Fix [needless_return] false negative when returned expression borrows a value

Fixes #12907

changelog: Fix [`needless_return`] false negative when returned expression borrows a value
This commit is contained in:
apoisternex 2024-08-03 21:24:51 -03:00
parent 377d72ae8b
commit af35dcd330
4 changed files with 39 additions and 5 deletions

View file

@ -1,7 +1,7 @@
use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_hir_and_then};
use clippy_utils::source::{snippet_opt, snippet_with_context};
use clippy_utils::sugg::has_enclosing_paren;
use clippy_utils::visitors::{for_each_expr, Descend};
use clippy_utils::visitors::{for_each_expr, for_each_unconsumed_temporary, Descend};
use clippy_utils::{
binary_expr_needs_parentheses, fn_def_id, is_from_proc_macro, is_inside_let_else, is_res_lang_ctor, path_res,
path_to_local_id, span_contains_cfg, span_find_starting_semi,
@ -384,10 +384,24 @@ fn check_final_expr<'tcx>(
}
};
let borrows = inner.map_or(false, |inner| last_statement_borrows(cx, inner));
if borrows {
return;
if let Some(inner) = inner {
if for_each_unconsumed_temporary(cx, inner, |temporary_ty| {
if temporary_ty.has_significant_drop(cx.tcx, cx.param_env)
&& temporary_ty
.walk()
.any(|arg| matches!(arg.unpack(), GenericArgKind::Lifetime(re) if !re.is_static()))
{
ControlFlow::Break(())
} else {
ControlFlow::Continue(())
}
})
.is_break()
{
return;
}
}
if ret_span.from_expansion() {
return;
}

View file

@ -355,4 +355,8 @@ fn conjunctive_blocks() -> String {
({ "a".to_string() } + "b" + { "c" })
}
fn issue12907() -> String {
"".split("").next().unwrap().to_string()
}
fn main() {}

View file

@ -365,4 +365,8 @@ fn conjunctive_blocks() -> String {
return { "a".to_string() } + "b" + { "c" };
}
fn issue12907() -> String {
return "".split("").next().unwrap().to_string();
}
fn main() {}

View file

@ -665,5 +665,17 @@ LL - return { "a".to_string() } + "b" + { "c" };
LL + ({ "a".to_string() } + "b" + { "c" })
|
error: aborting due to 53 previous errors
error: unneeded `return` statement
--> tests/ui/needless_return.rs:369:5
|
LL | return "".split("").next().unwrap().to_string();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
help: remove `return`
|
LL - return "".split("").next().unwrap().to_string();
LL + "".split("").next().unwrap().to_string()
|
error: aborting due to 54 previous errors