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Auto merge of rust-lang#7016 - camsteffen:bind-map-paths, r=Manishearth
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Remove paths from bind_instead_of_map

changelog: none
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@bors
bors committed Apr 2, 2021
2 parents 1931db2 + 08a8ad3 commit 9ce2373
Showing 1 changed file with 78 additions and 81 deletions.
159 changes: 78 additions & 81 deletions clippy_lints/src/methods/bind_instead_of_map.rs
View file
Original file line number Diff line number Diff line change
@@ -1,80 +1,66 @@
use super::{contains_return, BIND_INSTEAD_OF_MAP};
use clippy_utils::diagnostics::{multispan_sugg_with_applicability, span_lint_and_sugg, span_lint_and_then};
use clippy_utils::source::{snippet, snippet_with_macro_callsite};
use clippy_utils::ty::match_type;
use clippy_utils::{in_macro, match_qpath, method_calls, paths, remove_blocks, visitors::find_all_ret_expressions};
use clippy_utils::{in_macro, remove_blocks, visitors::find_all_ret_expressions};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
use rustc_hir::{LangItem, QPath};
use rustc_lint::LateContext;
use rustc_middle::ty::DefIdTree;
use rustc_span::Span;

pub(crate) struct OptionAndThenSome;

impl BindInsteadOfMap for OptionAndThenSome {
const TYPE_NAME: &'static str = "Option";
const TYPE_QPATH: &'static [&'static str] = &paths::OPTION;

const VARIANT_LANG_ITEM: LangItem = LangItem::OptionSome;
const BAD_METHOD_NAME: &'static str = "and_then";
const BAD_VARIANT_NAME: &'static str = "Some";
const BAD_VARIANT_QPATH: &'static [&'static str] = &paths::OPTION_SOME;

const GOOD_METHOD_NAME: &'static str = "map";
}

pub(crate) struct ResultAndThenOk;

impl BindInsteadOfMap for ResultAndThenOk {
const TYPE_NAME: &'static str = "Result";
const TYPE_QPATH: &'static [&'static str] = &paths::RESULT;

const VARIANT_LANG_ITEM: LangItem = LangItem::ResultOk;
const BAD_METHOD_NAME: &'static str = "and_then";
const BAD_VARIANT_NAME: &'static str = "Ok";
const BAD_VARIANT_QPATH: &'static [&'static str] = &paths::RESULT_OK;

const GOOD_METHOD_NAME: &'static str = "map";
}

pub(crate) struct ResultOrElseErrInfo;

impl BindInsteadOfMap for ResultOrElseErrInfo {
const TYPE_NAME: &'static str = "Result";
const TYPE_QPATH: &'static [&'static str] = &paths::RESULT;

const VARIANT_LANG_ITEM: LangItem = LangItem::ResultErr;
const BAD_METHOD_NAME: &'static str = "or_else";
const BAD_VARIANT_NAME: &'static str = "Err";
const BAD_VARIANT_QPATH: &'static [&'static str] = &paths::RESULT_ERR;

const GOOD_METHOD_NAME: &'static str = "map_err";
}

pub(crate) trait BindInsteadOfMap {
const TYPE_NAME: &'static str;
const TYPE_QPATH: &'static [&'static str];

const VARIANT_LANG_ITEM: LangItem;
const BAD_METHOD_NAME: &'static str;
const BAD_VARIANT_NAME: &'static str;
const BAD_VARIANT_QPATH: &'static [&'static str];

const GOOD_METHOD_NAME: &'static str;

fn no_op_msg() -> String {
format!(
fn no_op_msg(cx: &LateContext<'_>) -> Option<String> {
let variant_id = cx.tcx.lang_items().require(Self::VARIANT_LANG_ITEM).ok()?;
let item_id = cx.tcx.parent(variant_id)?;
Some(format!(
"using `{}.{}({})`, which is a no-op",
Self::TYPE_NAME,
cx.tcx.item_name(item_id),
Self::BAD_METHOD_NAME,
Self::BAD_VARIANT_NAME
)
cx.tcx.item_name(variant_id),
))
}

fn lint_msg() -> String {
format!(
fn lint_msg(cx: &LateContext<'_>) -> Option<String> {
let variant_id = cx.tcx.lang_items().require(Self::VARIANT_LANG_ITEM).ok()?;
let item_id = cx.tcx.parent(variant_id)?;
Some(format!(
"using `{}.{}(|x| {}(y))`, which is more succinctly expressed as `{}(|x| y)`",
Self::TYPE_NAME,
cx.tcx.item_name(item_id),
Self::BAD_METHOD_NAME,
Self::BAD_VARIANT_NAME,
cx.tcx.item_name(variant_id),
Self::GOOD_METHOD_NAME
)
))
}

fn lint_closure_autofixable(
Expand All @@ -85,17 +71,12 @@ pub(crate) trait BindInsteadOfMap {
closure_args_span: Span,
) -> bool {
if_chain! {
if let hir::ExprKind::Call(ref some_expr, ref some_args) = closure_expr.kind;
if let hir::ExprKind::Path(ref qpath) = some_expr.kind;
if match_qpath(qpath, Self::BAD_VARIANT_QPATH);
if some_args.len() == 1;
if let hir::ExprKind::Call(ref some_expr, [inner_expr]) = closure_expr.kind;
if let hir::ExprKind::Path(QPath::Resolved(_, path)) = some_expr.kind;
if Self::is_variant(cx, path.res);
if !contains_return(inner_expr);
if let Some(msg) = Self::lint_msg(cx);
then {
let inner_expr = &some_args[0];

if contains_return(inner_expr) {
return false;
}

let some_inner_snip = if inner_expr.span.from_expansion() {
snippet_with_macro_callsite(cx, inner_expr.span, "_")
} else {
Expand All @@ -109,7 +90,7 @@ pub(crate) trait BindInsteadOfMap {
cx,
BIND_INSTEAD_OF_MAP,
expr.span,
Self::lint_msg().as_ref(),
&msg,
"try this",
note,
Applicability::MachineApplicable,
Expand All @@ -126,41 +107,46 @@ pub(crate) trait BindInsteadOfMap {
let can_sugg: bool = find_all_ret_expressions(cx, closure_expr, |ret_expr| {
if_chain! {
if !in_macro(ret_expr.span);
if let hir::ExprKind::Call(ref func_path, ref args) = ret_expr.kind;
if let hir::ExprKind::Path(ref qpath) = func_path.kind;
if match_qpath(qpath, Self::BAD_VARIANT_QPATH);
if args.len() == 1;
if !contains_return(&args[0]);
if let hir::ExprKind::Call(ref func_path, [arg]) = ret_expr.kind;
if let hir::ExprKind::Path(QPath::Resolved(_, path)) = func_path.kind;
if Self::is_variant(cx, path.res);
if !contains_return(arg);
then {
suggs.push((ret_expr.span, args[0].span.source_callsite()));
suggs.push((ret_expr.span, arg.span.source_callsite()));
true
} else {
false
}
}
});

if can_sugg {
span_lint_and_then(cx, BIND_INSTEAD_OF_MAP, expr.span, Self::lint_msg().as_ref(), |diag| {
multispan_sugg_with_applicability(
diag,
"try this",
Applicability::MachineApplicable,
std::iter::once((*method_calls(expr, 1).2.get(0).unwrap(), Self::GOOD_METHOD_NAME.into())).chain(
suggs
.into_iter()
.map(|(span1, span2)| (span1, snippet(cx, span2, "_").into())),
),
)
});
}
can_sugg
let (span, msg) = if_chain! {
if can_sugg;
if let hir::ExprKind::MethodCall(_, span, ..) = expr.kind;
if let Some(msg) = Self::lint_msg(cx);
then { (span, msg) } else { return false; }
};
span_lint_and_then(cx, BIND_INSTEAD_OF_MAP, expr.span, &msg, |diag| {
multispan_sugg_with_applicability(
diag,
"try this",
Applicability::MachineApplicable,
std::iter::once((span, Self::GOOD_METHOD_NAME.into())).chain(
suggs
.into_iter()
.map(|(span1, span2)| (span1, snippet(cx, span2, "_").into())),
),
)
});
true
}

/// Lint use of `_.and_then(|x| Some(y))` for `Option`s
fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, recv: &hir::Expr<'_>, arg: &hir::Expr<'_>) -> bool {
if !match_type(cx, cx.typeck_results().expr_ty(recv), Self::TYPE_QPATH) {
return false;
if_chain! {
if let Some(adt) = cx.typeck_results().expr_ty(recv).ty_adt_def();
if let Ok(vid) = cx.tcx.lang_items().require(Self::VARIANT_LANG_ITEM);
if Some(adt.did) == cx.tcx.parent(vid);
then {} else { return false; }
}

match arg.kind {
Expand All @@ -175,19 +161,30 @@ pub(crate) trait BindInsteadOfMap {
}
},
// `_.and_then(Some)` case, which is no-op.
hir::ExprKind::Path(ref qpath) if match_qpath(qpath, Self::BAD_VARIANT_QPATH) => {
span_lint_and_sugg(
cx,
BIND_INSTEAD_OF_MAP,
expr.span,
Self::no_op_msg().as_ref(),
"use the expression directly",
snippet(cx, recv.span, "..").into(),
Applicability::MachineApplicable,
);
hir::ExprKind::Path(QPath::Resolved(_, path)) if Self::is_variant(cx, path.res) => {
if let Some(msg) = Self::no_op_msg(cx) {
span_lint_and_sugg(
cx,
BIND_INSTEAD_OF_MAP,
expr.span,
&msg,
"use the expression directly",
snippet(cx, recv.span, "..").into(),
Applicability::MachineApplicable,
);
}
true
},
_ => false,
}
}

fn is_variant(cx: &LateContext<'_>, res: Res) -> bool {
if let Res::Def(DefKind::Ctor(CtorOf::Variant, CtorKind::Fn), id) = res {
if let Ok(variant_id) = cx.tcx.lang_items().require(Self::VARIANT_LANG_ITEM) {
return cx.tcx.parent(id) == Some(variant_id);
}
}
false
}
}

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