Bug 13394 – invariant fail to link since 2.066 when using separate compilation

a.d : module a; import std.utf; class A { this() { } } class Btpl(T) : T { this()() { } invariant {} } alias B = Btpl!A; ------------- b.d : module b; import a; void main() { new B(); } ------------- $ dmd -c a.d && dmd -c b.d && dmd *.o Undefined symbols for architecture x86_64: "_D1a15__T4BtplTC1a1AZ4Btpl11__invariantMxFZv", referenced from: _D1a15__T4BtplTC1a1AZ4Btpl11__T6__ctorZ6__ctorMFZC1a15__T4BtplTC1a1AZ4Btpl in b.o ld: symbol(s) not found for architecture x86_64 collect2: error: ld returned 1 exit status --- errorlevel 1 It has to be noted that importing std.utf seems to play a role here, which is weird.

Introduced in: https://github.com/D-Programming-Language/dmd/pull/3775 ==== When a.d is compiled, compiler instantiates Btpl!A and outputs its invariant objcode to a.obj. Next b.d is compiled, the `new B` expression instantiates the Btpl!A template constructor. It implicitly calls the invariant in post-condition, bug Btpl!A is explicitly instantiated in the non-root module (== a module which not directly compiled from command line) a. So compiler assumes that the Btpl!A.invariant objcode will be provided in linking phase and skips its codegen. However, currently dmd always adds the inferred function attributes into the symbol name of instantiated functions. Therefore, dmd a.d will emit the objcode of Btpl!A.invariant with the symbol name: _D1a15__T4BtplTC1a1AZ4Btpl11__invariantMxFNaNbNiNfZv But dmd b.d does not invoke semantic3 of Btpl!A.invariant. Then b.obj refer the invariant by using the symbol name: _D1a15__T4BtplTC1a1AZ4Btpl11__invariantMxFZv <-- does not contain the inferred attributes NaNbNiNf Then link-failure happens.

(In reply to Kenji Hara from comment #1) > Introduced in: https://github.com/D-Programming-Language/dmd/pull/3775 > > ==== > > When a.d is compiled, compiler instantiates Btpl!A and outputs its invariant > objcode to a.obj. > > Next b.d is compiled, the `new B` expression instantiates the Btpl!A > template constructor. It implicitly calls the invariant in post-condition, > bug Btpl!A is explicitly instantiated in the non-root module (== a module > which not directly compiled from command line) a. So compiler assumes that > the Btpl!A.invariant objcode will be provided in linking phase and skips its > codegen. > > However, currently dmd always adds the inferred function attributes into the > symbol name of instantiated functions. Therefore, dmd a.d will emit the > objcode of Btpl!A.invariant with the symbol name: > _D1a15__T4BtplTC1a1AZ4Btpl11__invariantMxFNaNbNiNfZv > > But dmd b.d does not invoke semantic3 of Btpl!A.invariant. Then b.obj refer > the invariant by using the symbol name: > _D1a15__T4BtplTC1a1AZ4Btpl11__invariantMxFZv > <-- does not contain the inferred attributes NaNbNiNf > > Then link-failure happens. That is interesting. Do you know why the import alter the behavior of DMD ?

(In reply to deadalnix from comment #2) > That is interesting. Do you know why the import alter the behavior of DMD ? In my Windows environment, importing std.utf in a.d was unnecessary to reproduce the link-failure.

Commits pushed to master at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/7683136e580c73fa6aa150c4c3ea4b54ed6f9b32 fix Issue 13394 - invariant fail to link since 2.066 when using separate compilation https://github.com/D-Programming-Language/dmd/commit/f6c130e66791ba9eb047334dec0645d06e74cc89 Merge pull request #3918 from 9rnsr/fix13394 [REG2.066] Issue 13394 - invariant fail to link since 2.066 when using separate compilation

Commit pushed to 2.066 at https://github.com/D-Programming-Language/dmd https://github.com/D-Programming-Language/dmd/commit/6bfc3341a04ff6b4bc431703473646c35bbd0c87 Merge pull request #3918 from 9rnsr/fix13394 [REG2.066] Issue 13394 - invariant fail to link since 2.066 when using separate compilation