Bug 12146 – Linker error with __xopCmp, __xopEq, TypeInfo

cat > bar.d << CODE struct Bar { bool opCmp(ubyte val) { return false; } } CODE cat > foo.d << CODE import bar; struct Appender { Bar[] tokens; // references TypeInfo of Bar!(ubyte) // TypeInfo references __xopCmp } void main() { } CODE dmd -lib bar dmd foo bar.a ---- foo.o:(.data._D18TypeInfo_S3bar3Bar6__initZ+0x40): undefined reference to `_D3bar3Bar8__xopCmpFKxS3bar3BarKxS3bar3BarZi' ---- It seems, that during compilation of the bar lib the generated _xOpCmp function isn't emitted to the object file.

I think this is caused by this change. https://github.com/D-Programming-Language/dmd/pull/2582/files#diff-ffa5582af7d723c487d4a11ac6743b85L739

Looks like a duplicate of bug 12144.

Also happens with a sensible opCmp, like int opCmp(const ref Bar) { return 0; } It must deviate from the default signature though, i.e. can't be int opCmp(const ref Bar) const { return 0; }

*** This issue has been marked as a duplicate of issue 12144 ***

I think we should try to solve this by only creating one TypeInfo per struct, but always generate it, when the struct is defined. If the TypeInfo is referenced somewhere else, it will need to link against the module that defined the struct.

The root cause for this bug was, that the TypeInfo for structs can only be generated after semantic3 for that struct was run. This is not possible if the TypeInfo is needed during the obj generation pass, e.g. because it is referenced by an array TypeInfo. https://github.com/D-Programming-Language/dmd/pull/3255