-use crate::utils::{get_parent_expr, higher, if_sequence, same_tys, snippet, span_lint_and_then, span_note_and_lint};
-use crate::utils::{SpanlessEq, SpanlessHash};
-use rustc::hir::*;
-use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
-use rustc::ty::Ty;
-use rustc::{declare_lint_pass, declare_tool_lint};
-use rustc_data_structures::fx::FxHashMap;
-use std::cmp::Ordering;
-use std::collections::hash_map::Entry;
-use std::hash::BuildHasherDefault;
-use syntax::symbol::Symbol;
+use crate::utils::{eq_expr_value, in_macro, search_same, SpanlessEq, SpanlessHash};
+use crate::utils::{get_parent_expr, if_sequence, span_lint_and_note};
+use rustc_hir::{Block, Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
declare_clippy_lint! {
/// **What it does:** Checks for consecutive `if`s with the same condition.
/// ```
pub IFS_SAME_COND,
correctness,
- "consecutive `ifs` with the same condition"
+ "consecutive `if`s with the same condition"
}
declare_clippy_lint! {
- /// **What it does:** Checks for `if/else` with the same body as the *then* part
- /// and the *else* part.
+ /// **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
- /// let foo = if … {
- /// 42
+ /// 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 {
- /// 42
- /// };
+ /// let second = foo();
+ /// if second == bar {
+ /// …
+ /// }
+ /// }
/// ```
- pub IF_SAME_THEN_ELSE,
- correctness,
- "if with the same *then* and *else* blocks"
+ pub SAME_FUNCTIONS_IN_IF_CONDITION,
+ pedantic,
+ "consecutive `if`s with the same function call"
}
declare_clippy_lint! {
- /// **What it does:** Checks for `match` with identical arm bodies.
+ /// **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. If arm bodies
- /// are the same on purpose, you can factor them
- /// [using `|`](https://doc.rust-lang.org/book/patterns.html#multiple-patterns).
+ /// **Why is this bad?** This is probably a copy & paste error.
///
- /// **Known problems:** False positive possible with order dependent `match`
- /// (see issue
- /// [#860](https://github.com/rust-lang/rust-clippy/issues/860)).
+ /// **Known problems:** Hopefully none.
///
/// **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(),
- /// }
+ /// ```ignore
+ /// let foo = if … {
+ /// 42
+ /// } else {
+ /// 42
+ /// };
/// ```
- pub MATCH_SAME_ARMS,
- pedantic,
- "`match` with identical arm bodies"
+ pub IF_SAME_THEN_ELSE,
+ correctness,
+ "`if` with the same `then` and `else` blocks"
}
-declare_lint_pass!(CopyAndPaste => [IFS_SAME_COND, IF_SAME_THEN_ELSE, MATCH_SAME_ARMS]);
+declare_lint_pass!(CopyAndPaste => [IFS_SAME_COND, SAME_FUNCTIONS_IN_IF_CONDITION, IF_SAME_THEN_ELSE]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for CopyAndPaste {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
+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;
- }
+ if let Some(&Expr {
+ kind: ExprKind::If(_, _, Some(ref else_expr)),
+ ..
+ }) = get_parent_expr(cx, 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_match_arms(cx, expr);
+ lint_same_fns_in_if_cond(cx, &conds);
}
}
}
/// 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) };
+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_note_and_lint(
+ span_lint_and_note(
cx,
IF_SAME_THEN_ELSE,
j.span,
"this `if` has identical blocks",
- i.span,
+ 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, cx.tables);
+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) };
+ let eq: &dyn Fn(&&Expr<'_>, &&Expr<'_>) -> bool = &|&lhs, &rhs| -> bool { eq_expr_value(cx, lhs, rhs) };
for (i, j) in search_same(conds, hash, eq) {
- span_note_and_lint(
+ span_lint_and_note(
cx,
IFS_SAME_COND,
j.span,
- "this `if` has the same condition as a previous if",
- i.span,
+ "this `if` has the same condition 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>(
- cx: &LateContext<'_, '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| same_tys(cx, l_ty, r_ty)))
- }
-
- if let ExprKind::Match(_, ref arms, MatchSource::Normal) = expr.node {
- let hash = |&(_, arm): &(usize, &Arm)| -> u64 {
- let mut h = SpanlessHash::new(cx, cx.tables);
- 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(cx, &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",
- |db| {
- db.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>");
+/// 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()
+ };
- if let PatKind::Wild = j.pat.node {
- // 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
- db.span_note(
- i.body.span,
- &format!(
- "`{}` has the same arm body as the `_` wildcard, consider removing it`",
- lhs
- ),
- );
- } else {
- db.span_help(i.pat.span, &format!("consider refactoring into `{} | {}`", lhs, rhs));
- }
- },
- );
+ let eq: &dyn Fn(&&Expr<'_>, &&Expr<'_>) -> bool = &|&lhs, &rhs| -> bool {
+ // Do not lint if any expr originates from a macro
+ if in_macro(lhs.span) || in_macro(rhs.span) {
+ return false;
}
- }
-}
-
-/// Returns the list of bindings in a pattern.
-fn bindings<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, pat: &Pat) -> FxHashMap<Symbol, Ty<'tcx>> {
- fn bindings_impl<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, pat: &Pat, map: &mut FxHashMap<Symbol, Ty<'tcx>>) {
- match pat.node {
- PatKind::Box(ref pat) | PatKind::Ref(ref pat, _) => bindings_impl(cx, pat, map),
- PatKind::TupleStruct(_, ref 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(ref fields) | PatKind::Tuple(ref fields, _) => {
- for pat in fields {
- bindings_impl(cx, pat, map);
- }
- },
- PatKind::Struct(_, ref fields, _) => {
- for pat in fields {
- bindings_impl(cx, &pat.pat, map);
- }
- },
- PatKind::Slice(ref lhs, ref mid, ref 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(..) => (),
+ // Do not spawn warning if `IFS_SAME_COND` already produced it.
+ if eq_expr_value(cx, lhs, rhs) {
+ return false;
}
- }
+ SpanlessEq::new(cx).eq_expr(lhs, rhs)
+ };
- let mut result = FxHashMap::default();
- bindings_impl(cx, pat, &mut result);
- result
+ 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",
+ );
+ }
}
fn search_same_sequenced<T, Eq>(exprs: &[T], eq: Eq) -> Option<(&T, &T)>
}
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
-}
projects / rust.git / blobdiff