From 6a38f4371de46c7c5f6ea7364d8f610b227129a0 Mon Sep 17 00:00:00 2001
From: Markus Westerlind <marwes91@gmail.com>
Date: Sat, 26 Jan 2019 22:43:34 +0100
Subject: [PATCH] perf: Avoid recursing in gather_foralls

---
 check/src/typecheck/generalize.rs | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/check/src/typecheck/generalize.rs b/check/src/typecheck/generalize.rs
index cee3f2d3b4..84bb4e166b 100644
--- a/check/src/typecheck/generalize.rs
+++ b/check/src/typecheck/generalize.rs
@@ -3,7 +3,7 @@ use crate::base::{
     fnv::{FnvMap, FnvSet},
     pos::{BytePos, Span},
     symbol::Symbol,
-    types::{self, AppVec, ArcType, BuiltinType, Generic, Type, TypeInterner},
+    types::{self, AppVec, ArcType, BuiltinType, Flags, Generic, Type, TypeExt, TypeInterner},
 };
 
 use crate::{substitution::Substitution, typ::RcType, typecheck::Typecheck};
@@ -252,6 +252,12 @@ struct TypeVariableGenerator {
 impl TypeVariableGenerator {
     fn new(subs: &Substitution<RcType>, typ: &RcType) -> TypeVariableGenerator {
         fn gather_foralls(map: &mut FnvSet<Symbol>, subs: &Substitution<RcType>, typ: &RcType) {
+            if !typ
+                .flags()
+                .intersects(Flags::HAS_VARIABLES | Flags::HAS_FORALL)
+            {
+                return;
+            }
             let typ = subs.real(typ);
             if let Type::Forall(ref params, _) = **typ {
                 map.extend(params.iter().map(|param| param.id.clone()));