• Ellery Newcomer (9/9) Aug 22 2012 hey.
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (9/18) Aug 22 2012 The type of the function pointer does not include the values of the
• Ellery Newcomer (3/19) Aug 22 2012 typeof lies.
• =?UTF-8?B?QWxpIMOHZWhyZWxp?= (4/24) Aug 22 2012 Opened:
• Jonathan M Davis (7/19) Aug 22 2012 Default arguments are not part of the type. This behavior is very much o...

Ellery Newcomer <ellery-newcomer utulsa.edu> writes:

hey.

is this valid code?

void func1(int i, double j = 1.0) {
}

void main() {
     auto fn = &func1;
     func1(1); //dmd: ok
     fn(1); // dmd: not ok
}

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 08/22/2012 11:51 AM, Ellery Newcomer wrote:
 hey.

 is this valid code?

 void func1(int i, double j = 1.0) {
 }

 void main() {
 auto fn = &func1;
 func1(1); //dmd: ok
 fn(1); // dmd: not ok
 }

The type of the function pointer does not include the values of the 
default parameters.

The type of fn is "a function taking int and a double, returning 
nothing". So the compiler must require that information at the call site.

The alternative could work too: The compiler could keep a table from 
function pointers to default parameters. But that would be slow.

I am not surprised by dmd's behavior.

Ali

Ellery Newcomer <ellery-newcomer utulsa.edu> writes:

On 08/22/2012 12:03 PM, Ali Çehreli wrote:
 On 08/22/2012 11:51 AM, Ellery Newcomer wrote:
  > hey.
  >
  > is this valid code?
  >
  > void func1(int i, double j = 1.0) {
  > }
  >
  > void main() {
  > auto fn = &func1;
  > func1(1); //dmd: ok
  > fn(1); // dmd: not ok
  > }

 The type of the function pointer does not include the values of the
 default parameters.

typeof lies.

pragma(msg, typeof(fn));

 void function(int i, double j = 1)

=?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:

On 08/22/2012 12:15 PM, Ellery Newcomer wrote:
 On 08/22/2012 12:03 PM, Ali Çehreli wrote:
 On 08/22/2012 11:51 AM, Ellery Newcomer wrote:
 hey.

 is this valid code?

 void func1(int i, double j = 1.0) {
 }

 void main() {
 auto fn = &func1;
 func1(1); //dmd: ok
 fn(1); // dmd: not ok
 }

 The type of the function pointer does not include the values of the
 default parameters.

 typeof lies.

 pragma(msg, typeof(fn));

  > void function(int i, double j = 1)

Opened:

   http://d.puremagic.com/issues/show_bug.cgi?id=8579

Ali

"Jonathan M Davis" <jmdavisProg gmx.com> writes:

On Wednesday, August 22, 2012 11:51:45 Ellery Newcomer wrote:
 hey.
 
 is this valid code?
 
 void func1(int i, double j = 1.0) {
 }
 
 void main() {
 auto fn = &func1;
 func1(1); //dmd: ok
 fn(1); // dmd: not ok
 }

Default arguments are not part of the type. This behavior is very much on 
purpose.

http://d.puremagic.com/issues/show_bug.cgi?id=3866
http://d.puremagic.com/issues/show_bug.cgi?id=8402
http://d.puremagic.com/issues/show_bug.cgi?id=8515

- Jonathan M Davis