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Fix FP with `USELESS_VEC` and non-copy types

This commit is contained in:
mcarton 2016-07-14 19:31:17 +02:00
parent c1eb5828fa
commit ea665c38f1
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GPG Key ID: 5E427C794CBA45E8
4 changed files with 68 additions and 50 deletions
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15
clippy_lints/src/methods.rs
View File

@ -2,7 +2,7 @@ use rustc::hir;
use rustc::lint::*;
use rustc::middle::const_val::ConstVal;
use rustc::middle::const_qualif::ConstQualif;
use rustc::ty::subst::{Subst, TypeSpace};
use rustc::ty::subst::TypeSpace;
use rustc::ty;
use rustc_const_eval::EvalHint::ExprTypeChecked;
use rustc_const_eval::eval_const_expr_partial;
@ -10,9 +10,9 @@ use std::borrow::Cow;
use std::fmt;
use syntax::codemap::Span;
use syntax::ptr::P;
use utils::{get_trait_def_id, implements_trait, in_external_macro, in_macro, match_path, match_trait_method,
match_type, method_chain_args, return_ty, same_tys, snippet, span_lint,
span_lint_and_then, span_note_and_lint, walk_ptrs_ty, walk_ptrs_ty_depth};
use utils::{get_trait_def_id, implements_trait, in_external_macro, in_macro, is_copy, match_path,
match_trait_method, match_type, method_chain_args, return_ty, same_tys, snippet,
span_lint, span_lint_and_then, span_note_and_lint, walk_ptrs_ty, walk_ptrs_ty_depth};
use utils::MethodArgs;
use utils::paths;
use utils::sugg;
@ -471,7 +471,7 @@ impl LateLintPass for Pass {
// check conventions w.r.t. conversion method names and predicates
let ty = cx.tcx.lookup_item_type(cx.tcx.map.local_def_id(item.id)).ty;
let is_copy = is_copy(cx, ty, item);
let is_copy = is_copy(cx, ty, item.id);
for &(ref conv, self_kinds) in &CONVENTIONS {
if_let_chain! {[
conv.check(&name.as_str()),
@ -1163,8 +1163,3 @@ fn is_bool(ty: &hir::Ty) -> bool {
false
}
}
fn is_copy<'a, 'ctx>(cx: &LateContext<'a, 'ctx>, ty: ty::Ty<'ctx>, item: &hir::Item) -> bool {
let env = ty::ParameterEnvironment::for_item(cx.tcx, item.id);
!ty.subst(cx.tcx, env.free_substs).moves_by_default(cx.tcx.global_tcx(), &env, item.span)
}

7
clippy_lints/src/utils/mod.rs
View File

@ -15,7 +15,7 @@ use std::env;
use std::mem;
use std::str::FromStr;
use syntax::ast::{self, LitKind};
use syntax::codemap::{ExpnFormat, ExpnInfo, MultiSpan, Span};
use syntax::codemap::{ExpnFormat, ExpnInfo, MultiSpan, Span, DUMMY_SP};
use syntax::errors::DiagnosticBuilder;
use syntax::ptr::P;
@ -723,3 +723,8 @@ pub fn type_is_unsafe_function(ty: ty::Ty) -> bool {
_ => false,
}
}
pub fn is_copy<'a, 'ctx>(cx: &LateContext<'a, 'ctx>, ty: ty::Ty<'ctx>, env: NodeId) -> bool {
let env = ty::ParameterEnvironment::for_item(cx.tcx, env);
!ty.subst(cx.tcx, env.free_substs).moves_by_default(cx.tcx.global_tcx(), &env, DUMMY_SP)
}

87
clippy_lints/src/vec.rs
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@ -1,10 +1,10 @@
use rustc::lint::*;
use rustc::ty::TypeVariants;
use rustc::hir::*;
use rustc::lint::*;
use rustc::ty;
use rustc_const_eval::EvalHint::ExprTypeChecked;
use rustc_const_eval::eval_const_expr_partial;
use syntax::codemap::Span;
use utils::{higher, snippet, span_lint_and_then};
use utils::{higher, is_copy, snippet, span_lint_and_then};
/// **What it does:** This lint warns about using `&vec![..]` when using `&[..]` would be possible.
///
@ -35,50 +35,61 @@ impl LateLintPass for Pass {
fn check_expr(&mut self, cx: &LateContext, expr: &Expr) {
// search for `&vec![_]` expressions where the adjusted type is `&[_]`
if_let_chain!{[
let TypeVariants::TyRef(_, ref ty) = cx.tcx.expr_ty_adjusted(expr).sty,
let TypeVariants::TySlice(..) = ty.ty.sty,
let ty::TypeVariants::TyRef(_, ref ty) = cx.tcx.expr_ty_adjusted(expr).sty,
let ty::TypeVariants::TySlice(..) = ty.ty.sty,
let ExprAddrOf(_, ref addressee) = expr.node,
let Some(vec_args) = higher::vec_macro(cx, addressee),
], {
check_vec_macro(cx, addressee, expr.span);
check_vec_macro(cx, &vec_args, expr.span);
}}
// search for `for _ in vec![…]`
if let Some((_, arg, _)) = higher::for_loop(expr) {
if_let_chain!{[
let Some((_, arg, _)) = higher::for_loop(expr),
let Some(vec_args) = higher::vec_macro(cx, arg),
is_copy(cx, vec_type(cx.tcx.expr_ty_adjusted(arg)), cx.tcx.map.get_parent(expr.id)),
], {
// report the error around the `vec!` not inside `<std macros>:`
let span = cx.sess().codemap().source_callsite(arg.span);
check_vec_macro(cx, arg, span);
check_vec_macro(cx, &vec_args, span);
}}
}
}
fn check_vec_macro(cx: &LateContext, vec_args: &higher::VecArgs, span: Span) {
let snippet = match *vec_args {
higher::VecArgs::Repeat(elem, len) => {
if eval_const_expr_partial(cx.tcx, len, ExprTypeChecked, None).is_ok() {
format!("&[{}; {}]", snippet(cx, elem.span, "elem"), snippet(cx, len.span, "len")).into()
} else {
return;
}
}
}
higher::VecArgs::Vec(args) => {
if let Some(last) = args.iter().last() {
let span = Span {
lo: args[0].span.lo,
hi: last.span.hi,
expn_id: args[0].span.expn_id,
};
format!("&[{}]", snippet(cx, span, "..")).into()
} else {
"&[]".into()
}
}
};
span_lint_and_then(cx, USELESS_VEC, span, "useless use of `vec!`", |db| {
db.span_suggestion(span, "you can use a slice directly", snippet);
});
}
fn check_vec_macro(cx: &LateContext, vec: &Expr, span: Span) {
if let Some(vec_args) = higher::vec_macro(cx, vec) {
let snippet = match vec_args {
higher::VecArgs::Repeat(elem, len) => {
if eval_const_expr_partial(cx.tcx, len, ExprTypeChecked, None).is_ok() {
format!("&[{}; {}]", snippet(cx, elem.span, "elem"), snippet(cx, len.span, "len")).into()
} else {
return;
}
}
higher::VecArgs::Vec(args) => {
if let Some(last) = args.iter().last() {
let span = Span {
lo: args[0].span.lo,
hi: last.span.hi,
expn_id: args[0].span.expn_id,
};
format!("&[{}]", snippet(cx, span, "..")).into()
} else {
"&[]".into()
}
}
};
span_lint_and_then(cx, USELESS_VEC, span, "useless use of `vec!`", |db| {
db.span_suggestion(span, "you can use a slice directly", snippet);
});
/// Return the item type of the vector (ie. the `T` in `Vec<T>`).
fn vec_type(ty: ty::Ty) -> ty::Ty {
if let ty::TyStruct(_, substs) = ty.sty {
substs.types.get(ty::subst::ParamSpace::TypeSpace, 0)
} else {
panic!("The type of `vec!` is a not a struct?");
}
}

9
tests/compile-fail/vec.rs
View File

@ -3,6 +3,9 @@
#![deny(useless_vec)]
#[derive(Debug)]
struct NonCopy;
fn on_slice(_: &[u8]) {}
#[allow(ptr_arg)]
fn on_vec(_: &Vec<u8>) {}
@ -62,6 +65,10 @@ fn main() {
//~^ ERROR useless use of `vec!`
//~| HELP you can use
//~| SUGGESTION for a in &[1, 2, 3] {
println!("{}", a);
println!("{:?}", a);
}
for a in vec![NonCopy, NonCopy] {
println!("{:?}", a);
}
}