use rustc::hir::*;
use rustc::lint::*;
use syntax::codemap::Spanned;
use crate::consts::{constant, Constant};
use crate::utils::paths;
use crate::utils::{match_type, snippet, span_lint_and_sugg, walk_ptrs_ty};
declare_clippy_lint! {
pub DURATION_SUBSEC,
complexity,
"checks for calculation of subsecond microseconds or milliseconds"
}
#[derive(Copy, Clone)]
pub struct DurationSubsec;
impl LintPass for DurationSubsec {
fn get_lints(&self) -> LintArray {
lint_array!(DURATION_SUBSEC)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for DurationSubsec {
fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
if_chain! {
if let ExprBinary(Spanned { node: BiDiv, .. }, ref left, ref right) = expr.node;
if let ExprMethodCall(ref method_path, _ , ref args) = left.node;
if match_type(cx, walk_ptrs_ty(cx.tables.expr_ty(&args[0])), &paths::DURATION);
if let Some((Constant::Int(divisor), _)) = constant(cx, cx.tables, right);
then {
let suggested_fn = match (method_path.name.as_str().as_ref(), divisor) {
("subsec_micros", 1_000) => "subsec_millis",
("subsec_nanos", 1_000) => "subsec_micros",
("subsec_nanos", 1_000_000) => "subsec_millis",
_ => return,
};
span_lint_and_sugg(
cx,
DURATION_SUBSEC,
expr.span,
&format!("Calling `{}()` is more concise than this calculation", suggested_fn),
"try",
format!("{}.{}()", snippet(cx, args[0].span, "_"), suggested_fn),
);
}
}
}
}