136 lines
4.4 KiB
Rust
136 lines
4.4 KiB
Rust
use crate::utils::{differing_macro_contexts, snippet_with_applicability, span_lint_and_then};
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use crate::utils::{is_copy, is_type_diagnostic_item};
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use rustc_data_structures::fx::FxHashSet;
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use rustc_errors::Applicability;
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use rustc_hir::intravisit::{walk_path, NestedVisitorMap, Visitor};
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use rustc_hir::{self, HirId, Path};
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use rustc_lint::LateContext;
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use rustc_middle::hir::map::Map;
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use rustc_span::source_map::Span;
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use rustc_span::symbol::Symbol;
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use super::MAP_UNWRAP_OR;
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/// lint use of `map().unwrap_or()` for `Option`s
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pub(super) fn lint<'tcx>(
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cx: &LateContext<'tcx>,
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expr: &rustc_hir::Expr<'_>,
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map_args: &'tcx [rustc_hir::Expr<'_>],
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unwrap_args: &'tcx [rustc_hir::Expr<'_>],
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map_span: Span,
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) {
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// lint if the caller of `map()` is an `Option`
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if is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&map_args[0]), sym!(option_type)) {
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if !is_copy(cx, cx.typeck_results().expr_ty(&unwrap_args[1])) {
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// Do not lint if the `map` argument uses identifiers in the `map`
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// argument that are also used in the `unwrap_or` argument
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let mut unwrap_visitor = UnwrapVisitor {
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cx,
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identifiers: FxHashSet::default(),
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};
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unwrap_visitor.visit_expr(&unwrap_args[1]);
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let mut map_expr_visitor = MapExprVisitor {
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cx,
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identifiers: unwrap_visitor.identifiers,
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found_identifier: false,
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};
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map_expr_visitor.visit_expr(&map_args[1]);
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if map_expr_visitor.found_identifier {
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return;
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}
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}
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if differing_macro_contexts(unwrap_args[1].span, map_span) {
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return;
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}
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let mut applicability = Applicability::MachineApplicable;
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// get snippet for unwrap_or()
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let unwrap_snippet = snippet_with_applicability(cx, unwrap_args[1].span, "..", &mut applicability);
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// lint message
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// comparing the snippet from source to raw text ("None") below is safe
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// because we already have checked the type.
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let arg = if unwrap_snippet == "None" { "None" } else { "a" };
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let unwrap_snippet_none = unwrap_snippet == "None";
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let suggest = if unwrap_snippet_none {
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"and_then(f)"
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} else {
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"map_or(a, f)"
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};
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let msg = &format!(
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"called `map(f).unwrap_or({})` on an `Option` value. \
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This can be done more directly by calling `{}` instead",
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arg, suggest
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);
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span_lint_and_then(cx, MAP_UNWRAP_OR, expr.span, msg, |diag| {
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let map_arg_span = map_args[1].span;
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let mut suggestion = vec![
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(
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map_span,
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String::from(if unwrap_snippet_none { "and_then" } else { "map_or" }),
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),
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(expr.span.with_lo(unwrap_args[0].span.hi()), String::from("")),
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];
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if !unwrap_snippet_none {
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suggestion.push((map_arg_span.with_hi(map_arg_span.lo()), format!("{}, ", unwrap_snippet)));
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}
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diag.multipart_suggestion(&format!("use `{}` instead", suggest), suggestion, applicability);
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});
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}
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}
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struct UnwrapVisitor<'a, 'tcx> {
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cx: &'a LateContext<'tcx>,
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identifiers: FxHashSet<Symbol>,
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}
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impl<'a, 'tcx> Visitor<'tcx> for UnwrapVisitor<'a, 'tcx> {
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type Map = Map<'tcx>;
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fn visit_path(&mut self, path: &'tcx Path<'_>, _id: HirId) {
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self.identifiers.insert(ident(path));
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walk_path(self, path);
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}
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fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
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NestedVisitorMap::All(self.cx.tcx.hir())
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}
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}
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struct MapExprVisitor<'a, 'tcx> {
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cx: &'a LateContext<'tcx>,
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identifiers: FxHashSet<Symbol>,
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found_identifier: bool,
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}
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impl<'a, 'tcx> Visitor<'tcx> for MapExprVisitor<'a, 'tcx> {
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type Map = Map<'tcx>;
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fn visit_path(&mut self, path: &'tcx Path<'_>, _id: HirId) {
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if self.identifiers.contains(&ident(path)) {
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self.found_identifier = true;
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return;
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}
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walk_path(self, path);
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}
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fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
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NestedVisitorMap::All(self.cx.tcx.hir())
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}
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}
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fn ident(path: &Path<'_>) -> Symbol {
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path.segments
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.last()
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.expect("segments should be composed of at least 1 element")
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.ident
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.name
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}
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