81 lines
3.4 KiB
Rust
81 lines
3.4 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::source::snippet_opt;
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use clippy_utils::ty::implements_trait;
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use clippy_utils::{is_path_diagnostic_item, sugg};
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use rustc_errors::Applicability;
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use rustc_hir as hir;
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use rustc_lint::LateContext;
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use rustc_middle::ty::Ty;
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use rustc_span::sym;
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use super::FROM_ITER_INSTEAD_OF_COLLECT;
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pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, args: &[hir::Expr<'_>], func: &hir::Expr<'_>) {
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if is_path_diagnostic_item(cx, func, sym::from_iter_fn)
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&& let ty = cx.typeck_results().expr_ty(expr)
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&& let arg_ty = cx.typeck_results().expr_ty(&args[0])
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&& let Some(iter_id) = cx.tcx.get_diagnostic_item(sym::Iterator)
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&& implements_trait(cx, arg_ty, iter_id, &[])
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{
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// `expr` implements `FromIterator` trait
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let iter_expr = sugg::Sugg::hir(cx, &args[0], "..").maybe_par();
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let turbofish = extract_turbofish(cx, expr, ty);
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let sugg = format!("{iter_expr}.collect::<{turbofish}>()");
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span_lint_and_sugg(
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cx,
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FROM_ITER_INSTEAD_OF_COLLECT,
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expr.span,
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"usage of `FromIterator::from_iter`",
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"use `.collect()` instead of `::from_iter()`",
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sugg,
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Applicability::MaybeIncorrect,
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);
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}
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}
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fn extract_turbofish(cx: &LateContext<'_>, expr: &hir::Expr<'_>, ty: Ty<'_>) -> String {
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fn strip_angle_brackets(s: &str) -> Option<&str> {
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s.strip_prefix('<')?.strip_suffix('>')
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}
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let call_site = expr.span.source_callsite();
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if let Some(snippet) = snippet_opt(cx, call_site)
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&& let snippet_split = snippet.split("::").collect::<Vec<_>>()
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&& let Some((_, elements)) = snippet_split.split_last()
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{
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if let [type_specifier, _] = snippet_split.as_slice()
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&& let Some(type_specifier) = strip_angle_brackets(type_specifier)
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&& let Some((type_specifier, ..)) = type_specifier.split_once(" as ")
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{
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type_specifier.to_string()
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} else {
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// is there a type specifier? (i.e.: like `<u32>` in `collections::BTreeSet::<u32>::`)
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if let Some(type_specifier) = snippet_split.iter().find(|e| strip_angle_brackets(e).is_some()) {
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// remove the type specifier from the path elements
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let without_ts = elements
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.iter()
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.filter_map(|e| {
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if e == type_specifier {
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None
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} else {
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Some((*e).to_string())
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}
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})
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.collect::<Vec<_>>();
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// join and add the type specifier at the end (i.e.: `collections::BTreeSet<u32>`)
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format!("{}{type_specifier}", without_ts.join("::"))
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} else {
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// type is not explicitly specified so wildcards are needed
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// i.e.: 2 wildcards in `std::collections::BTreeMap<&i32, &char>`
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let ty_str = ty.to_string();
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let start = ty_str.find('<').unwrap_or(0);
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let end = ty_str.find('>').unwrap_or(ty_str.len());
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let nb_wildcard = ty_str[start..end].split(',').count();
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let wildcards = format!("_{}", ", _".repeat(nb_wildcard - 1));
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format!("{}<{wildcards}>", elements.join("::"))
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}
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}
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} else {
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ty.to_string()
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}
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}
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