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//! `inline-c` is a small crate that allows a user to write C
//! (including C++) code inside Rust. Both environments are strictly
//! sandboxed: it is non-obvious for a value to cross the
//! boundary. The C code is transformed into a string which is written
//! in a temporary file. This file is then compiled into an object
//! file, that is finally executed. It is possible to run assertions
//! about the execution of the C program.
//!
//! The primary goal of `inline-c` is to ease the testing of a C API
//! of a Rust program. Note that it's not tied to a Rust program
//! exclusively, it's just its initial reason to live.
//!
//! The [`assert_c`] and [`assert_cxx`] macros live in the
//! `inline-c-macro` crate, but are re-exported in this crate for the
//! sake of simplicity.
//!
//! Being able to write C code directly in Rust offers nice
//! opportunities, like having C examples inside the Rust
//! documentation that are executable and thus tested (with `cargo
//! test --doc`). Let's dig into some examples.
//!
//! ## Basic usage
//!
//! The following example is super basic: C prints `Hello, World!` on
//! the standard output, and Rust asserts that.
//!
//! ```rust
//! use inline_c::assert_c;
//!
//! fn test_stdout() {
//! (assert_c! {
//! #include <stdio.h>
//!
//! int main() {
//! printf("Hello, World!");
//!
//! return 0;
//! }
//! })
//! .success()
//! .stdout("Hello, World!");
//! }
//!
//! # fn main() { test_stdout(); }
//! ```
//!
//! Or with a C++ program:
//!
//! ```rust
//! use inline_c::assert_cxx;
//!
//! fn test_cxx() {
//! (assert_cxx! {
//! #include <iostream>
//!
//! int main() {
//! std::cout << "Hello, World!";
//!
//! return 0;
//! }
//! })
//! .success()
//! .stdout("Hello, World!");
//! }
//!
//! # fn main() {
//! # #[cfg(not(target_os = "windows"))]
//! # test_cxx();
//! # }
//! ```
//!
//! The [`assert_c`] and [`assert_cxx`] macros return a
//! `Result<Assert, Box<dyn Error>>`. See [`Assert`] to learn more
//! about the possible assertions.
//!
//! The following example tests the returned value:
//!
//! ```rust
//! use inline_c::assert_c;
//!
//! fn test_result() {
//! (assert_c! {
//! int main() {
//! int x = 1;
//! int y = 2;
//!
//! return x + y;
//! }
//! })
//! .failure()
//! .code(3);
//! }
//!
//! # fn main() { test_result() }
//! ```
//!
//! ## Environment variables
//!
//! It is possible to define environment variables for the execution
//! of the given C program. The syntax is using the special
//! `#inline_c_rs` C directive with the following syntax:
//!
//! ```c
//! #inline_c_rs <variable_name>: "<variable_value>"
//! ```
//!
//! Please note the double quotes around the variable value.
//!
//! ```rust
//! use inline_c::assert_c;
//!
//! fn test_environment_variable() {
//! (assert_c! {
//! #inline_c_rs FOO: "bar baz qux"
//!
//! #include <stdio.h>
//! #include <stdlib.h>
//!
//! int main() {
//! const char* foo = getenv("FOO");
//!
//! if (NULL == foo) {
//! return 1;
//! }
//!
//! printf("FOO is set to `%s`", foo);
//!
//! return 0;
//! }
//! })
//! .success()
//! .stdout("FOO is set to `bar baz qux`");
//! }
//!
//! # fn main() {
//! # std::env::set_var("INLINE_C_RS_CFLAGS", "-D_CRT_SECURE_NO_WARNINGS");
//! # test_environment_variable()
//! # }
//! ```
//!
//! ### Meta environment variables
//!
//! Using the `#inline_c_rs` C directive can be repetitive if one
//! needs to define the same environment variable again and
//! again. That's why meta environment variables exist. They have the
//! following syntax:
//!
//! ```sh
//! INLINE_C_RS_<variable_name>=<variable_value>
//! ```
//!
//! It is usually best to define them in [a `build.rs`
//! script](https://doc.rust-lang.org/cargo/reference/build-scripts.html)
//! for example. Let's see it in action with a tiny example:
//!
//! ```rust
//! use inline_c::assert_c;
//! use std::env::{set_var, remove_var};
//!
//! fn test_meta_environment_variable() {
//! set_var("INLINE_C_RS_FOO", "bar baz qux");
//!
//! (assert_c! {
//! #include <stdio.h>
//! #include <stdlib.h>
//!
//! int main() {
//! const char* foo = getenv("FOO");
//!
//! if (NULL == foo) {
//! return 1;
//! }
//!
//! printf("FOO is set to `%s`", foo);
//!
//! return 0;
//! }
//! })
//! .success()
//! .stdout("FOO is set to `bar baz qux`");
//!
//! remove_var("INLINE_C_RS_FOO");
//! }
//!
//! # fn main() {
//! # std::env::set_var("INLINE_C_RS_CFLAGS", "-D_CRT_SECURE_NO_WARNINGS");
//! # test_meta_environment_variable()
//! # }
//! ```
//!
//! ### `CFLAGS`, `CPPFLAGS`, `CXXFLAGS` and `LDFLAGS`
//!
//! Some classical `Makefile` variables like `CFLAGS`, `CPPFLAGS`,
//! `CXXFLAGS` and `LDFLAGS` are understood by `inline-c` and
//! consequently have a special treatment. Their values are added to
//! the appropriate compilers when the C code is compiled and linked
//! into an object file.
//!
//! Pro tip: Let's say we have a Rust crate named `foo`, and it
//! exports a C API. It is possible to define `CFLAGS` and `LDFLAGS`
//! as follow to correctly compile and link all the C codes to the
//! Rust `libfoo` shared object by writing this in a `build.rs` script
//! (it is assumed that `libfoo` lands in the `target/<profile>/`
//! directory, and that `foo.h` lands in the root directory):
//!
//! ```rust,ignore
//! use std::{env, ffi::OsStr};
//!
//! fn main() {
//! let include_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
//!
//! let mut shared_object_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR").unwrap());
//! shared_object_dir.push("target");
//! shared_object_dir.push(env::var("PROFILE").unwrap());
//! let shared_object_dir = shared_object_dir.as_path().to_string_lossy();
//!
//! // The following options mean:
//! //
//! // * `-I`, add `include_dir` to include search path,
//! // * `-L`, add `shared_object_dir` to library search path,
//! // * `-D_DEBUG`, enable debug mode to enable `assert.h`.
//! println!(
//! "cargo:rustc-env=INLINE_C_RS_CFLAGS=-I{I} -L{L} -D_DEBUG",
//! I = include_dir,
//! L = shared_object_dir.clone(),
//! );
//!
//! // Here, we pass the fullpath to the shared object with
//! // `LDFLAGS`.
//! println!(
//! "cargo:rustc-env=INLINE_C_RS_LDFLAGS={shared_object_dir}/{lib}",
//! shared_object_dir = shared_object_dir,
//! lib = if cfg!(target_os = "windows") {
//! "foo.dll".to_string()
//! } else if cfg!(target_os = "macos") {
//! "libfoo.dylib".to_string()
//! } else {
//! "libfoo.so".to_string()
//! }
//! );
//! }
//! ```
//!
//! _Et voilà !_ Now run `cargo build --release` (to generate the
//! shared objects) and then `cargo test --release` to see it in
//! action.
//!
//! ## Using `inline-c` inside Rust documentation
//!
//! Since it is now possible to write C code inside Rust, it is
//! consequently possible to write C examples, that are:
//!
//! 1. Part of the Rust documentation with `cargo doc`, and
//! 2. Tested with all the other Rust examples with `cargo test --doc`.
//!
//! Yes. Testing C code with `cargo test --doc`. How _fun_ is that? No
//! trick needed. One can write:
//!
//! ```rust,ignore
//! /// Blah blah blah.
//! ///
//! /// # Example
//! ///
//! /// ```rust
//! /// # use inline_c::assert_c;
//! /// #
//! /// # fn main() {
//! /// # (assert_c! {
//! /// #include <stdio.h>
//! ///
//! /// int main() {
//! /// printf("Hello, World!");
//! ///
//! /// return 0;
//! /// }
//! /// # })
//! /// # .success()
//! /// # .stdout("Hello, World!");
//! /// # }
//! /// ```
//! pub extern "C" fn some_function() {}
//! ```
//!
//! which will compile down into something like this:
//!
//! ```rust
//! # use inline_c::assert_c;
//! #
//! # fn main() {
//! # (assert_c! {
//! #include <stdio.h>
//!
//! int main() {
//! printf("Hello, World!");
//!
//! return 0;
//! }
//! # })
//! # .success()
//! # .stdout("Hello, World!");
//! # }
//! ```
//!
//! Notice that this example above is actually Rust code, with C code
//! inside. Only the C code is printed, due to the `#` hack of
//! `rustdoc`, but this example is a valid Rust example, and is fully
//! tested!
//!
//! There is one minor caveat though: the highlighting. The Rust set
//! of rules are applied, rather than the C ruleset. [See this issue
//! on `rustdoc` to follow the
//! fix](https://github.com/rust-lang/rust/issues/78917).
//!
//! ## C macros
//!
//! C macros with the `#define` directive is supported only with Rust
//! nightly. One can write:
//!
//! ```rust,ignore
//! use inline_c::assert_c;
//!
//! fn test_c_macro() {
//! (assert_c! {
//! #define sum(a, b) ((a) + (b))
//!
//! int main() {
//! return !(sum(1, 2) == 3);
//! }
//! })
//! .success();
//! }
//! ```
//!
//! Note that multi-lines macros don't work! That's because the `\` symbol
//! is consumed by the Rust lexer. The best workaround is to define the
//! macro in another `.h` file, and to include it with the `#include`
//! directive.
mod assert;
mod run;
pub use crate::run::{run, Language};
pub use assert::Assert;
pub use inline_c_macro::{assert_c, assert_cxx};
pub mod predicates {
//! Re-export the prelude of the `predicates` crate, which is useful for assertions.
//!
//! # Example
//!
//! An end of line on all systems are represented by the `\n`
//! character, except on Windows where it is `\r\n`. Even if C
//! writes `\n`, it will be translated into `\r\n`, so we need to
//! normalize this. This is where the `predicates` crate can be
//! helpful.
//!
//! ```rust
//! use inline_c::{assert_c, predicates::*};
//!
//! fn test_predicates() {
//! (assert_c! {
//! #include <stdio.h>
//!
//! int main() {
//! printf("Hello, World!\n");
//!
//! return 0;
//! }
//! })
//! .success()
//! .stdout(predicate::eq("Hello, World!\n").normalize());
//! }
//!
//! # fn main() { test_predicates() }
//! ```
pub use predicates::prelude::*;
}
#[cfg(test)]
mod tests {
use super::predicates::*;
use super::*;
use crate as inline_c;
use std::env::{remove_var, set_var};
#[test]
fn test_c_macro() {
(assert_c! {
int main() {
int x = 1;
int y = 2;
return x + y;
}
})
.failure()
.code(3);
}
#[test]
fn test_c_macro_with_include() {
(assert_c! {
#include <stdio.h>
int main() {
printf("Hello, World!\n");
return 0;
}
})
.success()
.stdout(predicate::eq("Hello, World!\n").normalize());
}
#[test]
fn test_c_macro_with_env_vars_inlined() {
set_var("INLINE_C_RS_CFLAGS", "-D_CRT_SECURE_NO_WARNINGS");
(assert_c! {
// Those are env variables.
#inline_c_rs FOO: "bar baz qux"
#inline_c_rs HELLO: "World!"
#include <stdio.h>
#include <stdlib.h>
int main() {
const char* foo = getenv("FOO");
const char* hello = getenv("HELLO");
if (NULL == foo || NULL == hello) {
return 1;
}
printf("FOO is set to `%s`\n", foo);
printf("HELLO is set to `%s`\n", hello);
return 0;
}
})
.success()
.stdout(
predicate::eq(
"FOO is set to `bar baz qux`\n\
HELLO is set to `World!`\n",
)
.normalize(),
);
remove_var("INLINE_C_RS_CFLAGS");
}
#[test]
fn test_c_macro_with_env_vars_from_env_vars() {
// Define env vars through env vars.
set_var("INLINE_C_RS_FOO", "bar baz qux");
set_var("INLINE_C_RS_HELLO", "World!");
set_var("INLINE_C_RS_CFLAGS", "-D_CRT_SECURE_NO_WARNINGS");
(assert_c! {
#include <stdio.h>
#include <stdlib.h>
int main() {
const char* foo = getenv("FOO");
const char* hello = getenv("HELLO");
if (NULL == foo || NULL == hello) {
return 1;
}
printf("FOO is set to `%s`\n", foo);
printf("HELLO is set to `%s`\n", hello);
return 0;
}
})
.success()
.stdout(
predicate::eq(
"FOO is set to `bar baz qux`\n\
HELLO is set to `World!`\n",
)
.normalize(),
);
remove_var("INLINE_C_RS_FOO");
remove_var("INLINE_C_RS_HELLO");
remove_var("INLINE_C_RS_CFLAGS");
}
#[cfg(nightly)]
#[test]
fn test_c_macro_with_define() {
(assert_c! {
#define sum(a, b) ((a) + (b))
int main() {
return !(sum(1, 2) == 3);
}
})
.success();
}
}