Don't fire the lint if there is a type annotation

Sometimes type annotations are needed for type inferrence to work,
or because of coercions. We don't know this, and we also don't
want users to possibly repeat the entire pattern.

Author: est31

clippy_lints/src/manual_let_else.rs

@@ -74,6 +74,7 @@ impl<'tcx> LateLintPass<'tcx> for ManualLetElse {
             if let StmtKind::Local(local) = stmt.kind;
             if let Some(init) = local.init;
             if local.els.is_none();
+            if local.ty.is_none();
             if init.span.ctxt() == stmt.span.ctxt();
             if let Some(if_let_or_match) = IfLetOrMatch::parse(cx, init);
             then {

tests/ui/manual_let_else.rs

@@ -197,4 +197,8 @@ fn not_fire() {
 
     // Already a let-else
     let Some(a) = (if let Some(b) = Some(Some(())) { b } else { return }) else { panic!() };
+
+    // If a type annotation is present, don't lint as
+    // expressing the type might be too hard
+    let v: () = if let Some(v_some) = g() { v_some } else { panic!() };
 }