Ensure stack when parsing large if expressions

Author: kanru

src/librustc_expand/expand.rs

@@ -17,6 +17,7 @@ use rustc_ast::visit::{self, AssocCtxt, Visitor};
 use rustc_ast_pretty::pprust;
 use rustc_attr::{self as attr, is_builtin_attr, HasAttrs};
 use rustc_data_structures::map_in_place::MapInPlace;
+use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::{Applicability, PResult};
 use rustc_feature::Features;
 use rustc_parse::parser::Parser;
@@ -1165,7 +1166,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
                 self.check_attributes(&expr.attrs);
                 self.collect_bang(mac, expr.span, AstFragmentKind::Expr).make_expr().into_inner()
             } else {
-                noop_visit_expr(&mut expr, self);
+                ensure_sufficient_stack(|| noop_visit_expr(&mut expr, self));
                 expr
             }
         });