78 lines
3.0 KiB
Rust
78 lines
3.0 KiB
Rust
use crate::utils::span_lint;
|
|
use rustc::hir::*;
|
|
use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
|
|
use rustc::ty::subst::Subst;
|
|
use rustc::ty::{self, Ty};
|
|
use rustc::{declare_lint_pass, declare_tool_lint};
|
|
|
|
declare_clippy_lint! {
|
|
/// **What it does:** Detects giving a mutable reference to a function that only
|
|
/// requires an immutable reference.
|
|
///
|
|
/// **Why is this bad?** The immutable reference rules out all other references
|
|
/// to the value. Also the code misleads about the intent of the call site.
|
|
///
|
|
/// **Known problems:** None.
|
|
///
|
|
/// **Example:**
|
|
/// ```ignore
|
|
/// my_vec.push(&mut value)
|
|
/// ```
|
|
pub UNNECESSARY_MUT_PASSED,
|
|
style,
|
|
"an argument passed as a mutable reference although the callee only demands an immutable reference"
|
|
}
|
|
|
|
declare_lint_pass!(UnnecessaryMutPassed => [UNNECESSARY_MUT_PASSED]);
|
|
|
|
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnnecessaryMutPassed {
|
|
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, e: &'tcx Expr) {
|
|
match e.node {
|
|
ExprKind::Call(ref fn_expr, ref arguments) => {
|
|
if let ExprKind::Path(ref path) = fn_expr.node {
|
|
check_arguments(
|
|
cx,
|
|
arguments,
|
|
cx.tables.expr_ty(fn_expr),
|
|
&print::to_string(print::NO_ANN, |s| s.print_qpath(path, false)),
|
|
);
|
|
}
|
|
},
|
|
ExprKind::MethodCall(ref path, _, ref arguments) => {
|
|
let def_id = cx.tables.type_dependent_def_id(e.hir_id).unwrap();
|
|
let substs = cx.tables.node_substs(e.hir_id);
|
|
let method_type = cx.tcx.type_of(def_id).subst(cx.tcx, substs);
|
|
check_arguments(cx, arguments, method_type, &path.ident.as_str())
|
|
},
|
|
_ => (),
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_arguments<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, arguments: &[Expr], type_definition: Ty<'tcx>, name: &str) {
|
|
match type_definition.kind {
|
|
ty::FnDef(..) | ty::FnPtr(_) => {
|
|
let parameters = type_definition.fn_sig(cx.tcx).skip_binder().inputs();
|
|
for (argument, parameter) in arguments.iter().zip(parameters.iter()) {
|
|
match parameter.kind {
|
|
ty::Ref(_, _, MutImmutable)
|
|
| ty::RawPtr(ty::TypeAndMut {
|
|
mutbl: MutImmutable, ..
|
|
}) => {
|
|
if let ExprKind::AddrOf(MutMutable, _) = argument.node {
|
|
span_lint(
|
|
cx,
|
|
UNNECESSARY_MUT_PASSED,
|
|
argument.span,
|
|
&format!("The function/method `{}` doesn't need a mutable reference", name),
|
|
);
|
|
}
|
|
},
|
|
_ => (),
|
|
}
|
|
}
|
|
},
|
|
_ => (),
|
|
}
|
|
}
|