Bug 18267 – array comparison broken in 2.078.3

Created attachment 1677 The module that generates code that can't be linked to Since this commit: commit 0fc1c36f4e611d92f903db90ee4d62dd7fdc4067 (HEAD) Author: somzzz <[email protected]> Date: Mon Oct 16 02:55:59 2017 -0700 array __equals lowering of dynamic arrays The following very simple dub project no longer links: dub.sdl: name "oops" dependency "std_data_json" version="~>0.18.2" source/app.d: void main() { import stdx.data.json.value; } $ dub build error: undefined reference to '_D15taggedalgebraic__T15TaggedAlgebraicTS4stdx4data4json5value9JSONValue12PayloadUnionZQCn__T8opEqualsTxSQDz__TQDlTQCxZQDtTxQuZQBiMxFKxQBfZb' Before the aforementioned commit, things work as expected. This is currently making our builds at work fail due a dependency on std_data_json. Investigating further, I inlined both std_data_json's value.d module and its dependency taggedalgebraic, and deleted as much code as possible while still getting a linker error and ended up with these two files: app.d: void main() { import oops; } oops.d: <attached> To reproduce: % dmd -g -c oops.d % dmd -g -debug app.d oops.o The issue goes away if the second line doesn't contain `-debug`. On this reduced example, what's happening is that the two modules don't agree on the attribute for opEquals. The linker error is that it can't find _D4oops__T15TaggedAlgebraicTSQBb9JSONValue12PayloadUnionZQBv__T8opEqualsTxSQCv__TQCtTQCfZQDbTxQuZQBiMxFKxQBfZb demangled: const bool oops.TaggedAlgebraic!(oops.JSONValue.PayloadUnion).TaggedAlgebraic.opEquals!(const(oops.TaggedAlgebraic!(oops.JSONValue.PayloadUnion).TaggedAlgebraic), const(oops.TaggedAlgebraic!(oops.JSONValue.PayloadUnion).TaggedAlgebraic)).opEquals(ref const(oops.TaggedAlgebraic!(oops.JSONValue.PayloadUnion).TaggedAlgebraic)) oops.o does contain a similar symbol, however: _D4oops__T15TaggedAlgebraicTSQBb9JSONValue12PayloadUnionZQBv__T8opEqualsTxSQCv__TQCtTQCfZQDbTxQuZQBiMxFNaNfKxQBjZb demangled: const pure @safe bool oops.TaggedAlgebraic!(oops.JSONValue.PayloadUnion).TaggedAlgebraic.opEquals!(const(oops.TaggedAlgebraic!(oops.JSONValue.PayloadUnion).TaggedAlgebraic), const(oops.TaggedAlgebraic!(oops.JSONValue.PayloadUnion).TaggedAlgebraic)).opEquals(ref const(oops.TaggedAlgebraic!(oops.JSONValue.PayloadUnion).TaggedAlgebraic)) Notice that the symbol that actually exists is `pure @safe`, whereas the one being looked for by app.d isn't. It seems then that for some reason the attribute inference happens differently when compiling each module.

opEquals changes attributes based on debug switch? What if it's marked as @safe?

If it's marked as `@safe` then `pure` is still an issue. At least with the very reduced example. I think the specifics depend on the code being compiled.

Here is a standalone file that demonstrates what I think is a symptom of the same bug: % cat oops.d struct JSONValue { TaggedAlgebraic payload; alias payload this; } struct TaggedAlgebraic { auto opEquals(T)(T other) const { static assert(is(typeof(performOp!(JSONValue[], T)))); return const(JSONValue[]).init == other; } } bool performOp(T, A)(T value, A arg) { return value == arg; } % dmd oops.d Undefined symbols for architecture x86_64: "_D6object__T8__equalsTxS4oops9JSONValueTxQsZQBgFNbAxQBdQfZb", referenced from: _D4oops15TaggedAlgebraic__T8opEqualsTAxSQBm9JSONValueZQBbMxFQxZb in oops.o ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

Attributing `opEquals` with `nothrow` resolves the linker error: struct S { P payload; alias payload this; } struct P { auto opEquals(T)(T other) const nothrow //*** Needs nothrow ***/ { static assert(is(typeof(performOp!(S[], T)))); return const(S[]).init == other; } } bool performOp(T, A)(T value, A arg) { return value == arg; }

This seems to have been fix as I cannot reproduce the example provided by John Colvin.

Atila's original example still fails with dmd master

@Atilla I have just tried your initial example and it compiles fine with the latest version of master. What I did: For the following files: ================================= // app.d void main() { import oops; } ================================= // oops.d <attached file> struct Location { string file; } struct JSONValue { union PayloadUnion { JSONValue[] array; } alias Payload = TaggedAlgebraic!PayloadUnion; Payload payload; Location location; alias payload this; } struct TaggedAlgebraic(U) .... ======================== Commands: % dmd -g -c oops.d % dmd -g -debug app.d oops.o I get a binary. So this seems to have been fixed. I am going to preemptively close as WORKSFORME, but please reopen if I'm missing something.