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-Zno-link is broken #77857

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#80187
Closed
-Zno-link is broken#77857
#80187
Labels
A-linkageArea: linking into static, shared libraries and binariesA-metadataArea: Crate metadataC-bugCategory: This is a bug.T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.requires-nightlyThis issue requires a nightly compiler in some way. When possible, use a F-* label instead.

Description

@bjorn3
bjorn3
opened on Oct 12, 2020

I tried this command:

$ echo "fn main() {}" | rustc -Zno-link -

I expected to see this happen: An .rlink file is generated.

Instead, this happened:

thread 'rustc' panicked at 'cannot encode `DefIndex` with `rustc_serialize::json::Encoder`', /rustc/381b445ff5751f9f39ec672b623372dff09c276e/compiler/rustc_span/src/def_id.rs:135:9
stack backtrace:
   0: rust_begin_unwind
             at /rustc/381b445ff5751f9f39ec672b623372dff09c276e/library/std/src/panicking.rs:483
   1: std::panicking::begin_panic_fmt
             at /rustc/381b445ff5751f9f39ec672b623372dff09c276e/library/std/src/panicking.rs:437
   2: <rustc_span::def_id::DefIndex as rustc_serialize::serialize::Encodable<E>>::encode
   3: <rustc_serialize::json::Encoder as rustc_serialize::serialize::Encoder>::emit_struct
   4: <rustc_serialize::json::Encoder as rustc_serialize::serialize::Encoder>::emit_struct
   5: <rustc_serialize::json::Encoder as rustc_serialize::serialize::Encoder>::emit_seq
   6: <rustc_serialize::json::Encoder as rustc_serialize::serialize::Encoder>::emit_map
   7: <rustc_serialize::json::Encoder as rustc_serialize::serialize::Encoder>::emit_struct
   8: <rustc_serialize::json::Encoder as rustc_serialize::serialize::Encoder>::emit_struct
   9: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::link
  10: rustc_interface::queries::Linker::link
  11: rustc_span::with_source_map
  12: rustc_interface::interface::create_compiler_and_run
  13: scoped_tls::ScopedKey<T>::set

Meta

rustc --version --verbose:

rustc 1.48.0-nightly (381b445ff 2020-09-29)
binary: rustc
commit-hash: 381b445ff5751f9f39ec672b623372dff09c276e
commit-date: 2020-09-29
host: x86_64-unknown-linux-gnu
release: 1.48.0-nightly
LLVM version: 11.0

Originally posted by @bjorn3 in #77795 (comment)

cc @0dvictor (original implementer of -Zno-link

Activity

  1. bjorn3
    added
    C-bugCategory: This is a bug.
    on Oct 12, 2020
  2. jonas-schievink
    added
    requires-nightlyThis issue requires a nightly compiler in some way. When possible, use a F-* label instead.
    T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.
    on Oct 12, 2020
  3. camelid
    added
    A-linkageArea: linking into static, shared libraries and binaries
    A-metadataArea: Crate metadata
    on Oct 12, 2020

  4. 0dvictor commented on Oct 26, 2020

    @0dvictor
    0dvictor
    on Oct 26, 2020

    PR #73851 changed the encode/decode method of DefId to call the encode/decode method of its field pub index: DefIndex; however, DefIndex is only encodable in metadata. It panics if encoded anywhere else.

    When no-link was implemented, the encode/decode of DefId was purposely crafted to avoid calling the encode/decode method of DefIndex. The most straightforward fix is to implement Encodable/Decodable for DefIndex to allow it be serialized outside of metadata.

    After that, may be now it is the time to re-think the way we store data in the rlink file.

    What do you think @bjorn3 ?

  5. bjorn3 commented on Oct 26, 2020

    @bjorn3
    bjorn3
    on Oct 26, 2020
    MemberAuthor

    I think DefId should completely be avoided in the input of the linker function. One of the uses if NativeLib in it's foreign_module field. This field doesn't seem to be used by the linking code.

  6. 0dvictor commented on Oct 27, 2020

    @0dvictor
    0dvictor
    on Oct 27, 2020

    Good suggestion, let me look into it.

  7. bjorn3 commented on Dec 12, 2020

    @bjorn3
    bjorn3
    on Dec 12, 2020
    MemberAuthor

    @0dvictor are you still working on this?

  8. 0dvictor commented on Dec 15, 2020

    @0dvictor
    0dvictor
    on Dec 15, 2020

    Thank you for reminding and apologize for the delay. I did create a prototype but haven't got a chance polish it yet. I'll create the PR this week.

  9. 0dvictor commented on Dec 19, 2020

    @0dvictor
    0dvictor
    on Dec 19, 2020

    Sorry again about the delay. I've created PR #80187, which fixes this issue.

  10. Dylan-DPC-zz
    added 4 commits that reference this issue on Dec 23, 2020

    Rollup merge of rust-lang#80187 - 0dvictor:nativelib, r=bjorn3

    5bf0ba9

    Rollup merge of rust-lang#80187 - 0dvictor:nativelib, r=bjorn3

    22d4da8

    Rollup merge of rust-lang#80187 - 0dvictor:nativelib, r=bjorn3

    11939c8

    Rollup merge of rust-lang#80187 - 0dvictor:nativelib, r=bjorn3

    d11537d
  11. bors
    added a commit that references this issue on Dec 25, 2020

    Auto merge of rust-lang#80187 - 0dvictor:nativelib, r=bjorn3

    198ec34
  12. bors
    closed this as completedin 198ec34on Dec 25, 2020
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