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Fix #1925

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This commit is contained in:
Oliver Schneider 2017-11-30 10:54:55 +01:00
parent 1c95a7cf35
commit 7d7fef1690
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GPG key ID: A69F8D225B3AD7D9
3 changed files with 73 additions and 9 deletions
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54
clippy_lints/src/methods.rs
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@ -7,6 +7,7 @@ use rustc::ty::subst::Substs;
use rustc_const_eval::ConstContext;
use std::borrow::Cow;
use std::fmt;
use std::iter;
use syntax::ast;
use syntax::codemap::Span;
use utils::{get_trait_def_id, implements_trait, in_external_macro, in_macro, is_copy, is_self, is_self_ty,
@ -944,7 +945,7 @@ fn lint_or_fun_call(cx: &LateContext, expr: &hir::Expr, name: &str, args: &[hir:
fn lint_clone_on_copy(cx: &LateContext, expr: &hir::Expr, arg: &hir::Expr, arg_ty: Ty) {
let ty = cx.tables.expr_ty(expr);
if let ty::TyRef(_, ty::TypeAndMut { ty: inner, .. }) = arg_ty.sty {
if let ty::TyRef(..) = inner.sty {
if let ty::TyRef(_, ty::TypeAndMut { ty: innermost, .. }) = inner.sty {
span_lint_and_then(
cx,
CLONE_DOUBLE_REF,
@ -952,7 +953,17 @@ fn lint_clone_on_copy(cx: &LateContext, expr: &hir::Expr, arg: &hir::Expr, arg_t
"using `clone` on a double-reference; \
this will copy the reference instead of cloning the inner type",
|db| if let Some(snip) = sugg::Sugg::hir_opt(cx, arg) {
db.span_suggestion(expr.span, "try dereferencing it", format!("({}).clone()", snip.deref()));
let mut ty = innermost;
let mut n = 0;
while let ty::TyRef(_, ty::TypeAndMut { ty: inner, .. }) = ty.sty {
ty = inner;
n += 1;
}
let refs: String = iter::repeat('&').take(n + 1).collect();
let derefs: String = iter::repeat('*').take(n).collect();
let explicit = format!("{}{}::clone({})", refs, ty, snip);
db.span_suggestion(expr.span, "try dereferencing it", format!("{}({}{}).clone()", refs, derefs, snip.deref()));
db.span_suggestion(expr.span, "or try being explicit about what type to clone", explicit);
},
);
return; // don't report clone_on_copy
@ -960,13 +971,40 @@ fn lint_clone_on_copy(cx: &LateContext, expr: &hir::Expr, arg: &hir::Expr, arg_t
}
if is_copy(cx, ty) {
span_lint_and_then(cx, CLONE_ON_COPY, expr.span, "using `clone` on a `Copy` type", |db| {
if let Some(snip) = sugg::Sugg::hir_opt(cx, arg) {
if let ty::TyRef(..) = cx.tables.expr_ty(arg).sty {
db.span_suggestion(expr.span, "try dereferencing it", format!("{}", snip.deref()));
} else {
db.span_suggestion(expr.span, "try removing the `clone` call", format!("{}", snip));
let snip;
if let Some(snippet) = sugg::Sugg::hir_opt(cx, arg) {
if let ty::TyRef(..) = cx.tables.expr_ty(arg).sty {
let parent = cx.tcx.hir.get_parent_node(expr.id);
match cx.tcx.hir.get(parent) {
hir::map::NodeExpr(parent) => match parent.node {
// &*x is a nop, &x.clone() is not
hir::ExprAddrOf(..) |
// (*x).func() is useless, x.clone().func() can work in case func borrows mutably
hir::ExprMethodCall(..) => return,
_ => {},
}
hir::map::NodeStmt(stmt) => {
if let hir::StmtDecl(ref decl, _) = stmt.node {
if let hir::DeclLocal(ref loc) = decl.node {
if let hir::PatKind::Ref(..) = loc.pat.node {
// let ref y = *x borrows x, let ref y = x.clone() does not
return;
}
}
}
},
_ => {},
}
snip = Some(("try dereferencing it", format!("{}", snippet.deref())));
} else {
snip = Some(("try removing the `clone` call", format!("{}", snippet)));
}
} else {
snip = None;
}
span_lint_and_then(cx, CLONE_ON_COPY, expr.span, "using `clone` on a `Copy` type", |db| {
if let Some((text, snip)) = snip {
db.span_suggestion(expr.span, text, snip);
}
});
}