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cryptonector · 2022-03-15 19:06:30

It can't. The problem is that .a files do not record their direct dependencies, unlike ELF objects, and instead depend on the final link-edit having the full tree of dependencies provided, but flattened into a list. That flattening loses critical information needed to correctly resolve conflicting symbols.

wakawaka28 | karma 142 | avg karma 0.22 · | 2024-04-12 19:55:20

The whole ELF interpreter thing is a security hole as far as I'm concerned. I'm not an expert on it but as far as I know, the existence of ELF interpreters seems to make it impossible to get a definitive list of dependencies.

cstrahan | karma 984 | avg karma 2.55 · | 2022-07-01 17:47:12

I believe it would be that way, if not for performance. The linker keeps track of unresolved symbols, and resolves those symbols while parsing subsequent object files. So if you list a dependency before it is used, that dependency won’t be linked at all, resulting in unresolved symbols — thus the need for object files to be listed in a particular order.

Edit: and the need for listing a dependency twice is to resolve mutually dependent object files. If A depends on symbols from B and B depends on symbols from A, you can link A,B,A or B,A,B (per the aforementioned reasoning).

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howinteresting | karma 774 | avg karma 0.68 · | 2022-12-17 11:56:04

This is only a problem if the tooling to track dependencies doesn't exist.

Many programming models (e.g. monomorphization as done in C++ and Rust) are fundamentally incompatible with dynamic linking. The tooling needs to handle those cases anyway.

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wyldfire | karma 20828 | avg karma 4.03 · | 2023-07-23 17:18:13

That's great, but unlike ldd, readelf won't walk the list of dependencies recursively.

vitaut | karma 668 | avg karma 4.48 · | 2024-01-07 09:48:41

AFAICS the main problem is that <string> pulls in a lot of dependencies.

NieDzejkob | karma 807 | avg karma 4.98 · | 2021-06-11 22:56:13

Workarounds exist, like for every other example I mentioned. I am mostly referring to the commonly used dependency graph.

Cyph0n | karma 8463 | avg karma 2.62 · | 2023-01-15 14:28:13

Probably comes down to either inline assembly or dependencies, or both.

agumonkey | karma 29727 | avg karma 1.44 · | 2022-07-20 12:18:24

And there's the tangling of dependencies. One fix in one lib may cause a bug in another that isn't maintained.

agbell | karma 1 | avg karma 0.0 · | 2021-07-09 22:39:23+00:00

Hi, just on my phone but Dependencies and parrellism are supported. It's inferred from the structure of targets.

worewood | karma 922 | avg karma 3.91 · | 2023-08-18 21:44:45

Only if it is statically linked with everything it needs. Otherwise good luck resolving dependencies.

Double_a_92 | karma 951 | avg karma 0.75 · | 2018-02-19 15:08:11+00:00

At first it doesn't sound particularly bad... But the dependency tree that comes with it seems problematic.

marcrosoft | karma 1025 | avg karma 2.68 · | 2019-09-25 10:06:16+00:00

It’s not that easy when you use C dependencies.

pspeter3 | karma 2497 | avg karma 3.83 · | 2016-02-03 00:13:33+00:00

Yeah, it was extremely frustrating for actively changing code and not an issue for third party dependencies. I wonder what the trade offs between submodules and subtrees are for this use case.

pmchorus | karma 8 | avg karma 0.8 · | 2017-04-08 11:30:20+00:00

It does not seem to handle dependencies.

dTal | karma 17131 | avg karma 2.88 · | 2020-06-06 08:58:49

And it checks them before checking for missing dependencies, so every time you fix a dependency, you have to do the whole rigamarole over again.

mbell | karma 5237 | avg karma 3.75 · | 2020-02-07 22:32:30+00:00

That doesn't help with transitive dependencies.

simonw | karma 58201 | avg karma 7.31 · | 2024-06-25 19:54:11

Yes! Love that about Lit. The problem is when I want to add other things that have their own dependency graph.

mattgreenrocks | karma 7288 | avg karma 3.13 · | 2024-01-15 21:14:09

It is hard to be confident whether the entire dependency tree is free of this issue.

bitwalker | karma 473 | avg karma 2.61 · | 2018-08-19 16:38:22+00:00

Unless you statically link your dependencies, but that comes with its own can of worms.