diff options
| -rw-r--r-- | clippy_lints/src/methods/map_flatten.rs | 118 | ||||
| -rw-r--r-- | clippy_lints/src/methods/mod.rs | 2 | ||||
| -rw-r--r-- | clippy_lints/src/utils/internal_lints/metadata_collector.rs | 3 | ||||
| -rw-r--r-- | clippy_utils/src/diagnostics.rs | 86 | ||||
| -rw-r--r-- | tests/ui/map_flatten.rs | 74 | ||||
| -rw-r--r-- | tests/ui/map_flatten.stderr | 125 | ||||
| -rw-r--r-- | tests/ui/map_flatten_fixable.fixed (renamed from tests/ui/map_flatten.fixed) | 0 | ||||
| -rw-r--r-- | tests/ui/map_flatten_fixable.rs | 31 | ||||
| -rw-r--r-- | tests/ui/map_flatten_fixable.stderr | 80 |
9 files changed, 395 insertions, 124 deletions
diff --git a/clippy_lints/src/methods/map_flatten.rs b/clippy_lints/src/methods/map_flatten.rs index e1212c31cfb..f447940ea3b 100644 --- a/clippy_lints/src/methods/map_flatten.rs +++ b/clippy_lints/src/methods/map_flatten.rs @@ -1,83 +1,73 @@ -use clippy_utils::diagnostics::span_lint_and_sugg; +use clippy_utils::diagnostics::span_lint_and_sugg_for_edges; use clippy_utils::is_trait_method; -use clippy_utils::source::snippet; +use clippy_utils::source::snippet_with_applicability; use clippy_utils::ty::is_type_diagnostic_item; use rustc_errors::Applicability; -use rustc_hir as hir; +use rustc_hir::Expr; use rustc_lint::LateContext; use rustc_middle::ty; -use rustc_span::symbol::sym; +use rustc_span::{symbol::sym, Span}; use super::MAP_FLATTEN; /// lint use of `map().flatten()` for `Iterators` and 'Options' -pub(super) fn check<'tcx>( - cx: &LateContext<'tcx>, - expr: &'tcx hir::Expr<'_>, - recv: &'tcx hir::Expr<'_>, - map_arg: &'tcx hir::Expr<'_>, -) { - // lint if caller of `.map().flatten()` is an Iterator - if is_trait_method(cx, expr, sym::Iterator) { - let map_closure_ty = cx.typeck_results().expr_ty(map_arg); - let is_map_to_option = match map_closure_ty.kind() { - ty::Closure(_, _) | ty::FnDef(_, _) | ty::FnPtr(_) => { - let map_closure_sig = match map_closure_ty.kind() { - ty::Closure(_, substs) => substs.as_closure().sig(), - _ => map_closure_ty.fn_sig(cx.tcx), - }; - let map_closure_return_ty = cx.tcx.erase_late_bound_regions(map_closure_sig.output()); - is_type_diagnostic_item(cx, map_closure_return_ty, sym::Option) - }, - _ => false, - }; - - let method_to_use = if is_map_to_option { - // `(...).map(...)` has type `impl Iterator<Item=Option<...>> - "filter_map" - } else { - // `(...).map(...)` has type `impl Iterator<Item=impl Iterator<...>> - "flat_map" - }; - let func_snippet = snippet(cx, map_arg.span, ".."); - let hint = format!(".{0}({1})", method_to_use, func_snippet); - span_lint_and_sugg( +pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, recv: &Expr<'_>, map_arg: &Expr<'_>, map_span: Span) { + if let Some((caller_ty_name, method_to_use)) = try_get_caller_ty_name_and_method_name(cx, expr, recv, map_arg) { + let mut applicability = Applicability::MachineApplicable; + let help_msgs = [ + &format!("try replacing `map` with `{}`", method_to_use), + "and remove the `.flatten()`", + ]; + let closure_snippet = snippet_with_applicability(cx, map_arg.span, "..", &mut applicability); + span_lint_and_sugg_for_edges( cx, MAP_FLATTEN, - expr.span.with_lo(recv.span.hi()), - "called `map(..).flatten()` on an `Iterator`", - &format!("try using `{}` instead", method_to_use), - hint, - Applicability::MachineApplicable, + expr.span.with_lo(map_span.lo()), + &format!("called `map(..).flatten()` on `{}`", caller_ty_name), + &help_msgs, + format!("{}({})", method_to_use, closure_snippet), + applicability, ); } +} - // lint if caller of `.map().flatten()` is an Option or Result - let caller_type = match cx.typeck_results().expr_ty(recv).kind() { - ty::Adt(adt, _) => { +fn try_get_caller_ty_name_and_method_name( + cx: &LateContext<'_>, + expr: &Expr<'_>, + caller_expr: &Expr<'_>, + map_arg: &Expr<'_>, +) -> Option<(&'static str, &'static str)> { + if is_trait_method(cx, expr, sym::Iterator) { + if is_map_to_option(cx, map_arg) { + // `(...).map(...)` has type `impl Iterator<Item=Option<...>> + Some(("Iterator", "filter_map")) + } else { + // `(...).map(...)` has type `impl Iterator<Item=impl Iterator<...>> + Some(("Iterator", "flat_map")) + } + } else { + if let ty::Adt(adt, _) = cx.typeck_results().expr_ty(caller_expr).kind() { if cx.tcx.is_diagnostic_item(sym::Option, adt.did()) { - "Option" + return Some(("Option", "and_then")); } else if cx.tcx.is_diagnostic_item(sym::Result, adt.did()) { - "Result" - } else { - return; + return Some(("Result", "and_then")); } - }, - _ => { - return; - }, - }; + } + None + } +} - let func_snippet = snippet(cx, map_arg.span, ".."); - let hint = format!(".and_then({})", func_snippet); - let lint_info = format!("called `map(..).flatten()` on an `{}`", caller_type); - span_lint_and_sugg( - cx, - MAP_FLATTEN, - expr.span.with_lo(recv.span.hi()), - &lint_info, - "try using `and_then` instead", - hint, - Applicability::MachineApplicable, - ); +fn is_map_to_option(cx: &LateContext<'_>, map_arg: &Expr<'_>) -> bool { + let map_closure_ty = cx.typeck_results().expr_ty(map_arg); + match map_closure_ty.kind() { + ty::Closure(_, _) | ty::FnDef(_, _) | ty::FnPtr(_) => { + let map_closure_sig = match map_closure_ty.kind() { + ty::Closure(_, substs) => substs.as_closure().sig(), + _ => map_closure_ty.fn_sig(cx.tcx), + }; + let map_closure_return_ty = cx.tcx.erase_late_bound_regions(map_closure_sig.output()); + is_type_diagnostic_item(cx, map_closure_return_ty, sym::Option) + }, + _ => false, + } } diff --git a/clippy_lints/src/methods/mod.rs b/clippy_lints/src/methods/mod.rs index aa9f86f292c..822f40179ee 100644 --- a/clippy_lints/src/methods/mod.rs +++ b/clippy_lints/src/methods/mod.rs @@ -2377,7 +2377,7 @@ fn check_methods<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, msrv: Optio flat_map_option::check(cx, expr, arg, span); }, (name @ "flatten", args @ []) => match method_call(recv) { - Some(("map", [recv, map_arg], _)) => map_flatten::check(cx, expr, recv, map_arg), + Some(("map", [recv, map_arg], map_span)) => map_flatten::check(cx, expr, recv, map_arg, map_span), Some(("cloned", [recv2], _)) => iter_overeager_cloned::check(cx, expr, recv2, name, args), _ => {}, }, diff --git a/clippy_lints/src/utils/internal_lints/metadata_collector.rs b/clippy_lints/src/utils/internal_lints/metadata_collector.rs index a617422bbeb..b3fad6ce7b6 100644 --- a/clippy_lints/src/utils/internal_lints/metadata_collector.rs +++ b/clippy_lints/src/utils/internal_lints/metadata_collector.rs @@ -85,7 +85,7 @@ macro_rules! CONFIGURATION_VALUE_TEMPLATE { }; } -const LINT_EMISSION_FUNCTIONS: [&[&str]; 7] = [ +const LINT_EMISSION_FUNCTIONS: [&[&str]; 8] = [ &["clippy_utils", "diagnostics", "span_lint"], &["clippy_utils", "diagnostics", "span_lint_and_help"], &["clippy_utils", "diagnostics", "span_lint_and_note"], @@ -93,6 +93,7 @@ const LINT_EMISSION_FUNCTIONS: [&[&str]; 7] = [ &["clippy_utils", "diagnostics", "span_lint_and_sugg"], &["clippy_utils", "diagnostics", "span_lint_and_then"], &["clippy_utils", "diagnostics", "span_lint_hir_and_then"], + &["clippy_utils", "diagnostics", "span_lint_and_sugg_for_edges"], ]; const SUGGESTION_DIAGNOSTIC_BUILDER_METHODS: [(&str, bool); 9] = [ ("span_suggestion", false), diff --git a/clippy_utils/src/diagnostics.rs b/clippy_utils/src/diagnostics.rs index a927788e6a4..625a53899df 100644 --- a/clippy_utils/src/diagnostics.rs +++ b/clippy_utils/src/diagnostics.rs @@ -8,7 +8,7 @@ //! Thank you! //! ~The `INTERNAL_METADATA_COLLECTOR` lint -use rustc_errors::{Applicability, Diagnostic}; +use rustc_errors::{emitter::MAX_SUGGESTION_HIGHLIGHT_LINES, Applicability, Diagnostic}; use rustc_hir::HirId; use rustc_lint::{LateContext, Lint, LintContext}; use rustc_span::source_map::{MultiSpan, Span}; @@ -213,6 +213,90 @@ pub fn span_lint_and_sugg<'a, T: LintContext>( }); } +/// Like [`span_lint_and_sugg`] with a focus on the edges. The output will either +/// emit single span or multispan suggestion depending on the number of its lines. +/// +/// If the given suggestion string has more lines than the maximum display length defined by +/// [`MAX_SUGGESTION_HIGHLIGHT_LINES`][`rustc_errors::emitter::MAX_SUGGESTION_HIGHLIGHT_LINES`], +/// this function will split the suggestion and span to showcase the change for the top and +/// bottom edge of the code. For normal suggestions, in one display window, the help message +/// will be combined with a colon. +/// +/// Multipart suggestions like the one being created here currently cannot be +/// applied by rustfix (See [rustfix#141](https://github.com/rust-lang/rustfix/issues/141)). +/// Testing rustfix with this lint emission function might require a file with +/// suggestions that can be fixed and those that can't. See +/// [clippy#8520](https://github.com/rust-lang/rust-clippy/pull/8520/files) for +/// an example and of this. +/// +/// # Example for a long suggestion +/// +/// ```text +/// error: called `map(..).flatten()` on `Option` +/// --> $DIR/map_flatten.rs:8:10 +/// | +/// LL | .map(|x| { +/// | __________^ +/// LL | | if x <= 5 { +/// LL | | Some(x) +/// LL | | } else { +/// ... | +/// LL | | }) +/// LL | | .flatten(); +/// | |__________________^ +/// | +/// = note: `-D clippy::map-flatten` implied by `-D warnings` +/// help: try replacing `map` with `and_then` +/// | +/// LL ~ .and_then(|x| { +/// LL + if x <= 5 { +/// LL + Some(x) +/// | +/// help: and remove the `.flatten()` +/// | +/// LL + None +/// LL + } +/// LL ~ }); +/// | +/// ``` +pub fn span_lint_and_sugg_for_edges( + cx: &LateContext<'_>, + lint: &'static Lint, + sp: Span, + msg: &str, + helps: &[&str; 2], + sugg: String, + applicability: Applicability, +) { + span_lint_and_then(cx, lint, sp, msg, |diag| { + let sugg_lines_count = sugg.lines().count(); + if sugg_lines_count > MAX_SUGGESTION_HIGHLIGHT_LINES { + let sm = cx.sess().source_map(); + if let (Ok(line_upper), Ok(line_bottom)) = (sm.lookup_line(sp.lo()), sm.lookup_line(sp.hi())) { + let split_idx = MAX_SUGGESTION_HIGHLIGHT_LINES / 2; + let span_upper = sm.span_until_char(sp.with_hi(line_upper.sf.lines[line_upper.line + split_idx]), '\n'); + let span_bottom = sp.with_lo(line_bottom.sf.lines[line_bottom.line - split_idx]); + + let sugg_lines_vec = sugg.lines().collect::<Vec<&str>>(); + let sugg_upper = sugg_lines_vec[..split_idx].join("\n"); + let sugg_bottom = sugg_lines_vec[sugg_lines_count - split_idx..].join("\n"); + + diag.span_suggestion(span_upper, helps[0], sugg_upper, applicability); + diag.span_suggestion(span_bottom, helps[1], sugg_bottom, applicability); + + return; + } + } + diag.span_suggestion_with_style( + sp, + &helps.join(", "), + sugg, + applicability, + rustc_errors::SuggestionStyle::ShowAlways, + ); + }); +} + /// Create a suggestion made from several `span → replacement`. /// /// Note: in the JSON format (used by `compiletest_rs`), the help message will diff --git a/tests/ui/map_flatten.rs b/tests/ui/map_flatten.rs index aa1f76e335a..7d47ee09dc1 100644 --- a/tests/ui/map_flatten.rs +++ b/tests/ui/map_flatten.rs @@ -1,31 +1,55 @@ -// run-rustfix - -#![warn(clippy::all, clippy::pedantic)] -#![allow(clippy::let_underscore_drop)] -#![allow(clippy::missing_docs_in_private_items)] -#![allow(clippy::map_identity)] -#![allow(clippy::redundant_closure)] -#![allow(clippy::unnecessary_wraps)] +#![warn(clippy::map_flatten)] #![feature(result_flattening)] -fn main() { - // mapping to Option on Iterator - fn option_id(x: i8) -> Option<i8> { - Some(x) - } - let option_id_ref: fn(i8) -> Option<i8> = option_id; - let option_id_closure = |x| Some(x); - let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id).flatten().collect(); - let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_ref).flatten().collect(); - let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_closure).flatten().collect(); - let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| x.checked_add(1)).flatten().collect(); +// issue #8506, multi-line +#[rustfmt::skip] +fn long_span() { + let _: Option<i32> = Some(1) + .map(|x| { + if x <= 5 { + Some(x) + } else { + None + } + }) + .flatten(); - // mapping to Iterator on Iterator - let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| 0..x).flatten().collect(); + let _: Result<i32, i32> = Ok(1) + .map(|x| { + if x == 1 { + Ok(x) + } else { + Err(0) + } + }) + .flatten(); - // mapping to Option on Option - let _: Option<_> = (Some(Some(1))).map(|x| x).flatten(); + let result: Result<i32, i32> = Ok(2); + fn do_something() { } + let _: Result<i32, i32> = result + .map(|res| { + if res > 0 { + do_something(); + Ok(res) + } else { + Err(0) + } + }) + .flatten(); + + let _: Vec<_> = vec![5_i8; 6] + .into_iter() + .map(|some_value| { + if some_value > 3 { + Some(some_value) + } else { + None + } + }) + .flatten() + .collect(); +} - // mapping to Result on Result - let _: Result<_, &str> = (Ok(Ok(1))).map(|x| x).flatten(); +fn main() { + long_span(); } diff --git a/tests/ui/map_flatten.stderr b/tests/ui/map_flatten.stderr index bcd2047e6fa..c9c60df838f 100644 --- a/tests/ui/map_flatten.stderr +++ b/tests/ui/map_flatten.stderr @@ -1,46 +1,107 @@ -error: called `map(..).flatten()` on an `Iterator` - --> $DIR/map_flatten.rs:18:46 +error: called `map(..).flatten()` on `Option` + --> $DIR/map_flatten.rs:8:10 | -LL | let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id).flatten().collect(); - | ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id)` +LL | .map(|x| { + | __________^ +LL | | if x <= 5 { +LL | | Some(x) +LL | | } else { +... | +LL | | }) +LL | | .flatten(); + | |__________________^ | = note: `-D clippy::map-flatten` implied by `-D warnings` - -error: called `map(..).flatten()` on an `Iterator` - --> $DIR/map_flatten.rs:19:46 +help: try replacing `map` with `and_then` | -LL | let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_ref).flatten().collect(); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id_ref)` - -error: called `map(..).flatten()` on an `Iterator` - --> $DIR/map_flatten.rs:20:46 +LL ~ .and_then(|x| { +LL + if x <= 5 { +LL + Some(x) | -LL | let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_closure).flatten().collect(); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(option_id_closure)` - -error: called `map(..).flatten()` on an `Iterator` - --> $DIR/map_flatten.rs:21:46 +help: and remove the `.flatten()` + | +LL + None +LL + } +LL ~ }); | -LL | let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| x.checked_add(1)).flatten().collect(); - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `filter_map` instead: `.filter_map(|x| x.checked_add(1))` -error: called `map(..).flatten()` on an `Iterator` - --> $DIR/map_flatten.rs:24:46 +error: called `map(..).flatten()` on `Result` + --> $DIR/map_flatten.rs:18:10 + | +LL | .map(|x| { + | __________^ +LL | | if x == 1 { +LL | | Ok(x) +LL | | } else { +... | +LL | | }) +LL | | .flatten(); + | |__________________^ + | +help: try replacing `map` with `and_then` + | +LL ~ .and_then(|x| { +LL + if x == 1 { +LL + Ok(x) + | +help: and remove the `.flatten()` + | +LL + Err(0) +LL + } +LL ~ }); | -LL | let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| 0..x).flatten().collect(); - | ^^^^^^^^^^^^^^^^^^^^^^^^ help: try using `flat_map` instead: `.flat_map(|x| 0..x)` -error: called `map(..).flatten()` on an `Option` - --> $DIR/map_flatten.rs:27:39 +error: called `map(..).flatten()` on `Result` + --> $DIR/map_flatten.rs:30:10 + | +LL | .map(|res| { + | __________^ +LL | | if res > 0 { +LL | | do_something(); +LL | | Ok(res) +... | +LL | | }) +LL | | .flatten(); + | |__________________^ + | +help: try replacing `map` with `and_then` + | +LL ~ .and_then(|res| { +LL + if res > 0 { +LL + do_something(); + | +help: and remove the `.flatten()` + | +LL + Err(0) +LL + } +LL ~ }); | -LL | let _: Option<_> = (Some(Some(1))).map(|x| x).flatten(); - | ^^^^^^^^^^^^^^^^^^^^^ help: try using `and_then` instead: `.and_then(|x| x)` -error: called `map(..).flatten()` on an `Result` - --> $DIR/map_flatten.rs:30:41 +error: called `map(..).flatten()` on `Iterator` + --> $DIR/map_flatten.rs:42:10 + | +LL | .map(|some_value| { + | __________^ +LL | | if some_value > 3 { +LL | | Some(some_value) +LL | | } else { +... | +LL | | }) +LL | | .flatten() + | |__________________^ + | +help: try replacing `map` with `filter_map` + | +LL ~ .filter_map(|some_value| { +LL + if some_value > 3 { +LL + Some(some_value) + | +help: and remove the `.flatten()` + | +LL + None +LL + } +LL + }) | -LL | let _: Result<_, &str> = (Ok(Ok(1))).map(|x| x).flatten(); - | ^^^^^^^^^^^^^^^^^^^^^ help: try using `and_then` instead: `.and_then(|x| x)` -error: aborting due to 7 previous errors +error: aborting due to 4 previous errors diff --git a/tests/ui/map_flatten.fixed b/tests/ui/map_flatten_fixable.fixed index fec3a95edd6..fec3a95edd6 100644 --- a/tests/ui/map_flatten.fixed +++ b/tests/ui/map_flatten_fixable.fixed diff --git a/tests/ui/map_flatten_fixable.rs b/tests/ui/map_flatten_fixable.rs new file mode 100644 index 00000000000..aa1f76e335a --- /dev/null +++ b/tests/ui/map_flatten_fixable.rs @@ -0,0 +1,31 @@ +// run-rustfix + +#![warn(clippy::all, clippy::pedantic)] +#![allow(clippy::let_underscore_drop)] +#![allow(clippy::missing_docs_in_private_items)] +#![allow(clippy::map_identity)] +#![allow(clippy::redundant_closure)] +#![allow(clippy::unnecessary_wraps)] +#![feature(result_flattening)] + +fn main() { + // mapping to Option on Iterator + fn option_id(x: i8) -> Option<i8> { + Some(x) + } + let option_id_ref: fn(i8) -> Option<i8> = option_id; + let option_id_closure = |x| Some(x); + let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id).flatten().collect(); + let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_ref).flatten().collect(); + let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_closure).flatten().collect(); + let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| x.checked_add(1)).flatten().collect(); + + // mapping to Iterator on Iterator + let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| 0..x).flatten().collect(); + + // mapping to Option on Option + let _: Option<_> = (Some(Some(1))).map(|x| x).flatten(); + + // mapping to Result on Result + let _: Result<_, &str> = (Ok(Ok(1))).map(|x| x).flatten(); +} diff --git a/tests/ui/map_flatten_fixable.stderr b/tests/ui/map_flatten_fixable.stderr new file mode 100644 index 00000000000..c91c73846b6 --- /dev/null +++ b/tests/ui/map_flatten_fixable.stderr @@ -0,0 +1,80 @@ +error: called `map(..).flatten()` on `Iterator` + --> $DIR/map_flatten_fixable.rs:18:47 + | +LL | let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id).flatten().collect(); + | ^^^^^^^^^^^^^^^^^^^^^^^^ + | + = note: `-D clippy::map-flatten` implied by `-D warnings` +help: try replacing `map` with `filter_map`, and remove the `.flatten()` + | +LL | let _: Vec<_> = vec![5_i8; 6].into_iter().filter_map(option_id).collect(); + | ~~~~~~~~~~~~~~~~~~~~~ + +error: called `map(..).flatten()` on `Iterator` + --> $DIR/map_flatten_fixable.rs:19:47 + | +LL | let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_ref).flatten().collect(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | +help: try replacing `map` with `filter_map`, and remove the `.flatten()` + | +LL | let _: Vec<_> = vec![5_i8; 6].into_iter().filter_map(option_id_ref).collect(); + | ~~~~~~~~~~~~~~~~~~~~~~~~~ + +error: called `map(..).flatten()` on `Iterator` + --> $DIR/map_flatten_fixable.rs:20:47 + | +LL | let _: Vec<_> = vec![5_i8; 6].into_iter().map(option_id_closure).flatten().collect(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | +help: try replacing `map` with `filter_map`, and remove the `.flatten()` + | +LL | let _: Vec<_> = vec![5_i8; 6].into_iter().filter_map(option_id_closure).collect(); + | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +error: called `map(..).flatten()` on `Iterator` + --> $DIR/map_flatten_fixable.rs:21:47 + | +LL | let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| x.checked_add(1)).flatten().collect(); + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + | +help: try replacing `map` with `filter_map`, and remove the `.flatten()` + | +LL | let _: Vec<_> = vec![5_i8; 6].into_iter().filter_map(|x| x.checked_add(1)).collect(); + | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +error: called `map(..).flatten()` on `Iterator` + --> $DIR/map_flatten_fixable.rs:24:47 + | +LL | let _: Vec<_> = vec![5_i8; 6].into_iter().map(|x| 0..x).flatten().collect(); + | ^^^^^^^^^^^^^^^^^^^^^^^ + | +help: try replacing `map` with `flat_map`, and remove the `.flatten()` + | +LL | let _: Vec<_> = vec![5_i8; 6].into_iter().flat_map(|x| 0..x).collect(); + | ~~~~~~~~~~~~~~~~~~ + +error: called `map(..).flatten()` on `Option` + --> $DIR/map_flatten_fixable.rs:27:40 + | +LL | let _: Option<_> = (Some(Some(1))).map(|x| x).flatten(); + | ^^^^^^^^^^^^^^^^^^^^ + | +help: try replacing `map` with `and_then`, and remove the `.flatten()` + | +LL | let _: Option<_> = (Some(Some(1))).and_then(|x| x); + | ~~~~~~~~~~~~~~~ + +error: called `map(..).flatten()` on `Result` + --> $DIR/map_flatten_fixable.rs:30:42 + | +LL | let _: Result<_, &str> = (Ok(Ok(1))).map(|x| x).flatten(); + | ^^^^^^^^^^^^^^^^^^^^ + | +help: try replacing `map` with `and_then`, and remove the `.flatten()` + | +LL | let _: Result<_, &str> = (Ok(Ok(1))).and_then(|x| x); + | ~~~~~~~~~~~~~~~ + +error: aborting due to 7 previous errors + |