use crate::utils::paths::FUTURE_FROM_GENERATOR;
-use crate::utils::{match_function_call, snippet_block, snippet_opt, span_lint_and_then};
+use crate::utils::{match_function_call, position_before_rarrow, snippet_block, snippet_opt, span_lint_and_then};
use if_chain::if_chain;
use rustc_errors::Applicability;
use rustc_hir::intravisit::FnKind;
use rustc_hir::{
- AsyncGeneratorKind, Block, Body, Expr, ExprKind, FnDecl, FnRetTy, GeneratorKind, GenericBound, HirId, IsAsync,
- ItemKind, TraitRef, Ty, TyKind, TypeBindingKind,
+ AsyncGeneratorKind, Block, Body, Expr, ExprKind, FnDecl, FnRetTy, GeneratorKind, GenericArg, GenericBound, HirId,
+ IsAsync, ItemKind, LifetimeName, TraitRef, Ty, TyKind, TypeBindingKind,
};
use rustc_lint::{LateContext, LateLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::Span;
+use rustc_span::{sym, Span};
declare_clippy_lint! {
/// **What it does:** It checks for manual implementations of `async` functions.
/// ```
/// Use instead:
/// ```rust
- /// use std::future::Future;
- ///
/// async fn foo() -> i32 { 42 }
/// ```
pub MANUAL_ASYNC_FN,
declare_lint_pass!(ManualAsyncFn => [MANUAL_ASYNC_FN]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ManualAsyncFn {
+impl<'tcx> LateLintPass<'tcx> for ManualAsyncFn {
fn check_fn(
&mut self,
- cx: &LateContext<'a, 'tcx>,
+ cx: &LateContext<'tcx>,
kind: FnKind<'tcx>,
decl: &'tcx FnDecl<'_>,
body: &'tcx Body<'_>,
if let IsAsync::NotAsync = header.asyncness;
// Check that this function returns `impl Future`
if let FnRetTy::Return(ret_ty) = decl.output;
- if let Some(trait_ref) = future_trait_ref(cx, ret_ty);
+ if let Some((trait_ref, output_lifetimes)) = future_trait_ref(cx, ret_ty);
if let Some(output) = future_output_ty(trait_ref);
+ if captures_all_lifetimes(decl.inputs, &output_lifetimes);
// Check that the body of the function consists of one async block
if let ExprKind::Block(block, _) = body.value.kind;
if block.stmts.is_empty();
|diag| {
if_chain! {
if let Some(header_snip) = snippet_opt(cx, header_span);
- if let Some(ret_pos) = header_snip.rfind("->");
+ if let Some(ret_pos) = position_before_rarrow(&header_snip);
if let Some((ret_sugg, ret_snip)) = suggested_ret(cx, output);
then {
let help = format!("make the function `async` and {}", ret_sugg);
}
}
-fn future_trait_ref<'tcx>(cx: &LateContext<'_, 'tcx>, ty: &'tcx Ty<'tcx>) -> Option<&'tcx TraitRef<'tcx>> {
+fn future_trait_ref<'tcx>(
+ cx: &LateContext<'tcx>,
+ ty: &'tcx Ty<'tcx>,
+) -> Option<(&'tcx TraitRef<'tcx>, Vec<LifetimeName>)> {
if_chain! {
- if let TyKind::OpaqueDef(item_id, _) = ty.kind;
- let item = cx.tcx.hir().item(item_id.id);
+ if let TyKind::OpaqueDef(item_id, bounds) = ty.kind;
+ let item = cx.tcx.hir().item(item_id);
if let ItemKind::OpaqueTy(opaque) = &item.kind;
- if opaque.bounds.len() == 1;
- if let GenericBound::Trait(poly, _) = &opaque.bounds[0];
- if poly.trait_ref.trait_def_id() == cx.tcx.lang_items().future_trait();
+ if let Some(trait_ref) = opaque.bounds.iter().find_map(|bound| {
+ if let GenericBound::Trait(poly, _) = bound {
+ Some(&poly.trait_ref)
+ } else {
+ None
+ }
+ });
+ if trait_ref.trait_def_id() == cx.tcx.lang_items().future_trait();
then {
- return Some(&poly.trait_ref);
+ let output_lifetimes = bounds
+ .iter()
+ .filter_map(|bound| {
+ if let GenericArg::Lifetime(lt) = bound {
+ Some(lt.name)
+ } else {
+ None
+ }
+ })
+ .collect();
+
+ return Some((trait_ref, output_lifetimes));
}
}
if let Some(args) = segment.args;
if args.bindings.len() == 1;
let binding = &args.bindings[0];
- if binding.ident.as_str() == "Output";
+ if binding.ident.name == sym::Output;
if let TypeBindingKind::Equality{ty: output} = binding.kind;
then {
return Some(output)
None
}
-fn desugared_async_block<'tcx>(cx: &LateContext<'_, 'tcx>, block: &'tcx Block<'tcx>) -> Option<&'tcx Body<'tcx>> {
+fn captures_all_lifetimes(inputs: &[Ty<'_>], output_lifetimes: &[LifetimeName]) -> bool {
+ let input_lifetimes: Vec<LifetimeName> = inputs
+ .iter()
+ .filter_map(|ty| {
+ if let TyKind::Rptr(lt, _) = ty.kind {
+ Some(lt.name)
+ } else {
+ None
+ }
+ })
+ .collect();
+
+ // The lint should trigger in one of these cases:
+ // - There are no input lifetimes
+ // - There's only one output lifetime bound using `+ '_`
+ // - All input lifetimes are explicitly bound to the output
+ input_lifetimes.is_empty()
+ || (output_lifetimes.len() == 1 && matches!(output_lifetimes[0], LifetimeName::Underscore))
+ || input_lifetimes
+ .iter()
+ .all(|in_lt| output_lifetimes.iter().any(|out_lt| in_lt == out_lt))
+}
+
+fn desugared_async_block<'tcx>(cx: &LateContext<'tcx>, block: &'tcx Block<'tcx>) -> Option<&'tcx Body<'tcx>> {
if_chain! {
if let Some(block_expr) = block.expr;
if let Some(args) = match_function_call(cx, block_expr, &FUTURE_FROM_GENERATOR);
None
}
-fn suggested_ret(cx: &LateContext<'_, '_>, output: &Ty<'_>) -> Option<(&'static str, String)> {
+fn suggested_ret(cx: &LateContext<'_>, output: &Ty<'_>) -> Option<(&'static str, String)> {
match output.kind {
TyKind::Tup(tys) if tys.is_empty() => {
let sugg = "remove the return type";
},
_ => {
let sugg = "return the output of the future directly";
- snippet_opt(cx, output.span).map(|snip| (sugg, format!("-> {}", snip)))
+ snippet_opt(cx, output.span).map(|snip| (sugg, format!(" -> {}", snip)))
},
}
}
projects / rust.git / blobdiff