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Diffstat (limited to '')
| -rw-r--r-- | src/tools/clippy/clippy_lints/src/utils/internal_lints/unnecessary_def_path.rs | 343 |
1 files changed, 343 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_lints/src/utils/internal_lints/unnecessary_def_path.rs b/src/tools/clippy/clippy_lints/src/utils/internal_lints/unnecessary_def_path.rs new file mode 100644 index 000000000..4cf76f536 --- /dev/null +++ b/src/tools/clippy/clippy_lints/src/utils/internal_lints/unnecessary_def_path.rs @@ -0,0 +1,343 @@ +use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_then}; +use clippy_utils::source::snippet_with_applicability; +use clippy_utils::{def_path_res, is_lint_allowed, match_any_def_paths, peel_hir_expr_refs}; +use if_chain::if_chain; +use rustc_ast::ast::LitKind; +use rustc_data_structures::fx::FxHashSet; +use rustc_errors::Applicability; +use rustc_hir as hir; +use rustc_hir::def::{DefKind, Namespace, Res}; +use rustc_hir::def_id::DefId; +use rustc_hir::{Expr, ExprKind, Local, Mutability, Node}; +use rustc_lint::{LateContext, LateLintPass}; +use rustc_middle::mir::interpret::{Allocation, ConstValue, GlobalAlloc}; +use rustc_middle::ty::{self, AssocKind, DefIdTree, Ty}; +use rustc_session::{declare_tool_lint, impl_lint_pass}; +use rustc_span::symbol::{Ident, Symbol}; +use rustc_span::Span; + +use std::str; + +declare_clippy_lint! { + /// ### What it does + /// Checks for usages of def paths when a diagnostic item or a `LangItem` could be used. + /// + /// ### Why is this bad? + /// The path for an item is subject to change and is less efficient to look up than a + /// diagnostic item or a `LangItem`. + /// + /// ### Example + /// ```rust,ignore + /// utils::match_type(cx, ty, &paths::VEC) + /// ``` + /// + /// Use instead: + /// ```rust,ignore + /// utils::is_type_diagnostic_item(cx, ty, sym::Vec) + /// ``` + pub UNNECESSARY_DEF_PATH, + internal, + "using a def path when a diagnostic item or a `LangItem` is available" +} + +impl_lint_pass!(UnnecessaryDefPath => [UNNECESSARY_DEF_PATH]); + +#[derive(Default)] +pub struct UnnecessaryDefPath { + array_def_ids: FxHashSet<(DefId, Span)>, + linted_def_ids: FxHashSet<DefId>, +} + +impl<'tcx> LateLintPass<'tcx> for UnnecessaryDefPath { + fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) { + if is_lint_allowed(cx, UNNECESSARY_DEF_PATH, expr.hir_id) { + return; + } + + match expr.kind { + ExprKind::Call(func, args) => self.check_call(cx, func, args, expr.span), + ExprKind::Array(elements) => self.check_array(cx, elements, expr.span), + _ => {}, + } + } + + fn check_crate_post(&mut self, cx: &LateContext<'tcx>) { + for &(def_id, span) in &self.array_def_ids { + if self.linted_def_ids.contains(&def_id) { + continue; + } + + let (msg, sugg) = if let Some(sym) = cx.tcx.get_diagnostic_name(def_id) { + ("diagnostic item", format!("sym::{sym}")) + } else if let Some(sym) = get_lang_item_name(cx, def_id) { + ("language item", format!("LangItem::{sym}")) + } else { + continue; + }; + + span_lint_and_help( + cx, + UNNECESSARY_DEF_PATH, + span, + &format!("hardcoded path to a {msg}"), + None, + &format!("convert all references to use `{sugg}`"), + ); + } + } +} + +impl UnnecessaryDefPath { + #[allow(clippy::too_many_lines)] + fn check_call(&mut self, cx: &LateContext<'_>, func: &Expr<'_>, args: &[Expr<'_>], span: Span) { + enum Item { + LangItem(Symbol), + DiagnosticItem(Symbol), + } + static PATHS: &[&[&str]] = &[ + &["clippy_utils", "match_def_path"], + &["clippy_utils", "match_trait_method"], + &["clippy_utils", "ty", "match_type"], + &["clippy_utils", "is_expr_path_def_path"], + ]; + + if_chain! { + if let [cx_arg, def_arg, args @ ..] = args; + if let ExprKind::Path(path) = &func.kind; + if let Some(id) = cx.qpath_res(path, func.hir_id).opt_def_id(); + if let Some(which_path) = match_any_def_paths(cx, id, PATHS); + let item_arg = if which_path == 4 { &args[1] } else { &args[0] }; + // Extract the path to the matched type + if let Some(segments) = path_to_matched_type(cx, item_arg); + let segments: Vec<&str> = segments.iter().map(|sym| &**sym).collect(); + if let Some(def_id) = inherent_def_path_res(cx, &segments[..]); + then { + // Check if the target item is a diagnostic item or LangItem. + #[rustfmt::skip] + let (msg, item) = if let Some(item_name) + = cx.tcx.diagnostic_items(def_id.krate).id_to_name.get(&def_id) + { + ( + "use of a def path to a diagnostic item", + Item::DiagnosticItem(*item_name), + ) + } else if let Some(item_name) = get_lang_item_name(cx, def_id) { + ( + "use of a def path to a `LangItem`", + Item::LangItem(item_name), + ) + } else { + return; + }; + + let has_ctor = match cx.tcx.def_kind(def_id) { + DefKind::Struct => { + let variant = cx.tcx.adt_def(def_id).non_enum_variant(); + variant.ctor_def_id.is_some() && variant.fields.iter().all(|f| f.vis.is_public()) + }, + DefKind::Variant => { + let variant = cx.tcx.adt_def(cx.tcx.parent(def_id)).variant_with_id(def_id); + variant.ctor_def_id.is_some() && variant.fields.iter().all(|f| f.vis.is_public()) + }, + _ => false, + }; + + let mut app = Applicability::MachineApplicable; + let cx_snip = snippet_with_applicability(cx, cx_arg.span, "..", &mut app); + let def_snip = snippet_with_applicability(cx, def_arg.span, "..", &mut app); + let (sugg, with_note) = match (which_path, item) { + // match_def_path + (0, Item::DiagnosticItem(item)) => ( + format!("{cx_snip}.tcx.is_diagnostic_item(sym::{item}, {def_snip})"), + has_ctor, + ), + (0, Item::LangItem(item)) => ( + format!("{cx_snip}.tcx.lang_items().require(LangItem::{item}).ok() == Some({def_snip})"), + has_ctor, + ), + // match_trait_method + (1, Item::DiagnosticItem(item)) => { + (format!("is_trait_method({cx_snip}, {def_snip}, sym::{item})"), false) + }, + // match_type + (2, Item::DiagnosticItem(item)) => ( + format!("is_type_diagnostic_item({cx_snip}, {def_snip}, sym::{item})"), + false, + ), + (2, Item::LangItem(item)) => ( + format!("is_type_lang_item({cx_snip}, {def_snip}, LangItem::{item})"), + false, + ), + // is_expr_path_def_path + (3, Item::DiagnosticItem(item)) if has_ctor => ( + format!("is_res_diag_ctor({cx_snip}, path_res({cx_snip}, {def_snip}), sym::{item})",), + false, + ), + (3, Item::LangItem(item)) if has_ctor => ( + format!("is_res_lang_ctor({cx_snip}, path_res({cx_snip}, {def_snip}), LangItem::{item})",), + false, + ), + (3, Item::DiagnosticItem(item)) => ( + format!("is_path_diagnostic_item({cx_snip}, {def_snip}, sym::{item})"), + false, + ), + (3, Item::LangItem(item)) => ( + format!( + "path_res({cx_snip}, {def_snip}).opt_def_id()\ + .map_or(false, |id| {cx_snip}.tcx.lang_items().require(LangItem::{item}).ok() == Some(id))", + ), + false, + ), + _ => return, + }; + + span_lint_and_then(cx, UNNECESSARY_DEF_PATH, span, msg, |diag| { + diag.span_suggestion(span, "try", sugg, app); + if with_note { + diag.help( + "if this `DefId` came from a constructor expression or pattern then the \ + parent `DefId` should be used instead", + ); + } + }); + + self.linted_def_ids.insert(def_id); + } + } + } + + fn check_array(&mut self, cx: &LateContext<'_>, elements: &[Expr<'_>], span: Span) { + let Some(path) = path_from_array(elements) else { return }; + + if let Some(def_id) = inherent_def_path_res(cx, &path.iter().map(AsRef::as_ref).collect::<Vec<_>>()) { + self.array_def_ids.insert((def_id, span)); + } + } +} + +fn path_to_matched_type(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<Vec<String>> { + match peel_hir_expr_refs(expr).0.kind { + ExprKind::Path(ref qpath) => match cx.qpath_res(qpath, expr.hir_id) { + Res::Local(hir_id) => { + let parent_id = cx.tcx.hir().get_parent_node(hir_id); + if let Some(Node::Local(Local { init: Some(init), .. })) = cx.tcx.hir().find(parent_id) { + path_to_matched_type(cx, init) + } else { + None + } + }, + Res::Def(DefKind::Static(_), def_id) => read_mir_alloc_def_path( + cx, + cx.tcx.eval_static_initializer(def_id).ok()?.inner(), + cx.tcx.type_of(def_id), + ), + Res::Def(DefKind::Const, def_id) => match cx.tcx.const_eval_poly(def_id).ok()? { + ConstValue::ByRef { alloc, offset } if offset.bytes() == 0 => { + read_mir_alloc_def_path(cx, alloc.inner(), cx.tcx.type_of(def_id)) + }, + _ => None, + }, + _ => None, + }, + ExprKind::Array(exprs) => path_from_array(exprs), + _ => None, + } +} + +fn read_mir_alloc_def_path<'tcx>(cx: &LateContext<'tcx>, alloc: &'tcx Allocation, ty: Ty<'_>) -> Option<Vec<String>> { + let (alloc, ty) = if let ty::Ref(_, ty, Mutability::Not) = *ty.kind() { + let &alloc = alloc.provenance().values().next()?; + if let GlobalAlloc::Memory(alloc) = cx.tcx.global_alloc(alloc) { + (alloc.inner(), ty) + } else { + return None; + } + } else { + (alloc, ty) + }; + + if let ty::Array(ty, _) | ty::Slice(ty) = *ty.kind() + && let ty::Ref(_, ty, Mutability::Not) = *ty.kind() + && ty.is_str() + { + alloc + .provenance() + .values() + .map(|&alloc| { + if let GlobalAlloc::Memory(alloc) = cx.tcx.global_alloc(alloc) { + let alloc = alloc.inner(); + str::from_utf8(alloc.inspect_with_uninit_and_ptr_outside_interpreter(0..alloc.len())) + .ok().map(ToOwned::to_owned) + } else { + None + } + }) + .collect() + } else { + None + } +} + +fn path_from_array(exprs: &[Expr<'_>]) -> Option<Vec<String>> { + exprs + .iter() + .map(|expr| { + if let ExprKind::Lit(lit) = &expr.kind { + if let LitKind::Str(sym, _) = lit.node { + return Some((*sym.as_str()).to_owned()); + } + } + + None + }) + .collect() +} + +// def_path_res will match field names before anything else, but for this we want to match +// inherent functions first. +fn inherent_def_path_res(cx: &LateContext<'_>, segments: &[&str]) -> Option<DefId> { + def_path_res(cx, segments, None).opt_def_id().map(|def_id| { + if cx.tcx.def_kind(def_id) == DefKind::Field { + let method_name = *segments.last().unwrap(); + cx.tcx + .def_key(def_id) + .parent + .and_then(|parent_idx| { + cx.tcx + .inherent_impls(DefId { + index: parent_idx, + krate: def_id.krate, + }) + .iter() + .find_map(|impl_id| { + cx.tcx.associated_items(*impl_id).find_by_name_and_kind( + cx.tcx, + Ident::from_str(method_name), + AssocKind::Fn, + *impl_id, + ) + }) + }) + .map_or(def_id, |item| item.def_id) + } else { + def_id + } + }) +} + +fn get_lang_item_name(cx: &LateContext<'_>, def_id: DefId) -> Option<Symbol> { + if let Some(lang_item) = cx.tcx.lang_items().items().iter().position(|id| *id == Some(def_id)) { + let lang_items = def_path_res(cx, &["rustc_hir", "lang_items", "LangItem"], Some(Namespace::TypeNS)).def_id(); + let item_name = cx + .tcx + .adt_def(lang_items) + .variants() + .iter() + .nth(lang_item) + .unwrap() + .name; + Some(item_name) + } else { + None + } +} |