rcc

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rcc: a Rust C compiler

A C compiler written in Rust, with a focus on good error messages. Warning: my first rust project, code quality is pretty low.

Running

rcc reads from standard in by default, so you can type in code directly. It's not interactive though, you have to hit Ctrl+D to indicate end of file (Ctrl+Z on Windows).

Use rcc --help for all options (or see below).

Running on Windows

You need to have cc on your PATH. You can either install mingw + gcc or MSVC. Other than that, it should work exactly the same as on Linux.

TODO

Examples

```c $ cat tests/runner-tests/readme.c // output: j is 6 int printf(const char *, ...);

typedef struct s *sp;

int i = 1; int a[3] = {1, 2, 3}; float f = 2.5;

struct s { int outer; } my_struct;

int g(int);

int main(void) { sp mystructpointer = &mystruct; const int c = mystruct_pointer->outer = 4; // should return 6 int j = i + f*a[2] - c/g(1); printf("j is %d\n", j); return j; }

int g(int i) { if (i < 0 || i >= 3) { return 0; } return a[i]; } $ rcc tests/runner-tests/readme.c $️ ./a.out j is 6 ```

Debug output

```c $ cat tests/runner-tests/cpp/if/defined.c // code: 2

define a

define b

if defined(a)

int i = 2;

endif

ifndef b

syntax error

endif

if defined b && defined(a)

int main() { return i; }

endif

$ rcc -E tests/runner-tests/cpp/if/defined.c int i = 2 ; int main ( ) { return i ; } ```

c $ echo 'int i = 1 + 2 ^ 3 % 5 / 2 & 1; int main(){}' | rcc --debug-ast auto int i = (int)(((1) + (2)) ^ ((((3) % (5)) / (2)) & (1))); extern int main() { }

```c $ cat tests/runner-tests/hello_world.c

include

int main() { puts("Hello, world!"); } $ rcc --debug-asm tests/runner-tests/helloworld.c function u0:0() -> i32 systemv { gv0 = symbol colocated u1:3 sig0 = (i64) -> i32 system_v fn0 = u0:26 sig0

block0: v0 = global_value.i64 gv0 v1 = call fn0(v0) v2 = iconst.i32 0 return v2 } $ ./a.out Hello, world! ```

All options

```txt $ rcc --help rcc 0.5.0 Joshua Nelson jyn514@gmail.com:Graham Scheaffer me@gisch.dev A C compiler written in Rust, with a focus on good error messages. Homepage: https://github.com/jyn514/rcc/

usage: rcc [FLAGS] [OPTIONS] []

FLAGS: --debug-asm If set, print the intermediate representation of the program in addition to compiling -a, --debug-ast If set, print the parsed abstract syntax tree in addition to compiling --debug-lex If set, print all tokens found by the lexer in addition to compiling. -h, --help Prints help information -c, --no-link If set, compile and assemble but do not link. Object file is machine-dependent. -E, --preprocess-only If set, preprocess only, but do not do anything else. Note that preprocessing discards whitespace and comments. There is not currently a way to disable this behavior. -V, --version Prints version information

OPTIONS: -o, --output The output file to use. [default: a.out] --max-errors The maximum number of errors to allow before giving up. Use 0 to allow unlimited errors. [default: 10]

ARGS: The file to read C source from. "-" means stdin (use ./- to read a file called '-'). Only one file at a time is currently accepted. [default: -] ```

Testing

```sh cargo test

optionally, you can fuzz the compiler

it may be more helpful to just grep -R unimplemented src, though

libFuzzer/AFL

tests/fuzz.sh

Honggfuzz:

Running Honggfuzz locally requires some parameters to use it at its full potential,

so it is probably a good idea to have a look here: https://github.com/rust-fuzz/honggfuzz-rs/blob/master/README.md

and here: https://github.com/google/honggfuzz/blob/master/docs/USAGE.md

we suggest the following:

HFUZZRUNARGS="--tmoutsigvtalrm --exitupon_crash" tests/hfuzz.sh ```

FAQ

See FAQ.md

Implementation Defined Behavior

See IMPLEMENTATION_DEFINED.md

Contributing

See CONTRIBUTING.md. This also includes reporting bugs.