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Destructure `mem:replace` arguments

This commit is contained in:
Krishna Veera Reddy 2019-12-22 11:05:19 -08:00
parent 78b4dfc57c
commit aa66f760c3
1 changed files with 20 additions and 20 deletions
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40
clippy_lints/src/mem_replace.rs
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@ -3,10 +3,11 @@ use crate::utils::{
};
use if_chain::if_chain;
use rustc::declare_lint_pass;
use rustc::hir::{BorrowKind, Expr, ExprKind, HirVec, Mutability, QPath};
use rustc::hir::{BorrowKind, Expr, ExprKind, Mutability, QPath};
use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintPass};
use rustc_errors::Applicability;
use rustc_session::declare_tool_lint;
use syntax::source_map::Span;
declare_clippy_lint! {
/// **What it does:** Checks for `mem::replace()` on an `Option` with
@ -94,8 +95,8 @@ declare_clippy_lint! {
declare_lint_pass!(MemReplace =>
[MEM_REPLACE_OPTION_WITH_NONE, MEM_REPLACE_WITH_UNINIT, MEM_REPLACE_WITH_DEFAULT]);
fn check_replace_option_with_none(cx: &LateContext<'_, '_>, expr: &'_ Expr, args: &HirVec<Expr>) {
if let ExprKind::Path(ref replacement_qpath) = args[1].kind {
fn check_replace_option_with_none(cx: &LateContext<'_, '_>, src: &Expr, dest: &Expr, expr_span: Span) {
if let ExprKind::Path(ref replacement_qpath) = src.kind {
// Check that second argument is `Option::None`
if match_qpath(replacement_qpath, &paths::OPTION_NONE) {
// Since this is a late pass (already type-checked),
@ -103,7 +104,7 @@ fn check_replace_option_with_none(cx: &LateContext<'_, '_>, expr: &'_ Expr, args
// `Option`, we do not need to check the first
// argument's type. All that's left is to get
// replacee's path.
let replaced_path = match args[0].kind {
let replaced_path = match dest.kind {
ExprKind::AddrOf(BorrowKind::Ref, Mutability::Mut, ref replaced) => {
if let ExprKind::Path(QPath::Resolved(None, ref replaced_path)) = replaced.kind {
replaced_path
@ -119,7 +120,7 @@ fn check_replace_option_with_none(cx: &LateContext<'_, '_>, expr: &'_ Expr, args
span_lint_and_sugg(
cx,
MEM_REPLACE_OPTION_WITH_NONE,
expr.span,
expr_span,
"replacing an `Option` with `None`",
"consider `Option::take()` instead",
format!(
@ -132,8 +133,8 @@ fn check_replace_option_with_none(cx: &LateContext<'_, '_>, expr: &'_ Expr, args
}
}
fn check_replace_with_uninit(cx: &LateContext<'_, '_>, expr: &'_ Expr, args: &HirVec<Expr>) {
if let ExprKind::Call(ref repl_func, ref repl_args) = args[1].kind {
fn check_replace_with_uninit(cx: &LateContext<'_, '_>, src: &Expr, expr_span: Span) {
if let ExprKind::Call(ref repl_func, ref repl_args) = src.kind {
if_chain! {
if repl_args.is_empty();
if let ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
@ -143,16 +144,16 @@ fn check_replace_with_uninit(cx: &LateContext<'_, '_>, expr: &'_ Expr, args: &Hi
span_help_and_lint(
cx,
MEM_REPLACE_WITH_UNINIT,
expr.span,
expr_span,
"replacing with `mem::uninitialized()`",
"consider using the `take_mut` crate instead",
);
} else if match_def_path(cx, repl_def_id, &paths::MEM_ZEROED) &&
!cx.tables.expr_ty(&args[1]).is_primitive() {
!cx.tables.expr_ty(src).is_primitive() {
span_help_and_lint(
cx,
MEM_REPLACE_WITH_UNINIT,
expr.span,
expr_span,
"replacing with `mem::zeroed()`",
"consider using a default value or the `take_mut` crate instead",
);
@ -162,10 +163,10 @@ fn check_replace_with_uninit(cx: &LateContext<'_, '_>, expr: &'_ Expr, args: &Hi
}
}
fn check_replace_with_default(cx: &LateContext<'_, '_>, expr: &'_ Expr, args: &HirVec<Expr>) {
if let ExprKind::Call(ref repl_func, _) = args[1].kind {
fn check_replace_with_default(cx: &LateContext<'_, '_>, src: &Expr, dest: &Expr, expr_span: Span) {
if let ExprKind::Call(ref repl_func, _) = src.kind {
if_chain! {
if !in_macro(expr.span) && !in_external_macro(cx.tcx.sess, expr.span);
if !in_macro(expr_span) && !in_external_macro(cx.tcx.sess, expr_span);
if let ExprKind::Path(ref repl_func_qpath) = repl_func.kind;
if let Some(repl_def_id) = cx.tables.qpath_res(repl_func_qpath, repl_func.hir_id).opt_def_id();
if match_def_path(cx, repl_def_id, &paths::DEFAULT_TRAIT_METHOD);
@ -175,12 +176,12 @@ fn check_replace_with_default(cx: &LateContext<'_, '_>, expr: &'_ Expr, args: &H
span_lint_and_sugg(
cx,
MEM_REPLACE_WITH_DEFAULT,
expr.span,
expr_span,
"replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take`",
"consider using",
format!(
"std::mem::take({})",
snippet_with_applicability(cx, args[0].span, "", &mut applicability)
snippet_with_applicability(cx, dest.span, "", &mut applicability)
),
applicability,
);
@ -194,15 +195,14 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MemReplace {
if_chain! {
// Check that `expr` is a call to `mem::replace()`
if let ExprKind::Call(ref func, ref func_args) = expr.kind;
if func_args.len() == 2;
if let ExprKind::Path(ref func_qpath) = func.kind;
if let Some(def_id) = cx.tables.qpath_res(func_qpath, func.hir_id).opt_def_id();
if match_def_path(cx, def_id, &paths::MEM_REPLACE);
if let [dest, src] = &**func_args;
then {
check_replace_option_with_none(cx, expr, &func_args);
check_replace_with_uninit(cx, expr, &func_args);
check_replace_with_default(cx, expr, &func_args);
check_replace_option_with_none(cx, src, dest, expr.span);
check_replace_with_uninit(cx, src, expr.span);
check_replace_with_default(cx, src, dest, expr.span);
}
}
}