do not trigger macro expansions

Author: donkomura

clippy_lints/src/loops/manual_flatten.rs

@@ -39,6 +39,9 @@ pub(super) fn check<'tcx>(
         && !is_local_used(cx, if_then, pat_hir_id)
         && msrv.meets(cx, msrvs::ITER_FLATTEN)
     {
+        if arg.span.from_expansion() || if_then.span.from_expansion() {
+            return;
+        }
         let if_let_type = if some_ctor { "Some" } else { "Ok" };
         // Prepare the error message
         let msg =

tests/ui/manual_flatten.fixed

@@ -91,6 +91,32 @@ fn main() {
         println!("{}", n);
     }
 
+    macro_rules! inner {
+        ($id:ident / $new:pat => $action:expr) => {
+            if let Some($new) = $id {
+                $action;
+            }
+        };
+    }
+
+    // Usage of `if let` expression with macro should not trigger lint
+    for ab in [Some((1, 2)), Some((3, 4))] {
+        inner!(ab / (c, d) => println!("{c}-{d}"));
+    }
+
+    macro_rules! args {
+        ($($arg:expr),*) => {
+            vec![$(Some($arg)),*]
+        };
+    }
+
+    // Usage of `if let` expression with macro should not trigger lint
+    for n in args!(1, 2, 3) {
+        if let Some(n) = n {
+            println!("{:?}", n);
+        }
+    }
+
     run_unformatted_tests();
 }
 

tests/ui/manual_flatten.rs

@@ -123,6 +123,32 @@ fn main() {
         println!("{}", n);
     }
 
+    macro_rules! inner {
+        ($id:ident / $new:pat => $action:expr) => {
+            if let Some($new) = $id {
+                $action;
+            }
+        };
+    }
+
+    // Usage of `if let` expression with macro should not trigger lint
+    for ab in [Some((1, 2)), Some((3, 4))] {
+        inner!(ab / (c, d) => println!("{c}-{d}"));
+    }
+
+    macro_rules! args {
+        ($($arg:expr),*) => {
+            vec![$(Some($arg)),*]
+        };
+    }
+
+    // Usage of `if let` expression with macro should not trigger lint
+    for n in args!(1, 2, 3) {
+        if let Some(n) = n {
+            println!("{:?}", n);
+        }
+    }
+
     run_unformatted_tests();
 }
 

tests/ui/manual_flatten.stderr

@@ -202,7 +202,7 @@ LL +     }
    |
 
 error: unnecessary `if let` since only the `Some` variant of the iterator element is used
-  --> tests/ui/manual_flatten.rs:132:5
+  --> tests/ui/manual_flatten.rs:158:5
    |
 LL | /     for n in vec![
 LL | |
@@ -213,7 +213,7 @@ LL | |     }
    | |_____^
    |
 help: try `.flatten()` and remove the `if let` statement in the for loop
-  --> tests/ui/manual_flatten.rs:139:9
+  --> tests/ui/manual_flatten.rs:165:9
    |
 LL | /         if let Some(n) = n {
 LL | |             println!("{:?}", n);