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Using many cxx libraries at the same time #252

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TheZoq2 opened this issue Aug 11, 2020 · 3 comments
Open

Using many cxx libraries at the same time #252

TheZoq2 opened this issue Aug 11, 2020 · 3 comments
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integration How cxx fits into the big picture of an organization's codebase and builds linking Issues that manifest as link failures

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@TheZoq2
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TheZoq2 commented Aug 11, 2020

Since I liked the first time I used this crate, I figured I could start RIIRing another part of my project. This part is a standalone library, so I don't want to merge it with my first converted part, but unfortunately that means I run into some linker errors because I now link against the cxx library twice.

  = note: /usr/bin/ld: /home/frans/Documents/phd/cinnabar/mercurous/target/debug/deps/libcxx-3ab177cc3e5e5c69.rlib(cxx-3ab177cc3e5e5c69.cxx.ed64qtld-cgu.13.rcgu.o): in function `cxxbridge03$str$valid':
          /home/frans/.cargo/registry/src/github.com-1ecc6299db9ec823/cxx-0.3.4/src/symbols/rust_str.rs:5: multiple definition of `cxxbridge03$str$valid'; ../affine-arith/build/libaffine_arith_rust.a(cxx-34c4476bdb46593d.cxx.c3ul3jrz-cgu.13.rcgu.o):cxx.c3ul3jrz-cgu.13:(.text.cxxbridge03$str$valid+0x0): first defined here
          /usr/bin/ld: /home/frans/Documents/phd/cinnabar/mercurous/target/debug/deps/libcxx-3ab177cc3e5e5c69.rlib(cxx-3ab177cc3e5e5c69.cxx.ed64qtld-cgu.5.rcgu.o): in function `cxxbridge03$exception':
          /home/frans/.cargo/registry/src/github.com-1ecc6299db9ec823/cxx-0.3.4/src/symbols/exception.rs:4: multiple definition of `cxxbridge03$exception'; ../affine-arith/build/libaffine_arith_rust.a(cxx-34c4476bdb46593d.cxx.c3ul3jrz-cgu.10.rcgu.o):cxx.c3ul3jrz-cgu.10:(.text.cxxbridge03$exception+0x0): first defined here
          /usr/bin/ld: /home/frans/Documents/phd/cinnabar/mercurous/target/debug/deps/libcxx-3ab177cc3e5e5c69.rlib(cxx-3ab177cc3e5e5c69.cxx.ed64qtld-cgu.8.rcgu.o): in function `cxxbridge03$string$clone':
          /home/frans/.cargo/registry/src/github.com-1ecc6299db9ec823/cxx-0.3.4/src/symbols/rust_string.rs:12: multiple definition of `cxxbridge03$string$clone'; ../affine-arith/build/libaffine_arith_rust.a(cxx-34c4476bdb46593d.cxx.c3ul3jrz-cgu.7.rcgu.o):cxx.c3ul3jrz-cgu.7:(.text.cxxbridge03$string$clone+0x0): first defined here
          /usr/bin/ld: /home/frans/Documents/phd/cinnabar/mercurous/target/debug/deps/libcxx-3ab177cc3e5e5c69.rlib(cxx-3ab177cc3e5e5c69.cxx.ed64qtld-cgu.8.rcgu.o): in function `cxxbridge03$string$drop':
          /home/frans/.cargo/registry/src/github.com-1ecc6299db9ec823/cxx-0.3.4/src/symbols/rust_string.rs:33: multiple definition of `cxxbridge03$string$drop'; ../affine-arith/build/libaffine_arith_rust.a(cxx-34c4476bdb46593d.cxx.c3ul3jrz-cgu.7.rcgu.o):cxx.c3ul3jrz-cgu.7:(.text.cxxbridge03$string$drop+0x0): first defined here
          /usr/bin/ld: /home/frans/Documents/phd/cinnabar/mercurous/target/debug/deps/libcxx-3ab177cc3e5e5c69.rlib(cxx-3ab177cc3e5e5c69.cxx.ed64qtld-cgu.8.rcgu.o): in function `cxxbridge03$string$from':
          /home/frans/.cargo/registry/src/github.com-1ecc6299db9ec823/cxx-0.3.4/src/symbols/rust_string.rs:17: multiple definition of `cxxbridge03$string$from'; ../affine-arith/build/libaffine_arith_rust.a(cxx-34c4476bdb46593d.cxx.c3ul3jrz-cgu.7.rcgu.o):cxx.c3ul3jrz-cgu.7:(.text.cxxbridge03$string$from+0x0): first defined here
          /usr/bin/ld: /home/frans/Documents/phd/cinnabar/mercurous/target/debug/deps/libcxx-3ab177cc3e5e5c69.rlib(cxx-3ab177cc3e5e5c69.cxx.ed64qtld-cgu.8.rcgu.o): in function `cxxbridge03$string$len':
          /home/frans/.cargo/registry/src/github.com-1ecc6299db9ec823/cxx-0.3.4/src/symbols/rust_string.rs:43: multiple definition of `cxxbridge03$string$len'; ../affine-arith/build/libaffine_arith_rust.a(cxx-34c4476bdb46593d.cxx.c3ul3jrz-cgu.7.rcgu.o):cxx.c3ul3jrz-cgu.7:(.text.cxxbridge03$string$len+0x0): first defined here
          /usr/bin/ld: /home/frans/Documents/phd/cinnabar/mercurous/target/debug/deps/libcxx-3ab177cc3e5e5c69.rlib(cxx-3ab177cc3e5e5c69.cxx.ed64qtld-cgu.8.rcgu.o): in function `cxxbridge03$string$new':
          /home/frans/.cargo/registry/src/github.com-1ecc6299db9ec823/cxx-0.3.4/src/symbols/rust_string.rs:7: multiple definition of `cxxbridge03$string$new'; ../affine-arith/build/libaffine_arith_rust.a(cxx-34c4476bdb46593d.cxx.c3ul3jrz-cgu.7.rcgu.o):cxx.c3ul3jrz-cgu.7:(.text.cxxbridge03$string$new+0x0): first defined here
          /usr/bin/ld: /home/frans/Documents/phd/cinnabar/mercurous/target/debug/deps/libcxx-3ab177cc3e5e5c69.rlib(cxx-3ab177cc3e5e5c69.cxx.ed64qtld-cgu.8.rcgu.o): in function `cxxbridge03$string$ptr':
          /home/frans/.cargo/registry/src/github.com-1ecc6299db9ec823/cxx-0.3.4/src/symbols/rust_string.rs:38: multiple definition of `cxxbridge03$string$ptr'; ../affine-arith/build/libaffine_arith_rust.a(cxx-34c4476bdb46593d.cxx.c3ul3jrz-cgu.7.rcgu.o):cxx.c3ul3jrz-cgu.7:(.text.cxxbridge03$string$ptr+0x0): first defined here
          collect2: error: ld returned 1 exit status

Is there a way to work around this, something like optionally not building against the cxx cpp file?
@TheZoq2
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TheZoq2 commented Aug 11, 2020 •
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I thought a bit more about this, and to me, it looks like these are symbols defined in rust, not in the cpp file, so just not building against the cxx cpp file probably won't help in this case

Edit: I was going to try to add a fix for this, so I added cxx as a submodule and now things compile as expected. I pressume that's not a solution though

@antonok-edm
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Mozilla's approach to the duplicate symbols problem is to compile all libraries into rlibs, and then create a single wrapper crate around all of them that compiles into a staticlib for linking purposes. I'm curious to see if that could be applicable for cxx as well; if so it would be nice to have a guide somewhere.

@dtolnay dtolnay added integration How cxx fits into the big picture of an organization's codebase and builds linking Issues that manifest as link failures labels Aug 30, 2020
@adetaylor
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I wrote some stuff here which may be relevant:
https://github.com/adetaylor/cxx/blob/book/book/src/building.md#linking-the-c-and-rust-together

but the bottom line is, @antonok-edm is right - the only realistic solution is to pull all your Rust code together into a single staticlib target :( There's a bit more discussion here: rust-lang/rust#73632

vlovich added a commit to vlovich/lol-html that referenced this issue Apr 26, 2021
@vlovich
Allow linking C bindings into Rust
73d6946 
When you have multiple disparate Rust libraries that you link into a
larger C/C++ executable, you need to create a super crate that links
all dependencies to avoid linkage issues (e.g. so that Cargo & Rust can
see semver incompatabilities & build them correctly among other things).
Add `rlib` to the `crate-type` list for C bindings to allow building
such a "super" crate.

The following links:

* https://github.com/adetaylor/cxx/blob/book/book/src/building.md#linking-the-c-and-rust-together
* dtolnay/cxx#252

have more context.
@vlovich vlovich mentioned this issue Apr 26, 2021
Merged
vlovich added a commit to vlovich/lol-html that referenced this issue Apr 26, 2021
@vlovich
Allow linking C bindings into Rust
a7db842 
When you have multiple disparate Rust libraries that you link into a
larger C/C++ executable, you need to create a super crate that links
all dependencies to avoid linkage issues (e.g. so that Cargo & Rust can
see semver incompatabilities & build them correctly among other things).
Add `rlib` to the `crate-type` list for C bindings to allow building
such a "super" crate.

The following links:

* https://github.com/adetaylor/cxx/blob/book/book/src/building.md#linking-the-c-and-rust-together
* dtolnay/cxx#252

have more context.
kornelski pushed a commit to cloudflare/lol-html that referenced this issue Apr 27, 2021
@vlovich @kornelski
Allow linking C bindings into Rust
7fd31c1 
When you have multiple disparate Rust libraries that you link into a
larger C/C++ executable, you need to create a super crate that links
all dependencies to avoid linkage issues (e.g. so that Cargo & Rust can
see semver incompatabilities & build them correctly among other things).
Add `rlib` to the `crate-type` list for C bindings to allow building
such a "super" crate.

The following links:

* https://github.com/adetaylor/cxx/blob/book/book/src/building.md#linking-the-c-and-rust-together
* dtolnay/cxx#252

have more context.
@dennisschagt dennisschagt mentioned this issue Apr 14, 2024
Closed
3 tasks
@dennisschagt dennisschagt mentioned this issue Jun 16, 2024
Merged
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@adetaylor @dtolnay @TheZoq2 @antonok-edm