From 6890d7c0ee424fb8e68a764393e85c21eed62374 Mon Sep 17 00:00:00 2001
From: dimvar <dimvar@google.com>
Date: Fri, 24 Feb 2017 09:55:42 -0800
Subject: [PATCH] [NTI] Remove code in FunctionType dealing with shadowing of
 type params.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148470987
---
 .../jscomp/newtypes/DeclaredFunctionType.java |  4 +--
 .../jscomp/newtypes/FunctionType.java         | 26 +++++--------------
 2 files changed, 9 insertions(+), 21 deletions(-)

diff --git a/src/com/google/javascript/jscomp/newtypes/DeclaredFunctionType.java b/src/com/google/javascript/jscomp/newtypes/DeclaredFunctionType.java
index be434791139..4a5a8004f01 100644
--- a/src/com/google/javascript/jscomp/newtypes/DeclaredFunctionType.java
+++ b/src/com/google/javascript/jscomp/newtypes/DeclaredFunctionType.java
@@ -286,8 +286,8 @@ public DeclaredFunctionType substituteNominalGenerics(NominalType nt) {
     }
     Map<String, JSType> typeMap = nt.getTypeMap();
     Preconditions.checkState(!typeMap.isEmpty());
-    // Before switching to unique generated names for type variables, a method's type variables
-    // could shadow type variables defined on the class. Check that it no longer happens.
+    // Before we switched to unique generated names for type variables, a method's type variables
+    // could shadow type variables defined on the class. Check that this no longer happens.
     for (String typeParam : typeParameters) {
       Preconditions.checkState(!typeMap.containsKey(typeParam));
     }
diff --git a/src/com/google/javascript/jscomp/newtypes/FunctionType.java b/src/com/google/javascript/jscomp/newtypes/FunctionType.java
index 4eff0531ab6..b4c54836bb0 100644
--- a/src/com/google/javascript/jscomp/newtypes/FunctionType.java
+++ b/src/com/google/javascript/jscomp/newtypes/FunctionType.java
@@ -965,36 +965,24 @@ private FunctionType substituteNominalGenerics(Map<String, JSType> typeMap) {
     if (typeMap.isEmpty() || this.isTopFunction()) {
       return this;
     }
-    Map<String, JSType> reducedMap = typeMap;
     if (!this.commonTypes.MAP_TO_UNKNOWN.equals(typeMap)) {
-      boolean foundShadowedTypeParam = false;
+      // Before we switched to unique generated names for type variables, a method's type variables
+      // could shadow type variables defined on the class. Check that this no longer happens.
       for (String typeParam : this.typeParameters) {
-        if (typeMap.containsKey(typeParam)) {
-          foundShadowedTypeParam = true;
-          break;
-        }
-      }
-      if (foundShadowedTypeParam) {
-        ImmutableMap.Builder<String, JSType> builder = ImmutableMap.builder();
-        for (Map.Entry<String, JSType> entry : typeMap.entrySet()) {
-          if (!typeParameters.contains(entry.getKey())) {
-            builder.put(entry);
-          }
-        }
-        reducedMap = builder.build();
+        Preconditions.checkState(!typeMap.containsKey(typeParam));
       }
     }
     FunctionTypeBuilder builder = new FunctionTypeBuilder(this.commonTypes);
     for (JSType reqFormal : this.requiredFormals) {
-      builder.addReqFormal(reqFormal.substituteGenerics(reducedMap));
+      builder.addReqFormal(reqFormal.substituteGenerics(typeMap));
     }
     for (JSType optFormal : this.optionalFormals) {
-      builder.addOptFormal(optFormal.substituteGenerics(reducedMap));
+      builder.addOptFormal(optFormal.substituteGenerics(typeMap));
     }
     if (this.restFormals != null) {
-      builder.addRestFormals(restFormals.substituteGenerics(reducedMap));
+      builder.addRestFormals(restFormals.substituteGenerics(typeMap));
     }
-    builder.addRetType(this.returnType.substituteGenerics(reducedMap));
+    builder.addRetType(this.returnType.substituteGenerics(typeMap));
     if (isLoose()) {
       builder.addLoose();
     }