Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 223 insertions, 0 deletions

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+# cc-rs
+
+A library to compile C/C++/assembly into a Rust library/application.
+
+[Documentation](https://docs.rs/cc)
+
+A simple library meant to be used as a build dependency with Cargo packages in
+order to build a set of C/C++ files into a static archive. This crate calls out
+to the most relevant compiler for a platform, for example using `cl` on MSVC.
+
+## Using cc-rs
+
+First, you'll want to both add a build script for your crate (`build.rs`) and
+also add this crate to your `Cargo.toml` via:
+
+```toml
+[build-dependencies]
+cc = "1.0"
+```
+
+Next up, you'll want to write a build script like so:
+
+```rust,no_run
+// build.rs
+
+fn main() {
+    cc::Build::new()
+        .file("foo.c")
+        .file("bar.c")
+        .compile("foo");
+}
+```
+
+And that's it! Running `cargo build` should take care of the rest and your Rust
+application will now have the C files `foo.c` and `bar.c` compiled into a file
+named `libfoo.a`. If the C files contain
+
+```c
+void foo_function(void) { ... }
+```
+
+and
+
+```c
+int32_t bar_function(int32_t x) { ... }
+```
+
+you can call them from Rust by declaring them in
+your Rust code like so:
+
+```rust,no_run
+extern {
+    fn foo_function();
+    fn bar_function(x: i32) -> i32;
+}
+
+pub fn call() {
+    unsafe {
+        foo_function();
+        bar_function(42);
+    }
+}
+
+fn main() {
+    // ...
+}
+```
+
+See [the Rustonomicon](https://doc.rust-lang.org/nomicon/ffi.html) for more details.
+
+## External configuration via environment variables
+
+To control the programs and flags used for building, the builder can set a
+number of different environment variables.
+
+* `CFLAGS` - a series of space separated flags passed to compilers. Note that
+             individual flags cannot currently contain spaces, so doing
+             something like: `-L=foo\ bar` is not possible.
+* `CC` - the actual C compiler used. Note that this is used as an exact
+         executable name, so (for example) no extra flags can be passed inside
+         this variable, and the builder must ensure that there aren't any
+         trailing spaces. This compiler must understand the `-c` flag. For
+         certain `TARGET`s, it also is assumed to know about other flags (most
+         common is `-fPIC`).
+* `AR` - the `ar` (archiver) executable to use to build the static library.
+* `CRATE_CC_NO_DEFAULTS` - the default compiler flags may cause conflicts in some cross compiling scenarios. Setting this variable will disable the generation of default compiler flags.
+* `CXX...` - see [C++ Support](#c-support).
+
+Each of these variables can also be supplied with certain prefixes and suffixes,
+in the following prioritized order:
+
+1. `<var>_<target>` - for example, `CC_x86_64-unknown-linux-gnu`
+2. `<var>_<target_with_underscores>` - for example, `CC_x86_64_unknown_linux_gnu`
+3. `<build-kind>_<var>` - for example, `HOST_CC` or `TARGET_CFLAGS`
+4. `<var>` - a plain `CC`, `AR` as above.
+
+If none of these variables exist, cc-rs uses built-in defaults
+
+In addition to the above optional environment variables, `cc-rs` has some
+functions with hard requirements on some variables supplied by [cargo's
+build-script driver][cargo] that it has the `TARGET`, `OUT_DIR`, `OPT_LEVEL`,
+and `HOST` variables.
+
+[cargo]: https://doc.rust-lang.org/cargo/reference/build-scripts.html#inputs-to-the-build-script
+
+## Optional features
+
+### Parallel
+
+Currently cc-rs supports parallel compilation (think `make -jN`) but this
+feature is turned off by default. To enable cc-rs to compile C/C++ in parallel,
+you can change your dependency to:
+
+```toml
+[build-dependencies]
+cc = { version = "1.0", features = ["parallel"] }
+```
+
+By default cc-rs will limit parallelism to `$NUM_JOBS`, or if not present it
+will limit it to the number of cpus on the machine. If you are using cargo,
+use `-jN` option of `build`, `test` and `run` commands as `$NUM_JOBS`
+is supplied by cargo.
+
+## Compile-time Requirements
+
+To work properly this crate needs access to a C compiler when the build script
+is being run. This crate does not ship a C compiler with it. The compiler
+required varies per platform, but there are three broad categories:
+
+* Unix platforms require `cc` to be the C compiler. This can be found by
+  installing cc/clang on Linux distributions and Xcode on macOS, for example.
+* Windows platforms targeting MSVC (e.g. your target triple ends in `-msvc`)
+  require `cl.exe` to be available and in `PATH`. This is typically found in
+  standard Visual Studio installations and the `PATH` can be set up by running
+  the appropriate developer tools shell.
+* Windows platforms targeting MinGW (e.g. your target triple ends in `-gnu`)
+  require `cc` to be available in `PATH`. We recommend the
+  [MinGW-w64](https://www.mingw-w64.org/) distribution, which is using the
+  [Win-builds](http://win-builds.org/) installation system.
+  You may also acquire it via
+  [MSYS2](https://www.msys2.org/), as explained [here][msys2-help].  Make sure
+  to install the appropriate architecture corresponding to your installation of
+  rustc. GCC from older [MinGW](http://www.mingw.org/) project is compatible
+  only with 32-bit rust compiler.
+
+[msys2-help]: https://github.com/rust-lang/rust#building-on-windows
+
+## C++ support
+
+`cc-rs` supports C++ libraries compilation by using the `cpp` method on
+`Build`:
+
+```rust,no_run
+fn main() {
+    cc::Build::new()
+        .cpp(true) // Switch to C++ library compilation.
+        .file("foo.cpp")
+        .compile("libfoo.a");
+}
+```
+
+For C++ libraries, the `CXX` and `CXXFLAGS` environment variables are used instead of `CC` and `CFLAGS`.
+
+The C++ standard library may be linked to the crate target. By default it's `libc++` for macOS, FreeBSD, and OpenBSD, `libc++_shared` for Android, nothing for MSVC, and `libstdc++` for anything else. It can be changed in one of two ways:
+
+1. by using the `cpp_link_stdlib` method on `Build`:
+    ```rust,no-run
+    fn main() {
+        cc::Build::new()
+            .cpp(true)
+            .file("foo.cpp")
+            .cpp_link_stdlib("stdc++") // use libstdc++
+            .compile("libfoo.a");
+    }
+    ```
+2. by setting the `CXXSTDLIB` environment variable.
+
+In particular, for Android you may want to [use `c++_static` if you have at most one shared library](https://developer.android.com/ndk/guides/cpp-support).
+
+Remember that C++ does name mangling so `extern "C"` might be required to enable Rust linker to find your functions.
+
+## CUDA C++ support
+
+`cc-rs` also supports compiling CUDA C++ libraries by using the `cuda` method
+on `Build` (currently for GNU/Clang toolchains only):
+
+```rust,no_run
+fn main() {
+    cc::Build::new()
+        // Switch to CUDA C++ library compilation using NVCC.
+        .cuda(true)
+        .cudart("static")
+        // Generate code for Maxwell (GTX 970, 980, 980 Ti, Titan X).
+        .flag("-gencode").flag("arch=compute_52,code=sm_52")
+        // Generate code for Maxwell (Jetson TX1).
+        .flag("-gencode").flag("arch=compute_53,code=sm_53")
+        // Generate code for Pascal (GTX 1070, 1080, 1080 Ti, Titan Xp).
+        .flag("-gencode").flag("arch=compute_61,code=sm_61")
+        // Generate code for Pascal (Tesla P100).
+        .flag("-gencode").flag("arch=compute_60,code=sm_60")
+        // Generate code for Pascal (Jetson TX2).
+        .flag("-gencode").flag("arch=compute_62,code=sm_62")
+        .file("bar.cu")
+        .compile("libbar.a");
+}
+```
+
+## License
+
+This project is licensed under either of
+
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
+   https://www.apache.org/licenses/LICENSE-2.0)
+ * MIT license ([LICENSE-MIT](LICENSE-MIT) or
+   https://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in cc-rs by you, as defined in the Apache-2.0 license, shall be
+dual licensed as above, without any additional terms or conditions.