[strong] Disallow implicit conversions for comparison

test/cctest/compiler/test-js-typed-lowering.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/js-graph.h"
 #include "src/compiler/js-typed-lowering.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/opcodes.h"
 #include "src/compiler/operator-properties.h"
@@ skipping 672 matching lines @@
                    Type::Union(Type::Number(), Type::String(), R.main_zone())};
 
   for (size_t i = 0; i < arraysize(types); i++) {
     Node* p0 = R.Parameter(types[i], 0);
 
     for (size_t j = 0; j < arraysize(types); j++) {
       Node* p1 = R.Parameter(types[j], 1);
       {
         Node* cmp = R.Binop(R.javascript.LessThan(language_mode), p0, p1);
         Node* r = R.reduce(cmp);
-
-        if (!types[i]->Maybe(Type::String()) ||
-            !types[j]->Maybe(Type::String())) {
-          if (types[i]->Is(Type::String()) && types[j]->Is(Type::String())) {
-            R.CheckPureBinop(R.simplified.StringLessThan(), r);
-          } else {
-            R.CheckPureBinop(R.simplified.NumberLessThan(), r);
-          }
+        if (types[i]->Is(Type::String()) && types[j]->Is(Type::String())) {
+          R.CheckPureBinop(R.simplified.StringLessThan(), r);
+        } else if ((types[i]->Is(Type::Number()) &&
+                    types[j]->Is(Type::Number())) ||
+                   (!is_strong(language_mode) &&
+                    (!types[i]->Maybe(Type::String()) ||
+                     !types[j]->Maybe(Type::String())))) {
+          R.CheckPureBinop(R.simplified.NumberLessThan(), r);
         } else {
           CHECK_EQ(cmp, r);  // No reduction of mixed types.
         }
       }
     }
   }
 }
 
 
 TEST_WITH_STRONG(RemoveToNumberEffects) {
@@ skipping 559 matching lines @@
           CHECK_EQ(p1, r->InputAt(0));
           CHECK_EQ(p0, r->InputAt(1));
         } else {
           CHECK_EQ(p0, r->InputAt(0));
           CHECK_EQ(p1, r->InputAt(1));
         }
       }
     }
   }
 }