rustc: Add some support for mixing rlibs and dylibs #13892
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cc #13851, this is blocking libcore on windows |
| //! into a crate D (because library A appears twice). | ||
| //! | ||
| //! The job of this module is to calculate what format each upstream crate | ||
| //! should be used when linking eachoutput type requested in this session. This |
Currently, rustc requires that a linkage be a product of 100% rlibs or 100% dylibs. This is to satisfy the requirement that each object appear at most once in the final output products. This is a bit limiting, and the upcoming libcore library cannot exist as a dylib, so these rules must change. The goal of this commit is to enable *some* use cases for mixing rlibs and dylibs, primarily libcore's use case. It is not targeted at allowing an exhaustive number of linkage flavors. There is a new dependency_format module in rustc which calculates what format each upstream library should be linked as in each output type of the current unit of compilation. The module itself contains many gory details about what's going on here. cc rust-lang#10729
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Now with all tests passing! (sorry, should have run |
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amazing work, very enlightening! thanks! |
bors
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Currently, rustc requires that a linkage be a product of 100% rlibs or 100% dylibs. This is to satisfy the requirement that each object appear at most once in the final output products. This is a bit limiting, and the upcoming libcore library cannot exist as a dylib, so these rules must change. The goal of this commit is to enable *some* use cases for mixing rlibs and dylibs, primarily libcore's use case. It is not targeted at allowing an exhaustive number of linkage flavors. There is a new dependency_format module in rustc which calculates what format each upstream library should be linked as in each output type of the current unit of compilation. The module itself contains many gory details about what's going on here. cc #10729
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I was thinking about this today: should we have a way to manually specify the desired linkage? #[link_to(rlib)] extern crate foo;
#[link_to(dylib)] extern crate bar;(or something) |
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I do think that we'll eventually have to grow use cases such as that, but for now I wanted to go with the "simple as possible" implementation. I was hoping to better understand the use case for manually specifying a linkage before adding it, mainly because I'm not convinced that the algorithm implemented here is always sufficient! |
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This is the second step in implementing #13851. This PR cannot currently land until a snapshot exists with #13892, but I imagine that this review will take longer. This PR refactors a large amount of functionality outside of the standard library into a new library, libcore. This new library has 0 dependencies (in theory). In practice, this library currently depends on these symbols being available: * `rust_begin_unwind` and `rust_fail_bounds_check` - These are the two entry points of failure in libcore. The symbols are provided by libstd currently. In the future (see the bullets on #13851) this will be officially supported with nice error mesages. Additionally, there will only be one failure entry point once `std::fmt` migrates to libcore. * `memcpy` - This is often generated by LLVM. This is also quite trivial to implement for any platform, so I'm not too worried about this. * `memcmp` - This is required for comparing strings. This function is quite common *everywhere*, so I don't feel to bad about relying on a consumer of libcore to define it. * `malloc` and `free` - This is quite unfortunate, and is a temporary stopgap until we deal with the `~` situation. More details can be found in the module `core::should_not_exist` * `fmod` and `fmodf` - These exist because the `Rem` trait is defined in libcore, so the `Rem` implementation for floats must also be defined in libcore. I imagine that any platform using floating-point modulus will have these symbols anyway, and otherwise they will be optimized out. * `fdim` and `fdimf` - Like `fmod`, these are from the `Signed` trait being defined in libcore. I don't expect this to be much of a problem These dependencies all "Just Work" for now because libcore only exists as an rlib, not as a dylib. The commits themselves are organized to show that the overall diff of this extraction is not all that large. Most modules were able to be moved with very few modifications. The primary module left out of this iteration is `std::fmt`. I plan on migrating the `fmt` module to libcore, but I chose to not do so at this time because it had implications on the `Writer` trait that I wanted to deal with in isolation. There are a few breaking changes in these commits, but they are fairly minor, and are all labeled with `[breaking-change]`. The nastiest parts of this movement come up with `~[T]` and `~str` being language-defined types today. I believe that much of this nastiness will get better over time as we migrate towards `Vec<T>` and `Str` (or whatever the types will be named). There will likely always be some extension traits, but the situation won't be as bad as it is today. Known deficiencies: * rustdoc will get worse in terms of readability. This is the next issue I will tackle as part of #13851. If others think that the rustdoc change should happen first, I can also table this to fix rustdoc first. * The compiler reveals that all these types are reexports via error messages like `core::option::Option`. This is filed as #13065, and I believe that issue would have a higher priority now. I do not currently plan on fixing that as part of #13851. If others believe that this issue should be fixed, I can also place it on the roadmap for #13851. I recommend viewing these changes on a commit-by-commit basis. The overall change is likely too overwhelming to take in.
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@alexcrichton this didn't change any of the documentation; at least the manual (http://static.rust-lang.org/doc/master/rust.html#linkage) has outdated information. |
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Oops, thanks! |
alexcrichton
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May 12, 2014
After allowing mixing rlibs and dylibs in rust-lang#13892, the documentation was not updated accordingly to reflect this new capability.
alexcrichton
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May 13, 2014
After allowing mixing rlibs and dylibs in rust-lang#13892, the documentation was not updated accordingly to reflect this new capability.
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Currently, rustc requires that a linkage be a product of 100% rlibs or 100%
dylibs. This is to satisfy the requirement that each object appear at most once
in the final output products. This is a bit limiting, and the upcoming libcore
library cannot exist as a dylib, so these rules must change.
The goal of this commit is to enable some use cases for mixing rlibs and
dylibs, primarily libcore's use case. It is not targeted at allowing an
exhaustive number of linkage flavors.
There is a new dependency_format module in rustc which calculates what format
each upstream library should be linked as in each output type of the current
unit of compilation. The module itself contains many gory details about what's
going on here.
cc #10729