Starting as a Contributor

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Revision as of 21:23, 3 August 2015 by AndreiAlexandrescu (talk | contribs) (4. Fetch and build phobos)
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This page contains a set of instructions that get anyone from having nothing D-related on their machine, to a full-blown development rig for the reference D compiler `dmd` and one or more of its paraphernalia: core runtime (aka druntime), standard library (aka phobos), website, and tools.

0. Prerequisites

This tutorial is written for a Posix system (Linux, OSX, FreeBSD etc) and assumes you have make, g++, libcurl4-openssl-dev, and git up and running on your system, as well as a working github account. To install the appropriate code on e.g. Ubuntu:

sudo apt-get install make g++ libcurl4-openssl-dev git

1. Fetch dmd from github

Let's start by getting the current development (master) branch of dmd from github. Assume the root directory for everything D-related is ~/code (replace appropriately). This is easily done by running at a command prompt:

cd ~/code
git clone

After this step completes successfully, the directory ~/code/dmd should be up and filled with good stuff.

2. Bootstrap dmd

This step is interesting because in order to build dmd, dmd is necessary. Fortunately, the steps of downloading and using a preexisting dmd compiler are automated. All you need to do is run this command:

cd ~/code/dmd
make -f posix.mak AUTO_BOOTSTRAP=1

That's going to take a while. To make it faster, passing -j8 accelerates things by running eight processes in parallel. The build produces the compiler binary ~/code/dmd/src/dmd.

To make dmd builds faster in the future, you need to obviate the need for bootstrapping. Install dmd from the download page or simply put the freshly built dmd binary in a place accessible through $PATH (a popular choice is ~/bin).

3. Fetch and build druntime

druntime is the core runtime library for D, needed for building most every D program, including the standard library itself. So it's the next step in the progression. To fetch and build druntime, issue these commands:

cd ~/code
git clone
cd druntime
make -f posix.mak

All that should go pretty fast. The somewhat anticlimactic result of the build is a library called libdruntime.a situated in an OS-dependent directory such as ~/code/druntime/generated/linux/release/64/. Make sure it's there.

4. Fetch and build phobos

Most D programs use D's standard library phobos. To get and build it:

cd ~/code
git clone
cd phobos
make -f posix.mak

The build produces (with similar anticlimacticity) static and shared libraries such as ~/code/phobos/generated/linux/release/64/libphobos2.a and ~/code/phobos/generated/linux/release/64/

4.1. Unittest phobos

If you want to work on phobos itself, you need to run unittests—either for the full library, a package, or a module. To unittest the entire library:

make -j16 -f posix.mak unittest

Adjust the parameter passed to -j depending on your machine (beefier machines support larger parameters). This command unittests phobos in both debug and release mode. To only test one of them, add BUILD=debug or BUILD=release to the command line, for example:

make -j16 -f posix.mak BUILD=debug unittest

Specifying BUILD makes unittesting faster so it is recommended in iterative development. Just make sure both debug and release builds are tested before e.g. submitting a pull request.

While changing one specific package or module, it's useful to be able to only unittest that particular entity. The following two commands only unittest (in debug mode) the std.algorithm package and the std.conv module, respectively:

make -j16 -f posix.mak BUILD=debug std/algorithm.test
make -j16 -f posix.mak BUILD=debug std/conv.test

Several modules, packages, or mix thereof may be specified for testing in the same command line. For example, this command also tests (and also in debug mode) the std.algorithm package and the std.conv module, with better parallelism:

make -j16 -f posix.mak BUILD=debug std/algorithm.test std/conv.test

6. Fetch and build

This step is optional but highly recommended. Significant changes to phobos' documentation require that the site (which includes automatically generated phobos documentation) builds successfully. So, without further ado:

cd ~/code
git clone
make -f posix.mak

All of dmd, druntime, and phobos are needed for the site to build. Note that one of the first lines output during the make run looks like this:

LATEST=2.067.1 <-- place in the command line to skip network traffic.

That's advice worth heeding because fetching LATEST automatically involves network traffic, which adds time to the build. So for future builds use this:

make -f posix.mak LATEST=2.067.1

Of course, parallelizing with -j improves speed as well.

The build produces the entire site at ~/code/ To informally test it, open the appropriate HTML documents in that directory. Note that the currently released phobos has documentation in ~/code/, whereas the current (fresh) build of phobos has documentation in ~/code/ So, for example, if you change the embedded documentation in ~/code/phobos/std/conv.d, the changes are visible in ~/code/ (The build process replaces the slashes in submodules with underscores.)