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Add for _ in vec![…] to the USELESS_VEC lint

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mcarton 2016-03-28 23:32:55 +02:00
parent 11eae72e6f
commit 777e810a39
4 changed files with 67 additions and 50 deletions
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60
src/vec.rs
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@ -4,7 +4,7 @@ use rustc_front::hir::*;
use syntax::codemap::Span;
use syntax::ptr::P;
use utils::VEC_FROM_ELEM_PATH;
use utils::{is_expn_of, match_path, snippet, span_lint_and_then};
use utils::{is_expn_of, match_path, recover_for_loop, snippet, span_lint_and_then};
/// **What it does:** This lint warns about using `&vec![..]` when using `&[..]` would be possible.
///
@ -38,32 +38,42 @@ impl LateLintPass for UselessVec {
let TypeVariants::TyRef(_, ref ty) = cx.tcx.expr_ty_adjusted(expr).sty,
let TypeVariants::TySlice(..) = ty.ty.sty,
let ExprAddrOf(_, ref addressee) = expr.node,
let Some(vec_args) = unexpand_vec(cx, addressee)
], {
let snippet = match vec_args {
VecArgs::Repeat(elem, len) => {
format!("&[{}; {}]", snippet(cx, elem.span, "elem"), snippet(cx, len.span, "len")).into()
}
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, expr.span, "useless use of `vec!`", |db| {
db.span_suggestion(expr.span, "you can use a slice directly", snippet);
});
check_vec_macro(cx, expr, addressee);
}}
// search for `for _ in vec![…]`
if let Some((_, arg, _)) = recover_for_loop(expr) {
check_vec_macro(cx, arg, arg);
}
}
}
fn check_vec_macro(cx: &LateContext, expr: &Expr, vec: &Expr) {
if let Some(vec_args) = unexpand_vec(cx, vec) {
let snippet = match vec_args {
VecArgs::Repeat(elem, len) => {
format!("&[{}; {}]", snippet(cx, elem.span, "elem"), snippet(cx, len.span, "len")).into()
}
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, expr.span, "useless use of `vec!`", |db| {
db.span_suggestion(expr.span, "you can use a slice directly", snippet);
});
}
}