toc

toc is a language which compiles to C.

About

toc is currently in development. It is not a stable language, and there are almost definitely bugs right now. I would recommend against using it for anything big or important. Many parts of it may change in the future.

toc improves on C’s syntax (and semantics) in many ways, To declare x as an integer and set it to 5, you can do:

x := 5; // Declare x and set x to 5 (infer type) x : int = 5; // Explicitly make the type int. x : int; x = 5; // Declare x as an integer, then set it to 5.

toc is statically typed and has many of C’s features, but it is nearly as fast in theory.

See docs for more information (in progress).

tests has some test programs written in toc.

To compile the compiler on a Unix-y system, just run ./build.sh release. You can supply a compiler by running CC=tcc ./build.sh release, or build it in debug mode without the release.

On other systems, you can just compile main.c with a C compiler. toc uses several C99 and a couple of C11 features, so it might not work on all compilers. But it does compile on quite a few, including clang, gcc, and tcc. It can also be compiled as if it were C++, but it does break the standard in a few places*. So, MSVC can also compile it. The outputted code should be C99-compliant.

Why it compiles to C

toc compiles to C for three reasons:

• Speed. C is one of the most performant programming languages out there. It also has compilers which are very good at optimizing (better than anything I could write).
• Portability. C is probably the most portable language. It has existed for >30 years and can run on practically anything. Furthermore, all major languages nowadays can call functions written in C.
• Laziness. I don’t really want to deal with writing something which outputs machine code, and it would certainly be more buggy than something which outputs C.

toc Source Code

toc is written in C, for speed and portability. It has no dependencies, other than the C runtime library.

Build system

toc is set up as a unity build, meaning that there is only one translation unit. So, main.c #includes toc.c, which #includes all of toc’s files.

Why?

This improves compilation speeds (especially from scratch), since you don’t have to include headers a bunch of times for each translation unit. This is more of a problem in C++, where, for example, doing #include <map> ends up turning into 25,000 lines after preprocessing. All of toc’s source code, which includes most of the C standard library, at the time of this writing (Dec 2019) is only 22,000 lines after preprocessing; imagine including all of that once for each translation unit which includes map. It also obviates the need for fancy build systems like CMake.

New features

Here are all the C99 features which toc depends on (I might have forgotten some…):

• Declare anywhere
• inttypes.h
• Non-constant struct literal initializers (e.g. int x[2] = {y, z};)
• Flexible array members

The last three of those could all be removed fairly easily (assuming the system actually has 8-, 16-, 32-, and 64-bit signed and unsigned types).

And here are all of its C11 features:

• Anonymous structures/unions
• max_align_t and alignof - It can still compile without these but it won’t technically be standard-compliant

More

See main.c for a bit more information.

Version history

Here are the major versions of toc.

Report a bug

If you find a bug, you can report it through GitHub’s issue tracker, or by emailing pommicket@gmail.com.

Just send me the toc source code which results in the bug, and I’ll try to fix it.

* for those curious, it has to do with goto. In C, this program:

int main() {  
    goto label;  
    int x = 5;  
    label:  
    return 0;  
}

Is completely fine. x will hold an unspecified value after the jump (but it isn’t used so it doesn’t really matter). Apparently, in C++, this is an ill-formed program. This is a bit ridiculous since

int main() {  
    goto label;  
    int x; x = 5;  
    label:  
    return 0;  
}

is fine. So that’s an interesting little “fun fact”: int x = 5; isn’t always the same as int x; x = 5; in C++.