We have a class that we need to upgrade to api version 18.0 to be able to use the new AggregateResult object. Once we changed the version to 18.0, we got a bunch of 'Method does not exist or incorrect signature' errors.  The errors occurred both in the IDE and the UI.

We have a custom object that contains a number field named 'quantity'.  It has 2 decimal places.  The schema browser indicates that the field is a Double.  So we have a bunch of code similar to this that works fine prior to version 18: 

public void foo(){

MyCustomObject__c obj = [select id, quantity__c from MyCustomObject__c limit 1];

foo(obj.quantity__c);

}

public void foo(Double d){

// do something

}

After changing to version 18, we get the error 'Method does not exist or incorrect signature: foo(Decimal) '. Apparently, v18 treats 'quantity' as a Decimal instead of a Double. So we have to cast our field to a Double as follows: 

public void foo(){

MyCustomObject__c obj = [select id, quantity__c from MyCustomObject__c limit 1];

foo(Double.valueOf(obj.quantity__c));

}

1.) Is there any other solution for this?  Is there any documentation on this?

2.) Will the Spring 10 IDE schema browser indicate the correct data types - Decimal vs. Double?