从 Fedora Linux 主机到 Windows 目标的交叉编译 Rust 找不到依赖项
Crosscompiling Rust from Fedora Linux host to Windows target does not find dependencies
我 运行 x86_64 Fedora Linux 31 主机，想编译一些最简单的 rust 代码：
fn main() {
println!("Hello, world!");
}
它从主机编译到这个主机本身很好，但是当我尝试将它交叉编译为 i686 或 x86_64 windows 时，它编译失败。
我阅读了 Whosebug（例如 ）并在互联网上进行了搜索，试图找出类似的问题以及如何解决它，但没有任何收益。
我已经安装了所有必要的目标：
[pfemidi@pfemidi hello_cargo]$ rustup show
Default host: x86_64-unknown-linux-gnu
rustup home: /home/pfemidi/.rustup
installed targets for active toolchain
--------------------------------------
i686-pc-windows-gnu
i686-unknown-linux-gnu
i686-unknown-linux-musl
x86_64-pc-windows-gnu
x86_64-unknown-linux-gnu
x86_64-unknown-linux-musl
active toolchain
----------------
stable-x86_64-unknown-linux-gnu (default)
rustc 1.39.0 (4560ea788 2019-11-04)
[pfemidi@pfemidi hello_cargo]$
我已经安装了 mingw32 as mingw64，这个小的测试 C++ 代码已经被 mingw32 as mingw64 编译得很好并且没有错误:
#include <iomanip>
#include <iostream>
int main() {
std::cout << "Hello, world!" << std::endl;
return 0;
}
我已将 windows 特定的 mingw 链接器和 ar 添加到我的 .cargo/config:
[target.i686-pc-windows-gnu]
linker = "i686-w64-mingw32-gcc"
ar = "i686-w64-mingw32-ar"
[target.x86_64-pc-windows-gnu]
linker = "x86_64-w64-mingw32-gcc"
ar = "x86_64-w64-mingw32-ar"
但是当我运行要么
cargo build --release --target i686-pc-windows-gnu --verbose
或
cargo build --release --target x86_64-pc-windows-gnu --verbose
都抱怨 "cannot find -lpthread":
[pfemidi@pfemidi hello_cargo]$ cargo build --release --target i686-pc-windows-gnu --verbose
Compiling hello_cargo v0.1.0 (/home/pfemidi/mywork/rust/hello_cargo)
Running `rustc --edition=2018 --crate-name hello_cargo src/main.rs --color always --crate-type bin --emit=dep-info,link -C opt-level=3 -C panic=abort -C metadata=3801b83c24480675 -C extra-filename=-3801b83c24480675 --out-dir /home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps --target i686-pc-windows-gnu -C ar=i686-w64-mingw32-ar -C linker=i686-w64-mingw32-gcc -L dependency=/home/r/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps -L dependency=/home/r/mywork/rust/hello_cargo/target/release/deps`
error: linking with `i686-w64-mingw32-gcc` failed: exit code: 1
|
= note: "i686-w64-mingw32-gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib" "-Wl,--large-address-aware" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/crt2.o" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/rsbegin.o" "-L" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.0.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.1.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.10.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.11.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.12.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.2.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.3.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.4.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.5.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.6.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.7.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.8.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.9.rcgu.o" "-o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.exe" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.3miif37looiovbes.rcgu.o" "-Wl,--gc-sections" "-nodefaultlibs" "-L" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps" "-L" "/home/pfemidi/mywork/rust/hello_cargo/target/release/deps" "-L" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib" "-Wl,--start-group" "-Wl,-Bstatic" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libstd-78187cf09a9bef6f.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libpanic_abort-699459bd9d6c1638.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libhashbrown-397a481a32803af5.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/librustc_std_workspace_alloc-27eb482dce24475f.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libbacktrace-046a61f77fc212c5.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libbacktrace_sys-8c6fe5218eaa7203.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/librustc_demangle-4d4d47417516248c.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libunwind-ef8ccbbd42d1b53f.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libcfg_if-bbe68dc13352b6cc.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/liblibc-b6447d8e4c58855b.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/liballoc-3890c13f15229667.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/librustc_std_workspace_core-ceab434c37c7417c.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libcore-3b2fced4ccf446c5.rlib" "-Wl,--end-group" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libcompiler_builtins-7e358676639674ac.rlib" "-Wl,-Bdynamic" "-ladvapi32" "-lws2_32" "-luserenv" "-Wl,-Bstatic" "-lgcc_eh" "-lpthread" "-Wl,-Bdynamic" "-lmingwex" "-lmingw32" "-lgcc" "-lmsvcrt" "-lmsvcrt" "-luser32" "-lkernel32" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/rsend.o"
= note: /usr/lib/gcc/i686-w64-mingw32/9.2.1/../../../../i686-w64-mingw32/bin/ld: cannot find -lpthread
collect2: error: ld returned 1 exit status
error: aborting due to previous error
error: could not compile `hello_cargo`.
Caused by:
process didn't exit successfully: `rustc --edition=2018 --crate-name hello_cargo src/main.rs --color always --crate-type bin --emit=dep-info,link -C opt-level=3 -C panic=abort -C metadata=3801b83c24480675 -C extra-filename=-3801b83c24480675 --out-dir /home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps --target i686-pc-windows-gnu -C ar=i686-w64-mingw32-ar -C linker=i686-w64-mingw32-gcc -L dependency=/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps -L dependency=/home/pfemidi/mywork/rust/hello_cargo/target/release/deps` (exit code: 1)
[pfemidi@pfemidi hello_cargo]$
为什么？还要做什么才能满足一切？
交叉编译并不像听起来那么容易。我建议不要发明自己的轮子并使用已经测试过的解决方案。
目前 "standard" 进行交叉编译的方法是使用 cross，这是一种货物包装器，可以让您摆脱交叉编译的细节。
在安装 cross 之前，您应该先安装它 dependencies。如何做到这一点完全取决于您的发行版。
依赖项准备就绪后，您应该像这样安装 cross（假设您有 cargo）。
$ cargo install cross
在那之后构建工作半神奇
cross build --target x86_64-pc-windows-gnu
经过深思熟虑，我能够解决从 Linux 主机到 Windows 目标的 Rust 交叉编译项目的问题，而无需使用 cross 和类似工具，而只是简单地通过在货物中指定特定目标。当然，测试和 运行 项目会失败（如果你没有安装像 wine 这样的模拟器），但是创建 Windows 目标会很顺利。顺便说一句，Rust 最初被开发为交叉编译器，因此拥有完整的工作项目并通过了 Linux 中的所有测试，几乎可以肯定 Windows 中该项目的简单交叉编译不会破坏它无论如何。
因为我 运行 Fedora Linux 31 以下所有内容都适用于此发行版。但我认为其他 Linux 发行版之间没有显着差异。而且我只考虑 pc-windows-gnu Rust 目标，pc-windows-msvc 目标不是我的兴趣。
首先，确保安装了交叉编译所需的所有 MinGW 包：
[pfemidi@pfemidi ~]$ rpm -qa | grep mingw | sort
mingw32-binutils-2.32-6.fc31.x86_64
mingw32-cpp-9.2.1-1.fc31.x86_64
mingw32-crt-6.0.0-2.fc31.noarch
mingw32-filesystem-110-1.fc31.noarch
mingw32-gcc-9.2.1-1.fc31.x86_64
mingw32-headers-6.0.0-2.fc31.noarch
mingw32-winpthreads-6.0.0-2.fc31.noarch
mingw32-winpthreads-static-6.0.0-2.fc31.noarch
mingw64-binutils-2.32-6.fc31.x86_64
mingw64-cpp-9.2.1-1.fc31.x86_64
mingw64-crt-6.0.0-2.fc31.noarch
mingw64-filesystem-110-1.fc31.noarch
mingw64-gcc-9.2.1-1.fc31.x86_64
mingw64-headers-6.0.0-2.fc31.noarch
mingw64-winpthreads-6.0.0-2.fc31.noarch
mingw64-winpthreads-static-6.0.0-2.fc31.noarch
mingw-binutils-generic-2.32-6.fc31.x86_64
mingw-filesystem-base-110-1.fc31.noarch
[pfemidi@pfemidi ~]$
让我们用 Rust 语言创建最简单的项目：
[pfemidi@pfemidi rust]$ cargo new foobar
Created binary (application) `foobar` package
[pfemidi@pfemidi rust]$ cat foobar/src/main.rs
fn main() {
println!("Hello, world!");
}
[pfemidi@pfemidi rust]$
在项目目录下用config文件创建.cargo目录，内容如下：
[pfemidi@pfemidi rust]$ cd foobar
[pfemidi@pfemidi foobar]$ mkdir .cargo
[pfemidi@pfemidi foobar]$ cat > .cargo/config
[target.i686-pc-windows-gnu]
linker = "i686-w64-mingw32-gcc"
ar = "i686-w64-mingw32-ar"
[target.x86_64-pc-windows-gnu]
linker = "x86_64-w64-mingw32-gcc"
ar = "x86_64-w64-mingw32-ar"
[pfemidi@pfemidi foobar]$
此步骤是必要的，以便在构建 Windows 目标时，Rust 不使用默认安装的 gcc 中的链接器，而是使用 MinGW 链接器。
现在尝试将项目构建为 i686-pc-windows-gnu 目标：
[pfemidi@pfemidi foobar]$ cargo build --target i686-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
error: linking with `i686-w64-mingw32-gcc` failed: exit code: 1
|
= note: "i686-w64-mingw32-gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib"
...
= note: /usr/lib/gcc/i686-w64-mingw32/9.2.1/../../../../i686-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/crt2.o:crtexe.c:(.text+0x75): undefined reference to `__onexitend'
/usr/lib/gcc/i686-w64-mingw32/9.2.1/../../../../i686-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/crt2.o:crtexe.c:(.text+0x7a): undefined reference to `__onexitbegin'
collect2: error: ld returned 1 exit status
error: aborting due to previous error
error: could not compile `foobar`.
To learn more, run the command again with --verbose.
[pfemidi@pfemidi foobar]$
错误！在 crt2.o 文件中得到 "undefined reference to __onexitend" 和 "undefined reference to __onexitbegin"。事实上，pc-windows-gnu 目标的 Rust 组件是用 MinGW 6.3.0 构建的，但 Fedora Linux 31 中有 MinGW 版本 9.2.1。因此 CRT 有所不同由于编译器版本不匹配。好的，让我们将 crt2.o 从 Fedora Linux MinGW 存储库复制到 i686-pc-windows-gnu 组件的 Rust 目录。与 crt2.o 一起，我们还复制了 dllcrt2.o，它是动态库的入口点，因为 crt2.o 是独立可执行文件的入口点。为了以防万一，我们保存原始文件：
[pfemidi@pfemidi foobar]$ cd ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/
[pfemidi@pfemidi lib]$ mv crt2.o crt2.o.ori
[pfemidi@pfemidi lib]$ mv dllcrt2.o dllcrt2.o.ori
[pfemidi@pfemidi lib]$ cp /usr/i686-w64-mingw32/sys-root/mingw/lib/crt2.o .
[pfemidi@pfemidi lib]$ cp /usr/i686-w64-mingw32/sys-root/mingw/lib/dllcrt2.o .
[pfemidi@pfemidi lib]$ cd -
/home/pfemidi/mywork/rust/foobar
[pfemidi@pfemidi foobar]$
现在再次尝试将项目构建为 i686-pc-windows-gnu 目标：
[pfemidi@pfemidi foobar]$ cargo build --target i686-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
Finished dev [unoptimized + debuginfo] target(s) in 0.19s
[pfemidi@pfemidi foobar]$
成功了！
现在尝试对 x86_64-pc-windows-gnu 目标执行相同的操作：
[pfemidi@pfemidi foobar]$ cargo build --target x86_64-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
error: linking with `x86_64-w64-mingw32-gcc` failed: exit code: 1
|
= note: "x86_64-w64-mingw32-gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib" "-m64"
...
= note: /usr/lib/gcc/x86_64-w64-mingw32/9.2.1/../../../../x86_64-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-pc-windows-gnu/lib/crt2.o:crtexe.c:(.rdata$.refptr.__onexitbegin[.refptr.__onexitbegin]+0x0): undefined reference to `__onexitbegin'
/usr/lib/gcc/x86_64-w64-mingw32/9.2.1/../../../../x86_64-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-pc-windows-gnu/lib/crt2.o:crtexe.c:(.rdata$.refptr.__onexitend[.refptr.__onexitend]+0x0): undefined reference to `__onexitend'
collect2: error: ld returned 1 exit status
error: aborting due to previous error
error: could not compile `foobar`.
To learn more, run the command again with --verbose.
[pfemidi@pfemidi foobar]$
该错误与之前提到的 i686-pc-windows-gnu 目标完全相同。让我们通过类比上面的 32 位目标来复制文件 crt2.o 和 dllcrt2.o：
[pfemidi@pfemidi foobar]$ cd ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-pc-windows-gnu/lib/
[pfemidi@pfemidi lib]$ mv crt2.o crt2.o.ori
[pfemidi@pfemidi lib]$ mv dllcrt2.o dllcrt2.o.ori
[pfemidi@pfemidi lib]$ cp /usr/x86_64-w64-mingw32/sys-root/mingw/lib/crt2.o .
[pfemidi@pfemidi lib]$ cp /usr/x86_64-w64-mingw32/sys-root/mingw/lib/dllcrt2.o .
[pfemidi@pfemidi lib]$ cd -
/home/pfemidi/mywork/rust/foobar
[pfemidi@pfemidi foobar]$
并再次尝试将项目构建为 x86_64-pc-windows-gnu 目标：
[pfemidi@pfemidi foobar]$ cargo build --target x86_64-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
Finished dev [unoptimized + debuginfo] target(s) in 0.20s
[pfemidi@pfemidi foobar]$
是的！它也有效！所以现在我们可以使用 Rust 发行版中包含的标准货物轻松地为 Windows 构建目标！对于 x86_64 目标，这是完全正确的。但是对于 x86 目标，一切都会好起来，直到我们在我们的项目中使用任何恐慌的函数（f.e。宏恐慌！，期望函数等）。
让我们为我们的简单项目添加恐慌：
[pfemidi@pfemidi foobar]$ cat src/main.rs
fn main() {
println!("Hello, world!");
panic!("I'm panicked!"); // <-- here it is
}
[pfemidi@pfemidi foobar]$
将其构建为 x86_64 目标：
[pfemidi@pfemidi foobar]$ cargo build --target x86_64-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
Finished dev [unoptimized + debuginfo] target(s) in 0.16s
[pfemidi@pfemidi foobar]$
一切顺利（我检查过，效果也很好）。现在尝试对 x86 目标执行相同的操作：
[pfemidi@pfemidi foobar]$ cargo build --target i686-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
error: linking with `i686-w64-mingw32-gcc` failed: exit code: 1
|
= note: "i686-w64-mingw32-gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib"
...
= note: /usr/lib/gcc/i686-w64-mingw32/9.2.1/../../../../i686-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libpanic_unwind-0c029c00da54fbf5.rlib(panic_unwind-0c029c00da54fbf5.panic_unwind.2hgzd7yq-cgu.0.rcgu.o): in function `ZN12panic_unwind3imp5panic17h03027a0e504502cdE':
/rustc/73528e339aae0f17a15ffa49a8ac608f50c6cf14\/src\libpanic_unwind/gcc.rs:73: undefined reference to `_Unwind_RaiseException'
/usr/lib/gcc/i686-w64-mingw32/9.2.1/../../../../i686-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libpanic_unwind-0c029c00da54fbf5.rlib(panic_unwind-0c029c00da54fbf5.panic_unwind.2hgzd7yq-cgu.0.rcgu.o): in function `rust_eh_unwind_resume':
/rustc/73528e339aae0f17a15ffa49a8ac608f50c6cf14\/src\libpanic_unwind/gcc.rs:327: undefined reference to `_Unwind_Resume'
collect2: error: ld returned 1 exit status
error: aborting due to previous error
error: could not compile `foobar`.
To learn more, run the command again with --verbose.
[pfemidi@pfemidi foobar]$
糟糕！我们在 Rust 标准库的 libpanic_unwind 模块中得到 "undefined reference to _Unwind_RaiseException" 和 "undefined reference to _Unwind_Resume"。不过这个问题也解决了，虽然没有上一个简单，只是替换CRTcrt2.o和dllcrt2.o文件
对于堆栈展开，Rust 对 32 位 Windows 目标使用 dwarf 方法，对 64 位 Windows 目标使用 seh 方法，而来自标准 Fedora Linux 发行版的 MinGW 使用 sjlj 方法进行32 位 Windows 目标和 64 位 Windows 目标的 seh 方法（了解差异 here）。因此，64 位目标由 MinGW 链接器链接没有任何问题，但对于 32 位目标，没有必要的符号和目标文件才能正确链接。要获得这些文件和符号，有必要为 32 位 Windows 目标重建具有 dwarf 支持的 MinGW 而不是默认的 sjlj 支持。
我不会在这里详细介绍如何重建 MinGW，我只说一件事：用 dwarf stack unwinding 而不是 sjlj 方法重建 MinGW 后，你只需要选择一个名为 libgcc_eh.a 来自刚刚构建的 MinGW，并将其放入 Rust i686-pc-windows-gnu 目标的库目录中。这样做之后，带有任何 panic 函数的项目不仅对于 64 位 Windows 目标，而且对于 32 位目标都将无错误地构建：
[pfemidi@pfemidi foobar]$ cd ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/
[pfemidi@pfemidi lib]$ cp ~/rpmbuild/BUILD/gcc-9.2.1-20190827/build_win32/i686-w64-mingw32/libgcc/libgcc_eh.a .
[pfemidi@pfemidi lib]$ cd -
/home/pfemidi/mywork/rust/foobar
[pfemidi@pfemidi foobar]$ cargo build --target i686-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
Finished dev [unoptimized + debuginfo] target(s) in 0.30s
[pfemidi@pfemidi foobar]$
RUSTing 快乐！ :-)
我 运行 x86_64 Fedora Linux 31 主机，想编译一些最简单的 rust 代码：
fn main() {
println!("Hello, world!");
}
它从主机编译到这个主机本身很好，但是当我尝试将它交叉编译为 i686 或 x86_64 windows 时，它编译失败。
我阅读了 Whosebug（例如
我已经安装了所有必要的目标：
[pfemidi@pfemidi hello_cargo]$ rustup show
Default host: x86_64-unknown-linux-gnu
rustup home: /home/pfemidi/.rustup
installed targets for active toolchain
--------------------------------------
i686-pc-windows-gnu
i686-unknown-linux-gnu
i686-unknown-linux-musl
x86_64-pc-windows-gnu
x86_64-unknown-linux-gnu
x86_64-unknown-linux-musl
active toolchain
----------------
stable-x86_64-unknown-linux-gnu (default)
rustc 1.39.0 (4560ea788 2019-11-04)
[pfemidi@pfemidi hello_cargo]$
我已经安装了 mingw32 as mingw64，这个小的测试 C++ 代码已经被 mingw32 as mingw64 编译得很好并且没有错误:
#include <iomanip>
#include <iostream>
int main() {
std::cout << "Hello, world!" << std::endl;
return 0;
}
我已将 windows 特定的 mingw 链接器和 ar 添加到我的 .cargo/config:
[target.i686-pc-windows-gnu]
linker = "i686-w64-mingw32-gcc"
ar = "i686-w64-mingw32-ar"
[target.x86_64-pc-windows-gnu]
linker = "x86_64-w64-mingw32-gcc"
ar = "x86_64-w64-mingw32-ar"
但是当我运行要么
cargo build --release --target i686-pc-windows-gnu --verbose
或
cargo build --release --target x86_64-pc-windows-gnu --verbose
都抱怨 "cannot find -lpthread":
[pfemidi@pfemidi hello_cargo]$ cargo build --release --target i686-pc-windows-gnu --verbose
Compiling hello_cargo v0.1.0 (/home/pfemidi/mywork/rust/hello_cargo)
Running `rustc --edition=2018 --crate-name hello_cargo src/main.rs --color always --crate-type bin --emit=dep-info,link -C opt-level=3 -C panic=abort -C metadata=3801b83c24480675 -C extra-filename=-3801b83c24480675 --out-dir /home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps --target i686-pc-windows-gnu -C ar=i686-w64-mingw32-ar -C linker=i686-w64-mingw32-gcc -L dependency=/home/r/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps -L dependency=/home/r/mywork/rust/hello_cargo/target/release/deps`
error: linking with `i686-w64-mingw32-gcc` failed: exit code: 1
|
= note: "i686-w64-mingw32-gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib" "-Wl,--large-address-aware" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/crt2.o" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/rsbegin.o" "-L" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.0.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.1.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.10.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.11.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.12.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.2.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.3.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.4.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.5.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.6.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.7.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.8.rcgu.o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.hello_cargo.ejabbyqy-cgu.9.rcgu.o" "-o" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.exe" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps/hello_cargo-3801b83c24480675.3miif37looiovbes.rcgu.o" "-Wl,--gc-sections" "-nodefaultlibs" "-L" "/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps" "-L" "/home/pfemidi/mywork/rust/hello_cargo/target/release/deps" "-L" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib" "-Wl,--start-group" "-Wl,-Bstatic" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libstd-78187cf09a9bef6f.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libpanic_abort-699459bd9d6c1638.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libhashbrown-397a481a32803af5.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/librustc_std_workspace_alloc-27eb482dce24475f.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libbacktrace-046a61f77fc212c5.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libbacktrace_sys-8c6fe5218eaa7203.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/librustc_demangle-4d4d47417516248c.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libunwind-ef8ccbbd42d1b53f.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libcfg_if-bbe68dc13352b6cc.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/liblibc-b6447d8e4c58855b.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/liballoc-3890c13f15229667.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/librustc_std_workspace_core-ceab434c37c7417c.rlib" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libcore-3b2fced4ccf446c5.rlib" "-Wl,--end-group" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libcompiler_builtins-7e358676639674ac.rlib" "-Wl,-Bdynamic" "-ladvapi32" "-lws2_32" "-luserenv" "-Wl,-Bstatic" "-lgcc_eh" "-lpthread" "-Wl,-Bdynamic" "-lmingwex" "-lmingw32" "-lgcc" "-lmsvcrt" "-lmsvcrt" "-luser32" "-lkernel32" "/home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/rsend.o"
= note: /usr/lib/gcc/i686-w64-mingw32/9.2.1/../../../../i686-w64-mingw32/bin/ld: cannot find -lpthread
collect2: error: ld returned 1 exit status
error: aborting due to previous error
error: could not compile `hello_cargo`.
Caused by:
process didn't exit successfully: `rustc --edition=2018 --crate-name hello_cargo src/main.rs --color always --crate-type bin --emit=dep-info,link -C opt-level=3 -C panic=abort -C metadata=3801b83c24480675 -C extra-filename=-3801b83c24480675 --out-dir /home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps --target i686-pc-windows-gnu -C ar=i686-w64-mingw32-ar -C linker=i686-w64-mingw32-gcc -L dependency=/home/pfemidi/mywork/rust/hello_cargo/target/i686-pc-windows-gnu/release/deps -L dependency=/home/pfemidi/mywork/rust/hello_cargo/target/release/deps` (exit code: 1)
[pfemidi@pfemidi hello_cargo]$
为什么？还要做什么才能满足一切？
交叉编译并不像听起来那么容易。我建议不要发明自己的轮子并使用已经测试过的解决方案。
目前 "standard" 进行交叉编译的方法是使用 cross，这是一种货物包装器，可以让您摆脱交叉编译的细节。
在安装 cross 之前，您应该先安装它 dependencies。如何做到这一点完全取决于您的发行版。
依赖项准备就绪后，您应该像这样安装 cross（假设您有 cargo）。
$ cargo install cross
在那之后构建工作半神奇
cross build --target x86_64-pc-windows-gnu
经过深思熟虑，我能够解决从 Linux 主机到 Windows 目标的 Rust 交叉编译项目的问题，而无需使用 cross 和类似工具，而只是简单地通过在货物中指定特定目标。当然，测试和 运行 项目会失败（如果你没有安装像 wine 这样的模拟器），但是创建 Windows 目标会很顺利。顺便说一句，Rust 最初被开发为交叉编译器，因此拥有完整的工作项目并通过了 Linux 中的所有测试，几乎可以肯定 Windows 中该项目的简单交叉编译不会破坏它无论如何。
因为我 运行 Fedora Linux 31 以下所有内容都适用于此发行版。但我认为其他 Linux 发行版之间没有显着差异。而且我只考虑 pc-windows-gnu Rust 目标，pc-windows-msvc 目标不是我的兴趣。
首先，确保安装了交叉编译所需的所有 MinGW 包：
[pfemidi@pfemidi ~]$ rpm -qa | grep mingw | sort
mingw32-binutils-2.32-6.fc31.x86_64
mingw32-cpp-9.2.1-1.fc31.x86_64
mingw32-crt-6.0.0-2.fc31.noarch
mingw32-filesystem-110-1.fc31.noarch
mingw32-gcc-9.2.1-1.fc31.x86_64
mingw32-headers-6.0.0-2.fc31.noarch
mingw32-winpthreads-6.0.0-2.fc31.noarch
mingw32-winpthreads-static-6.0.0-2.fc31.noarch
mingw64-binutils-2.32-6.fc31.x86_64
mingw64-cpp-9.2.1-1.fc31.x86_64
mingw64-crt-6.0.0-2.fc31.noarch
mingw64-filesystem-110-1.fc31.noarch
mingw64-gcc-9.2.1-1.fc31.x86_64
mingw64-headers-6.0.0-2.fc31.noarch
mingw64-winpthreads-6.0.0-2.fc31.noarch
mingw64-winpthreads-static-6.0.0-2.fc31.noarch
mingw-binutils-generic-2.32-6.fc31.x86_64
mingw-filesystem-base-110-1.fc31.noarch
[pfemidi@pfemidi ~]$
让我们用 Rust 语言创建最简单的项目：
[pfemidi@pfemidi rust]$ cargo new foobar
Created binary (application) `foobar` package
[pfemidi@pfemidi rust]$ cat foobar/src/main.rs
fn main() {
println!("Hello, world!");
}
[pfemidi@pfemidi rust]$
在项目目录下用config文件创建.cargo目录，内容如下：
[pfemidi@pfemidi rust]$ cd foobar
[pfemidi@pfemidi foobar]$ mkdir .cargo
[pfemidi@pfemidi foobar]$ cat > .cargo/config
[target.i686-pc-windows-gnu]
linker = "i686-w64-mingw32-gcc"
ar = "i686-w64-mingw32-ar"
[target.x86_64-pc-windows-gnu]
linker = "x86_64-w64-mingw32-gcc"
ar = "x86_64-w64-mingw32-ar"
[pfemidi@pfemidi foobar]$
此步骤是必要的，以便在构建 Windows 目标时，Rust 不使用默认安装的 gcc 中的链接器，而是使用 MinGW 链接器。
现在尝试将项目构建为 i686-pc-windows-gnu 目标：
[pfemidi@pfemidi foobar]$ cargo build --target i686-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
error: linking with `i686-w64-mingw32-gcc` failed: exit code: 1
|
= note: "i686-w64-mingw32-gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib"
...
= note: /usr/lib/gcc/i686-w64-mingw32/9.2.1/../../../../i686-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/crt2.o:crtexe.c:(.text+0x75): undefined reference to `__onexitend'
/usr/lib/gcc/i686-w64-mingw32/9.2.1/../../../../i686-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/crt2.o:crtexe.c:(.text+0x7a): undefined reference to `__onexitbegin'
collect2: error: ld returned 1 exit status
error: aborting due to previous error
error: could not compile `foobar`.
To learn more, run the command again with --verbose.
[pfemidi@pfemidi foobar]$
错误！在 crt2.o 文件中得到 "undefined reference to __onexitend" 和 "undefined reference to __onexitbegin"。事实上，pc-windows-gnu 目标的 Rust 组件是用 MinGW 6.3.0 构建的，但 Fedora Linux 31 中有 MinGW 版本 9.2.1。因此 CRT 有所不同由于编译器版本不匹配。好的，让我们将 crt2.o 从 Fedora Linux MinGW 存储库复制到 i686-pc-windows-gnu 组件的 Rust 目录。与 crt2.o 一起，我们还复制了 dllcrt2.o，它是动态库的入口点，因为 crt2.o 是独立可执行文件的入口点。为了以防万一，我们保存原始文件：
[pfemidi@pfemidi foobar]$ cd ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/
[pfemidi@pfemidi lib]$ mv crt2.o crt2.o.ori
[pfemidi@pfemidi lib]$ mv dllcrt2.o dllcrt2.o.ori
[pfemidi@pfemidi lib]$ cp /usr/i686-w64-mingw32/sys-root/mingw/lib/crt2.o .
[pfemidi@pfemidi lib]$ cp /usr/i686-w64-mingw32/sys-root/mingw/lib/dllcrt2.o .
[pfemidi@pfemidi lib]$ cd -
/home/pfemidi/mywork/rust/foobar
[pfemidi@pfemidi foobar]$
现在再次尝试将项目构建为 i686-pc-windows-gnu 目标：
[pfemidi@pfemidi foobar]$ cargo build --target i686-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
Finished dev [unoptimized + debuginfo] target(s) in 0.19s
[pfemidi@pfemidi foobar]$
成功了！
现在尝试对 x86_64-pc-windows-gnu 目标执行相同的操作：
[pfemidi@pfemidi foobar]$ cargo build --target x86_64-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
error: linking with `x86_64-w64-mingw32-gcc` failed: exit code: 1
|
= note: "x86_64-w64-mingw32-gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib" "-m64"
...
= note: /usr/lib/gcc/x86_64-w64-mingw32/9.2.1/../../../../x86_64-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-pc-windows-gnu/lib/crt2.o:crtexe.c:(.rdata$.refptr.__onexitbegin[.refptr.__onexitbegin]+0x0): undefined reference to `__onexitbegin'
/usr/lib/gcc/x86_64-w64-mingw32/9.2.1/../../../../x86_64-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-pc-windows-gnu/lib/crt2.o:crtexe.c:(.rdata$.refptr.__onexitend[.refptr.__onexitend]+0x0): undefined reference to `__onexitend'
collect2: error: ld returned 1 exit status
error: aborting due to previous error
error: could not compile `foobar`.
To learn more, run the command again with --verbose.
[pfemidi@pfemidi foobar]$
该错误与之前提到的 i686-pc-windows-gnu 目标完全相同。让我们通过类比上面的 32 位目标来复制文件 crt2.o 和 dllcrt2.o：
[pfemidi@pfemidi foobar]$ cd ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/x86_64-pc-windows-gnu/lib/
[pfemidi@pfemidi lib]$ mv crt2.o crt2.o.ori
[pfemidi@pfemidi lib]$ mv dllcrt2.o dllcrt2.o.ori
[pfemidi@pfemidi lib]$ cp /usr/x86_64-w64-mingw32/sys-root/mingw/lib/crt2.o .
[pfemidi@pfemidi lib]$ cp /usr/x86_64-w64-mingw32/sys-root/mingw/lib/dllcrt2.o .
[pfemidi@pfemidi lib]$ cd -
/home/pfemidi/mywork/rust/foobar
[pfemidi@pfemidi foobar]$
并再次尝试将项目构建为 x86_64-pc-windows-gnu 目标：
[pfemidi@pfemidi foobar]$ cargo build --target x86_64-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
Finished dev [unoptimized + debuginfo] target(s) in 0.20s
[pfemidi@pfemidi foobar]$
是的！它也有效！所以现在我们可以使用 Rust 发行版中包含的标准货物轻松地为 Windows 构建目标！对于 x86_64 目标，这是完全正确的。但是对于 x86 目标，一切都会好起来，直到我们在我们的项目中使用任何恐慌的函数（f.e。宏恐慌！，期望函数等）。
让我们为我们的简单项目添加恐慌：
[pfemidi@pfemidi foobar]$ cat src/main.rs
fn main() {
println!("Hello, world!");
panic!("I'm panicked!"); // <-- here it is
}
[pfemidi@pfemidi foobar]$
将其构建为 x86_64 目标：
[pfemidi@pfemidi foobar]$ cargo build --target x86_64-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
Finished dev [unoptimized + debuginfo] target(s) in 0.16s
[pfemidi@pfemidi foobar]$
一切顺利（我检查过，效果也很好）。现在尝试对 x86 目标执行相同的操作：
[pfemidi@pfemidi foobar]$ cargo build --target i686-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
error: linking with `i686-w64-mingw32-gcc` failed: exit code: 1
|
= note: "i686-w64-mingw32-gcc" "-Wl,--enable-long-section-names" "-fno-use-linker-plugin" "-Wl,--nxcompat" "-nostdlib"
...
= note: /usr/lib/gcc/i686-w64-mingw32/9.2.1/../../../../i686-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libpanic_unwind-0c029c00da54fbf5.rlib(panic_unwind-0c029c00da54fbf5.panic_unwind.2hgzd7yq-cgu.0.rcgu.o): in function `ZN12panic_unwind3imp5panic17h03027a0e504502cdE':
/rustc/73528e339aae0f17a15ffa49a8ac608f50c6cf14\/src\libpanic_unwind/gcc.rs:73: undefined reference to `_Unwind_RaiseException'
/usr/lib/gcc/i686-w64-mingw32/9.2.1/../../../../i686-w64-mingw32/bin/ld: /home/pfemidi/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/libpanic_unwind-0c029c00da54fbf5.rlib(panic_unwind-0c029c00da54fbf5.panic_unwind.2hgzd7yq-cgu.0.rcgu.o): in function `rust_eh_unwind_resume':
/rustc/73528e339aae0f17a15ffa49a8ac608f50c6cf14\/src\libpanic_unwind/gcc.rs:327: undefined reference to `_Unwind_Resume'
collect2: error: ld returned 1 exit status
error: aborting due to previous error
error: could not compile `foobar`.
To learn more, run the command again with --verbose.
[pfemidi@pfemidi foobar]$
糟糕！我们在 Rust 标准库的 libpanic_unwind 模块中得到 "undefined reference to _Unwind_RaiseException" 和 "undefined reference to _Unwind_Resume"。不过这个问题也解决了，虽然没有上一个简单，只是替换CRTcrt2.o和dllcrt2.o文件
对于堆栈展开，Rust 对 32 位 Windows 目标使用 dwarf 方法，对 64 位 Windows 目标使用 seh 方法，而来自标准 Fedora Linux 发行版的 MinGW 使用 sjlj 方法进行32 位 Windows 目标和 64 位 Windows 目标的 seh 方法（了解差异 here）。因此，64 位目标由 MinGW 链接器链接没有任何问题，但对于 32 位目标，没有必要的符号和目标文件才能正确链接。要获得这些文件和符号，有必要为 32 位 Windows 目标重建具有 dwarf 支持的 MinGW 而不是默认的 sjlj 支持。
我不会在这里详细介绍如何重建 MinGW，我只说一件事：用 dwarf stack unwinding 而不是 sjlj 方法重建 MinGW 后，你只需要选择一个名为 libgcc_eh.a 来自刚刚构建的 MinGW，并将其放入 Rust i686-pc-windows-gnu 目标的库目录中。这样做之后，带有任何 panic 函数的项目不仅对于 64 位 Windows 目标，而且对于 32 位目标都将无错误地构建：
[pfemidi@pfemidi foobar]$ cd ~/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/i686-pc-windows-gnu/lib/
[pfemidi@pfemidi lib]$ cp ~/rpmbuild/BUILD/gcc-9.2.1-20190827/build_win32/i686-w64-mingw32/libgcc/libgcc_eh.a .
[pfemidi@pfemidi lib]$ cd -
/home/pfemidi/mywork/rust/foobar
[pfemidi@pfemidi foobar]$ cargo build --target i686-pc-windows-gnu
Compiling foobar v0.1.0 (/home/pfemidi/mywork/rust/foobar)
Finished dev [unoptimized + debuginfo] target(s) in 0.30s
[pfemidi@pfemidi foobar]$
RUSTing 快乐！ :-)