79 lines
2.7 KiB
Rust
79 lines
2.7 KiB
Rust
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use crate::utils::{is_type_diagnostic_item, match_qpath, paths, snippet, span_lint_and_sugg};
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_lint::LateContext;
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use rustc_span::symbol::sym;
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use super::OPTION_MAP_OR_NONE;
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use super::RESULT_MAP_OR_INTO_OPTION;
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/// lint use of `_.map_or(None, _)` for `Option`s and `Result`s
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pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, map_or_args: &'tcx [hir::Expr<'_>]) {
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let is_option = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&map_or_args[0]), sym::option_type);
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let is_result = is_type_diagnostic_item(cx, cx.typeck_results().expr_ty(&map_or_args[0]), sym::result_type);
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// There are two variants of this `map_or` lint:
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// (1) using `map_or` as an adapter from `Result<T,E>` to `Option<T>`
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// (2) using `map_or` as a combinator instead of `and_then`
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//
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// (For this lint) we don't care if any other type calls `map_or`
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if !is_option && !is_result {
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return;
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}
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let (lint_name, msg, instead, hint) = {
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let default_arg_is_none = if let hir::ExprKind::Path(ref qpath) = map_or_args[1].kind {
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match_qpath(qpath, &paths::OPTION_NONE)
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} else {
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return;
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};
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if !default_arg_is_none {
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// nothing to lint!
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return;
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}
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let f_arg_is_some = if let hir::ExprKind::Path(ref qpath) = map_or_args[2].kind {
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match_qpath(qpath, &paths::OPTION_SOME)
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} else {
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false
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};
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if is_option {
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let self_snippet = snippet(cx, map_or_args[0].span, "..");
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let func_snippet = snippet(cx, map_or_args[2].span, "..");
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let msg = "called `map_or(None, ..)` on an `Option` value. This can be done more directly by calling \
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`and_then(..)` instead";
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(
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OPTION_MAP_OR_NONE,
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msg,
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"try using `and_then` instead",
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format!("{0}.and_then({1})", self_snippet, func_snippet),
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)
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} else if f_arg_is_some {
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let msg = "called `map_or(None, Some)` on a `Result` value. This can be done more directly by calling \
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`ok()` instead";
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let self_snippet = snippet(cx, map_or_args[0].span, "..");
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(
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RESULT_MAP_OR_INTO_OPTION,
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msg,
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"try using `ok` instead",
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format!("{0}.ok()", self_snippet),
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)
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} else {
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// nothing to lint!
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return;
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}
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};
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span_lint_and_sugg(
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cx,
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lint_name,
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expr.span,
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msg,
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instead,
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hint,
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Applicability::MachineApplicable,
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);
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}
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