This comment was originally written by ngeoffray@google.com

Added Area-Compiler, Triaged labels.

This comment was originally written by zundel@google.com

The spec says that any non-boolean value must be converted to a boolean using boolean conversion. Here's the def'n:

Boolean conversion maps any object o into a boolean defined as

(bool v){
          assert(v != null);
    return v === true;
}(o)

So it appears we need to change dartc code generation to add this logic to most conditional expressions, as even if type information is declared, at runtime a non-boolean type might be a part of an expression.

This comment was originally written by molino....@gmail.com

Also with 'checked mode' this example display the print statement:

Code:
  
  var fullName;
  if (!fullName) {
    print("Please enter a full name");
  }

  var fullName;
  if (!fullName) {
    print("Please enter a full name");
  }

The correct behavior of the code above is:

• production mode: print text
• checked mode: throw exception (type 'Null' is not assignable to type 'bool' of 'boolean expression')

This comment was originally written by gcod...@chqrlie.org

What is the rationale for this dogmatic stance? Such a complete departure from commonly understood behaviour is so counter intuitive and error prone! Why not amend the boolean conversion semantics?

This comment was originally written by zundel@google.com

The issue about the language definition has been brought up in other places. Since dartc no longer generates code, I'm closing this bug as obsolete.

Added WontFix label.