zig/README.md

# zig lang

An experiment in writing a low-level programming language with the intent to
replace C. Zig intends to be a small language, yet powerful enough to write
optimal, readable, safe, and concise code to solve any computing problem.

Porting a C project to Zig should be a pleasant experience - every C feature
needs a corresponding Zig feature which solves the problem equivalently or
better.

Zig is not afraid to roll the major version number of the language if it
improves simplicity, fixes poor design decisions, or adds a new feature which
compromises backward compatibility.

## Goals

 * Completely compatible with C libraries with no wrapper necessary.
 * In addition to creating executables, creating a C library is a primary use
   case. You can export an auto-generated .h file.
 * Do not depend on libc unless explicitly linked.
 * Provide standard library which competes with the C standard library and is
   always compiled against statically in source form.
 * Generics so that one can write efficient data structures that work for any
   data type.
 * Ability to run arbitrary code at compile time and generate code.
 * No null pointer. Convenient syntax for dealing with a maybe type so that
   null pointer is not missed.
 * A type which represents an error and has some convenience syntax with
   regards to resources.
 * Defer statement.
 * Eliminate the need for configure, make, cmake, etc.
 * Eliminate the need for header files (when using zig internally).
 * Tagged union enum type.
 * Resilient to parsing errors to make IDE integration work well.
 * Eliminate the preprocessor, but have a plan for how to do things you would
   want to use the preprocessor for such as conditional compilation.
 * Ability to mark functions as test and automatically run them in test mode.
   This mode should automatically provide test coverage.
 * Friendly toward package maintainers.
 * Ability to declare dependencies as Git URLS with commit locking (can
   provide a tag or sha1).
 * Include documentation generator.
 * Shebang line OK so language can be used for "scripting" as well.
 * Have the compiler run continuously, watching the file system for source
   changes and automatically perform multithreaded compilation to build projects
   quickly.
 * Hot code swapping. When integrated with the previous feature, you could
   press "save" in your editor and see the change immediately in your running
   software.

### Current Status

 * Have a look in the examples/ folder to see some code examples.
 * Basic language features available such as loops, inline assembly,
   expressions, literals, functions, importing, structs, tagged unions.
 * Linux x86_64 is supported.
 * Building for the native target is supported.
 * Optimized machine code that Zig produces is indistinguishable from
   optimized machine code produced from equivalent C program.
 * Zig can generate dynamic libraries, executables, object files, and C
   header files.
 * The binaries produced by Zig have complete debugging information so you can,
   for example, use GDB to debug your software.

## Building

### Debug / Development Build

If you have gcc or clang installed, you can find out what `ZIG_LIBC_DIR` should
be set to (example below).

```
mkdir build
cd build
cmake .. -DCMAKE_INSTALL_PREFIX=$(pwd) -DZIG_LIBC_DIR=$(dirname $(cc -print-file-name=crt1.o))
make
make install
./run_tests
```

### Release / Install Build

Once installed, `ZIG_LIBC_DIR` can be overridden by the `--libc-path` parameter
to the zig binary.

```
mkdir build
cd build
cmake .. -DCMAKE_BUILD_TYPE=Release -DZIG_LIBC_DIR=path/to/libc/dir
make
sudo make install
```

### Troubleshooting

If you get one of these:

```
undefined reference to `_ZNK4llvm17SubtargetFeatures9getStringB5cxx11Ev'
undefined reference to `llvm::SubtargetFeatures::getString() const'
```

This is because of
[C++'s Dual ABI](https://gcc.gnu.org/onlinedocs/libstdc++/manual/using_dual_abi.html).
Most likely LLVM was compiled with one compiler while Zig was compiled with a
different one, for example GCC vs clang.

To fix this, you have 2 options:

 * Compile Zig with the same compiler that LLVM was compiled with.
 * Add `-DZIG_LLVM_OLD_CXX_ABI=yes` to the cmake configure line.