--- /dev/null
+use super::FOR_LOOPS_OVER_FALLIBLES;
+use crate::utils::{is_type_diagnostic_item, snippet, span_lint_and_help};
+use rustc_hir::{Expr, Pat};
+use rustc_lint::LateContext;
+use rustc_span::symbol::sym;
+
+/// Checks for `for` loops over `Option`s and `Result`s.
+pub(super) fn check(cx: &LateContext<'_>, pat: &Pat<'_>, arg: &Expr<'_>) {
+ let ty = cx.typeck_results().expr_ty(arg);
+ if is_type_diagnostic_item(cx, ty, sym::option_type) {
+ span_lint_and_help(
+ cx,
+ FOR_LOOPS_OVER_FALLIBLES,
+ arg.span,
+ &format!(
+ "for loop over `{0}`, which is an `Option`. This is more readably written as an \
+ `if let` statement",
+ snippet(cx, arg.span, "_")
+ ),
+ None,
+ &format!(
+ "consider replacing `for {0} in {1}` with `if let Some({0}) = {1}`",
+ snippet(cx, pat.span, "_"),
+ snippet(cx, arg.span, "_")
+ ),
+ );
+ } else if is_type_diagnostic_item(cx, ty, sym::result_type) {
+ span_lint_and_help(
+ cx,
+ FOR_LOOPS_OVER_FALLIBLES,
+ arg.span,
+ &format!(
+ "for loop over `{0}`, which is a `Result`. This is more readably written as an \
+ `if let` statement",
+ snippet(cx, arg.span, "_")
+ ),
+ None,
+ &format!(
+ "consider replacing `for {0} in {1}` with `if let Ok({0}) = {1}`",
+ snippet(cx, pat.span, "_"),
+ snippet(cx, arg.span, "_")
+ ),
+ );
+ }
+}