• cc (37/37) Apr 06 2021 Just encountered this compilation failure in DMD winx64 2.096,
• MoonlightSentinel (10/18) Apr 06 2021 DMD 2.094.2 fails with the same error?

cc <cc nevernet.com> writes:

Just encountered this compilation failure in DMD winx64 2.096, 
which previously worked in 2.095 and prior versions.  Just 
wondering if it's a bug, or a new issue to keep in mind when 
importing modules?  Sorry for the complex nature of this scenario 
but I'll try to keep it as simple as possible.

Given the following 4-file setup:

// main.d
import cream;
void main() {}

// cream/package.d
module cream;
public import cream.dcream;
public import cream.callbacks;

// cream/callbacks.d
module cream.callbacks;
import cream;
extern(C++) class CallbackBase {}

// cream/dcream.d
module cream.dcream;
import cream;
import std.container.array;
Array!CallbackBase callbackTracker;


Compilation fails with the following error:
C:\D\dmd2\windows\bin\..\..\src\phobos\std\container\array.d(519): Error:
incompatible types for array comparison: `const(CallbackBase[])` and
`const(CallbackBase[])`
C:\D\dmd2\windows\bin\..\..\src\phobos\std\container\array.d(189): Error:
template instance `std.container.array.RangeT!(const(Array!(CallbackBase)))`
error instantiating
C:\D\dmd2\windows\bin\..\..\src\phobos\std\container\array.d(528):       
instantiated from here: `RangeT!(Array!(CallbackBase))`
cream\dcream.d(4):        instantiated from here: 
`Array!(CallbackBase)`

It seems I can fix this by changing the order the other modules 
are imported in package.d like so:
// cream/package.d
module cream;
public import cream.callbacks;
public import cream.dcream;

I'm curious why this worked in prior dmd versions, and if it's 
something I'll need to worry about going forward when creating 
complex multi-file modules.

MoonlightSentinel <moonlightsentinel disroot.org> writes:

On Tuesday, 6 April 2021 at 09:33:32 UTC, cc wrote:
 Just encountered this compilation failure in DMD winx64 2.096, 
 which previously worked in 2.095 and prior versions.

DMD 2.094.2 fails with the same error?
But current master works for me.


 Just wondering if it's a bug, or a new issue to keep in mind 
 when importing modules?  Sorry for the complex nature of this 
 scenario but I'll try to keep it as simple as possible.

That's a bug, ordering of import should never affect whether some 
code compiles or not.

 I'm curious why this worked in prior dmd versions, and if it's 
 something I'll need to worry about going forward when creating 
 complex multi-file modules.

The ordering of imports can make a difference in some cases 
because it affects the order in which dmd analyses declarations - 
which might hide or reveal a bug.

Please file a bug report at https://issues.dlang.org if you 
encounter such issues.