Re: Strange template problem - Comeau vs EDG

=?iso-8859-1?q?Daniel_Kr=FCgler?= <>
Thu, 19 Apr 2007 15:41:54 CST
albrecht.fritzsche schrieb:

What does the standard says about the following

   class Base {};

   template <typename T>
   class Derived : public T

   int main() {
     Derived<const Base> d;

Is this correct Xor not correct?

The strange thing is that Comeau (and gcc and VC++ 8) compiles this
without even a warning while the EDG (and icc) triggers an error. (And
I'd thought Comeau and EDG behaved somewhat the same.)

Unfortunately I cannot find anything in the standard about this issue,
except a little note 14.1(5)

   The top-level cv-qualifiers on the template-parameter are ignored when
   determining its type.

This very last quote is not related to this issue, because it
concerns only non-type template-parameters.

According to the resolution of the defect report

(which can already be found in the current draft N2134) the intend
is to allow cv qualifiers in typedef-name's.
Further on typedef-name's and type-parameter's are
synchronized according to 14.1/3:

"A type-parameter defines its identifier to be a typedef-name (if
declared with class or typename) or template-name (if declared
with template) in the scope of the template declaration.[..]"

From this we can conclude that your example is feasible

according to the most recent interpretation, which explains
deviations in current compiler reactions.

Greetings from Bremen,

Daniel Kr?gler

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