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digitalmars.D - Send/Receive bug in std.concurrency with immutable(ubyte[]) ?

reply Vijay Nayar <madric gmail.com> writes:
import std.concurrency;
import std.stdio;

void testThread() {
   receive(
       (immutable(ubyte[]) data) => writeln("Got it!"),
       (Variant v) => writeln("Mismatch: ", v.type()));
}

void main() {
   immutable(ubyte[]) data = [1, 2, 3];
   auto tid = spawn(&testThread);
   send(tid, data);
}

The output of this program is:
   Mismatch: immutable(ubyte)[]

Why does calling send with data of type immutable(ubyte[]) get 
converted to immutable(byte)[] when it is called with 
std.concurrency's send() and receive().  Is this a bug?
Aug 04
parent reply Paul Backus <snarwin gmail.com> writes:
On Sunday, 4 August 2019 at 13:57:14 UTC, Vijay Nayar wrote:
 import std.concurrency;
 import std.stdio;

 void testThread() {
   receive(
       (immutable(ubyte[]) data) => writeln("Got it!"),
       (Variant v) => writeln("Mismatch: ", v.type()));
 }

 void main() {
   immutable(ubyte[]) data = [1, 2, 3];
   auto tid = spawn(&testThread);
   send(tid, data);
 }

 The output of this program is:
   Mismatch: immutable(ubyte)[]

 Why does calling send with data of type immutable(ubyte[]) get 
 converted to immutable(byte)[] when it is called with 
 std.concurrency's send() and receive().  Is this a bug?
immutable(T[]) "decays" to immutable(T)[] when passed to a function (most of the time [1]): import std.stdio; void checkType(T)(T arg) { writeln(typeof(arg).stringof); } void main() { immutable(ubyte[]) a; checkType(a); // immutable(ubyte)[] } [1] https://issues.dlang.org/show_bug.cgi?id=18268
Aug 04
parent reply Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:
On Sunday, August 4, 2019 8:29:05 AM MDT Paul Backus via Digitalmars-d 
wrote:
 On Sunday, 4 August 2019 at 13:57:14 UTC, Vijay Nayar wrote:
 import std.concurrency;
 import std.stdio;

 void testThread() {

   receive(

       (immutable(ubyte[]) data) => writeln("Got it!"),
       (Variant v) => writeln("Mismatch: ", v.type()));

 }

 void main() {

   immutable(ubyte[]) data = [1, 2, 3];
   auto tid = spawn(&testThread);
   send(tid, data);

 }

 The output of this program is:
   Mismatch: immutable(ubyte)[]

 Why does calling send with data of type immutable(ubyte[]) get
 converted to immutable(byte)[] when it is called with
 std.concurrency's send() and receive().  Is this a bug?
immutable(T[]) "decays" to immutable(T)[] when passed to a function (most of the time [1]): import std.stdio; void checkType(T)(T arg) { writeln(typeof(arg).stringof); } void main() { immutable(ubyte[]) a; checkType(a); // immutable(ubyte)[] } [1] https://issues.dlang.org/show_bug.cgi?id=18268
When you slice a const or immutable dynamic array, the type of the resulting dynamic array is tail-const or tail-immutable. When templates are implicitly instantiated with IFTI, and a dynamic array is passed in, the type is always inferred using the type of the slice of the dynamic array. That's completely consistent. You only get a fully const or immutable dynamic array with a template when the template is explicitly instantiated with that type. However, based on the examples in that bug report, what happens with lambdas and function/delegate literals is not consistent - or at least, the reasons why the type inference uses the type of the slice in some cases and the type of the array being sliced in others isn't immediately clear. - Jonathan M Davis
Aug 04
parent reply GreatSam4sure <greatsam4sure gmail.com> writes:
On Sunday, 4 August 2019 at 15:19:49 UTC, Jonathan M Davis wrote:
 On Sunday, August 4, 2019 8:29:05 AM MDT Paul Backus via 
 Digitalmars-d wrote:
 On Sunday, 4 August 2019 at 13:57:14 UTC, Vijay Nayar wrote:
 import std.concurrency;
 import std.stdio;

 void testThread() {

   receive(

       (immutable(ubyte[]) data) => writeln("Got it!"),
       (Variant v) => writeln("Mismatch: ", v.type()));

 }

 void main() {

   immutable(ubyte[]) data = [1, 2, 3];
   auto tid = spawn(&testThread);
   send(tid, data);

 }

 The output of this program is:
   Mismatch: immutable(ubyte)[]

 Why does calling send with data of type immutable(ubyte[]) 
 get
 converted to immutable(byte)[] when it is called with
 std.concurrency's send() and receive().  Is this a bug?
immutable(T[]) "decays" to immutable(T)[] when passed to a function (most of the time [1]): import std.stdio; void checkType(T)(T arg) { writeln(typeof(arg).stringof); } void main() { immutable(ubyte[]) a; checkType(a); // immutable(ubyte)[] } [1] https://issues.dlang.org/show_bug.cgi?id=18268
When you slice a const or immutable dynamic array, the type of the resulting dynamic array is tail-const or tail-immutable. When templates are implicitly instantiated with IFTI, and a dynamic array is passed in, the type is always inferred using the type of the slice of the dynamic array. That's completely consistent. You only get a fully const or immutable dynamic array with a template when the template is explicitly instantiated with that type. However, based on the examples in that bug report, what happens with lambdas and function/delegate literals is not consistent - or at least, the reasons why the type inference uses the type of the slice in some cases and the type of the array being sliced in others isn't immediately clear. - Jonathan M Davis
Sorry, sir, this day your participation in this forum is very limited. Is it due to work load? I really want to know. You can reach me personally with this mail: greatsam4sure gmail.com Sorry sir, is just that I don't know how else to reach you.
Aug 04
parent reply Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:
On Sunday, August 4, 2019 12:30:37 PM MDT GreatSam4sure via Digitalmars-d 
wrote:
 Sorry, sir, this day your participation in this forum is very
 limited. Is it due to work load? I really want to know. You can
 reach me personally with this mail: greatsam4sure gmail.com

 Sorry sir, is just that I don't know how else to reach you.
I still participate, but I don't want it to suck up my time as it sometimes has. A combination of some health issues and trying to focus on work have reduced how much time I've been spending on D in general outside of work, though I do need to figure out how to spend some more time contributing. If you wish to contact me about something, the about page on my website provides my e-mail address: http://jmdavisprog.com/about.html - Jonathan M Davis
Aug 06
parent GreatSam4sure <greatsam4sure gmail.com> writes:
On Tuesday, 6 August 2019 at 10:27:49 UTC, Jonathan M Davis wrote:
 On Sunday, August 4, 2019 12:30:37 PM MDT GreatSam4sure via 
 Digitalmars-d wrote:
 [...]
I still participate, but I don't want it to suck up my time as it sometimes has. A combination of some health issues and trying to focus on work have reduced how much time I've been spending on D in general outside of work, though I do need to figure out how to spend some more time contributing. If you wish to contact me about something, the about page on my website provides my e-mail address: http://jmdavisprog.com/about.html - Jonathan M Davis
Thanks, it is cool to hear from you
Aug 06