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Add lint manual_split_once

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Jason Newcomb 2021-07-17 13:52:03 -04:00
parent 8cf6dae0ca
commit a7f376fbd3
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GPG key ID: DA59E8643A37ED06
14 changed files with 459 additions and 26 deletions
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3
clippy_lints/src/lib.rs
View file

@ -773,6 +773,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
methods::MANUAL_FILTER_MAP,
methods::MANUAL_FIND_MAP,
methods::MANUAL_SATURATING_ARITHMETIC,
methods::MANUAL_SPLIT_ONCE,
methods::MANUAL_STR_REPEAT,
methods::MAP_COLLECT_RESULT_UNIT,
methods::MAP_FLATTEN,
@ -1319,6 +1320,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(methods::MANUAL_FILTER_MAP),
LintId::of(methods::MANUAL_FIND_MAP),
LintId::of(methods::MANUAL_SATURATING_ARITHMETIC),
LintId::of(methods::MANUAL_SPLIT_ONCE),
LintId::of(methods::MANUAL_STR_REPEAT),
LintId::of(methods::MAP_COLLECT_RESULT_UNIT),
LintId::of(methods::MAP_IDENTITY),
@ -1617,6 +1619,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
LintId::of(methods::ITER_COUNT),
LintId::of(methods::MANUAL_FILTER_MAP),
LintId::of(methods::MANUAL_FIND_MAP),
LintId::of(methods::MANUAL_SPLIT_ONCE),
LintId::of(methods::MAP_IDENTITY),
LintId::of(methods::OPTION_AS_REF_DEREF),
LintId::of(methods::OPTION_FILTER_MAP),

213
clippy_lints/src/methods/manual_split_once.rs Normal file
View file

@ -0,0 +1,213 @@
use clippy_utils::consts::{constant, Constant};
use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::source::snippet_with_context;
use clippy_utils::{is_diag_item_method, match_def_path, paths};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind, HirId, LangItem, Node, QPath};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, adjustment::Adjust};
use rustc_span::{symbol::sym, Span, SyntaxContext};
use super::MANUAL_SPLIT_ONCE;
pub(super) fn check(cx: &LateContext<'_>, method_name: &str, expr: &Expr<'_>, self_arg: &Expr<'_>, pat_arg: &Expr<'_>) {
if !cx.typeck_results().expr_ty_adjusted(self_arg).peel_refs().is_str() {
return;
}
let ctxt = expr.span.ctxt();
let usage = match parse_iter_usage(cx, ctxt, cx.tcx.hir().parent_iter(expr.hir_id)) {
Some(x) => x,
None => return,
};
let (method_name, msg) = if method_name == "splitn" {
("split_once", "manual implementation of `split_once`")
} else {
("rsplit_once", "manual implementation of `rsplit_once`")
};
let mut app = Applicability::MachineApplicable;
let self_snip = snippet_with_context(cx, self_arg.span, ctxt, "..", &mut app).0;
let pat_snip = snippet_with_context(cx, pat_arg.span, ctxt, "..", &mut app).0;
match usage.kind {
IterUsageKind::NextTuple => {
span_lint_and_sugg(
cx,
MANUAL_SPLIT_ONCE,
usage.span,
msg,
"try this",
format!("{}.{}({})", self_snip, method_name, pat_snip),
app,
);
},
IterUsageKind::Next => {
let self_deref = {
let adjust = cx.typeck_results().expr_adjustments(self_arg);
if adjust.is_empty() {
String::new()
} else if cx.typeck_results().expr_ty(self_arg).is_box()
|| adjust
.iter()
.any(|a| matches!(a.kind, Adjust::Deref(Some(_))) || a.target.is_box())
{
format!("&{}", "*".repeat(adjust.len() - 1))
} else {
"*".repeat(adjust.len() - 2)
}
};
let sugg = if usage.unwrap_kind.is_some() {
format!(
"{}.{}({}).map_or({}{}, |x| x.0)",
&self_snip, method_name, pat_snip, self_deref, &self_snip
)
} else {
format!(
"Some({}.{}({}).map_or({}{}, |x| x.0))",
&self_snip, method_name, pat_snip, self_deref, &self_snip
)
};
span_lint_and_sugg(cx, MANUAL_SPLIT_ONCE, usage.span, msg, "try this", sugg, app);
},
IterUsageKind::Second => {
let access_str = match usage.unwrap_kind {
Some(UnwrapKind::Unwrap) => ".unwrap().1",
Some(UnwrapKind::QuestionMark) => "?.1",
None => ".map(|x| x.1)",
};
span_lint_and_sugg(
cx,
MANUAL_SPLIT_ONCE,
usage.span,
msg,
"try this",
format!("{}.{}({}){}", self_snip, method_name, pat_snip, access_str),
app,
);
},
}
}
enum IterUsageKind {
Next,
Second,
NextTuple,
}
enum UnwrapKind {
Unwrap,
QuestionMark,
}
struct IterUsage {
kind: IterUsageKind,
unwrap_kind: Option<UnwrapKind>,
span: Span,
}
fn parse_iter_usage(
cx: &LateContext<'tcx>,
ctxt: SyntaxContext,
mut iter: impl Iterator<Item = (HirId, Node<'tcx>)>,
) -> Option<IterUsage> {
let (kind, span) = match iter.next() {
Some((_, Node::Expr(e))) if e.span.ctxt() == ctxt => {
let (name, args) = if let ExprKind::MethodCall(name, _, [_, args @ ..], _) = e.kind {
(name, args)
} else {
return None;
};
let did = cx.typeck_results().type_dependent_def_id(e.hir_id)?;
let iter_id = cx.tcx.get_diagnostic_item(sym::Iterator)?;
match (&*name.ident.as_str(), args) {
("next", []) if cx.tcx.trait_of_item(did) == Some(iter_id) => (IterUsageKind::Next, e.span),
("next_tuple", []) => {
if_chain! {
if match_def_path(cx, did, &paths::ITERTOOLS_NEXT_TUPLE);
if let ty::Adt(adt_def, subs) = cx.typeck_results().expr_ty(e).kind();
if cx.tcx.is_diagnostic_item(sym::option_type, adt_def.did);
if let ty::Tuple(subs) = subs.type_at(0).kind();
if subs.len() == 2;
then {
return Some(IterUsage { kind: IterUsageKind::NextTuple, span: e.span, unwrap_kind: None });
} else {
return None;
}
}
},
("nth" | "skip", [idx_expr]) if cx.tcx.trait_of_item(did) == Some(iter_id) => {
if let Some((Constant::Int(idx), _)) = constant(cx, cx.typeck_results(), idx_expr) {
let span = if name.ident.as_str() == "nth" {
e.span
} else {
if_chain! {
if let Some((_, Node::Expr(next_expr))) = iter.next();
if let ExprKind::MethodCall(next_name, _, [_], _) = next_expr.kind;
if next_name.ident.name == sym::next;
if next_expr.span.ctxt() == ctxt;
if let Some(next_id) = cx.typeck_results().type_dependent_def_id(next_expr.hir_id);
if cx.tcx.trait_of_item(next_id) == Some(iter_id);
then {
next_expr.span
} else {
return None;
}
}
};
match idx {
0 => (IterUsageKind::Next, span),
1 => (IterUsageKind::Second, span),
_ => return None,
}
} else {
return None;
}
},
_ => return None,
}
},
_ => return None,
};
let (unwrap_kind, span) = if let Some((_, Node::Expr(e))) = iter.next() {
match e.kind {
ExprKind::Call(
Expr {
kind: ExprKind::Path(QPath::LangItem(LangItem::TryTraitBranch, _)),
..
},
_,
) => {
let parent_span = e.span.parent().unwrap();
if parent_span.ctxt() == ctxt {
(Some(UnwrapKind::QuestionMark), parent_span)
} else {
(None, span)
}
},
_ if e.span.ctxt() != ctxt => (None, span),
ExprKind::MethodCall(name, _, [_], _)
if name.ident.name == sym::unwrap
&& cx
.typeck_results()
.type_dependent_def_id(e.hir_id)
.map_or(false, |id| is_diag_item_method(cx, id, sym::option_type)) =>
{
(Some(UnwrapKind::Unwrap), e.span)
},
_ => (None, span),
}
} else {
(None, span)
};
Some(IterUsage {
kind,
unwrap_kind,
span,
})
}

44
clippy_lints/src/methods/mod.rs
View file

@ -33,6 +33,7 @@ mod iter_nth_zero;
mod iter_skip_next;
mod iterator_step_by_zero;
mod manual_saturating_arithmetic;
mod manual_split_once;
mod manual_str_repeat;
mod map_collect_result_unit;
mod map_flatten;
@ -64,6 +65,7 @@ mod wrong_self_convention;
mod zst_offset;
use bind_instead_of_map::BindInsteadOfMap;
use clippy_utils::consts::{constant, Constant};
use clippy_utils::diagnostics::{span_lint, span_lint_and_help};
use clippy_utils::ty::{contains_adt_constructor, contains_ty, implements_trait, is_copy, is_type_diagnostic_item};
use clippy_utils::{contains_return, get_trait_def_id, in_macro, iter_input_pats, meets_msrv, msrvs, paths, return_ty};
@ -1771,6 +1773,31 @@ declare_clippy_lint! {
"manual implementation of `str::repeat`"
}
declare_clippy_lint! {
/// **What it does:** Checks for usages of `splitn(2, _)`
///
/// **Why is this bad?** `split_once` is clearer.
///
/// **Known problems:** None.
///
/// **Example:**
///
/// ```rust
/// // Bad
/// let some_str = "name=value";
/// let mut iter = some_str.splitn(2, '=');
/// let name = iter.next().unwrap();
/// let value = iter.next().unwrap_or("");
///
/// // Good
/// let some_str = "name=value";
/// let (name, value) = some_str.split_once('=').unwrap_or((some_str, ""));
/// ```
pub MANUAL_SPLIT_ONCE,
complexity,
"replace `.splitn(2, pat)` with `.split_once(pat)`"
}
pub struct Methods {
avoid_breaking_exported_api: bool,
msrv: Option<RustcVersion>,
@ -1848,7 +1875,8 @@ impl_lint_pass!(Methods => [
IMPLICIT_CLONE,
SUSPICIOUS_SPLITN,
MANUAL_STR_REPEAT,
EXTEND_WITH_DRAIN
EXTEND_WITH_DRAIN,
MANUAL_SPLIT_ONCE
]);
/// Extracts a method call name, args, and `Span` of the method name.
@ -2176,8 +2204,18 @@ fn check_methods<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, msrv: Optio
unnecessary_lazy_eval::check(cx, expr, recv, arg, "or");
}
},
("splitn" | "splitn_mut" | "rsplitn" | "rsplitn_mut", [count_arg, _]) => {
suspicious_splitn::check(cx, name, expr, recv, count_arg);
("splitn" | "rsplitn", [count_arg, pat_arg]) => {
if let Some((Constant::Int(count), _)) = constant(cx, cx.typeck_results(), count_arg) {
suspicious_splitn::check(cx, name, expr, recv, count);
if count == 2 && meets_msrv(msrv, &msrvs::STR_SPLIT_ONCE) {
manual_split_once::check(cx, name, expr, recv, pat_arg);
}
}
},
("splitn_mut" | "rsplitn_mut", [count_arg, _]) => {
if let Some((Constant::Int(count), _)) = constant(cx, cx.typeck_results(), count_arg) {
suspicious_splitn::check(cx, name, expr, recv, count);
}
},
("step_by", [arg]) => iterator_step_by_zero::check(cx, expr, arg),
("to_os_string" | "to_owned" | "to_path_buf" | "to_vec", []) => {

14
clippy_lints/src/methods/suspicious_splitn.rs
View file

@ -1,4 +1,3 @@
use clippy_utils::consts::{constant, Constant};
use clippy_utils::diagnostics::span_lint_and_note;
use if_chain::if_chain;
use rustc_ast::LitKind;
@ -8,15 +7,8 @@ use rustc_span::source_map::Spanned;
use super::SUSPICIOUS_SPLITN;
pub(super) fn check(
cx: &LateContext<'_>,
method_name: &str,
expr: &Expr<'_>,
self_arg: &Expr<'_>,
count_arg: &Expr<'_>,
) {
pub(super) fn check(cx: &LateContext<'_>, method_name: &str, expr: &Expr<'_>, self_arg: &Expr<'_>, count: u128) {
if_chain! {
if let Some((Constant::Int(count), _)) = constant(cx, cx.typeck_results(), count_arg);
if count <= 1;
if let Some(call_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id);
if let Some(impl_id) = cx.tcx.impl_of_method(call_id);
@ -24,9 +16,9 @@ pub(super) fn check(
if lang_items.slice_impl() == Some(impl_id) || lang_items.str_impl() == Some(impl_id);
then {
// Ignore empty slice and string literals when used with a literal count.
if (matches!(self_arg.kind, ExprKind::Array([]))
if matches!(self_arg.kind, ExprKind::Array([]))
|| matches!(self_arg.kind, ExprKind::Lit(Spanned { node: LitKind::Str(s, _), .. }) if s.is_empty())
) && matches!(count_arg.kind, ExprKind::Lit(_))
{
return;
}

2
clippy_lints/src/utils/conf.rs
View file

@ -136,7 +136,7 @@ define_Conf! {
///
/// Suppress lints whenever the suggested change would cause breakage for other crates.
(avoid_breaking_exported_api: bool = true),
/// Lint: MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE.
/// Lint: MANUAL_SPLIT_ONCE, MANUAL_STR_REPEAT, CLONED_INSTEAD_OF_COPIED, REDUNDANT_FIELD_NAMES, REDUNDANT_STATIC_LIFETIMES, FILTER_MAP_NEXT, CHECKED_CONVERSIONS, MANUAL_RANGE_CONTAINS, USE_SELF, MEM_REPLACE_WITH_DEFAULT, MANUAL_NON_EXHAUSTIVE, OPTION_AS_REF_DEREF, MAP_UNWRAP_OR, MATCH_LIKE_MATCHES_MACRO, MANUAL_STRIP, MISSING_CONST_FOR_FN, UNNESTED_OR_PATTERNS, FROM_OVER_INTO, PTR_AS_PTR, IF_THEN_SOME_ELSE_NONE.
///
/// The minimum rust version that the project supports
(msrv: Option<String> = None),