applicability: MachineApplicable if the suggestion is complete, otherwise MaybeIncorrect

Author: donkomura

clippy_lints/src/loops/manual_flatten.rs

@@ -2,9 +2,9 @@ use super::MANUAL_FLATTEN;
 use super::utils::make_iterator_snippet;
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::msrvs::{self, Msrv};
-use clippy_utils::source::{indent_of, reindent_multiline, snippet_with_applicability};
+use clippy_utils::source::{HasSession, indent_of, reindent_multiline, snippet_with_applicability};
 use clippy_utils::visitors::is_local_used;
-use clippy_utils::{higher, path_to_local_id, peel_blocks_with_stmt};
+use clippy_utils::{higher, path_to_local_id, peel_blocks_with_stmt, span_contains_comment};
 use rustc_errors::Applicability;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::{Expr, Pat, PatKind};
@@ -47,8 +47,11 @@ pub(super) fn check<'tcx>(
         let msg =
             format!("unnecessary `if let` since only the `{if_let_type}` variant of the iterator element is used");
 
-        // Prepare the help message
-        let mut applicability = Applicability::MaybeIncorrect;
+        let mut applicability = if span_contains_comment(cx.sess().source_map(), body.span) {
+            Applicability::MaybeIncorrect
+        } else {
+            Applicability::MachineApplicable
+        };
         let arg_snippet = make_iterator_snippet(cx, arg, &mut applicability);
         let copied = match cx.typeck_results().expr_ty(let_expr).kind() {
             ty::Ref(_, inner, _) => match inner.kind() {

tests/ui/manual_flatten.fixed

@@ -117,6 +117,12 @@ fn main() {
         }
     }
 
+    // This should trigger the lint, but the applicability is `MaybeIncorrect`
+    let z = vec![Some(1), Some(2), Some(3)];
+    for n in z.into_iter().flatten() {
+        println!("{:?}", n);
+    }
+
     run_unformatted_tests();
 }
 

tests/ui/manual_flatten.rs

@@ -149,6 +149,17 @@ fn main() {
         }
     }
 
+    // This should trigger the lint, but the applicability is `MaybeIncorrect`
+    let z = vec![Some(1), Some(2), Some(3)];
+    for n in z {
+        //~^ manual_flatten
+
+        if let Some(n) = n {
+            println!("{:?}", n);
+        }
+        // foo
+    }
+
     run_unformatted_tests();
 }
 

tests/ui/manual_flatten.stderr

@@ -202,7 +202,32 @@ LL +     }
    |
 
 error: unnecessary `if let` since only the `Some` variant of the iterator element is used
-  --> tests/ui/manual_flatten.rs:158:5
+  --> tests/ui/manual_flatten.rs:154:5
+   |
+LL | /     for n in z {
+LL | |
+LL | |
+LL | |         if let Some(n) = n {
+...  |
+LL | |     }
+   | |_____^
+   |
+help: try `.flatten()` and remove the `if let` statement in the for loop
+  --> tests/ui/manual_flatten.rs:157:9
+   |
+LL | /         if let Some(n) = n {
+LL | |             println!("{:?}", n);
+LL | |         }
+   | |_________^
+help: try
+   |
+LL ~     for n in z.into_iter().flatten() {
+LL +         println!("{:?}", n);
+LL +     }
+   |
+
+error: unnecessary `if let` since only the `Some` variant of the iterator element is used
+  --> tests/ui/manual_flatten.rs:169:5
    |
 LL | /     for n in vec![
 LL | |
@@ -213,7 +238,7 @@ LL | |     }
    | |_____^
    |
 help: try `.flatten()` and remove the `if let` statement in the for loop
-  --> tests/ui/manual_flatten.rs:165:9
+  --> tests/ui/manual_flatten.rs:176:9
    |
 LL | /         if let Some(n) = n {
 LL | |             println!("{:?}", n);
@@ -229,5 +254,5 @@ LL +         println!("{:?}", n);
 LL +     }
    |
 
-error: aborting due to 9 previous errors
+error: aborting due to 10 previous errors