C# compiler and standard discrepancy

  • Thread starter Thread starter Andrey Simanovsky
  • Start date Start date
A

Andrey Simanovsky

VS 2003 C# compiler (as well as Rotor one) compiles the
following code:

System.Console.WriteLine(o2 as C + (o2 as C)); //!?
System.Console.WriteLine(o2 as C << 1); //!?

whereas the syntactic grammar of the specification says
(including the .doc on msdn said to reflect the actual
compiler) that this code is invalid: 'o2 as C' cannot be
deduced from an additive-expression or a shift-expression
non-terminals.
 
Andrey Simanovsky said:
VS 2003 C# compiler (as well as Rotor one) compiles the
following code:

System.Console.WriteLine(o2 as C + (o2 as C)); //!?
System.Console.WriteLine(o2 as C << 1); //!?

whereas the syntactic grammar of the specification says
(including the .doc on msdn said to reflect the actual
compiler) that this code is invalid: 'o2 as C' cannot be
deduced from an additive-expression or a shift-expression
non-terminals.
Click to expand...

Are you trying to write this yourself? If you are, chances are you aren't
writing something correctly.

The as expression should be something like:
relational-expression as type

where type eventually resolves down to an identifier, a qualified
identifier(name.name.name), or one of the built in type keywords(object,
string, etc). That shouldn't be ambigious with a shift expression. The
additive and shift expressions would operate on the *result* of the as
expression, not C.

Atleast, thats what my reading of the grammer says.
 
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