Bug 12750 – Vector compare operator is broken

• Component: JavaScriptCore
• Status: RESOLVED FIXED

[Dex Deacon]

Try running this code:
    Vector<char> a, b;
    a.fill('x', 10);
    b.fill('x', 10);
    ASSERT(a == b);

The assertion will fail.  There are two problems here:
1. The (templated) operator== for Vectors is defined as returning void, so it never actually gets instantiated!
2. Even if #1 is fixed, the operator== still isn't used by the compiler.  Instead, the implicit cast to char* is being called (Vector<char>::operator char*()), and the data pointers are being compared.

This affects a few other operator== functions that depend on Vector<T>::operator==, such as FormDataElement.

The only reasonable solution I can think of is to remove the implicit cast, and just use the .data() accessor everywhere.

Tested on Mac and Windows.

[Dex Deacon]

Created attachment 13144 [details]
patch for Vector comparison operators

Actually, it turns out that after fixing #1, the implicit cast was being used only because the operator== was still broken in other ways.  Specifically, it didn't accept const Vectors, so it wouldn't be used for all callers.

After fixing Vector's operator==, I had to also add an operator!= for a class that previously wasn't being compared at all in RenderStyle.h.

[Darin Adler]

Comment on attachment 13144 [details]
patch for Vector comparison operators

r=me

[Darin Adler]

I also think we should remove the implicit cast.

[Darin Adler]

Committed revision 19606.