Immutable Structs and std.concurrency

[Russel Winder]

The program:

        import std.concurrency ;
        import std.stdio ;
        
        /*immutable*/ struct X { int i ; }
        
        void printI ( ) {
          receive (
                   ( X x ) { writeln ( x.i ) ; }
                   ) ;
        }
        
        int main ( immutable string[] args ) {
          auto x = spawn ( & printI ) ;
          x.send ( X ( 3 ) ) ;
          return 0 ;
        }

behaves entirely as expected.  Taking the comments off the immutable
leads to:

core.exception.AssertError@/home/users/russel/lib.Linux.x86_64/DMD2/bin64/../../src/phobos/std/variant.d(286): X
----------------
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(_d_assert_msg+0x1f) [0x43f81f]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(long std.variant.VariantN!(32uL).VariantN.handler!(immutableStruct.X).handler(std.variant.VariantN!(32uL).VariantN.OpID, ubyte[32]*, void*).bool tryPutting(immutableStruct.X*, TypeInfo, void*)+0x7a) [0x43b0fa]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(long std.variant.VariantN!(32uL).VariantN.handler!(immutableStruct.X).handler(std.variant.VariantN!(32uL).VariantN.OpID, ubyte[32]*, void*)+0x103) [0x43ae03]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(@property immutableStruct.X std.variant.VariantN!(32uL).VariantN.get!(immutableStruct.X).get()+0x57) [0x434cf7]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(void std.concurrency.Message.map!(void function(immutableStruct.X)*).map(void function(immutableStruct.X)*)+0x46) [0x434c96]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(bool std.concurrency.MessageBox.get!(void function(immutableStruct.X)*).get(scope void function(immutableStruct.X)*).bool onStandardMsg(ref std.concurrency.Message)+0x2d) [0x434731]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(bool std.concurrency.MessageBox.get!(void function(immutableStruct.X)*).get(scope void function(immutableStruct.X)*).bool scan(ref std.concurrency.List!(std.concurrency.Message).List)+0xd3) [0x434a47]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(bool std.concurrency.MessageBox.get!(void function(immutableStruct.X)*).get(scope void function(immutableStruct.X)*)+0x15e) [0x434692]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(void std.concurrency.receive!(void function(immutableStruct.X)*).receive(void function(immutableStruct.X)*)+0x2e) [0x434526]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(void immutableStruct.printI()+0x13) [0x433d1b]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(_D3std11concurrency11__T6_spawnZ6_spawnFbPFZvZS3std11concurrency3Tid4execMFZv+0x3d) [0x43abb5]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(void core.thread.Thread.run()+0x2a) [0x449caa]
/tmp/.rdmd-1000/home/users/russel/Progs/OddsByLanguage/D/Odds/immutableStruct.d.EDDA68DBDAF917356C855298813D6CD2(thread_entryPoint+0xf3) [0x449a43]
----------------

I believe this is wrong on so many levels, but is it because I don't
know D?

-- 
Russel.
=============================================================================
Dr Russel Winder      t: +44 20 7585 2200   voip: sip:russel.winder at ekiga.net
41 Buckmaster Road    m: +44 7770 465 077   xmpp: russel at winder.org.uk
London SW11 1EN, UK   w: www.russel.org.uk  skype: russel_winder
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