Bug 8655 – bitfields and Typedef don't mix

import std.typecons; import std.bitmanip; static import core.stdc.config; alias Typedef!(core.stdc.config.c_ulong) c_ulong; struct Foo { mixin(bitfields!( c_ulong, "NameOffset", 31, c_ulong, "NameIsString", 1 )); } void main() { } It's great to see we've deprecated typedef for a library solution that doesn't work. :\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(77): Error: Cannot interpret Typedef!(uint,0u) at compile time D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(77): Error: expression (Typedef!(uint,0u)).opDispatch() < 0u is not constant or does not evaluate to a bool D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(111): Error: Cannot interpret Typedef!(uint,0u) at compile time D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(159): Error: template instance std.bitmanip.createAccessors!("_NameOffset_NameIsString",Typedef!(uint,0u),"NameOffset",31,0u) error instantiating D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(213): instantiated from here: createFields!("_NameOffset_NameIsString",0,Typedef!(uint,0u),"NameOffset",31,Typedef!(uint,0u),"NameIsString",1) test.d(11): instantiated from here: bitfields!(Typedef!(uint,0u),"NameOffset",31,Typedef!(uint,0u),"NameIsString",1) D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(77): Error: Cannot interpret Typedef!(uint,0u) at compile time D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(77): Error: expression (Typedef!(uint,0u)).opDispatch() < 0u is not constant or does not evaluate to a bool D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(111): Error: Cannot interpret Typedef!(uint,0u) at compile time D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(159): Error: template instance std.bitmanip.createAccessors!("_NameOffset_NameIsString",Typedef!(uint,0u),"NameIsString",1,31u) error instantiating D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(160): instantiated from here: createFields!("_NameOffset_NameIsString",31u,Typedef!(uint,0u),"NameIsString",1) D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(213): instantiated from here: createFields!("_NameOffset_NameIsString",0,Typedef!(uint,0u),"NameOffset",31,Typedef!(uint,0u),"NameIsString",1) test.d(11): instantiated from here: bitfields!(Typedef!(uint,0u),"NameOffset",31,Typedef!(uint,0u),"NameIsString",1) D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(160): Error: template instance std.bitmanip.createFields!("_NameOffset_NameIsString",31u,Typedef!(uint,0u),"NameIsString",1) error instantiating D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(213): instantiated from here: createFields!("_NameOffset_NameIsString",0,Typedef!(uint,0u),"NameOffset",31,Typedef!(uint,0u),"NameIsString",1) test.d(11): instantiated from here: bitfields!(Typedef!(uint,0u),"NameOffset",31,Typedef!(uint,0u),"NameIsString",1) D:\DMD\dmd2\windows\bin\..\..\src\phobos\std\bitmanip.d(213): Error: template instance std.bitmanip.createFields!("_NameOffset_NameIsString",0,Typedef!(uint,0u),"NameOffset",31,Typedef!(uint,0u),"NameIsString",1) error instantiating test.d(11): instantiated from here: bitfields!(Typedef!(uint,0u),"NameOffset",31,Typedef!(uint,0u),"NameIsString",1) test.d(11): Error: template instance std.bitmanip.bitfields!(Typedef!(uint,0u),"NameOffset",31,Typedef!(uint,0u),"NameIsString",1) error instantiating

(In reply to comment #0) > import std.typecons; > import std.bitmanip; > static import core.stdc.config; > > alias Typedef!(core.stdc.config.c_ulong) c_ulong; > > struct Foo > { > mixin(bitfields!( > c_ulong, "NameOffset", 31, > c_ulong, "NameIsString", 1 > )); > } > > void main() > { } This is a problem with mixin template Proxy(alias a). It uses a template dispatch but doesn't take into account type properties (min, max, init..). Although this can be fixed another issue pops up: Error: e2ir: cannot cast result of type uint to type Typedef!(int,0) Here's the hackish temporary workaround of Proxy.opDispatch: template opDispatch(string name) { static if (canFind(["min", "max", "init", "sizeof", "nan", "mangleof", "stringof", "alignof", "infinity", "dig", "epsilon", "mant_dig", "max_10_exp", "max_exp", "min_10_exp", "min_exp", "min_normal", "re", "im", "classinfo"], name)) { mixin("enum opDispatch = typeof(a)." ~ name ~ ";"); } else static if (is(typeof(__traits(getMember, a, name)) == function)) { // non template function auto ref opDispatch(this X, Args...)(Args args) { return mixin("a."~name~"(args)"); } } else static if (is(typeof(mixin("a."~name))) || __traits(getOverloads, a, name).length != 0) { // field or property function @property auto ref opDispatch(this X)() { return mixin("a."~name); } @property auto ref opDispatch(this X, V)(auto ref V v) { return mixin("a."~name~" = v"); } } else { // member template template opDispatch(T...) { auto ref opDispatch(this X, Args...)(Args args){ return mixin("a."~name~"!T(args)"); } } } }