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use rustc::lint::*;
use rustc::ty;
use rustc::hir::*;
use utils::{match_def_path, paths, span_note_and_lint};
declare_lint! {
pub DROP_REF,
Warn,
"calls to `std::mem::drop` with a reference instead of an owned value"
}
declare_lint! {
pub FORGET_REF,
Warn,
"calls to `std::mem::forget` with a reference instead of an owned value"
}
#[allow(missing_copy_implementations)]
pub struct Pass;
impl LintPass for Pass {
fn get_lints(&self) -> LintArray {
lint_array!(DROP_REF, FORGET_REF)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
if_let_chain!{[
let ExprCall(ref path, ref args) = expr.node,
let ExprPath(ref qpath) = path.node,
args.len() == 1,
], {
let def_id = cx.tcx.tables().qpath_def(qpath, path.id).def_id();
let lint;
let msg;
if match_def_path(cx, def_id, &paths::DROP) {
lint = DROP_REF;
msg = "call to `std::mem::drop` with a reference argument. \
Dropping a reference does nothing";
} else if match_def_path(cx, def_id, &paths::MEM_FORGET) {
lint = FORGET_REF;
msg = "call to `std::mem::forget` with a reference argument. \
Forgetting a reference does nothing";
} else {
return;
}
let arg = &args[0];
let arg_ty = cx.tcx.tables().expr_ty(arg);
if let ty::TyRef(..) = arg_ty.sty {
span_note_and_lint(cx,
lint,
expr.span,
msg,
arg.span,
&format!("argument has type {}", arg_ty.sty));
}
}}
}
}