// main
void main() {
   import A;
// import B;
   import std.stdio;

   writeln("Entered main");

   fnA1();

   writeln("Leaving main");
}

module A;

void fnA1() {

   import B;
   import std.stdio;

   writeln("Entered fnA1");
   fnB1();
   writeln("Leaving fnA1");
}

module B;

void fnB1() {

   import std.stdio;

   writeln("Entered fnB1");
   writeln("Leaving fnB1");
}

1. Code above compiles but fails on linker step with 'Error 42 Symbol Undefined'.
   To me, unexpected behaviour as imports arranged to pick up symbols (with minimum scope).

2. Uncommenting the 'import B' in main everything works correctly.
   To me, particularly unexpected behaviour as no symbol from B directly used in main (also undesirable to set scope unnecessarily wide).

Best regards

On Saturday, 15 May 2021 at 06:55:47 UTC, DLearner wrote:

Your error is a linker error. Imports have nothing to do with the linker. They are for the compiler to know which symbols are available in the module it's currently compiling. But every symbol that you use needs to be linked by the linker, and that's a separate step.

That's odd. What's your command line?

Whether you use a symbol in main or not is irrelevant to the linker. Any symbol accessed anywhere in your program must ultimately be linked in.

On Saturday, 15 May 2021 at 07:05:00 UTC, Mike Parker wrote:

rdmd main.d

On Saturday, 15 May 2021 at 07:15:51 UTC, DLearner wrote:

Then it must be an issue with rdmd. The following both work as expected, whether your the import B; in main is commented out or not:

dmd -i main.d
dmd main.d A.d B.d

On Saturday, 15 May 2021 at 07:15:51 UTC, DLearner wrote:

Okay, so it's definitely a bug in rdmd. Change module A to look like this and it works properly:

module A;

import B;

void fnA1() {

   import std.stdio;

   writeln("Entered fnA1");
   fnB1();
   writeln("Leaving fnA1");
}

On Saturday, 15 May 2021 at 07:19:08 UTC, Mike Parker wrote:

rdmd build 20210311
Running under Win-10.

On Saturday, 15 May 2021 at 07:15:51 UTC, DLearner wrote:

rdmd sucks, it runs the compiler twice and get the list of imports and even then it might not see them all.

Just use

dmd -i main.d

instead. It will be about 2x faster and more reliable.

The downside differences though:

• rdmd runs the program too, dmd -i just compiles. You run the program separately.
• rdmd will cache the executable, dmd -i will always recompile. But since running the program is a separate step, you just run it yourself if you don't want to recompile, and run dmd if you do.

On Saturday, 15 May 2021 at 11:38:22 UTC, Adam D. Ruppe wrote:

You can do dmd -i -run main.d

On Saturday, 15 May 2021 at 11:46:49 UTC, Dennis wrote:

Yeah but that's weird with how it handles arguments and without the compilation cache it gets really annoying to use.

In unix i give the compiler:

ldc2 `find . -name \*.d -print`

So he always takes all sourcefiles