if_then_some_else_none: Check HIR tree before other checks.

Author: Jarcho

clippy_lints/src/if_then_some_else_none.rs

@@ -61,26 +61,6 @@ impl_lint_pass!(IfThenSomeElseNone => [IF_THEN_SOME_ELSE_NONE]);
 
 impl<'tcx> LateLintPass<'tcx> for IfThenSomeElseNone {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) {
-        if !self.msrv.meets(msrvs::BOOL_THEN) {
-            return;
-        }
-
-        if in_external_macro(cx.sess(), expr.span) {
-            return;
-        }
-
-        // We only care about the top-most `if` in the chain
-        if is_else_clause(cx.tcx, expr) {
-            return;
-        }
-
-        // `bool::then()` and `bool::then_some()` are not const
-        if in_constant(cx, expr.hir_id) {
-            return;
-        }
-
-        let ctxt = expr.span.ctxt();
-
         if let Some(higher::If {
             cond,
             then,
@@ -89,9 +69,14 @@ impl<'tcx> LateLintPass<'tcx> for IfThenSomeElseNone {
             && let ExprKind::Block(then_block, _) = then.kind
             && let Some(then_expr) = then_block.expr
             && let ExprKind::Call(then_call, [then_arg]) = then_expr.kind
+            && let ctxt = expr.span.ctxt()
             && then_expr.span.ctxt() == ctxt
             && is_res_lang_ctor(cx, path_res(cx, then_call), OptionSome)
             && is_res_lang_ctor(cx, path_res(cx, peel_blocks(els)), OptionNone)
+            && !is_else_clause(cx.tcx, expr)
+            && !in_constant(cx, expr.hir_id)
+            && !in_external_macro(cx.sess(), expr.span)
+            && self.msrv.meets(msrvs::BOOL_THEN)
             && !contains_return(then_block.stmts)
         {
             let mut app = Applicability::Unspecified;