id: ExpnId,
-        derives: Vec<ast::Path>,
         force: bool,
+        derive_paths: &dyn Fn() -> DeriveResolutions,
     ) -> Result<(), Indeterminate>;
     /// Take resolutions for paths inside the `#[derive(...)]` attribute with the given `ExpnId`
     /// back from resolver.
-    fn take_derive_resolutions(
-        &mut self,
-        expn_id: ExpnId,
-    ) -> Option<Vec<(Lrc<SyntaxExtension>, ast::Path)>>;
+    fn take_derive_resolutions(&mut self, expn_id: ExpnId) -> Option<DeriveResolutions>;
     /// Path resolution logic for `#[cfg_accessible(path)]`.
     fn cfg_accessible(&mut self, expn_id: ExpnId, path: &ast::Path) -> Result<bool, Indeterminate>;
 }

compiler/rustc_expand/src/expand.rs

@@ -515,7 +515,7 @@ impl<'a, 'b> MacroExpander<'a, 'b> {
                             invocations.reserve(derives.len());
                             derives
                                 .into_iter()
-                                .map(|(_exts, path)| {
+                                .map(|(path, _exts)| {
                                     // FIXME: Consider using the derive resolutions (`_exts`)
                                     // instead of enqueuing the derives to be resolved again later.
                                     let expn_id = ExpnId::fresh(None);

compiler/rustc_interface/src/passes.rs

@@ -16,6 +16,7 @@ use rustc_hir::def_id::{CrateNum, LOCAL_CRATE};
 use rustc_hir::definitions::Definitions;
 use rustc_hir::Crate;
 use rustc_lint::LintStore;
+use rustc_metadata::creader::CStore;
 use rustc_middle::arena::Arena;
 use rustc_middle::dep_graph::DepGraph;
 use rustc_middle::middle;
@@ -831,6 +832,12 @@ fn analysis(tcx: TyCtxt<'_>, cnum: CrateNum) -> Result<()> {
                 });
 
                 sess.time("looking_for_derive_registrar", || proc_macro_decls::find(tcx));
+
+                let cstore = tcx
+                    .cstore_as_any()
+                    .downcast_ref::<CStore>()
+                    .expect("`tcx.cstore` is not a `CStore`");
+                cstore.report_unused_deps(tcx);
             },
             {
                 par_iter(&tcx.hir().krate().modules).for_each(|(&module, _)| {

compiler/rustc_metadata/src/creader.rs

@@ -46,6 +46,9 @@ pub struct CStore {
     /// This map is used to verify we get no hash conflicts between
     /// `StableCrateId` values.
     stable_crate_ids: FxHashMap<StableCrateId, CrateNum>,
+
+    /// Unused externs of the crate
+    unused_externs: Vec<Symbol>,
 }
 
 pub struct CrateLoader<'a> {
@@ -190,6 +193,27 @@ impl CStore {
     crate fn has_global_allocator(&self) -> bool {
         self.has_global_allocator
     }
+
+    pub fn report_unused_deps(&self, tcx: TyCtxt<'_>) {
+        // We put the check for the option before the lint_level_at_node call
+        // because the call mutates internal state and introducing it
+        // leads to some ui tests failing.
+        if !tcx.sess.opts.json_unused_externs {
+            return;
+        }
+        let level = tcx
+            .lint_level_at_node(lint::builtin::UNUSED_CRATE_DEPENDENCIES, rustc_hir::CRATE_HIR_ID)
+            .0;
+        if level != lint::Level::Allow {
+            let unused_externs =
+                self.unused_externs.iter().map(|ident| ident.to_ident_string()).collect::<Vec<_>>();
+            let unused_externs = unused_externs.iter().map(String::as_str).collect::<Vec<&str>>();
+            tcx.sess
+                .parse_sess
+                .span_diagnostic
+                .emit_unused_externs(level.as_str(), &unused_externs);
+        }
+    }
 }
 
 impl<'a> CrateLoader<'a> {
@@ -217,6 +241,7 @@ impl<'a> CrateLoader<'a> {
                 allocator_kind: None,
                 has_global_allocator: false,
                 stable_crate_ids,
+                unused_externs: Vec::new(),
             },
             used_extern_options: Default::default(),
         }
@@ -904,11 +929,17 @@ impl<'a> CrateLoader<'a> {
                 // Don't worry about pathless `--extern foo` sysroot references
                 continue;
             }
-            if self.used_extern_options.contains(&Symbol::intern(name)) {
+            let name_interned = Symbol::intern(name);
+            if self.used_extern_options.contains(&name_interned) {
                 continue;
             }
 
             // Got a real unused --extern
+            if self.sess.opts.json_unused_externs {
+                self.cstore.unused_externs.push(name_interned);
+                continue;
+            }
+
             let diag = match self.sess.opts.extern_dep_specs.get(name) {
                 Some(loc) => BuiltinLintDiagnostics::ExternDepSpec(name.clone(), loc.into()),
                 None => {
@@ -941,9 +972,9 @@ impl<'a> CrateLoader<'a> {
         self.inject_allocator_crate(krate);
         self.inject_panic_runtime(krate);
 
-        info!("{:?}", CrateDump(&self.cstore));
-
         self.report_unused_deps(krate);
+
+        info!("{:?}", CrateDump(&self.cstore));
     }
 
     pub fn process_extern_crate(

compiler/rustc_middle/src/mir/mod.rs

@@ -1482,7 +1482,7 @@ pub enum StatementKind<'tcx> {
     ///
     /// Note that this also is emitted for regular `let` bindings to ensure that locals that are
     /// never accessed still get some sanity checks for, e.g., `let x: ! = ..;`
-    FakeRead(FakeReadCause, Box<Place<'tcx>>),
+    FakeRead(Box<(FakeReadCause, Place<'tcx>)>),
 
     /// Write the discriminant for a variant to the enum Place.
     SetDiscriminant { place: Box<Place<'tcx>>, variant_index: VariantIdx },
@@ -1575,7 +1575,12 @@ pub enum FakeReadCause {
 
     /// `let x: !; match x {}` doesn't generate any read of x so we need to
     /// generate a read of x to check that it is initialized and safe.
-    ForMatchedPlace,
+    ///
+    /// If a closure pattern matches a Place starting with an Upvar, then we introduce a
+    /// FakeRead for that Place outside the closure, in such a case this option would be
+    /// Some(closure_def_id).
+    /// Otherwise, the value of the optional DefId will be None.
+    ForMatchedPlace(Option<DefId>),
 
     /// A fake read of the RefWithinGuard version of a bind-by-value variable
     /// in a match guard to ensure that it's value hasn't change by the time
@@ -1594,7 +1599,12 @@ pub enum FakeReadCause {
     /// but in some cases it can affect the borrow checker, as in #53695.
     /// Therefore, we insert a "fake read" here to ensure that we get
     /// appropriate errors.
-    ForLet,
+    ///
+    /// If a closure pattern matches a Place starting with an Upvar, then we introduce a
+    /// FakeRead for that Place outside the closure, in such a case this option would be
+    /// Some(closure_def_id).
+    /// Otherwise, the value of the optional DefId will be None.
+    ForLet(Option<DefId>),
 
     /// If we have an index expression like
     ///
@@ -1618,7 +1628,9 @@ impl Debug for Statement<'_> {
         use self::StatementKind::*;
         match self.kind {
             Assign(box (ref place, ref rv)) => write!(fmt, "{:?} = {:?}", place, rv),
-            FakeRead(ref cause, ref place) => write!(fmt, "FakeRead({:?}, {:?})", cause, place),
+            FakeRead(box (ref cause, ref place)) => {
+                write!(fmt, "FakeRead({:?}, {:?})", cause, place)
+            }
             Retag(ref kind, ref place) => write!(
                 fmt,
                 "Retag({}{:?})",