Saltwater

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saltwater: the part of the sea causing lots of rust

A C compiler written in Rust, with a focus on good error messages.

Running

swcc 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 swcc --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.

Homebrew

brew install saltwater

Unimplemented features

• Defining functions taking variadic arguments. Note that calling variadic functions (like printf) is already supported.
• Variable-length arrays (int a[n])
• Multiple translation units (files)
• Bitfields
• Compiling on non-x86 platforms
• Cross-compilation

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]; } $ swcc 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

$ swcc -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(){}' | swcc --debug-ast ast: int i = ((1) + (2)) ^ ((((3) % (5)) / (2)) & (1)); ast: int main(){ }

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

include

int main() { puts("Hello, world!"); } $ swcc --debug-ir 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 $ swcc --help swcc 0.9.0 Joshua Nelson jyn514@gmail.com A C compiler written in Rust, with a focus on good error messages. Homepage: https://github.com/jyn514/rcc/

usage: swcc [FLAGS] [OPTIONS] []

FLAGS: --debug-ast If set, print the parsed abstract syntax tree (AST) in addition to compiling. The AST does no type checking or validation, it only parses. --debug-hir If set, print the high intermediate representation (HIR) in addition to compiling. This does type checking and validation and also desugars various expressions. --debug-ir If set, print the intermediate representation (IR) of the program in addition to compiling. --debug-lex If set, print all tokens found by the lexer in addition to compiling. --jit If set, will use JIT compilation for C code and instantly run compiled code (No files produced). NOTE: this option only works if swcc was compiled with the jit feature. -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: --color When to use color. May be "never", "auto", or "always". [default: auto] -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] -I, --include