dmd -unittest against a library not compiled with -unittest gives undefined symbols

[dlangBugzillaToGithub]

Timothee Cour (@timotheecour) reported this on 2017-12-09T00:08:32Z

Transferred from https://issues.dlang.org/show_bug.cgi?id=18049

CC List

• Johannes Pfau (@jpf91)
• Rainer Schuetze
• Timothee Cour

Description

This is a serious blocker, which could potentially lead to not being able to compile with -unittest some code that depends on another library that was not compiled with -unittest (eg could be phobos if phobos code uses pattern shown in this bug)

dmd -lib -unittest -oflibfun.a fun.d
dmd -main -unittest main.d libfun.a
#works

dmd -lib -oflibfun.a fun.d
dmd -main -unittest main.d libfun.a
Undefined symbols for architecture x86_64:
  "_D3fun__T1ATtZQf8opEqualsMxFNaNbNiNfSQBj__TQBiTtZQBoZb", referenced from:
      _D3fun__T1ATtZQf11__xopEqualsFKxSQBf__TQBeTtZQBkKxQsZb in main.o
ld: symbol(s) not found for architecture x86_64


------------------
fun.d:
module fun;
struct A(T){
    bool opEquals(A!T) const {
        auto a=typeid(A!T);
        return true;
    }

    unittest {
        alias b = A!(ushort);
    }
}
enum ignore = A!int();

main.d:
module main;
import fun;


NOTE: this was obtained after painful manual reduction from https://issues.dlang.org/show_bug.cgi?id=16477

[dlangBugzillaToGithub]

timothee.cour2 commented on 2017-12-09T00:10:07Z

demangled error:

echo _D3fun__T1ATtZQf8opEqualsMxFNaNbNiNfSQBj__TQBiTtZQBoZb|ddemangle
const pure nothrow @nogc @safe bool fun.A!(ushort).A.opEquals(fun.A!(ushort).A)

echo _D3fun__T1ATtZQf11__xopEqualsFKxSQBf__TQBeTtZQBkKxQsZb|ddemangle
bool fun.A!(ushort).A.__xopEquals(ref const(fun.A!(ushort).A), ref const(fun.A!(ushort).A))

[dlangBugzillaToGithub]

timothee.cour2 commented on 2017-12-09T00:11:00Z

*** Issue 16477 has been marked as a duplicate of this issue. ***

[dlangBugzillaToGithub]

timothee.cour2 commented on 2017-12-09T00:20:51Z

same error whether we compile as .a, .dylib, or .o

[dlangBugzillaToGithub]

timothee.cour2 commented on 2017-12-09T00:23:42Z

likewise with ldc

[dlangBugzillaToGithub]

r.sagitario commented on 2018-01-05T09:14:53Z

That's a use case where the dreaded -allinst was added for: seperate compilation with different version, debug or unittest settings. In that case the template emission optimization fails to work because it assumes that the template is already emitted.

It's a bit strange that the optimization does not also avoid generating any code for the unittests, though.

[dlangBugzillaToGithub]

timothee.cour2 commented on 2018-01-05T15:25:21Z

confirmed that adding -allinst works (both with dmd and ldc), but indeed, this should be fixed.

question: what are downsides of -allinst?

[dlangBugzillaToGithub]

r.sagitario commented on 2018-01-05T21:33:40Z

downsides are slower compilation and bloated object files. Should not make a difference in the size of the executable.