66 lines
2.4 KiB
Rust
66 lines
2.4 KiB
Rust
use crate::rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
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use crate::rustc::{declare_tool_lint, lint_array};
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use if_chain::if_chain;
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use crate::rustc::hir::*;
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use crate::utils::{match_type, method_chain_args, paths, snippet, span_help_and_lint};
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/// **What it does:*** Checks for unnecessary `ok()` in if let.
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///
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/// **Why is this bad?** Calling `ok()` in if let is unnecessary, instead match
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/// on `Ok(pat)`
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// for result in iter {
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/// if let Some(bench) = try!(result).parse().ok() {
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/// vec.push(bench)
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/// }
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/// }
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/// ```
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/// Could be written:
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///
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/// ```rust
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/// for result in iter {
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/// if let Ok(bench) = try!(result).parse() {
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/// vec.push(bench)
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/// }
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/// }
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/// ```
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declare_clippy_lint! {
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pub IF_LET_SOME_RESULT,
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style,
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"usage of `ok()` in `if let Some(pat)` statements is unnecessary, match on `Ok(pat)` instead"
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}
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#[derive(Copy, Clone)]
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pub struct Pass;
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impl LintPass for Pass {
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fn get_lints(&self) -> LintArray {
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lint_array!(IF_LET_SOME_RESULT)
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
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fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
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if_chain! { //begin checking variables
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if let ExprKind::Match(ref op, ref body, ref source) = expr.node; //test if expr is a match
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if let MatchSource::IfLetDesugar { .. } = *source; //test if it is an If Let
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if let ExprKind::MethodCall(_, _, ref result_types) = op.node; //check is expr.ok() has type Result<T,E>.ok()
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if let PatKind::TupleStruct(QPath::Resolved(_, ref x), ref y, _) = body[0].pats[0].node; //get operation
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if method_chain_args(op, &["ok"]).is_some(); //test to see if using ok() methoduse std::marker::Sized;
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then {
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let is_result_type = match_type(cx, cx.tables.expr_ty(&result_types[0]), &paths::RESULT);
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let some_expr_string = snippet(cx, y[0].span, "");
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if print::to_string(print::NO_ANN, |s| s.print_path(x, false)) == "Some" && is_result_type {
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span_help_and_lint(cx, IF_LET_SOME_RESULT, expr.span,
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"Matching on `Some` with `ok()` is redundant",
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&format!("Consider matching on `Ok({})` and removing the call to `ok` instead", some_expr_string));
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}
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}
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}
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}
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}
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