Direct call to eval passes strict mode through.

src/compilation-cache.h

 // Copyright 2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 31 matching lines @@
   // string. Returns an empty handle if the cache doesn't contain a
   // script for the given source string with the right origin.
   static Handle<SharedFunctionInfo> LookupScript(Handle<String> source,
                                                  Handle<Object> name,
                                                  int line_offset,
                                                  int column_offset);
 
   // Finds the shared function info for a source string for eval in a
   // given context.  Returns an empty handle if the cache doesn't
   // contain a script for the given source string.
   static Handle<SharedFunctionInfo> LookupEval(Handle<String> source,

[Martin Maly, 2011/02/02 23:56:22]

compiled pieces of eval code are cached so we must consider strict as part of
the equality comparison on the compiled snippets. Consider:
a.js:

eval("function arguments(){};");

b.js:

"use strict";
eval("function arguments(){};");

When executing both files (d8 a.js b.js) the second eval would experience cache
hit and code would never be compiled, error never reported etc.

[Lasse Reichstein, 2011/02/03 12:36:01]

Good catch. We wouldn't want that.

                                                Handle<Context> context,
-                                               bool is_global);
+                                               bool is_global,
+                                               bool is_strict);
 
   // Returns the regexp data associated with the given regexp if it
   // is in cache, otherwise an empty handle.
   static Handle<FixedArray> LookupRegExp(Handle<String> source,
                                          JSRegExp::Flags flags);
 
   // Associate the (source, kind) pair to the shared function
   // info. This may overwrite an existing mapping.
   static void PutScript(Handle<String> source,
                         Handle<SharedFunctionInfo> function_info);
@@ skipping 37 matching lines @@
   // Enable/disable compilation cache. Used by debugger to disable compilation
   // cache during debugging to make sure new scripts are always compiled.
   static void Enable();
   static void Disable();
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_COMPILATION_CACHE_H_