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-// file      : doc/intro2.cli
-// copyright : Copyright (c) 2014-2017 Code Synthesis Ltd
-// license   : MIT; see accompanying LICENSE file
-
-"\name=build2-toolchain-intro"
-"\subject=toolchain"
-"\title=Toolchain Introduction"
-
-// TODO
-//
-// @@ refs to further docs
-//
-// STYLE
-//
-// @@ section boundary page breaks (<hr class="page-break"/>)
-// @@ when printed, code background is gone, but spaces still there
-//
-// PDF
-//
-// @@ tree output is garbled
-// @@ Could we use a nicer font, seeing that we embed them?
-//
-
-// NOTES
-//
-// - Maximum <pre> line is 70 characters.
-//
-
-"
-\h1#tldr|TL;DR|
-
-\
-$ git clone ssh://example.org/hello.git
-$ tree hello
-hello/
-├── hello/
-│   ├── hello.cxx
-│   └── buildfile
-├── manifest
-└── repositories.manifest
-
-$ cd hello
-$ bdep init --config-create ../hello-gcc cc config.cxx=g++
-initializing project /tmp/hello/
-created configuration /tmp/hello-gcc/ (default, auto-synchronized)
-synchronizing:
-  new hello/0.1.0
-
-$ b
-c++ hello/cxx{hello}@../hello-gcc/hello/hello/
-ld ../hello-gcc/hello/hello/exe{hello}
-ln ../hello-gcc/hello/hello/exe{hello} -> hello/
-
-$ hello/hello World
-Hello, World!
-
-$ edit repositories.manifest   # add https://example.org/libhello.git
-$ edit manifest                # add 'depends: libhello ^1.0.0'
-$ edit hello/buildfile         # import libhello
-$ edit hello/hello.cxx         # use libhello
-
-$ b
-fetching from https://example.org/libhello.git
-synchronizing /tmp/hello-gcc/:
-  new libhello/1.0.0 (required by hello)
-  reconfigure hello/0.1.0
-c++ ../hello-gcc/libhello-1.0.0/libhello/cxx{hello}
-ld ../hello-gcc/libhello-1.0.0/libhello/libs{hello}
-c++ hello/cxx{hello}@../hello-gcc/hello/hello/
-ld ../hello-gcc/hello/hello/exe{hello}
-ln ../hello-gcc/hello/hello/exe{hello} -> hello/
-
-$ bdep fetch                   # refresh available versions
-$ bdep status -i               # review available versions
-hello configured 0.1.0
-  libhello ^1.0.0 configured 1.0.0 available [1.1.0]
-
-$ bdep sync libhello           # upgrade to latest
-synchronizing:
-  new libformat/1.0.0 (required by libhello)
-  new libprint/1.0.0 (required by libhello)
-  upgrade libhello/1.1.0
-  reconfigure hello/0.1.0
-
-$ bdep sync libhello/1.0.0     # downgrade
-synchronizing:
-  drop libprint/1.0.0 (unused)
-  drop libformat/1.0.0 (unused)
-  downgrade libhello/1.0.0
-  reconfigure hello/0.1.0
-\
-
-\h1#guide|Getting Started Guide|
-
-The aim of this guide is to get you started developing C/C++ projects with the
-\c{build2} toolchain. All the examples in this section include the relevant
-command output so if you just want to get a sense of what \c{build2} is about,
-then you don't have to install the toolchain and run the commands in order to
-follow along. If at the end you find \c{build2} appealing and would like to
-start using it or try the examples for yourself, you can jump straight to
-\l{build2-toolchain-install.xhtml The \c{build2} Toolchain Installation and
-Upgrade}.
-
-One of the primary goals of the \c{build2} toolchain is to provide a uniform
-interface across all the platforms and compilers. While the examples in this
-document assume a UNIX-like operation system, they will look pretty similar if
-you are on Windows. You just have to use appropriate paths, compilers, and
-options.
-
-The question we will try to answer in this section can be summarized as:
-
-\
-$ git clone .../hello.git && now-what?
-\
-
-That is, we clone an existing C/C++ project or would like to create a new one
-and then start hacking on it. We want to spend as little time and energy as
-possible on the initial and ongoing infrastructure maintenance: setting up
-build configurations, managing dependencies, continuous integration and
-testing, release management, etc. Or, as one C++ user aptly put it, \"\i{All I
-want to do is program.}\"
-
-\h#guide-hello|Hello, World|
-
-Let's see what programming with \c{build2} feels like by starting with a
-customary \i{\"Hello, World!\"} program (here we assume our current working
-directory is \c{/tmp}):
-
-\
-$ bdep new -t exe -l c++ hello
-created new executable project hello in /tmp/hello/
-\
-
-The \l{bdep-new(1)} command creates a \i{canonical} \c{build2} project. In
-our case it is an executable implemented in C++.
-
-\N|To create a library, pass \c{-t\ lib}. By default \c{new} also initializes
-a \c{git} repository and generates suitable \c{.gitignore} files (pass \c{-s\
-none} if you don't want that).|
-
-Let's take a look inside our new project:
-
-\
-$ tree hello
-hello/
-├── .git/
-├── .bdep/
-├── build/
-├── hello/
-│   ├── hello.cxx
-│   ├── buildfile
-│   └── testscript
-├── buildfile
-├── manifest
-└── repositories.manifest
-\
-
-\N|While the canonical project structure is strongly recommended, especially
-for new projects, \c{build2} is flexible enough to allow most commonly used
-arrangements.|
-
-Similar to version control tools, we normally run all \c{build2} tools from
-the project's source directory or one of its subdirectories, so:
-
-\
-$ cd hello
-\
-
-While the project layout is discussed in more detail in later sections, let's
-examine a couple of interesting files to get a sense of what's going on. We
-start with the source file which should look familiar:
-
-\
-$ cat hello/hello.cxx
-
-#include <iostream>
-
-using namespace std;
-
-int main (int argc, char* argv[])
-{
-  if (argc < 2)
-  {
-    cerr << \"error: missing name\" << endl;
-    return 1;
-  }
-
-  cout << \"Hello, \" << argv[1] << '!' << endl;
-}
-\
-
-\N|If you prefer the \c{.?pp} extensions over \c{.?xx} for your C++ source
-files, pass \c{-l\ c++,cpp} to the \c{new} command. See \l{bdep-new(1)} for
-details on this and other customization options.|
-
-Let's take a look at the accompanying \c{buildfile}:
-
-\
-$ cat hello/buildfile
-
-libs =
-#import libs += libhello%lib{hello}
-
-exe{hello}: {hxx ixx txx cxx}{*} $libs test{testscript}
-\
-
-As the name suggests, this file describes how to build things. While its
-content might look a bit cryptic, let's try to infer a couple of points
-without going into too much detail (the details are discussed in the following
-sections). That \c{exe{hello\}} on the left of \c{:} is a \i{target}
-(executable named \c{hello}) and what we have on the right are
-\i{prerequisites} (C++ source files, libraries, etc). This \c{buildfile} uses
-\l{b#name-patterns wildcard patterns} (that \c{*}) to automatically locate all
-the C++ source files. This means we don't have to edit our \c{buildfile} every
-time we add a source file to our project. There also appears to be some
-(commented out) infrastructure for importing and linking libraries (that
-\c{libs} variable). We will see how to use it in a moment. Finally, the
-\c{buildfile} also lists \c{testscript} as a prerequisite of \c{hello}. This
-file tests our target. Let's take a look inside:
-
-\
-$ cat hello/testscript
-
-: basics
-:
-$* 'World' >'Hello, World!'
-
-: missing-name
-:
-$* 2>>EOE != 0
-error: missing name
-EOE
-\
-
-Again, we are not going into detail here (see \l{testscript#intro Testscript
-Introduction} for a proper introduction), but to give you an idea, here we
-have two tests: the first (with id \c{basics}) verifies that our program
-prints the expected greeting while the second makes sure it handles the
-missing name error condition. Tests written in Testscript are concise,
-portable, and executed in parallel.
-
-Next up is \c{manifest}:
-
-\
-$ cat manifest
-: 1
-name: hello
-version: 0.1.0-a.0.z
-summary: hello executable project
-license: proprietary
-url: https://example.org/hello
-email: you@example.org
-#depends: libhello ^1.0.0
-\
-
-The \c{manifest} file is what makes a build system project a \i{package}. It
-contains all the metadata that a user of a package might need to know: its
-name, version, license, dependencies, etc., all in one place.
-
-\N|Refer to \l{bpkg#manifest-format Manifest Format} for the general format of
-\c{build2} manifest files and to \l{bpkg#manifest-package Package Manifest}
-for details on the package manifest values.|
-
-As you can see, \c{manifest} created by \l{bdep-new(1)} contains some dummy
-values which you would want to adjust before publishing your package. But
-let's resist the urge to adjust that strange looking \c{0.1.0-a.0.z} until we
-discuss package versioning.
-
-\N|Next to \c{manifest} you might have noticed the \c{repositories.manifest}
-file \- we will discuss its function later, when we talk about dependencies
-and where they come from.|
-
-Project in hand, let's build it. Unlike other programming languages, C++
-development usually involves juggling a handful of build configurations:
-several compilers and/or targets (\c{build2} is big on cross-compiling),
-debug/release, different sanitizers and/or static analysis tools, and so
-on. As a result, \c{build2} is optimized for multi-configuration
-usage. However, as we will see shortly, one build configuration can be
-designated as the default with additional conveniences.
-
-The \l{bdep-init(1)} command is used to initialize a project in a build
-configuration. As a shortcut, it can also create a new build configuration in
-the process, which is just what we need here. Let's start with GCC (remember
-we are in the project's root directory):
-
-\
-$ bdep init -C ../hello-gcc @gcc cc config.cxx=g++
-initializing project /tmp/hello/
-created configuration @gcc /tmp/hello-gcc/ (default, auto-synchronized)
-synchronizing:
-  new hello/0.1.0-a.0.19700101000000
-\
-
-The \cb{--create|-C} option instructs \c{init} to create a new configuration
-in the specified directory (\c{../hello-gcc} in our case). To make referring
-to configurations easier, we can give it a name, which is what we do with
-\c{@gcc}. The next argument (\c{cc}, stands for \i{C-common}) is the build
-system module we would like to configure. It implements compilation and
-linking rules for the C and C++ languages. Finally, \c{config.cxx=g++} is (one
-of) this module's configuration variables that specifies the C++ compiler we
-would like to use (the corresponding C compiler will be determined
-automatically). Let's for now also ignore that \c{synchronizing:...} bit along
-with strange-looking \c{19700101000000} in the version \- it will become clear
-what's going on here in a moment.
-
-Now the same for Clang:
-
-\
-$ bdep init -C ../hello-clang @clang cc config.cxx=clang++
-initializing project /tmp/hello/
-created configuration @clang /tmp/hello-clang/ (auto-synchronized)
-synchronizing:
-  new hello/0.1.0-a.0.19700101000000
-\
-
-If we check the parent directory, we should now see two build configurations
-next to our project:
-
-\
-$ ls ..
-hello/
-hello-gcc/
-hello-clang/
-\
-
-Things will also look pretty similar if you are on Windows instead of a
-UNIX-like operating system. For example, to initialize our project on Windows
-with Visual Studio, start the Visual Studio development command prompt and
-then run:
-
-\N|Currently we have to run \c{build2} tools from a suitable Visual Studio
-development command prompt. This requirement will likely be removed in the
-future.|
-
-\
-> bdep init -C ..\hello-debug @debug cc     ^
-  config.cxx=cl                             ^
-  \"config.cc.coptions=/MDd /Z7\"             ^
-  config.cc.loptions=/DEBUG
-
-> bdep init -C ..\hello-release @release cc ^
-  config.cxx=cl                             ^
-  config.cc.coptions=/O2
-\
-
-\N|Besides the \c{coptions} (compile options) and \c{loptions} (link options),
-other commonly used \c{cc} module configuration variables are \c{poptions}
-(preprocess options) and \c{libs} (extra libraries to link). We can also use
-their \c{config.c.*} (C compilation) and \c{config.cxx.*} (C++ compilation)
-variants if we only want them applied during the respective language
-compilation. For example:
-
-\
-$ bdep init ... cc       \
-  config.cxx=clang++     \
-  config.cc.coptions=-g  \
-  config.cxx.coptions=-stdlib=libc++
-\
-
-|
-
-One difference you might have noticed when creating the \c{gcc} and \c{clang}
-configurations above is that the first one was designated as the default. The
-default configuration is used by \c{bdep} commands if no configuration is
-specified explicitly (see \l{bdep-projects-configs(1)} for details). It is
-also the configuration that is used if we run the build system in the
-project's source directory. So, normally, you would make your every day
-development configuration the default. Let's try that:
-
-\
-$ bdep status
-hello configured 0.1.0-a.0.19700101000000
-
-$ b
-c++ hello/cxx{hello}@../hello-gcc/hello/hello/
-ld ../hello-gcc/hello/hello/exe{hello}
-ln ../hello-gcc/hello/hello/exe{hello} -> hello/
-
-$ b test
-test hello/test{testscript} ../hello-gcc/hello/hello/exe{hello}
-
-$ hello/hello World
-Hello, World!
-\
-
-In contrast, the Clang configuration has to be requested explicitly:
-
-\
-$ bdep status @clang
-hello configured 0.1.0-a.0.19700101000000
-
-$ b ../hello-clang/hello/
-c++ hello/cxx{hello}@../hello-clang/hello/hello/
-ld ../hello-clang/hello/hello/exe{hello}
-
-$ b test: ../hello-clang/hello/
-test hello/test{testscript} ../hello-clang/hello/hello/exe{hello}
-
-$ ../hello-clang/hello/hello/hello World
-Hello, World!
-\
-
-\N|To see the actual compilation command lines, run \c{b\ -v} and for even
-more details, run \c{b\ -V}. See \l{b(1)} for more information on these
-and other build system options.|
-
-While we are here, let's also check how hard it would be to cross-compile:
-
-\
-$ bdep init -C ../hello-mingw @mingw cc config.cxx=x86_64-w64-mingw32-g++
-initializing project /tmp/hello/
-created configuration @mingw /tmp/hello-mingw/ (auto-synchronized)
-synchronizing:
-  new hello/0.1.0-a.0.19700101000000
-
-$ b ../hello-mingw/hello/
-c++ hello/cxx{hello}@../hello-mingw/hello/hello/
-ld ../hello-mingw/hello/hello/exe{hello}
-\
-
-As you can see, cross-compiling in \c{build2} is nothing special. In our case,
-on a properly setup GNU/Linux machine (that automatically uses \c{wine} as an
-\c{.exe} interpreter) we can even run tests (in \c{build2} this is called
-\i{cross-testing}):
-
-\
-$ b test: ../hello-mingw/hello/
-test hello/test{testscript} ../hello-mingw/hello/hello/exe{hello}
-
-$ ../hello-mingw/hello/hello/hello.exe Windows
-Hello, Windows!
-\
-
-Let's review what it takes to initialize a project's infrastructure and
-perform the first build. For an existing project:
-
-\
-$ git clone .../hello.git
-$ cd hello
-$ bdep init -C ../hello-gcc @gcc cc config.cxx=g++
-$ b
-\
-
-For a new project:
-
-\
-$ bdep new -t exe -l c++ hello
-$ cd hello
-$ bdep init -C ../hello-gcc @gcc cc config.cxx=g++
-$ b
-\
-
-If you prefer, the \c{new} and \c{init} steps can be combined into a single
-command:
-
-\
-$ bdep new -t exe -l c++ hello -C hello-gcc @gcc cc config.cxx=g++
-\
-
-Now is also a good time to get an overview of the \c{build2} toolchain. After
-all, we have already used two of its tools (\c{bdep} and \c{b}) without a
-clear understanding of what they actually are.
-
-Unlike most other programming languages that encapsulate the build system,
-package dependency manager, and project dependency manager into a single tool
-(such as Rust's \c{cargo} or Go's \c{go}), \c{build2} is a hierarchy of
-several tools that you will be using directly and which together with your
-version control system (VCS) will constitute the core of your project
-management toolset.
-
-\N|While \c{build2} can work without a VCS, this will result in reduced
-functionality.|
-
-At the bottom of the hierarchy is the build system, \l{b(1)}. Next comes the
-package dependency manager, \l{bpkg(1)}. It is primarily used for \i{package
-consumption} and depends on the build system. The top of the hierarchy is the
-project dependency manager, \l{bdep(1)}. It is used for \i{project
-development} and relies on \c{bpkg} for building project packages and their
-dependencies.
-
-\N|The main reason for this separation is modularity and the resulting
-flexibility: there are situations where we only need the build system (for
-example, when building a package for a system package manager where all the
-dependencies should be satisfied from the system repository), or only the
-build system and package manager (for example, when a build bot is building a
-package for testing).
-
-Note also that strictly speaking \c{build2} is not C/C++-specific; its build
-model is general enough to handle any DAG-based operations and its
-package/project dependency management can be used for any compiled language.|
-
-\N|As we will see in a moment, \c{build2} also integrates with your VCS in
-order to automate project versioning. Note that currently only \c{git(1)} is
-supported.|
-
-Let's now move on to the reason why there is \i{dep} in the \c{bdep} name:
-dependency management.
-
-
-\h#guide-repositories|Package Repositories|
-
-Say we have realized that writing \i{\"Hello, World!\"} programs is a fairly
-common task and that someone must have written a library to help with that. So
-let's see if we can find something suitable to use in our project.
-
-Where should we look? That's a good question. But before we can try to answer
-it, we need to understand where \c{build2} can source dependencies. In
-\c{build2} packages come from \i{package repositories}. Two commonly used
-repository types are \i{version control} and \i{archive}-based (see
-\l{bpkg-repository-types(1)} for details).
-
-As the name suggests, a version control-based repository uses a VCS as its
-distribution mechanism. \N{Currently, only \c{git} is supported.} Such a
-repository normally contains multiple versions of a single package or,
-perhaps, of a few related packages.
-
-An archive-based repository contains multiple, potentially unrelated
-packages/versions as archives along with some meta information (package list,
-prerequisite/complement repositories, signatures, etc) that are all accessible
-via HTTP(S).
-
-Version control and archive-based repositories have different
-trade-offs. Version control-based repositories are great for package
-developers: With services like GitHub they are trivial to setup. In fact, your
-project's (already existing) VCS repository will normally be the \c{build2}
-package repository \- you might need to add a few files, but that's about it.
-
-However, version control-based repositories are not without drawbacks: It will
-be hard for your users to discover your packages (try searching for \"hello
-library\" on GitHub \- most of the results are not even in C++ let alone
-packaged for \c{build2}). There is also the issue of continuous availability:
-users can delete their repositories, services may change their policies or go
-out of business, and so on. Version control-based repositories also lack
-repository authentication and package signing. Finally, obtaining the
-available package list for such repositories can be slow.
-
-A central, archive-based repository would address all these drawbacks: It
-would be a single place to search for packages. Published packages will never
-disappear and can be easily mirrored. Packages are signed and the repository
-is authenticated (see \l{bpkg-repository-signing(1)} for details). And, last,
-but not least, archive-based repositories are fast.
-
-\l{https://cppget.org cppget.org} is the \c{build2} community's central
-package repository (which we hope one day will become \i{the C++ package
-repository}). As an added benefit, packages on \l{https://cppget.org
-cppget.org} are continuously \l{https://cppget.org/?builds built and tested} on
-all the major platform/compiler combinations with the results available as
-part of the package description.
-
-\N|The main drawback of archive-based repositories is the setup cost. Getting
-a basic repository going is relatively easy \- all you need is an HTTP(S)
-server. Adding a repository web interface like that on \l{https://cppget.org
-cppget.org} will require running \l{https://cppget.org/brep \c{brep}}. And
-adding CI will require running a bunch of build bots
-(\l{https://cppget.org/bbot \c{bbot}}).|
-
-\N|CI support for version control-based repositories is a work in progress.|
-
-To summarize, version control-based repositories are great for package
-developers while a central, archive-based repository is convenient for package
-consumers. A reasonable strategy is then for package developers to publish
-their releases to a central repository. Package consumers can then decide
-which repository to use based on their needs. For example, one could use
-\l{https://cppget.org cppget.org} as a (fast, reliable, and secure) source of
-stable versions but also add, say, \c{git} repositories for select packages
-(perhaps with the \c{#HEAD} fragment filter to improve download speed) for
-testing development snapshots. In this model the two repository types
-complement each other.
-
-\N|Support for automated publishing of tagged releases to an archive-based
-repository is a work in progress.|
-
-Let's see how all this works in practice. Go over to \l{https://cppget.org
-cppget.org} and type \"hello library\" in the search box. At the top of the
-search result you should see the \l{https://cppget.org/libhello \c{libhello}}
-package and if you follow the link you will see the package description page
-along with a list of available versions. Pick a version that you like and you
-will see the package version description page with quite a bit of information,
-including the list of platform/compiler combinations that this version has
-been successfully (or unsuccessfully) tested with. If you like what you see,
-copy the \c{location} value \- this is the repository location where this
-package version can be sourced from.
-
-\N|The \l{https://cppget.org cppget.org} repository is split into several
-sections: \c{stable}, \c{testing}, \c{beta}, \c{alpha} and \c{legacy}, with
-each section having its own repository location (see the repository's
-\l{https://cppget.org/?about about} page for details on each section's
-policies). Note also that \c{testing} is complemented by \c{stable}, \c{beta}
-by \c{testing}, and so on, so you only need to choose the lowest stability
-level and you will automatically \"see\" packages from the more stable
-sections.|
-
-\N|The \l{https://cppget.org cppget.org} \c{stable} sections will always
-contain the \c{libhello} library version \c{1.0.X} that was generated using
-the following \l{bdep-new(1)} command line:
-
-\
-$ bdep new -t lib -l c++ libhello
-\
-
-It can be used as a predictable test dependency when setting up new projects.|
-
-Let's say we've visited the \c{libhello} project's
-\l{https://git.build2.org/cgit/hello/libhello/ home page} (for example by
-following a link from the package details page) and noticed that it is being
-developed in a \c{git} repository. How can we see what's available there? If
-the releases are tagged, then we can infer the available released versions
-from the tags. But that doesn't tell us anything about what's happening on the
-\c{HEAD} or in the branches. For that we can use the package manager's
-\l{bpkg-rep-info(1)} command:
-
-\
-$ bpkg rep-info https://git.build2.org/hello/libhello.git
-libhello/1.0.0
-libhello/1.1.0
-\
-
-As you can see, besides \c{1.0.0} that we have seen on \c{cppget.org/stable},
-there is also \c{1.1.0} (which is perhaps being tested in
-\c{cppget.org/testing}). We can also check what might be available on the
-\c{HEAD} (see \l{bpkg-repository-types(1)} for details on the \c{git}
-repository URL format):
-
-\
-$ bpkg rep-info https://git.build2.org/hello/libhello.git#HEAD
-libhello/1.1.1-a.0.20180504111511.2e82f7378519
-\
-
-\N|We can also use the \c{rep-info} command on archive-based repositories,
-however, if available, the web interface is usually more convenient and
-provides more information.|
-
-To summarize, we found two repositories for the \c{libhello} package: the
-archive-based \l{https://cppget.org cppget.org} that contains the released
-versions as well as its development \c{git} repository where we can get the
-bleeding edge stuff. Let's now see how we can add \c{libhello} to our
-project.
-
-
-\h#guide-add-remove-deps|Adding and Removing Dependencies|
-
-So we found \c{libhello} that we would like to use in our \c{hello}
-project. First, we edit the \c{repositories.manifest} file found in the root
-directory of our project and add one of the \c{libhello} repositories as a
-prerequisite. Let's start with \l{https://cppget.org cppget.org}:
-
-\
-role: prerequisite
-location: https://pkg.cppget.org/1/stable
-\
-
-\N|Refer to \l{bpkg#manifest-repository Repository Manifest} for details on
-the repository manifest values.|
-
-Next, we edit the \c{manifest} file (again, found in the root of our project)
-and specify the dependency on \c{libhello} with optional version constraint.
-For example:
-
-\
-depends: libhello ^1.0.0
-\
-
-Let's briefly discuss version constraints (for details see the
-\l{bpkg#manifest-package-depends \c{depends}} value documentation). A version
-constraint can be expressed with a comparison operator (\c{==}, \c{>},
-\c{<}, \c{>=}, \c{<=}), a range shortcut operator (\c{~} and \c{^}), or a
-range. Here are a few examples:
-
-\
-depends: libhello == 1.2.3
-depends: libhello >= 1.2.3
-
-depends: libhello ~1.2.3
-depends: libhello ^1.2.3
-
-depends: libhello [1.2.3 1.2.9)
-\
-
-You may already be familiar with the tilde (\c{~}) and caret (\c{^})
-constraints from dependency managers for other languages. To recap, tilde
-allows upgrades to any further patch versions while caret also allows upgrades
-to further minor versions. They are equivalent to the following ranges:
-
-\
-~X.Y.Z  [X.Y.Z  X.Y+1.0)
-
-^X.Y.Z  [X.Y.Z  X+1.0.0)  if X >  0
-^0.Y.Z  [0.Y.Z  0.Y+1.0)  if X == 0
-\
-
-\N|Zero major version component is customarily used during early development
-where the minor version effectively becomes major. As a result, the tilde
-constraint has a special treatment of this case.|
-
-Unless you have good reasons not to (for example, a dependency does not use
-semantic versioning), we suggest that you use the \c{^} constraint which
-provides a good balance between compatibility and upgradability with \c{~}
-being a more conservative option.
-
-Ok, we've specified where our package comes from (\c{repositories.manifest})
-and which versions we find acceptable (\c{manifest}). The next step is to edit
-\c{hello/buildfile} and import the \c{libhello} library into our build:
-
-\
-import libs += libhello%lib{hello}
-\
-
-Finally, we modify our source code to use the library:
-
-\
-#include <libhello/hello.hxx>
-...
-
-int main (int argc, char* argv[])
-{
-  ...
-  hello::say_hello (cout, argv[1]);
-}
-\
-
-\N|You are probably wondering why we have to specify this repeating
-information in so many places. Let's start with the source code: we can't
-specify the version constraint or location there because it will have to be
-repeated in every source file that uses the dependency.
-
-Moving up, \c{buildfile} is also not a good place to specify this information
-for the same reason (a library can be imported in multiple buildfiles) plus
-the build system doesn't really know anything about version constraints or
-repositories which is the purview of the dependency management tools.
-
-Finally, we have to separate the version constraint and the location because
-the same package can be present in multiple repositories with different
-policies. For example, when a package from a version control-based repository
-is published in an archive-based repository, its \c{repositories.manifest}
-file is ignored and all its dependencies should be available from the
-archive-based repository itself (or its fixed set of prerequisite
-repositories). In other words, \c{manifest} belongs to a package while
-\c{repositories.manifest} \- to a repository.
-
-Also note that this is unlikely to become burdensome since adding new
-dependencies is not something that happens often. There are also plans to
-automate this with a \c{bdep-add(1)} command in the future.|
-
-To summarize, these are the files we had to modify to add a dependency
-to our project:
-
-\
-repositories.manifest   # add https://pkg.cppget.org/1/stable
-manifest                # add 'depends: libhello ^1.0.0'
-buildfile               # import libhello
-hello.cxx               # use libhello
-\
-
-With a new dependency added, let's check the status of our project:
-
-\
-$ bdep status
-fetching pkg:cppget.org/stable (prerequisite of dir:/tmp/hello)
-warning: authenticity of the certificate for pkg:cppget.org/stable
-         cannot be established
-certificate is for cppget.org, \"Code Synthesis\" <admin@cppget.org>
-certificate SHA256 fingerprint:
-86:BA:D4:DE:2C:87:1A:EE:38:<...>:5A:EA:F4:F7:8C:1D:63:30:C6
-trust this certificate? [y/n] y
-
-hello configured 0.1.0-a.0.19700101000000
-      available  0.1.0-a.0.19700101000000#1
-\
-
-The \l{bdep-status(1)} command has detected that the dependency information
-has changed and tells us that a new \i{iteration} of our project (that \c{#1})
-is now available for \i{synchronization} with the build configuration.
-
-We've also been prompted to authenticate the prerequisite repository. This
-will have to happen once for every build configuration we initialize our
-project in and can quickly become tedious. To overcome this, we can mention
-the certificate fingerprint that we wish to automatically trust in the
-\c{repositories.manifest} file (replace it with the actual fingerprint from
-the repository's about page):
-
-\
-role: prerequisite
-location: https://pkg.cppget.org/1/stable
-trust: 86:BA:D4:DE:2C:87:1A:EE:38:<...>:5A:EA:F4:F7:8C:1D:63:30:C6
-\
-
-To synchronize a project with one or more build configurations we use the
-\l{bdep-sync(1)} command:
-
-\
-$ bdep sync
-synchronizing:
-  new libhello/1.0.0 (required by hello)
-  upgrade hello/0.1.0-a.0.19700101000000#1
-\
-
-Or we could just build the project without an explicit \c{sync} \- if
-necessary, it will be automatically synchronized:
-
-\
-$ b
-synchronizing:
-  new libhello/1.0.0 (required by hello)
-  upgrade hello/0.1.0-a.0.19700101000000#1
-c++ ../hello-gcc/libhello-1.0.0/libhello/cxx{hello}
-ld ../hello-gcc/libhello-1.0.0/libhello/libs{hello}
-c++ hello/cxx{hello}@../hello-gcc/hello/hello/
-ld ../hello-gcc/hello/hello/exe{hello}
-ln ../hello-gcc/hello/hello/exe{hello} -> hello/
-\
-
-The synchronization as performed by the \c{sync} command is two-way:
-dependency packages are first added, removed, upgraded, or downgraded in build
-configurations according to the project's version constraints and user
-input. Then the actual versions of the dependencies present in the build
-configurations are recorded in the project's \c{lockfile} so that if desired,
-the build can be reproduced exactly. \N{The \c{lockfile} functionality is not
-yet implemented.} For a new dependency the latest available version that
-satisfies the version constraint is used.
-
-\N|Synchronization is also the last step in the \l{bdep-init(1)} command's
-logic.|
-
-Let's now examine the status in all (\c{--all|-a}) the build configurations
-and include the immediate dependencies (\c{--immediate|-i}):
-
-\
-$ bdep status -ai
-in configuration @gcc:
-hello configured 0.1.0-a.0.19700101000000#1
-  libhello ^1.0.0 configured 1.0.0
-
-in configuration @clang:
-hello configured 0.1.0-a.0.19700101000000
-      available 0.1.0-a.0.19700101000000#1
-\
-
-Since we didn't specify a configuration explicitly, only the default (\c{gcc})
-was synchronized. Normally, you would try a new dependency in one
-configuration, make sure everything looks good, then synchronize the rest with
-\c{--all|-a} (or, again, just build what you need directly). Here are a few
-examples (see \l{bdep-projects-configs(1)} for details):
-
-\
-$ bdep sync -a
-$ bdep sync @gcc @clang
-$ bdep sync -c ../hello-mingw
-\
-
-To get rid of a dependency, we simply remove it from the \c{manifest} file
-and synchronize the project. For example, assuming \c{libhello} is no longer
-mentioned as a dependency in our \c{manifests}:
-
-\
-$ bdep status
-hello configured 0.1.0-a.0.19700101000000#1
-      available  0.1.0-a.0.19700101000000#2
-
-$ bdep sync
-synchronizing:
-  drop libhello/1.0.0 (unused)
-  upgrade hello/0.1.0-a.0.19700101000000#2
-\
-
-
-\h#guide-upgrade-downgrade-deps|Upgrading and Downgrading Dependencies|
-
-Let's say we would like to try that \c{1.1.0} version we have seen in
-the \c{libhello} \c{git} repository. First, we need to add the
-repository to the \c{repositories.manifest} file:
-
-\
-role: prerequisite
-location: https://git.build2.org/hello/libhello.git
-\
-
-\N|Note that we don't need the \c{trust} value since \c{git} repositories
-are not authenticated.|
-
-To refresh the list of available dependency versions we use the
-\l{bdep-fetch(1)} command (or the \c{--fetch|-f} option to \c{status}):
-
-\
-$ bdep fetch
-$ bdep status libhello
-libhello configured 1.0.0 available [1.1.0]
-\
-
-To upgrade (or downgrade) dependencies we again use the \l{bdep-sync(1)}
-command. We can upgrade one or more specific dependencies by listing them
-as arguments to \c{sync}:
-
-\
-$ bdep sync libhello
-synchronizing:
-  new libformat/1.0.0 (required by libhello)
-  new libprint/1.0.0 (required by libhello)
-  upgrade libhello/1.1.0
-  upgrade hello/0.1.0-a.0.19700101000000#3
-\
-
-Without an explicit version or the \c{--patch|-p} option, \c{sync} will
-upgrade the specified dependencies to the latest available versions. For
-example, if we don't like version \c{1.1.0}, we can downgrade it back to
-\c{1.0.0} by specifying the version explicitly (we pass \c{--old-available|-o}
-to \c{status} to see the old versions):
-
-\
-$ bdep status -o libhello
-libhello configured 1.1.0 available (1.1.0) [1.0.0]
-
-$ bdep sync libhello/1.0.0
-synchronizing:
-  drop libprint/1.0.0 (unused)
-  drop libformat/1.0.0 (unused)
-  downgrade libhello/1.0.0
-  reconfigure hello/0.1.0-a.0.19700101000000#3
-\
-
-\N|The available versions are listed in the descending order with \c{[]}
-indicating that the version is only available as a dependency and \c{()}
-marking the current version.|
-
-Instead of specific dependencies we can also upgrade (\c{--upgrade|-u}) or
-patch (\c{--patch|-p}) immediate (\c{--immediate|-i}) or all
-(\c{--recursive|-r}) dependencies of our project.
-
-As a more realistic example, version \c{1.1.0} of \c{libhello} depends on two
-other libraries: \c{libformat} and \c{libprint}. Here is our project's
-dependency tree while we were still using that version:
-
-\
-$ bdep status -r
-hello configured 0.1.0-a.0.19700101000000#3
-  libhello ^1.0.0 configured 1.1.0
-    libformat ^1.0.0 configured 1.0.0
-    libprint ^1.0.0 configured 1.0.0
-\
-
-A typical conservative dependency management workflow would look like this:
-
-\
-$ bdep status -fi  # refresh and examine immediate dependencies
-hello configured 0.1.0-a.0.19700101000000#3
-  libhello configured 1.1.0 available [2.0.0] [1.2.0] [1.1.2] [1.1.1]
-
-$ bdep sync -pi    # upgrade immediate to latest patch version
-synchronizing:
-  upgrade libhello/1.1.2
-  reconfigure hello/0.1.0-a.0.19700101000000#3
-continue? [Y/n] y
-\
-
-Notice that in case of such mass upgrades you are prompted for confirmation
-before anything is actually changed (unless you pass \c{--yes|-y}).
-
-In contrast, the following would be a fairly aggressive workflow where we
-upgrade everything to the latest available version (version constraints
-permitting; here we assume \c{^1.0.0} was used for all the dependencies):
-
-\
-$ bdep status -fr  # refresh and examine all dependencies
-hello configured 0.1.0-a.0.19700101000000#3
-  libhello configured 1.1.0 available [2.0.0] [1.2.0] [1.1.1]
-    libprint configured 1.0.0 available [2.0.0] [1.1.0] [1.0.1]
-    libformat configured 1.0.0 available [2.0.0] [1.1.0] [1.0.1]
-
-$ bdep sync -ur    # upgrade all to latest available version
-synchronizing:
-  upgrade libprint/1.1.0
-  upgrade libformat/1.1.0
-  upgrade libhello/1.2.0
-  reconfigure hello/0.1.0-a.0.19700101000000#3
-continue? [Y/n] y
-\
-
-We can also have something in between: patch all (\c{sync\ -pr}), upgrade
-immediate (\c{sync\ -ui}), or even upgrade immediate and patch the rest
-(\c{sync\ -ui} followed by \c{sync\ -pr}).
-
-
-\h#guide-versioning-releasing|Versioning and Release Management|
-
-Let's now discuss versioning and release management and, yes, that
-strange-looking \c{0.1.0-a.0.19700101000000} we keep seeing. While a build
-system project doesn't need a version and a \c{bpkg} package can use custom
-versioning schemes (see \l{bpkg#package-version Package Version}), a project
-managed by \c{bdep} must use \i{standard versioning}. \N{A dependency, which
-is a \c{bpkg} package, need not use standard versioning.}
-
-Standard versioning (\i{stdver}) is a \l{https://semver.org semantic
-versioning} (\i{semver}) scheme with a more precisely defined pre-release
-component and without any build metadata.
-
-\N|If you believe that \i{semver} is just \c{\i{major}.\i{minor}.\i{patch}},
-then in your worldview \i{stdver} would be the same as \i{semver}. In reality,
-\i{semver} also allows loosely defined pre-release and build metadata
-components. For example, \c{1.2.3-beta.1+build.23456} is a valid \i{semver}.|
-
-A standard version has the following form:
-
-\c{\i{major}\b{.}\i{minor}\b{.}\i{patch}[\b{-}\i{prerel}]}
-
-The \ci{major}, \ci{minor}, and \ci{patch} components have the same meaning as
-in \i{semver}. The \ci{prerel} component is used to provide \i{continuous
-versioning} of our project between releases. Specifically, during development
-of a new version we may want to publish several pre-releases, for example,
-alpha or beta. In between those we may also want to publish a number of
-snapshots, for example, for CI. With continuous versioning all these releases,
-pre-releases, and snapshots are assigned unique, properly ordered versions.
-
-\N|Continuous versioning is a cornerstone of the \c{build2} project dependency
-management. In case of snapshots, an appropriate version is assigned
-automatically in cooperation with your VCS.|
-
-The \ci{prerel} component for a pre-release has the following form:
-
-\c{(\b{a}|\b{b})\b{.}\i{num}}
-
-Here \cb{a} stands for alpha, \cb{b} stands for beta, and \ci{num} is the
-alpha/beta number. For example:
-
-\
-1.1.0        # final              release  for 1.1.0
-1.2.0-a.1    # first  alpha   pre-release  for 1.2.0
-1.2.0-a.2    # second alpha   pre-release  for 1.2.0
-1.2.0-b.1    # first  beta    pre-release  for 1.2.0
-1.2.0        # final              release  for 1.2.0
-\
-
-The \ci{prerel} component for a snapshot has the following form:
-
-\c{(\b{a}|\b{b})\b{.}\i{num}\b{.}\i{snapsn}[\b{.}\i{snapid}]}
-
-Where \ci{snapsn} is the snapshot sequence number and \ci{snapid} is
-the snapshot id. In case of \c{git}, \ci{snapsn} is the commit timestamp
-in the \c{YYYYMMDDhhmmss} form and UTC timezone while \ci{snapid} is
-a 12-character abbreviated commit id. For example:
-
-\
-1.2.3-a.1.20180319215815.26efe301f4a7
-\
-
-Notice also that a snapshot version is ordered \i{after} the corresponding
-pre-release version. That is, \c{1.2.3-a.1\ <\ 1.2.3-a.1.1}. As a result, it
-is customary to start the development of a new version with \c{X.Y.Z-a.0.z},
-that is, a snapshot after the (non-existent) zero'th alpha release. \N{We will
-explain the meaning of \cb{z} in this version momentarily.} The following
-chronologically-ordered versions illustrate a typical release flow of a
-project that uses \c{git} as its VCS:
-
-\
-0.1.0-a.0.19700101000000               # snapshot (no commits yet)
-0.1.0-a.0.20180319215815.26efe301f4a7  # snapshot (first commit)
-...                                    # more commits/snapshots
-0.1.0-a.1                              # pre-release (first alpha)
-0.1.0-a.1.20180319221826.a6f0f41205b8  # snapshot
-...                                    # more commits/snapshots
-0.1.0-a.2                              # pre-release (second alpha)
-0.1.0-a.2.20180319231937.b701052316c9  # snapshot
-...                                    # more commits/snapshots
-0.1.0-b.1                              # pre-release (first beta)
-0.1.0-b.1.20180319242038.c812163417da  # snapshot
-...                                    # more commits/snapshots
-0.1.0                                  # release
-0.2.0-a.0.20180319252139.d923274528eb  # snapshot (first in 0.2.0)
-...
-\
-
-For a more detailed discussion of standard versioning and its support in
-\c{build2} refer to \l{b#module-version Version Module}.
-
-Let's now see how this works in practice by publishing a couple of versions
-for our \c{hello} project. By now it should be clear what that
-\c{0.1.0-a.0.19700101000000} means \- it is the first snapshot version of our
-project. Since there are no commits yet, it has the UNIX epoch as its commit
-timestamp. As the first step, let's try to commit our project and see what
-changes:
-
-\
-$ git add .
-$ git commit -m \"Start hello project\"
-
-$ bdep status
-hello configured 0.1.0-a.0.19700101000000
-      available  0.1.0-a.0.20180507062614.ee006880fc7e
-\
-
-Just like with changes to dependency information, \c{status} has detected that
-a new (snapshot) version of our project is available for synchronization.
-
-\N|Another way to view the project's version (which works even if we are
-not using \c{bdep}) is with the build system's \c{info} operation:
-
-\
-$ b info
-project: hello
-version: 0.1.0-a.0.20180507062614.ee006880fc7e
-summary: hello executable project
-...
-\
-
-|
-
-Let's synchronize with the default build configuration:
-
-\
-$ bdep sync
-synchronizing:
-  upgrade hello/0.1.0-a.0.20180507062614.ee006880fc7e
-
-$ bdep status
-hello configured 0.1.0-a.0.20180507062614.ee006880fc7e
-\
-
-\N|Notice that we didn't have to manually change the version anywhere. All we
-had to do was commit our changes and a new snapshot version was automatically
-derived by \c{build2} from the new \c{git} commit. Without this automation
-continuous versioning would hardly be practical.|
-
-If we now make another commit, we will see a similar picture:
-
-\
-$ bdep status
-hello configured 0.1.0-a.0.20180507062614.ee006880fc7e
-      available  0.1.0-a.0.20180507062615.8fb9de05b38f
-\
-
-\N|Note that you don't need to manually run \c{sync} after every commit. As
-discussed earlier, you can simply run the build system to update your project
-and things will get automatically synchronized if necessary.|
-
-Ok, time for our first release. Let's start with \c{0.1.0-a.1}. Unlike
-snapshots, for pre-releases as well as final releases we have to update the
-version in the \c{manifest} file manually:
-
-\
-version: 0.1.0-a.1
-\
-
-\N|The \c{manifest} file is the singular place where we specify the package
-version. The build system's \l{b#module-version \c{version} module} makes it
-available in various forms in buildfiles and even source code.|
-
-To ensure continuous versioning, this change to version must be the last commit
-for this (pre-)release which itself must be immediately followed by a second
-change to the version starting the development of the next (pre-)release. We
-also recommend that you tag the release commit with a tag name in the
-\c{\b{v}\i{X}.\i{Y}.\i{Z}} form.
-
-\N|Having regular release tag names with the \cb{v} prefix allows one to
-distinguish them from other tags, for example, with wildcard patterns.|
-
-Here is the release workflow for our example:
-
-\
-$ git commit -a -m \"Release version 0.1.0-a.1\"
-$ git tag -a v0.1.0-a.1 -m \"Tag version 0.1.0-a.1\"
-$ git push --follow-tags
-
-# Version 0.1.0-a.1 is now public.
-
-$ edit manifest  # change 'version: 0.1.0-a.1.z'
-$ git commit -a -m \"Change version to 0.1.0-a.1.z\"
-$ git push
-
-# Master is now open for business.
-\
-
-\N|In the future release management will be automated with a
-\c{bdep-release(1)} command.|
-
-Notice also that when specifying a snapshot version in \c{manifest} we use the
-special \cb{z} snapshot value (for example, \c{0.1.0-a.1.z}) which is
-recognized and automatically replaced by \c{build2} with, in case of \c{git},
-a commit timestamp and id (refer to \l{b#module-version Version Module} for
-details).
-
-Publishing the final release is exactly the same. For completeness, here
-are the commands:
-
-\
-$ edit manifest  # change 'version: 0.1.0'
-$ git commit -a -m \"Release version 0.1.0\"
-$ git tag -a v0.1.0 -m \"Tag version 0.1.0\"
-$ git push --follow-tags
-
-$ edit manifest  # change 'version: 0.2.0-a.0.z'
-$ git commit -a -m \"Change version to 0.2.0-a.0.z\"
-$ git push
-\
-
-\N|One sticky point of continuous versioning is choosing the next version.
-For example, above should we continue with \c{0.1.1-a.0}, \c{0.2.0-a.0},
-or \c{1.0.0-a.0}? The important rule to keep in mind is that we can jump
-forward to any further version at any time and without breaking continuous
-versioning. But we can never jump backwards.
-
-For example, we can start with \c{0.2.0-a.0} but if we later realize that this
-will actually be a new major release, we can easily change it to
-\c{1.0.0-a.0}. As a result, the general recommendation is to start
-conservatively by either incrementing the patch or the minor version
-component. The recommended strategy is to increment the minor component and,
-if required, release patch versions from a separate branch (created by
-branching off from the release commit).
-
-Note also that you don't have to make any pre-releases if you don't need them.
-While during development you would still keep the version as \c{X.Y.Z-a.0}, at
-release you simply change it directly to the final \c{X.Y.Z}.|
-
-When publishing the final release you may also want to clean up now
-obsolete pre-release tags. For example:
-
-\
-$ git tag -l 'v0.1.0-*' | xargs git push --delete origin
-$ git tag -l 'v0.1.0-*' | xargs git tag --delete
-\
-
-\N|While at first removing such tags may seem like a bad idea, pre-releases
-are by nature temporary and their use only makes sense until the final release
-is published.
-
-Also note that having a \c{git} repository with a large number of published
-but unused version tags may result in a significant download overhead.|
-
-Let's also briefly discuss in which situations we should increment each of the
-version components. While \i{semver} gives basic guidelines, there are several
-ways to apply them in the context of C/C++ where there is a distinction
-between binary and source compatibility. We recommend that you reserve
-\i{patch} releases for specific bug fixes and security issues that you can
-guarantee with a high level of certainty to be binary-compatible. Otherwise,
-if the changes are source-compatible, increment \i{minor}. And if they are
-breaking (that is, the user code likely will need adjustments), increment
-\i{major}. During early development, when breaking changes are frequent, it is
-customary to use the \c{0.Y.Z} versions where \c{Y} effectively becomes the
-\i{major} component. Again, refer to the \l{b#module-version Version Module}
-for a more detailed discussion of this topic.
-
-\h#guide-consume-pkg|Package Consumption|
-
-Ok, now that we have published a few releases of \c{hello}, how would the
-users of our project get them? While they could clone the repository and use
-\c{bdep} just like we did, this is more of a development rather than
-consumption workflow. For consumption it is much easier to use the package
-dependency manager, \l{bpkg(1)}, directly.
-
-First, we create a suitable build configuration with the
-\l{bpkg-cfg-create(1)} command. We can use the same place for building all our
-tools so let's call the directory \c{tools}. Seeing that we are only
-interested in using (rather than developing) such tools, let's build them
-optimized and also configure a suitable installation location:
-
-\
-$ bpkg create -d tools cc        \
-  config.cxx=g++                 \
-  config.cc.coptions=-O3         \
-  config.install.root=/usr/local \
-  config.install.sudo=sudo
-created new configuration in /tmp/tools/
-
-$ cd tools
-\
-
-\N|The \c{bdep} build configurations we were creating with \c{init\ -C} are
-actually \c{bpkg} build configurations. In fact, underneath, \l{bdep-init(1)}
-calls \l{bpkg-cfg-create(1)}.|
-
-To fetch and build packages (as well as all their dependencies) we use the
-\l{bpkg-pkg-build(1)} command. We can use either an archive-based repository
-like \l{https://cppget.org cppget.org} or build directly from \c{git}:
-
-\
-$ bpkg build hello@https://git.build2.org/hello/hello.git
-fetching from https://git.build2.org/hello/hello.git
-  new libformat/1.0.0 (required by libhello)
-  new libprint/1.0.0 (required by libhello)
-  new libhello/1.1.0 (required by hello)
-  new hello/1.0.0
-continue? [Y/n] y
-configured libformat/1.0.0
-configured libprint/1.0.0
-configured libhello/1.1.0
-configured hello/1.0.0
-c++ libprint-1.0.0/libprint/cxx{print}
-c++ hello-1.0.0/hello/cxx{hello}
-c++ libhello-1.1.0/libhello/cxx{hello}
-c++ libformat-1.0.0/libformat/cxx{format}
-ld libprint-1.0.0/libprint/libs{print}
-ld libformat-1.0.0/libformat/libs{format}
-ld libhello-1.1.0/libhello/libs{hello}
-ld hello-1.0.0/hello/exe{hello}
-updated hello/1.0.0
-\
-
-\N|Passing a repository URL to the \c{build} command is a shortcut to the
-following sequence of commands:
-
-\
-$ bpkg add https://git.build2.org/hello/hello.git  # add repository
-$ bpkg fetch                             # fetch package list
-$ bpkg build hello                       # build package by name
-\
-
-|
-
-Once built, we can install the package to the location that we have specified
-with \c{config.install.root} using the \l{bpkg-pkg-install(1)} command:
-
-\
-$ bpkg install hello
-...
-install libformat-1.0.0/libformat/libs{format}
-install libprint-1.0.0/libprint/libs{print}
-install libhello-1.1.0/libhello/libs{hello}
-install hello-1.0.0/hello/exe{hello}
-
-$ hello World
-Hello, World!
-\
-
-\N|If on your system the installed executables don't run from \c{/usr/local}
-because of the unresolved shared libraries (or if you are installing somewhere
-else, such as \c{/opt}), then the easiest way to fix this is with \i{rpath}.
-Simply add the following configuration variable when creating the build
-configuration (or as an argument to the \c{install} command):
-
-\
-config.bin.rpath=/usr/local/lib
-\
-
-|
-
-If we need to uninstall a previously installed package, there is the
-\l{bpkg-pkg-uninstall(1)} command:
-
-\
-$ bpkg uninstall hello
-uninstall hello-1.0.0/hello/exe{hello}
-uninstall libhello-1.1.0/libhello/libs{hello}
-uninstall libprint-1.0.0/libprint/libs{print}
-uninstall libformat-1.0.0/libformat/libs{format}
-...
-\
-
-To upgrade or downgrade packages we again use the \c{build} command. Here
-is a typical upgrade workflow:
-
-\
-$ bpkg fetch              # refresh available package list
-$ bpkg status             # see if new versions are available
-
-$ bpkg uninstall hello    # uninstall old version
-$ bpkg build     hello    # upgrade to the latest version
-$ bpkg install   hello    # install new version
-\
-
-Similar to \c{bdep}, to downgrade we have to specify the desired version
-explicitly. There are also the \c{--upgrade|-u} and \c{--patch|-p} as well as
-\c{--immediate|-i} and \c{--recursive|-r} options that allow us to upgrade or
-patch packages that we have built and/or their immediate or all dependencies
-(see \l{bpkg-pkg-build(1)} for details). For example, to make sure everything
-is patched, run:
-
-\
-$ bpkg fetch
-$ bpkg build -pr
-\
-
-If a package is no longer needed, we can remove it from the configuration with
-\l{bpkg-pkg-drop(1)}:
-
-\
-$ bpkg drop hello
-following dependencies were automatically built but
-will no longer be used:
-  libhello
-  libformat
-  libprint
-drop unused packages? [Y/n] y
-  drop hello
-  drop libhello
-  drop libformat
-  drop libprint
-continue? [Y/n] y
-purged hello
-purged libhello
-purged libformat
-purged libprint
-\
-"