[Issue 16397] missing coverage from template instances when using separate compilation

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=16397

--- Comment #2 from Martin Nowak <code at dawg.eu> ---
cat > a.d << CODE
module a;
import b;

unittest
{
    foo!int();
}
CODE

cat > b.d << CODE
module b;

void foo(T)()
{
    return; // line is covered
}

unittest
{
    foo!int();
}
CODE

dmd -c -cov -unittest a.d
dmd -c -cov -unittest b.d
dmd -main a.o b.o -ofbug
./bug

cat a.lst b.lst
----
       |module a;
       |import b;
       |
       |unittest
       |{
      1|    foo!int();
       |}
a.d is 100% covered
       |module b;
       |
       |void foo(T)()
       |{
0000000|    return; // line is covered
       |}
       |
       |unittest
       |{
      1|    foo!int();
       |}
b.d is 50% covered
----

With different linker order, both calls use the foo instantiation with coverage
instrumentation.

dmd -main b.o a.o -ofbug
./bug

cat a.lst b.lst
----
       |module a;
       |import b;
       |
       |unittest
       |{
      1|    foo!int();
       |}
a.d is 100% covered
       |module b;
       |
       |void foo(T)()
       |{
      2|    return; // line is covered
       |}
       |
       |unittest
       |{
      1|    foo!int();
       |}
b.d is 100% covered
➜  D cat a.lst b.lst                                                           
                                             20:18:21
       |module a;
       |import b;
       |
       |unittest
       |{
      1|    foo!int();
       |}
a.d is 100% covered
       |module b;
       |
       |void foo(T)()
       |{
      2|    return; // line is covered
       |}
       |
       |unittest
       |{
      1|    foo!int();
       |}
b.d is 100% covered
----

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