Fix needless_match FP on if-lets

Author: blyxyas

clippy_lints/src/matches/needless_match.rs

@@ -91,6 +91,24 @@ fn check_if_let_inner(cx: &LateContext<'_>, if_let: &higher::IfLet<'_>) -> bool
 
         // Recursively check for each `else if let` phrase,
         if let Some(ref nested_if_let) = higher::IfLet::hir(cx, if_else) {
+            if let ExprKind::Call(
+                Expr {
+                    kind: ExprKind::Path(QPath::Resolved(_, Path { res: outer_res, .. })),
+                    ..
+                },
+                ..,
+            ) = if_let.let_expr.kind
+                && let ExprKind::Call(
+                    Expr {
+                        kind: ExprKind::Path(QPath::Resolved(_, Path { res: nested_res, .. })),
+                        ..
+                    },
+                    ..,
+                ) = nested_if_let.let_expr.kind
+                && outer_res != nested_res
+            {
+                return false;
+            }
             return check_if_let_inner(cx, nested_if_let);
         }
 

tests/ui/needless_match.fixed

@@ -245,4 +245,29 @@ mod issue9084 {
     }
 }
 
+fn a() -> Option<()> {
+    Some(())
+}
+fn b() -> Option<()> {
+    Some(())
+}
+fn c() -> Option<()> {
+    Some(())
+}
+
+#[allow(clippy::ifs_same_cond)]
+pub fn issue13574() -> Option<()> {
+    // Do not lint.
+    // The right hand of all these arms are different functions.
+    if let Some(a) = a() {
+        Some(a)
+    } else if let Some(b) = b() {
+        Some(b)
+    } else if let Some(c) = c() {
+        Some(c)
+    } else {
+        None
+    }
+}
+
 fn main() {}

tests/ui/needless_match.rs

@@ -289,4 +289,29 @@ mod issue9084 {
     }
 }
 
+fn a() -> Option<()> {
+    Some(())
+}
+fn b() -> Option<()> {
+    Some(())
+}
+fn c() -> Option<()> {
+    Some(())
+}
+
+#[allow(clippy::ifs_same_cond)]
+pub fn issue13574() -> Option<()> {
+    // Do not lint.
+    // The right hand of all these arms are different functions.
+    if let Some(a) = a() {
+        Some(a)
+    } else if let Some(b) = b() {
+        Some(b)
+    } else if let Some(c) = c() {
+        Some(c)
+    } else {
+        None
+    }
+}
+
 fn main() {}