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use clippy_utils::diagnostics::span_lint_and_sugg;
use clippy_utils::eager_or_lazy::switch_to_lazy_eval;
use clippy_utils::source::{snippet, snippet_with_macro_callsite};
use clippy_utils::ty::{implements_trait, match_type};
use clippy_utils::{contains_return, is_trait_item, last_path_segment, paths};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::LateContext;
use rustc_span::source_map::Span;
use rustc_span::symbol::{kw, sym};
use std::borrow::Cow;
use super::OR_FUN_CALL;
/// Checks for the `OR_FUN_CALL` lint.
#[allow(clippy::too_many_lines)]
pub(super) fn check<'tcx>(
cx: &LateContext<'tcx>,
expr: &hir::Expr<'_>,
method_span: Span,
name: &str,
args: &'tcx [hir::Expr<'_>],
) {
/// Checks for `unwrap_or(T::new())` or `unwrap_or(T::default())`.
#[allow(clippy::too_many_arguments)]
fn check_unwrap_or_default(
cx: &LateContext<'_>,
name: &str,
fun: &hir::Expr<'_>,
arg: &hir::Expr<'_>,
or_has_args: bool,
span: Span,
method_span: Span,
) -> bool {
let is_default_default = || is_trait_item(cx, fun, sym::Default);
let implements_default = |arg, default_trait_id| {
let arg_ty = cx.typeck_results().expr_ty(arg);
implements_trait(cx, arg_ty, default_trait_id, &[])
};
if_chain! {
if !or_has_args;
if name == "unwrap_or";
if let hir::ExprKind::Path(ref qpath) = fun.kind;
if let Some(default_trait_id) = cx.tcx.get_diagnostic_item(sym::Default);
let path = last_path_segment(qpath).ident.name;
// needs to target Default::default in particular or be *::new and have a Default impl
// available
if (matches!(path, kw::Default) && is_default_default())
|| (matches!(path, sym::new) && implements_default(arg, default_trait_id));
then {
span_lint_and_sugg(
cx,
OR_FUN_CALL,
method_span.with_hi(span.hi()),
&format!("use of `{}` followed by a call to `{}`", name, path),
"try this",
"unwrap_or_default()".to_string(),
Applicability::MachineApplicable,
);
true
} else {
false
}
}
}
/// Checks for `*or(foo())`.
#[allow(clippy::too_many_arguments)]
fn check_general_case<'tcx>(
cx: &LateContext<'tcx>,
name: &str,
method_span: Span,
self_expr: &hir::Expr<'_>,
arg: &'tcx hir::Expr<'_>,
span: Span,
// None if lambda is required
fun_span: Option<Span>,
) {
// (path, fn_has_argument, methods, suffix)
static KNOW_TYPES: [(&[&str], bool, &[&str], &str); 4] = [
(&paths::BTREEMAP_ENTRY, false, &["or_insert"], "with"),
(&paths::HASHMAP_ENTRY, false, &["or_insert"], "with"),
(&paths::OPTION, false, &["map_or", "ok_or", "or", "unwrap_or"], "else"),
(&paths::RESULT, true, &["or", "unwrap_or"], "else"),
];
if_chain! {
if KNOW_TYPES.iter().any(|k| k.2.contains(&name));
if switch_to_lazy_eval(cx, arg);
if !contains_return(arg);
let self_ty = cx.typeck_results().expr_ty(self_expr);
if let Some(&(_, fn_has_arguments, poss, suffix)) =
KNOW_TYPES.iter().find(|&&i| match_type(cx, self_ty, i.0));
if poss.contains(&name);
then {
let macro_expanded_snipped;
let sugg: Cow<'_, str> = {
let (snippet_span, use_lambda) = match (fn_has_arguments, fun_span) {
(false, Some(fun_span)) => (fun_span, false),
_ => (arg.span, true),
};
let snippet = {
let not_macro_argument_snippet = snippet_with_macro_callsite(cx, snippet_span, "..");
if not_macro_argument_snippet == "vec![]" {
macro_expanded_snipped = snippet(cx, snippet_span, "..");
match macro_expanded_snipped.strip_prefix("$crate::vec::") {
Some(stripped) => Cow::from(stripped),
None => macro_expanded_snipped
}
}
else {
not_macro_argument_snippet
}
};
if use_lambda {
let l_arg = if fn_has_arguments { "_" } else { "" };
format!("|{}| {}", l_arg, snippet).into()
} else {
snippet
}
};
let span_replace_word = method_span.with_hi(span.hi());
span_lint_and_sugg(
cx,
OR_FUN_CALL,
span_replace_word,
&format!("use of `{}` followed by a function call", name),
"try this",
format!("{}_{}({})", name, suffix, sugg),
Applicability::HasPlaceholders,
);
}
}
}
if let [self_arg, arg] = args {
let inner_arg = if let hir::ExprKind::Block(
hir::Block {
stmts: [],
expr: Some(expr),
..
},
_,
) = arg.kind
{
expr
} else {
arg
};
match inner_arg.kind {
hir::ExprKind::Call(fun, or_args) => {
let or_has_args = !or_args.is_empty();
if !check_unwrap_or_default(cx, name, fun, arg, or_has_args, expr.span, method_span) {
let fun_span = if or_has_args { None } else { Some(fun.span) };
check_general_case(cx, name, method_span, self_arg, arg, expr.span, fun_span);
}
},
hir::ExprKind::Index(..) | hir::ExprKind::MethodCall(..) => {
check_general_case(cx, name, method_span, self_arg, arg, expr.span, None);
},
_ => (),
}
}
}
|
