src/third_party/angle/tools/flex-bison/README.md

# flex and bison binaries

This folder contains the flex and bison binaries. We use these binaries to
generate the ANGLE translator's lexer and parser.

Use the script [`update_flex_bison_binaries.py`](update_flex_bison_binaries.py)
to update the versions of these binaries in cloud storage. It must be run on
Linux or Windows. It will update the SHAs for your platform. After running the
script run `git commit` and then `git cl upload` to code review using the normal
review process. You will also want to run
[`scripts/run_code_generation.py`](../../scripts/run_code_generation.py) to
update the generated files.

Please update both Windows and Linux binaries at the same time. Use two CLs. One
for each platform. Note that we don't currently support Mac for generating the
lexer and parser files. If we do we should add a flex/bison download for Mac as
well.

Contact jmadill or syoussefi for any help with updating the binaries.

## Updating flex and bison binaries

This is expected to be a rare operation, and is currently done based on the
following instructions.  Note: get the binaries first on windows, as only a
single option is available, then build the binaries for the same version on
Linux.

### On Windows

Install MSys2 (x86_64) from http://www.msys2.org/ on Windows.  `flex` should
already be installed.  Install bison:

```
$ pacman -S bison
```

Note the versions of flex and bison so the same versions can be build on Linux.
For example:

```
$ flex --version
flex 2.6.4

$ bison --version
bison (GNU Bison) 3.3.2
```

The only dependencies from MSys2 should be the following:

```
msys-intl-8.dll
msys-iconv-2.dll
msys-2.0.dll
```

This can be verified with:

```
$ ldd /usr/bin/flex
$ ldd /usr/bin/bison
```

Additionally, we need the binary for m4 at `/usr/bin/m4`.

Copy all these 5 files to this directory:

```
$ cd angle/
$ cp /usr/bin/flex.exe \
     /usr/bin/bison.exe \
     /usr/bin/m4.exe \
     /usr/bin/msys-intl-8.dll \
     /usr/bin/msys-iconv-2.dll \
     /usr/bin/msys-2.0.dll \
     tools/flex-bison/windows/
```

Upload the binaries:

```
$ cd angle/
$ python tools/flex-bison/update_flex_bison_binaries.py
```

### On Linux

```
# Get the source of flex
$ git clone https://github.com/westes/flex.git
$ cd flex/
# Checkout the same version as msys2 on windows
$ git checkout v2.6.4
# Build
$ autoreconf -i
$ mkdir build && cd build
$ ../configure CFLAGS="-O2 -D_GNU_SOURCE"
$ make -j
```

```
# Get the source of bison
$ curl http://ftp.gnu.org/gnu/bison/bison-3.3.2.tar.xz | tar -xJ
$ cd bison-3.3.2
# Build
$ mkdir build && cd build
$ ../configure CFLAGS="-O2"
$ make -j
```

Note: Bison's [home page][Bison] lists ftp server and other mirrors.  If the
above link is broken, replace with a mirror.

Copy the 2 executables to this directory:

```
$ cd angle/
$ cp /path/to/flex/build/src/flex \
     /path/to/bison/build/src/bison \
     tools/flex-bison/linux/
```

Upload the binaries:

```
$ cd angle/
$ python tools/flex-bison/update_flex_bison_binaries.py
```

[Bison]: https://www.gnu.org/software/bison/