| use crate::utils::{get_parent_expr, higher, if_sequence, snippet, span_lint_and_note, span_lint_and_then}; |
| use crate::utils::{SpanlessEq, SpanlessHash}; |
| use rustc_data_structures::fx::FxHashMap; |
| use rustc_hir::{Arm, Block, Expr, ExprKind, MatchSource, Pat, PatKind}; |
| use rustc_lint::{LateContext, LateLintPass}; |
| use rustc_middle::ty::{Ty, TyS}; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| use rustc_span::symbol::Symbol; |
| use std::collections::hash_map::Entry; |
| use std::hash::BuildHasherDefault; |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for consecutive `if`s with the same condition. |
| /// |
| /// **Why is this bad?** This is probably a copy & paste error. |
| /// |
| /// **Known problems:** Hopefully none. |
| /// |
| /// **Example:** |
| /// ```ignore |
| /// if a == b { |
| /// … |
| /// } else if a == b { |
| /// … |
| /// } |
| /// ``` |
| /// |
| /// Note that this lint ignores all conditions with a function call as it could |
| /// have side effects: |
| /// |
| /// ```ignore |
| /// if foo() { |
| /// … |
| /// } else if foo() { // not linted |
| /// … |
| /// } |
| /// ``` |
| pub IFS_SAME_COND, |
| correctness, |
| "consecutive `if`s with the same condition" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for consecutive `if`s with the same function call. |
| /// |
| /// **Why is this bad?** This is probably a copy & paste error. |
| /// Despite the fact that function can have side effects and `if` works as |
| /// intended, such an approach is implicit and can be considered a "code smell". |
| /// |
| /// **Known problems:** Hopefully none. |
| /// |
| /// **Example:** |
| /// ```ignore |
| /// if foo() == bar { |
| /// … |
| /// } else if foo() == bar { |
| /// … |
| /// } |
| /// ``` |
| /// |
| /// This probably should be: |
| /// ```ignore |
| /// if foo() == bar { |
| /// … |
| /// } else if foo() == baz { |
| /// … |
| /// } |
| /// ``` |
| /// |
| /// or if the original code was not a typo and called function mutates a state, |
| /// consider move the mutation out of the `if` condition to avoid similarity to |
| /// a copy & paste error: |
| /// |
| /// ```ignore |
| /// let first = foo(); |
| /// if first == bar { |
| /// … |
| /// } else { |
| /// let second = foo(); |
| /// if second == bar { |
| /// … |
| /// } |
| /// } |
| /// ``` |
| pub SAME_FUNCTIONS_IN_IF_CONDITION, |
| pedantic, |
| "consecutive `if`s with the same function call" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for `if/else` with the same body as the *then* part |
| /// and the *else* part. |
| /// |
| /// **Why is this bad?** This is probably a copy & paste error. |
| /// |
| /// **Known problems:** Hopefully none. |
| /// |
| /// **Example:** |
| /// ```ignore |
| /// let foo = if … { |
| /// 42 |
| /// } else { |
| /// 42 |
| /// }; |
| /// ``` |
| pub IF_SAME_THEN_ELSE, |
| correctness, |
| "`if` with the same `then` and `else` blocks" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for `match` with identical arm bodies. |
| /// |
| /// **Why is this bad?** This is probably a copy & paste error. If arm bodies |
| /// are the same on purpose, you can factor them |
| /// [using `|`](https://doc.rust-lang.org/book/patterns.html#multiple-patterns). |
| /// |
| /// **Known problems:** False positive possible with order dependent `match` |
| /// (see issue |
| /// [#860](https://github.com/rust-lang/rust-clippy/issues/860)). |
| /// |
| /// **Example:** |
| /// ```rust,ignore |
| /// match foo { |
| /// Bar => bar(), |
| /// Quz => quz(), |
| /// Baz => bar(), // <= oops |
| /// } |
| /// ``` |
| /// |
| /// This should probably be |
| /// ```rust,ignore |
| /// match foo { |
| /// Bar => bar(), |
| /// Quz => quz(), |
| /// Baz => baz(), // <= fixed |
| /// } |
| /// ``` |
| /// |
| /// or if the original code was not a typo: |
| /// ```rust,ignore |
| /// match foo { |
| /// Bar | Baz => bar(), // <= shows the intent better |
| /// Quz => quz(), |
| /// } |
| /// ``` |
| pub MATCH_SAME_ARMS, |
| pedantic, |
| "`match` with identical arm bodies" |
| } |
| |
| declare_lint_pass!(CopyAndPaste => [IFS_SAME_COND, SAME_FUNCTIONS_IN_IF_CONDITION, IF_SAME_THEN_ELSE, MATCH_SAME_ARMS]); |
| |
| impl<'tcx> LateLintPass<'tcx> for CopyAndPaste { |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| if !expr.span.from_expansion() { |
| // skip ifs directly in else, it will be checked in the parent if |
| if let Some(expr) = get_parent_expr(cx, expr) { |
| if let Some((_, _, Some(ref else_expr))) = higher::if_block(&expr) { |
| if else_expr.hir_id == expr.hir_id { |
| return; |
| } |
| } |
| } |
| |
| let (conds, blocks) = if_sequence(expr); |
| lint_same_then_else(cx, &blocks); |
| lint_same_cond(cx, &conds); |
| lint_same_fns_in_if_cond(cx, &conds); |
| lint_match_arms(cx, expr); |
| } |
| } |
| } |
| |
| /// Implementation of `IF_SAME_THEN_ELSE`. |
| fn lint_same_then_else(cx: &LateContext<'_>, blocks: &[&Block<'_>]) { |
| let eq: &dyn Fn(&&Block<'_>, &&Block<'_>) -> bool = |
| &|&lhs, &rhs| -> bool { SpanlessEq::new(cx).eq_block(lhs, rhs) }; |
| |
| if let Some((i, j)) = search_same_sequenced(blocks, eq) { |
| span_lint_and_note( |
| cx, |
| IF_SAME_THEN_ELSE, |
| j.span, |
| "this `if` has identical blocks", |
| Some(i.span), |
| "same as this", |
| ); |
| } |
| } |
| |
| /// Implementation of `IFS_SAME_COND`. |
| fn lint_same_cond(cx: &LateContext<'_>, conds: &[&Expr<'_>]) { |
| let hash: &dyn Fn(&&Expr<'_>) -> u64 = &|expr| -> u64 { |
| let mut h = SpanlessHash::new(cx); |
| h.hash_expr(expr); |
| h.finish() |
| }; |
| |
| let eq: &dyn Fn(&&Expr<'_>, &&Expr<'_>) -> bool = |
| &|&lhs, &rhs| -> bool { SpanlessEq::new(cx).ignore_fn().eq_expr(lhs, rhs) }; |
| |
| for (i, j) in search_same(conds, hash, eq) { |
| span_lint_and_note( |
| cx, |
| IFS_SAME_COND, |
| j.span, |
| "this `if` has the same condition as a previous `if`", |
| Some(i.span), |
| "same as this", |
| ); |
| } |
| } |
| |
| /// Implementation of `SAME_FUNCTIONS_IN_IF_CONDITION`. |
| fn lint_same_fns_in_if_cond(cx: &LateContext<'_>, conds: &[&Expr<'_>]) { |
| let hash: &dyn Fn(&&Expr<'_>) -> u64 = &|expr| -> u64 { |
| let mut h = SpanlessHash::new(cx); |
| h.hash_expr(expr); |
| h.finish() |
| }; |
| |
| let eq: &dyn Fn(&&Expr<'_>, &&Expr<'_>) -> bool = &|&lhs, &rhs| -> bool { |
| // Do not spawn warning if `IFS_SAME_COND` already produced it. |
| if SpanlessEq::new(cx).ignore_fn().eq_expr(lhs, rhs) { |
| return false; |
| } |
| SpanlessEq::new(cx).eq_expr(lhs, rhs) |
| }; |
| |
| for (i, j) in search_same(conds, hash, eq) { |
| span_lint_and_note( |
| cx, |
| SAME_FUNCTIONS_IN_IF_CONDITION, |
| j.span, |
| "this `if` has the same function call as a previous `if`", |
| Some(i.span), |
| "same as this", |
| ); |
| } |
| } |
| |
| /// Implementation of `MATCH_SAME_ARMS`. |
| fn lint_match_arms<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>) { |
| fn same_bindings<'tcx>(lhs: &FxHashMap<Symbol, Ty<'tcx>>, rhs: &FxHashMap<Symbol, Ty<'tcx>>) -> bool { |
| lhs.len() == rhs.len() |
| && lhs |
| .iter() |
| .all(|(name, l_ty)| rhs.get(name).map_or(false, |r_ty| TyS::same_type(l_ty, r_ty))) |
| } |
| |
| if let ExprKind::Match(_, ref arms, MatchSource::Normal) = expr.kind { |
| let hash = |&(_, arm): &(usize, &Arm<'_>)| -> u64 { |
| let mut h = SpanlessHash::new(cx); |
| h.hash_expr(&arm.body); |
| h.finish() |
| }; |
| |
| let eq = |&(lindex, lhs): &(usize, &Arm<'_>), &(rindex, rhs): &(usize, &Arm<'_>)| -> bool { |
| let min_index = usize::min(lindex, rindex); |
| let max_index = usize::max(lindex, rindex); |
| |
| // Arms with a guard are ignored, those can’t always be merged together |
| // This is also the case for arms in-between each there is an arm with a guard |
| (min_index..=max_index).all(|index| arms[index].guard.is_none()) && |
| SpanlessEq::new(cx).eq_expr(&lhs.body, &rhs.body) && |
| // all patterns should have the same bindings |
| same_bindings(&bindings(cx, &lhs.pat), &bindings(cx, &rhs.pat)) |
| }; |
| |
| let indexed_arms: Vec<(usize, &Arm<'_>)> = arms.iter().enumerate().collect(); |
| for (&(_, i), &(_, j)) in search_same(&indexed_arms, hash, eq) { |
| span_lint_and_then( |
| cx, |
| MATCH_SAME_ARMS, |
| j.body.span, |
| "this `match` has identical arm bodies", |
| |diag| { |
| diag.span_note(i.body.span, "same as this"); |
| |
| // Note: this does not use `span_suggestion` on purpose: |
| // there is no clean way |
| // to remove the other arm. Building a span and suggest to replace it to "" |
| // makes an even more confusing error message. Also in order not to make up a |
| // span for the whole pattern, the suggestion is only shown when there is only |
| // one pattern. The user should know about `|` if they are already using it… |
| |
| let lhs = snippet(cx, i.pat.span, "<pat1>"); |
| let rhs = snippet(cx, j.pat.span, "<pat2>"); |
| |
| if let PatKind::Wild = j.pat.kind { |
| // if the last arm is _, then i could be integrated into _ |
| // note that i.pat cannot be _, because that would mean that we're |
| // hiding all the subsequent arms, and rust won't compile |
| diag.span_note( |
| i.body.span, |
| &format!( |
| "`{}` has the same arm body as the `_` wildcard, consider removing it", |
| lhs |
| ), |
| ); |
| } else { |
| diag.span_help(i.pat.span, &format!("consider refactoring into `{} | {}`", lhs, rhs)); |
| } |
| }, |
| ); |
| } |
| } |
| } |
| |
| /// Returns the list of bindings in a pattern. |
| fn bindings<'tcx>(cx: &LateContext<'tcx>, pat: &Pat<'_>) -> FxHashMap<Symbol, Ty<'tcx>> { |
| fn bindings_impl<'tcx>(cx: &LateContext<'tcx>, pat: &Pat<'_>, map: &mut FxHashMap<Symbol, Ty<'tcx>>) { |
| match pat.kind { |
| PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => bindings_impl(cx, pat, map), |
| PatKind::TupleStruct(_, pats, _) => { |
| for pat in pats { |
| bindings_impl(cx, pat, map); |
| } |
| }, |
| PatKind::Binding(.., ident, ref as_pat) => { |
| if let Entry::Vacant(v) = map.entry(ident.name) { |
| v.insert(cx.tables().pat_ty(pat)); |
| } |
| if let Some(ref as_pat) = *as_pat { |
| bindings_impl(cx, as_pat, map); |
| } |
| }, |
| PatKind::Or(fields) | PatKind::Tuple(fields, _) => { |
| for pat in fields { |
| bindings_impl(cx, pat, map); |
| } |
| }, |
| PatKind::Struct(_, fields, _) => { |
| for pat in fields { |
| bindings_impl(cx, &pat.pat, map); |
| } |
| }, |
| PatKind::Slice(lhs, ref mid, rhs) => { |
| for pat in lhs { |
| bindings_impl(cx, pat, map); |
| } |
| if let Some(ref mid) = *mid { |
| bindings_impl(cx, mid, map); |
| } |
| for pat in rhs { |
| bindings_impl(cx, pat, map); |
| } |
| }, |
| PatKind::Lit(..) | PatKind::Range(..) | PatKind::Wild | PatKind::Path(..) => (), |
| } |
| } |
| |
| let mut result = FxHashMap::default(); |
| bindings_impl(cx, pat, &mut result); |
| result |
| } |
| |
| fn search_same_sequenced<T, Eq>(exprs: &[T], eq: Eq) -> Option<(&T, &T)> |
| where |
| Eq: Fn(&T, &T) -> bool, |
| { |
| for win in exprs.windows(2) { |
| if eq(&win[0], &win[1]) { |
| return Some((&win[0], &win[1])); |
| } |
| } |
| None |
| } |
| |
| fn search_common_cases<'a, T, Eq>(exprs: &'a [T], eq: &Eq) -> Option<(&'a T, &'a T)> |
| where |
| Eq: Fn(&T, &T) -> bool, |
| { |
| if exprs.len() == 2 && eq(&exprs[0], &exprs[1]) { |
| Some((&exprs[0], &exprs[1])) |
| } else { |
| None |
| } |
| } |
| |
| fn search_same<T, Hash, Eq>(exprs: &[T], hash: Hash, eq: Eq) -> Vec<(&T, &T)> |
| where |
| Hash: Fn(&T) -> u64, |
| Eq: Fn(&T, &T) -> bool, |
| { |
| if let Some(expr) = search_common_cases(&exprs, &eq) { |
| return vec![expr]; |
| } |
| |
| let mut match_expr_list: Vec<(&T, &T)> = Vec::new(); |
| |
| let mut map: FxHashMap<_, Vec<&_>> = |
| FxHashMap::with_capacity_and_hasher(exprs.len(), BuildHasherDefault::default()); |
| |
| for expr in exprs { |
| match map.entry(hash(expr)) { |
| Entry::Occupied(mut o) => { |
| for o in o.get() { |
| if eq(o, expr) { |
| match_expr_list.push((o, expr)); |
| } |
| } |
| o.get_mut().push(expr); |
| }, |
| Entry::Vacant(v) => { |
| v.insert(vec![expr]); |
| }, |
| } |
| } |
| |
| match_expr_list |
| } |