mirror of
https://github.com/rust-lang/rust-clippy
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Allow filter_map_identity when the closure is typed
This extends the `filter_map_identity` lint to support typed closures. For untyped closures, we know that the program compiles, and therefore we can safely suggest using flatten. For typed closures, they may participate in type resolution. In this case we use `Applicability::MaybeIncorrect`. Details: https://rust-lang.zulipchat.com/#narrow/stream/257328-clippy/topic/Should.20.60filter_map_identity.60.20lint.20when.20closures.20are.20typed.3F
This commit is contained in:
Quinn Sinclair
parent
ca6a647490
commit
9655231eb8
4 changed files with 288 additions and 36 deletions
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@ -1,5 +1,5 @@
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use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::{is_expr_untyped_identity_function, is_trait_method};
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use clippy_utils::{is_expr_identity_function, is_expr_untyped_identity_function, is_trait_method};
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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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@ -7,8 +7,20 @@ use rustc_span::{sym, Span};
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use super::FILTER_MAP_IDENTITY;
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fn is_identity(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<Applicability> {
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if is_expr_untyped_identity_function(cx, expr) {
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return Some(Applicability::MachineApplicable);
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}
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if is_expr_identity_function(cx, expr) {
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return Some(Applicability::MaybeIncorrect);
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}
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None
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}
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pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, filter_map_arg: &hir::Expr<'_>, filter_map_span: Span) {
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if is_trait_method(cx, expr, sym::Iterator) && is_expr_untyped_identity_function(cx, filter_map_arg) {
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if is_trait_method(cx, expr, sym::Iterator)
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&& let Some(applicability) = is_identity(cx, filter_map_arg)
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{
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span_lint_and_sugg(
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cx,
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FILTER_MAP_IDENTITY,
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@ -16,7 +28,7 @@ pub(super) fn check(cx: &LateContext<'_>, expr: &hir::Expr<'_>, filter_map_arg:
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"use of `filter_map` with an identity function",
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"try",
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"flatten()".to_string(),
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Applicability::MachineApplicable,
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applicability,
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);
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}
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}
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@ -1,17 +1,83 @@
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#![allow(unused_imports, clippy::needless_return)]
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#![allow(unused_imports, clippy::needless_return, clippy::useless_vec)]
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#![warn(clippy::filter_map_identity)]
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#![feature(stmt_expr_attributes)]
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use std::option::Option;
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struct NonCopy;
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use std::convert::identity;
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fn non_copy_vec() -> Vec<Option<NonCopy>> {
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todo!()
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}
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fn copy_vec<T: Copy>() -> Vec<Option<T>> {
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todo!()
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}
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fn copy_vec_non_inferred() -> Vec<Option<i32>> {
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todo!()
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}
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fn opaque<T: Default>() -> impl IntoIterator<Item = Option<T>> {
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vec![Some(T::default())]
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}
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fn main() {
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let iterator = vec![Some(1), None, Some(2)].into_iter();
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let _ = iterator.flatten();
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{
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// into_iter
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copy_vec_non_inferred().into_iter().flatten();
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//~^ ERROR: use of
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copy_vec_non_inferred().into_iter().flatten();
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//~^ ERROR: use of
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copy_vec_non_inferred().into_iter().flatten();
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//~^ ERROR: use of
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copy_vec_non_inferred().into_iter().flatten();
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//~^ ERROR: use of
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copy_vec_non_inferred().into_iter().flatten();
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//~^ ERROR: use of
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let iterator = vec![Some(1), None, Some(2)].into_iter();
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let _ = iterator.flatten();
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non_copy_vec().into_iter().flatten();
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//~^ ERROR: use of
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non_copy_vec().into_iter().flatten();
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//~^ ERROR: use of
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use std::convert::identity;
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let iterator = vec![Some(1), None, Some(2)].into_iter();
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let _ = iterator.flatten();
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non_copy_vec().into_iter().flatten();
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//~^ ERROR: use of
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non_copy_vec().into_iter().flatten();
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//~^ ERROR: use of
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non_copy_vec().into_iter().flatten();
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//~^ ERROR: use of
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non_copy_vec().into_iter().flatten();
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//~^ ERROR: use of
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let iterator = vec![Some(1), None, Some(2)].into_iter();
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let _ = iterator.flatten();
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copy_vec::<i32>().into_iter().flatten();
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().flatten();
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().flatten();
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().flatten();
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//~^ ERROR: use of
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// we are forced to pass the type in the call.
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copy_vec::<i32>().into_iter().flatten();
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().flatten();
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().flatten();
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().flatten();
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//~^ ERROR: use of
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#[rustfmt::skip]
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copy_vec::<i32>().into_iter().flatten();
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//~^ ERROR: use of
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#[rustfmt::skip]
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copy_vec::<i32>().into_iter().flatten();
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//~^ ERROR: use of
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// note, the compiler requires that we pass the type to `opaque`. This is mostly for reference,
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// it behaves the same as copy_vec.
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opaque::<i32>().into_iter().flatten();
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//~^ ERROR: use of
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}
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}
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@ -1,17 +1,83 @@
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#![allow(unused_imports, clippy::needless_return)]
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#![allow(unused_imports, clippy::needless_return, clippy::useless_vec)]
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#![warn(clippy::filter_map_identity)]
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#![feature(stmt_expr_attributes)]
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use std::option::Option;
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struct NonCopy;
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use std::convert::identity;
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fn non_copy_vec() -> Vec<Option<NonCopy>> {
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todo!()
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}
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fn copy_vec<T: Copy>() -> Vec<Option<T>> {
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todo!()
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}
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fn copy_vec_non_inferred() -> Vec<Option<i32>> {
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todo!()
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}
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fn opaque<T: Default>() -> impl IntoIterator<Item = Option<T>> {
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vec![Some(T::default())]
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}
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fn main() {
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let iterator = vec![Some(1), None, Some(2)].into_iter();
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let _ = iterator.filter_map(|x| x);
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{
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// into_iter
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copy_vec_non_inferred().into_iter().filter_map(|x| x);
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//~^ ERROR: use of
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copy_vec_non_inferred().into_iter().filter_map(std::convert::identity);
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//~^ ERROR: use of
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copy_vec_non_inferred().into_iter().filter_map(identity);
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//~^ ERROR: use of
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copy_vec_non_inferred().into_iter().filter_map(|x| return x);
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//~^ ERROR: use of
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copy_vec_non_inferred().into_iter().filter_map(|x| return x);
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//~^ ERROR: use of
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let iterator = vec![Some(1), None, Some(2)].into_iter();
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let _ = iterator.filter_map(std::convert::identity);
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non_copy_vec().into_iter().filter_map(|x| x);
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//~^ ERROR: use of
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non_copy_vec().into_iter().filter_map(|x| x);
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//~^ ERROR: use of
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use std::convert::identity;
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let iterator = vec![Some(1), None, Some(2)].into_iter();
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let _ = iterator.filter_map(identity);
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non_copy_vec().into_iter().filter_map(std::convert::identity);
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//~^ ERROR: use of
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non_copy_vec().into_iter().filter_map(identity);
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//~^ ERROR: use of
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non_copy_vec().into_iter().filter_map(|x| return x);
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//~^ ERROR: use of
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non_copy_vec().into_iter().filter_map(|x| return x);
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//~^ ERROR: use of
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let iterator = vec![Some(1), None, Some(2)].into_iter();
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let _ = iterator.filter_map(|x| return x);
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copy_vec::<i32>().into_iter().filter_map(|x: Option<_>| x);
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().filter_map(|x: Option<_>| x);
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().filter_map(|x: Option<_>| return x);
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().filter_map(|x: Option<_>| return x);
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//~^ ERROR: use of
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// we are forced to pass the type in the call.
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copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| x);
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| x);
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| return x);
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//~^ ERROR: use of
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copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| return x);
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//~^ ERROR: use of
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#[rustfmt::skip]
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copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| -> Option<i32> {{ x }});
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//~^ ERROR: use of
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#[rustfmt::skip]
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copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| -> Option<i32> {{ return x }});
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//~^ ERROR: use of
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// note, the compiler requires that we pass the type to `opaque`. This is mostly for reference,
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// it behaves the same as copy_vec.
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opaque::<i32>().into_iter().filter_map(|x| x);
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//~^ ERROR: use of
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}
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}
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@ -1,29 +1,137 @@
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:6:22
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--> tests/ui/filter_map_identity.rs:28:45
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LL | let _ = iterator.filter_map(|x| x);
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| ^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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LL | copy_vec_non_inferred().into_iter().filter_map(|x| x);
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| ^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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= note: `-D clippy::filter-map-identity` implied by `-D warnings`
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= help: to override `-D warnings` add `#[allow(clippy::filter_map_identity)]`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:9:22
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--> tests/ui/filter_map_identity.rs:30:45
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LL | let _ = iterator.filter_map(std::convert::identity);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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LL | copy_vec_non_inferred().into_iter().filter_map(std::convert::identity);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:13:22
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--> tests/ui/filter_map_identity.rs:32:45
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LL | let _ = iterator.filter_map(identity);
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| ^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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LL | copy_vec_non_inferred().into_iter().filter_map(identity);
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| ^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:16:22
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--> tests/ui/filter_map_identity.rs:34:45
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LL | let _ = iterator.filter_map(|x| return x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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LL | copy_vec_non_inferred().into_iter().filter_map(|x| return x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: aborting due to 4 previous errors
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:36:45
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LL | copy_vec_non_inferred().into_iter().filter_map(|x| return x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:39:36
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LL | non_copy_vec().into_iter().filter_map(|x| x);
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| ^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:41:36
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LL | non_copy_vec().into_iter().filter_map(|x| x);
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| ^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:44:36
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LL | non_copy_vec().into_iter().filter_map(std::convert::identity);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:46:36
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LL | non_copy_vec().into_iter().filter_map(identity);
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| ^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:48:36
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LL | non_copy_vec().into_iter().filter_map(|x| return x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:50:36
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LL | non_copy_vec().into_iter().filter_map(|x| return x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:53:39
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LL | copy_vec::<i32>().into_iter().filter_map(|x: Option<_>| x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:55:39
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LL | copy_vec::<i32>().into_iter().filter_map(|x: Option<_>| x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:57:39
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LL | copy_vec::<i32>().into_iter().filter_map(|x: Option<_>| return x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:59:39
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LL | copy_vec::<i32>().into_iter().filter_map(|x: Option<_>| return x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:63:39
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LL | copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:65:39
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LL | copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:67:39
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LL | copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| return x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:69:39
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LL | copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| return x);
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:72:43
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LL | copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| -> Option<i32> {{ x }});
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:75:43
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LL | copy_vec::<i32>().into_iter().filter_map(|x: Option<i32>| -> Option<i32> {{ return x }});
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: use of `filter_map` with an identity function
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--> tests/ui/filter_map_identity.rs:80:37
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LL | opaque::<i32>().into_iter().filter_map(|x| x);
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| ^^^^^^^^^^^^^^^^^ help: try: `flatten()`
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error: aborting due to 22 previous errors
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