mv compiler to compiler/

compiler/rustc_resolve/src/check_unused.rs

@@ -0,0 +1,328 @@
+//
+// Unused import checking
+//
+// Although this is mostly a lint pass, it lives in here because it depends on
+// resolve data structures and because it finalises the privacy information for
+// `use` items.
+//
+// Unused trait imports can't be checked until the method resolution. We save
+// candidates here, and do the actual check in librustc_typeck/check_unused.rs.
+//
+// Checking for unused imports is split into three steps:
+//
+//  - `UnusedImportCheckVisitor` walks the AST to find all the unused imports
+//    inside of `UseTree`s, recording their `NodeId`s and grouping them by
+//    the parent `use` item
+//
+//  - `calc_unused_spans` then walks over all the `use` items marked in the
+//    previous step to collect the spans associated with the `NodeId`s and to
+//    calculate the spans that can be removed by rustfix; This is done in a
+//    separate step to be able to collapse the adjacent spans that rustfix
+//    will remove
+//
+//  - `check_crate` finally emits the diagnostics based on the data generated
+//    in the last step
+
+use crate::imports::ImportKind;
+use crate::Resolver;
+
+use rustc_ast as ast;
+use rustc_ast::node_id::NodeMap;
+use rustc_ast::visit::{self, Visitor};
+use rustc_ast_lowering::ResolverAstLowering;
+use rustc_data_structures::fx::FxHashSet;
+use rustc_errors::pluralize;
+use rustc_middle::ty;
+use rustc_session::lint::builtin::{MACRO_USE_EXTERN_CRATE, UNUSED_IMPORTS};
+use rustc_session::lint::BuiltinLintDiagnostics;
+use rustc_span::{MultiSpan, Span, DUMMY_SP};
+
+struct UnusedImport<'a> {
+    use_tree: &'a ast::UseTree,
+    use_tree_id: ast::NodeId,
+    item_span: Span,
+    unused: FxHashSet<ast::NodeId>,
+}
+
+impl<'a> UnusedImport<'a> {
+    fn add(&mut self, id: ast::NodeId) {
+        self.unused.insert(id);
+    }
+}
+
+struct UnusedImportCheckVisitor<'a, 'b> {
+    r: &'a mut Resolver<'b>,
+    /// All the (so far) unused imports, grouped path list
+    unused_imports: NodeMap<UnusedImport<'a>>,
+    base_use_tree: Option<&'a ast::UseTree>,
+    base_id: ast::NodeId,
+    item_span: Span,
+}
+
+impl<'a, 'b> UnusedImportCheckVisitor<'a, 'b> {
+    // We have information about whether `use` (import) items are actually
+    // used now. If an import is not used at all, we signal a lint error.
+    fn check_import(&mut self, id: ast::NodeId) {
+        let mut used = false;
+        self.r.per_ns(|this, ns| used |= this.used_imports.contains(&(id, ns)));
+        let def_id = self.r.local_def_id(id);
+        if !used {
+            if self.r.maybe_unused_trait_imports.contains(&def_id) {
+                // Check later.
+                return;
+            }
+            self.unused_import(self.base_id).add(id);
+        } else {
+            // This trait import is definitely used, in a way other than
+            // method resolution.
+            self.r.maybe_unused_trait_imports.remove(&def_id);
+            if let Some(i) = self.unused_imports.get_mut(&self.base_id) {
+                i.unused.remove(&id);
+            }
+        }
+    }
+
+    fn unused_import(&mut self, id: ast::NodeId) -> &mut UnusedImport<'a> {
+        let use_tree_id = self.base_id;
+        let use_tree = self.base_use_tree.unwrap();
+        let item_span = self.item_span;
+
+        self.unused_imports.entry(id).or_insert_with(|| UnusedImport {
+            use_tree,
+            use_tree_id,
+            item_span,
+            unused: FxHashSet::default(),
+        })
+    }
+}
+
+impl<'a, 'b> Visitor<'a> for UnusedImportCheckVisitor<'a, 'b> {
+    fn visit_item(&mut self, item: &'a ast::Item) {
+        self.item_span = item.span;
+
+        // Ignore is_public import statements because there's no way to be sure
+        // whether they're used or not. Also ignore imports with a dummy span
+        // because this means that they were generated in some fashion by the
+        // compiler and we don't need to consider them.
+        if let ast::ItemKind::Use(..) = item.kind {
+            if item.vis.node.is_pub() || item.span.is_dummy() {
+                return;
+            }
+        }
+
+        visit::walk_item(self, item);
+    }
+
+    fn visit_use_tree(&mut self, use_tree: &'a ast::UseTree, id: ast::NodeId, nested: bool) {
+        // Use the base UseTree's NodeId as the item id
+        // This allows the grouping of all the lints in the same item
+        if !nested {
+            self.base_id = id;
+            self.base_use_tree = Some(use_tree);
+        }
+
+        if let ast::UseTreeKind::Nested(ref items) = use_tree.kind {
+            if items.is_empty() {
+                self.unused_import(self.base_id).add(id);
+            }
+        } else {
+            self.check_import(id);
+        }
+
+        visit::walk_use_tree(self, use_tree, id);
+    }
+}
+
+enum UnusedSpanResult {
+    Used,
+    FlatUnused(Span, Span),
+    NestedFullUnused(Vec<Span>, Span),
+    NestedPartialUnused(Vec<Span>, Vec<Span>),
+}
+
+fn calc_unused_spans(
+    unused_import: &UnusedImport<'_>,
+    use_tree: &ast::UseTree,
+    use_tree_id: ast::NodeId,
+) -> UnusedSpanResult {
+    // The full span is the whole item's span if this current tree is not nested inside another
+    // This tells rustfix to remove the whole item if all the imports are unused
+    let full_span = if unused_import.use_tree.span == use_tree.span {
+        unused_import.item_span
+    } else {
+        use_tree.span
+    };
+    match use_tree.kind {
+        ast::UseTreeKind::Simple(..) | ast::UseTreeKind::Glob => {
+            if unused_import.unused.contains(&use_tree_id) {
+                UnusedSpanResult::FlatUnused(use_tree.span, full_span)
+            } else {
+                UnusedSpanResult::Used
+            }
+        }
+        ast::UseTreeKind::Nested(ref nested) => {
+            if nested.is_empty() {
+                return UnusedSpanResult::FlatUnused(use_tree.span, full_span);
+            }
+
+            let mut unused_spans = Vec::new();
+            let mut to_remove = Vec::new();
+            let mut all_nested_unused = true;
+            let mut previous_unused = false;
+            for (pos, (use_tree, use_tree_id)) in nested.iter().enumerate() {
+                let remove = match calc_unused_spans(unused_import, use_tree, *use_tree_id) {
+                    UnusedSpanResult::Used => {
+                        all_nested_unused = false;
+                        None
+                    }
+                    UnusedSpanResult::FlatUnused(span, remove) => {
+                        unused_spans.push(span);
+                        Some(remove)
+                    }
+                    UnusedSpanResult::NestedFullUnused(mut spans, remove) => {
+                        unused_spans.append(&mut spans);
+                        Some(remove)
+                    }
+                    UnusedSpanResult::NestedPartialUnused(mut spans, mut to_remove_extra) => {
+                        all_nested_unused = false;
+                        unused_spans.append(&mut spans);
+                        to_remove.append(&mut to_remove_extra);
+                        None
+                    }
+                };
+                if let Some(remove) = remove {
+                    let remove_span = if nested.len() == 1 {
+                        remove
+                    } else if pos == nested.len() - 1 || !all_nested_unused {
+                        // Delete everything from the end of the last import, to delete the
+                        // previous comma
+                        nested[pos - 1].0.span.shrink_to_hi().to(use_tree.span)
+                    } else {
+                        // Delete everything until the next import, to delete the trailing commas
+                        use_tree.span.to(nested[pos + 1].0.span.shrink_to_lo())
+                    };
+
+                    // Try to collapse adjacent spans into a single one. This prevents all cases of
+                    // overlapping removals, which are not supported by rustfix
+                    if previous_unused && !to_remove.is_empty() {
+                        let previous = to_remove.pop().unwrap();
+                        to_remove.push(previous.to(remove_span));
+                    } else {
+                        to_remove.push(remove_span);
+                    }
+                }
+                previous_unused = remove.is_some();
+            }
+            if unused_spans.is_empty() {
+                UnusedSpanResult::Used
+            } else if all_nested_unused {
+                UnusedSpanResult::NestedFullUnused(unused_spans, full_span)
+            } else {
+                UnusedSpanResult::NestedPartialUnused(unused_spans, to_remove)
+            }
+        }
+    }
+}
+
+impl Resolver<'_> {
+    crate fn check_unused(&mut self, krate: &ast::Crate) {
+        for import in self.potentially_unused_imports.iter() {
+            match import.kind {
+                _ if import.used.get()
+                    || import.vis.get() == ty::Visibility::Public
+                    || import.span.is_dummy() =>
+                {
+                    if let ImportKind::MacroUse = import.kind {
+                        if !import.span.is_dummy() {
+                            self.lint_buffer.buffer_lint(
+                                MACRO_USE_EXTERN_CRATE,
+                                import.id,
+                                import.span,
+                                "deprecated `#[macro_use]` attribute used to \
+                                import macros should be replaced at use sites \
+                                with a `use` item to import the macro \
+                                instead",
+                            );
+                        }
+                    }
+                }
+                ImportKind::ExternCrate { .. } => {
+                    let def_id = self.local_def_id(import.id);
+                    self.maybe_unused_extern_crates.push((def_id, import.span));
+                }
+                ImportKind::MacroUse => {
+                    let msg = "unused `#[macro_use]` import";
+                    self.lint_buffer.buffer_lint(UNUSED_IMPORTS, import.id, import.span, msg);
+                }
+                _ => {}
+            }
+        }
+
+        let mut visitor = UnusedImportCheckVisitor {
+            r: self,
+            unused_imports: Default::default(),
+            base_use_tree: None,
+            base_id: ast::DUMMY_NODE_ID,
+            item_span: DUMMY_SP,
+        };
+        visit::walk_crate(&mut visitor, krate);
+
+        for unused in visitor.unused_imports.values() {
+            let mut fixes = Vec::new();
+            let mut spans = match calc_unused_spans(unused, unused.use_tree, unused.use_tree_id) {
+                UnusedSpanResult::Used => continue,
+                UnusedSpanResult::FlatUnused(span, remove) => {
+                    fixes.push((remove, String::new()));
+                    vec![span]
+                }
+                UnusedSpanResult::NestedFullUnused(spans, remove) => {
+                    fixes.push((remove, String::new()));
+                    spans
+                }
+                UnusedSpanResult::NestedPartialUnused(spans, remove) => {
+                    for fix in &remove {
+                        fixes.push((*fix, String::new()));
+                    }
+                    spans
+                }
+            };
+
+            let len = spans.len();
+            spans.sort();
+            let ms = MultiSpan::from_spans(spans.clone());
+            let mut span_snippets = spans
+                .iter()
+                .filter_map(|s| match visitor.r.session.source_map().span_to_snippet(*s) {
+                    Ok(s) => Some(format!("`{}`", s)),
+                    _ => None,
+                })
+                .collect::<Vec<String>>();
+            span_snippets.sort();
+            let msg = format!(
+                "unused import{}{}",
+                pluralize!(len),
+                if !span_snippets.is_empty() {
+                    format!(": {}", span_snippets.join(", "))
+                } else {
+                    String::new()
+                }
+            );
+
+            let fix_msg = if fixes.len() == 1 && fixes[0].0 == unused.item_span {
+                "remove the whole `use` item"
+            } else if spans.len() > 1 {
+                "remove the unused imports"
+            } else {
+                "remove the unused import"
+            };
+
+            visitor.r.lint_buffer.buffer_lint_with_diagnostic(
+                UNUSED_IMPORTS,
+                unused.use_tree_id,
+                ms,
+                &msg,
+                BuiltinLintDiagnostics::UnusedImports(fix_msg.into(), fixes),
+            );
+        }
+    }
+}

compiler/rustc_resolve/src/def_collector.rs

@@ -0,0 +1,293 @@
+use crate::Resolver;
+use rustc_ast::token::{self, Token};
+use rustc_ast::visit::{self, FnKind};
+use rustc_ast::walk_list;
+use rustc_ast::*;
+use rustc_ast_lowering::ResolverAstLowering;
+use rustc_expand::expand::AstFragment;
+use rustc_hir::def_id::LocalDefId;
+use rustc_hir::definitions::*;
+use rustc_span::hygiene::ExpnId;
+use rustc_span::symbol::{kw, sym};
+use rustc_span::Span;
+use tracing::debug;
+
+crate fn collect_definitions(
+    resolver: &mut Resolver<'_>,
+    fragment: &AstFragment,
+    expansion: ExpnId,
+) {
+    let parent_def = resolver.invocation_parents[&expansion];
+    fragment.visit_with(&mut DefCollector { resolver, parent_def, expansion });
+}
+
+/// Creates `DefId`s for nodes in the AST.
+struct DefCollector<'a, 'b> {
+    resolver: &'a mut Resolver<'b>,
+    parent_def: LocalDefId,
+    expansion: ExpnId,
+}
+
+impl<'a, 'b> DefCollector<'a, 'b> {
+    fn create_def(&mut self, node_id: NodeId, data: DefPathData, span: Span) -> LocalDefId {
+        let parent_def = self.parent_def;
+        debug!("create_def(node_id={:?}, data={:?}, parent_def={:?})", node_id, data, parent_def);
+        self.resolver.create_def(parent_def, node_id, data, self.expansion, span)
+    }
+
+    fn with_parent<F: FnOnce(&mut Self)>(&mut self, parent_def: LocalDefId, f: F) {
+        let orig_parent_def = std::mem::replace(&mut self.parent_def, parent_def);
+        f(self);
+        self.parent_def = orig_parent_def;
+    }
+
+    fn collect_field(&mut self, field: &'a StructField, index: Option<usize>) {
+        let index = |this: &Self| {
+            index.unwrap_or_else(|| {
+                let node_id = NodeId::placeholder_from_expn_id(this.expansion);
+                this.resolver.placeholder_field_indices[&node_id]
+            })
+        };
+
+        if field.is_placeholder {
+            let old_index = self.resolver.placeholder_field_indices.insert(field.id, index(self));
+            assert!(old_index.is_none(), "placeholder field index is reset for a node ID");
+            self.visit_macro_invoc(field.id);
+        } else {
+            let name = field.ident.map_or_else(|| sym::integer(index(self)), |ident| ident.name);
+            let def = self.create_def(field.id, DefPathData::ValueNs(name), field.span);
+            self.with_parent(def, |this| visit::walk_struct_field(this, field));
+        }
+    }
+
+    fn visit_macro_invoc(&mut self, id: NodeId) {
+        let old_parent =
+            self.resolver.invocation_parents.insert(id.placeholder_to_expn_id(), self.parent_def);
+        assert!(old_parent.is_none(), "parent `LocalDefId` is reset for an invocation");
+    }
+}
+
+impl<'a, 'b> visit::Visitor<'a> for DefCollector<'a, 'b> {
+    fn visit_item(&mut self, i: &'a Item) {
+        debug!("visit_item: {:?}", i);
+
+        // Pick the def data. This need not be unique, but the more
+        // information we encapsulate into, the better
+        let def_data = match &i.kind {
+            ItemKind::Impl { .. } => DefPathData::Impl,
+            ItemKind::Mod(..) if i.ident.name == kw::Invalid => {
+                return visit::walk_item(self, i);
+            }
+            ItemKind::Mod(..)
+            | ItemKind::Trait(..)
+            | ItemKind::TraitAlias(..)
+            | ItemKind::Enum(..)
+            | ItemKind::Struct(..)
+            | ItemKind::Union(..)
+            | ItemKind::ExternCrate(..)
+            | ItemKind::ForeignMod(..)
+            | ItemKind::TyAlias(..) => DefPathData::TypeNs(i.ident.name),
+            ItemKind::Static(..) | ItemKind::Const(..) | ItemKind::Fn(..) => {
+                DefPathData::ValueNs(i.ident.name)
+            }
+            ItemKind::MacroDef(..) => DefPathData::MacroNs(i.ident.name),
+            ItemKind::MacCall(..) => return self.visit_macro_invoc(i.id),
+            ItemKind::GlobalAsm(..) => DefPathData::Misc,
+            ItemKind::Use(..) => {
+                return visit::walk_item(self, i);
+            }
+        };
+        let def = self.create_def(i.id, def_data, i.span);
+
+        self.with_parent(def, |this| {
+            match i.kind {
+                ItemKind::Struct(ref struct_def, _) | ItemKind::Union(ref struct_def, _) => {
+                    // If this is a unit or tuple-like struct, register the constructor.
+                    if let Some(ctor_hir_id) = struct_def.ctor_id() {
+                        this.create_def(ctor_hir_id, DefPathData::Ctor, i.span);
+                    }
+                }
+                _ => {}
+            }
+            visit::walk_item(this, i);
+        });
+    }
+
+    fn visit_fn(&mut self, fn_kind: FnKind<'a>, span: Span, _: NodeId) {
+        if let FnKind::Fn(_, _, sig, _, body) = fn_kind {
+            if let Async::Yes { closure_id, return_impl_trait_id, .. } = sig.header.asyncness {
+                self.create_def(return_impl_trait_id, DefPathData::ImplTrait, span);
+
+                // For async functions, we need to create their inner defs inside of a
+                // closure to match their desugared representation. Besides that,
+                // we must mirror everything that `visit::walk_fn` below does.
+                self.visit_fn_header(&sig.header);
+                visit::walk_fn_decl(self, &sig.decl);
+                let closure_def = self.create_def(closure_id, DefPathData::ClosureExpr, span);
+                self.with_parent(closure_def, |this| walk_list!(this, visit_block, body));
+                return;
+            }
+        }
+
+        visit::walk_fn(self, fn_kind, span);
+    }
+
+    fn visit_use_tree(&mut self, use_tree: &'a UseTree, id: NodeId, _nested: bool) {
+        self.create_def(id, DefPathData::Misc, use_tree.span);
+        visit::walk_use_tree(self, use_tree, id);
+    }
+
+    fn visit_foreign_item(&mut self, foreign_item: &'a ForeignItem) {
+        if let ForeignItemKind::MacCall(_) = foreign_item.kind {
+            return self.visit_macro_invoc(foreign_item.id);
+        }
+
+        let def = self.create_def(
+            foreign_item.id,
+            DefPathData::ValueNs(foreign_item.ident.name),
+            foreign_item.span,
+        );
+
+        self.with_parent(def, |this| {
+            visit::walk_foreign_item(this, foreign_item);
+        });
+    }
+
+    fn visit_variant(&mut self, v: &'a Variant) {
+        if v.is_placeholder {
+            return self.visit_macro_invoc(v.id);
+        }
+        let def = self.create_def(v.id, DefPathData::TypeNs(v.ident.name), v.span);
+        self.with_parent(def, |this| {
+            if let Some(ctor_hir_id) = v.data.ctor_id() {
+                this.create_def(ctor_hir_id, DefPathData::Ctor, v.span);
+            }
+            visit::walk_variant(this, v)
+        });
+    }
+
+    fn visit_variant_data(&mut self, data: &'a VariantData) {
+        // The assumption here is that non-`cfg` macro expansion cannot change field indices.
+        // It currently holds because only inert attributes are accepted on fields,
+        // and every such attribute expands into a single field after it's resolved.
+        for (index, field) in data.fields().iter().enumerate() {
+            self.collect_field(field, Some(index));
+        }
+    }
+
+    fn visit_generic_param(&mut self, param: &'a GenericParam) {
+        if param.is_placeholder {
+            self.visit_macro_invoc(param.id);
+            return;
+        }
+        let name = param.ident.name;
+        let def_path_data = match param.kind {
+            GenericParamKind::Lifetime { .. } => DefPathData::LifetimeNs(name),
+            GenericParamKind::Type { .. } => DefPathData::TypeNs(name),
+            GenericParamKind::Const { .. } => DefPathData::ValueNs(name),
+        };
+        self.create_def(param.id, def_path_data, param.ident.span);
+
+        visit::walk_generic_param(self, param);
+    }
+
+    fn visit_assoc_item(&mut self, i: &'a AssocItem, ctxt: visit::AssocCtxt) {
+        let def_data = match &i.kind {
+            AssocItemKind::Fn(..) | AssocItemKind::Const(..) => DefPathData::ValueNs(i.ident.name),
+            AssocItemKind::TyAlias(..) => DefPathData::TypeNs(i.ident.name),
+            AssocItemKind::MacCall(..) => return self.visit_macro_invoc(i.id),
+        };
+
+        let def = self.create_def(i.id, def_data, i.span);
+        self.with_parent(def, |this| visit::walk_assoc_item(this, i, ctxt));
+    }
+
+    fn visit_pat(&mut self, pat: &'a Pat) {
+        match pat.kind {
+            PatKind::MacCall(..) => self.visit_macro_invoc(pat.id),
+            _ => visit::walk_pat(self, pat),
+        }
+    }
+
+    fn visit_anon_const(&mut self, constant: &'a AnonConst) {
+        let def = self.create_def(constant.id, DefPathData::AnonConst, constant.value.span);
+        self.with_parent(def, |this| visit::walk_anon_const(this, constant));
+    }
+
+    fn visit_expr(&mut self, expr: &'a Expr) {
+        let parent_def = match expr.kind {
+            ExprKind::MacCall(..) => return self.visit_macro_invoc(expr.id),
+            ExprKind::Closure(_, asyncness, ..) => {
+                // Async closures desugar to closures inside of closures, so
+                // we must create two defs.
+                let closure_def = self.create_def(expr.id, DefPathData::ClosureExpr, expr.span);
+                match asyncness {
+                    Async::Yes { closure_id, .. } => {
+                        self.create_def(closure_id, DefPathData::ClosureExpr, expr.span)
+                    }
+                    Async::No => closure_def,
+                }
+            }
+            ExprKind::Async(_, async_id, _) => {
+                self.create_def(async_id, DefPathData::ClosureExpr, expr.span)
+            }
+            _ => self.parent_def,
+        };
+
+        self.with_parent(parent_def, |this| visit::walk_expr(this, expr));
+    }
+
+    fn visit_ty(&mut self, ty: &'a Ty) {
+        match ty.kind {
+            TyKind::MacCall(..) => return self.visit_macro_invoc(ty.id),
+            TyKind::ImplTrait(node_id, _) => {
+                self.create_def(node_id, DefPathData::ImplTrait, ty.span);
+            }
+            _ => {}
+        }
+        visit::walk_ty(self, ty);
+    }
+
+    fn visit_stmt(&mut self, stmt: &'a Stmt) {
+        match stmt.kind {
+            StmtKind::MacCall(..) => self.visit_macro_invoc(stmt.id),
+            _ => visit::walk_stmt(self, stmt),
+        }
+    }
+
+    fn visit_token(&mut self, t: Token) {
+        if let token::Interpolated(nt) = t.kind {
+            if let token::NtExpr(ref expr) = *nt {
+                if let ExprKind::MacCall(..) = expr.kind {
+                    self.visit_macro_invoc(expr.id);
+                }
+            }
+        }
+    }
+
+    fn visit_arm(&mut self, arm: &'a Arm) {
+        if arm.is_placeholder { self.visit_macro_invoc(arm.id) } else { visit::walk_arm(self, arm) }
+    }
+
+    fn visit_field(&mut self, f: &'a Field) {
+        if f.is_placeholder { self.visit_macro_invoc(f.id) } else { visit::walk_field(self, f) }
+    }
+
+    fn visit_field_pattern(&mut self, fp: &'a FieldPat) {
+        if fp.is_placeholder {
+            self.visit_macro_invoc(fp.id)
+        } else {
+            visit::walk_field_pattern(self, fp)
+        }
+    }
+
+    fn visit_param(&mut self, p: &'a Param) {
+        if p.is_placeholder { self.visit_macro_invoc(p.id) } else { visit::walk_param(self, p) }
+    }
+
+    // This method is called only when we are visiting an individual field
+    // after expanding an attribute on it.
+    fn visit_struct_field(&mut self, field: &'a StructField) {
+        self.collect_field(field, None);
+    }
+}