c# - .Net 2+: why does if( 1 == null ) no longer throw a compiler exception? -

i'm using int example, applies value type in .net

in .net 1 following throw compiler exception:

int = somefunctionthatreturnsint();  if( == null ) //compiler exception here 

now (in .net 2 or 3.5) exception has gone.

i know why is:

int? j = null; //nullable int  if( == j )   //this shouldn't throw exception 

the problem because int? nullable , int has implicit cast int?. syntax above compiler magic. we're doing:

nullable<int> j = null; //nullable int  //compiler smart enough if( (nullable<int>) == j)     //and not if( == (int) j) 

so now, when i == null get:

if( (nullable<int>) == null ) 

given c# doing compiler logic calculate anyway why can't smart enough not when dealing absolute values null?

i don't think compiler problem per se; integer value never null, idea of equating them isn't invalid; it's valid function returns false. , compiler knows; code

bool oneisnull = 1 == null; 

compiles, gives compiler warning: the result of expression 'false' since value of type 'int' never equal 'null' of type '<null>'.

so if want compiler error back, go project properties , turn on 'treat warnings errors' error, , you'll start seeing them build-breaking problems again.