Multi-lined pattern of if let

From https://github.com/rust-lang/rust-clippy/pull/4123#issuecomment-504837192:

     F: FnMut(&ast::Block, Option<&ast::Label>),
 {
     if let ast::ExprKind::While(_, loop_block, label)
-        | ast::ExprKind::ForLoop(_, _, loop_block, label)
-        | ast::ExprKind::Loop(loop_block, label)
-        = &expr.node
+    | ast::ExprKind::ForLoop(_, _, loop_block, label)
+    | ast::ExprKind::Loop(loop_block, label) = &expr.node
     {
         func(loop_block, label.as_ref());
     }

In this case,

1. Should we add indentation to each clause that appears after the first one?
2. Should we keep the expression (&expr.node) on the same line as the last clause, or put it on the next line?

Note that for multi-lined patterns of match's arm, rustfmt does not add indentation.

match some_value {
    ast::ExprKind::While(_, loop_block, label)
    | ast::ExprKind::ForLoop(_, _, loop_block, label)
    | ast::ExprKind::Loop(loop_block, label) = &expr.node
    => {
        // ...
    }

Start by reading the linked rustfmt pull request comment and comparing the shown multi-line if-let pattern with the existing multi-line match-arm behavior. Determine the intended indentation and placement of the expression, then confirm the decision with formatting examples and tests for both cases.