chore(3p/immer): Remove vendored copy of immer r/2029

We ended up dropping the use of this library again.

Change-Id: I2c44cd22a6128d23f87a582402bf5fb84991d608
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2292
Tested-by: BuildkiteCI
Reviewed-by: Profpatsch <mail@profpatsch.de>

1 files changed, 0 insertions, 225 deletions

diff --git a/third_party/immer/README.rst b/third_party/immer/README.rst
deleted file mode 100644
index afa2fecbb3bc..000000000000
--- a/third_party/immer/README.rst
+++ /dev/null
@@ -1,225 +0,0 @@
-
-.. image:: https://travis-ci.org/arximboldi/immer.svg?branch=master
-   :target: https://travis-ci.org/arximboldi/immer
-   :alt: Travis Badge
-
-.. image:: https://codecov.io/gh/arximboldi/immer/branch/master/graph/badge.svg
-   :target: https://codecov.io/gh/arximboldi/immer
-   :alt: CodeCov Badge
-
-.. image:: https://cdn.rawgit.com/arximboldi/immer/355a113782aedc2ea22463444014809269c2376d/doc/_static/sinusoidal-badge.svg
-   :target: https://sinusoid.al
-   :alt: Sinusoidal Engineering badge
-   :align: right
-
-.. raw:: html
-
-   <img width="100%" src="https://cdn.rawgit.com/arximboldi/immer/3888170d247359cc0905eed548cd46897caef0f4/doc/_static/logo-front.svg" alt="Logotype"/>
-
-.. include:introduction/start
-
-**immer** is a library of persistent_ and immutable_ data structures
-written in C++.  These enable whole new kinds of architectures for
-interactive and concurrent programs of striking simplicity,
-correctness, and performance.
-
-.. _persistent: https://en.wikipedia.org/wiki/Persistent_data_structure
-.. _immutable:  https://en.wikipedia.org/wiki/Immutable_object
-
-* **Documentation** (Contents_)
-* **Code** (GitHub_)
-* **CppCon'17 Talk**: *Postmodern Immutable Data Structures* (YouTube_, Slides_)
-* **ICFP'17 Paper**: *Persistence for the masses* (Preprint_)
-
-.. _contents: https://sinusoid.es/immer/#contents
-.. _github: https://github.com/arximboldi/immer
-.. _youtube: https://www.youtube.com/watch?v=sPhpelUfu8Q
-.. _slides: https://sinusoid.es/talks/immer-cppcon17
-.. _preprint: https://public.sinusoid.es/misc/immer/immer-icfp17.pdf
-
-
-  .. raw:: html
-
-     <a href="https://www.patreon.com/sinusoidal">
-         <img align="right" src="https://cdn.rawgit.com/arximboldi/immer/master/doc/_static/patreon.svg">
-     </a>
-
-  This library has full months of *pro bono* research and development
-  invested in it.  This is just the first step in a long-term vision
-  of making interactive and concurrent C++ programs easier to
-  write. **Put your logo here and help this project's long term
-  sustainability by buying a sponsorship package:** immer@sinusoid.al
-
-.. include:index/end
-
-Example
--------
-
-.. github does not support the ``literalinclude`` directive.  This
-   example is copy pasted from ``example/vector/intro.cpp``
-
-.. code-block:: c++
-
-   #include <immer/vector.hpp>
-   int main()
-   {
-       const auto v0 = immer::vector<int>{};
-       const auto v1 = v0.push_back(13);
-       assert(v0.size() == 0 && v1.size() == 1 && v1[0] == 13);
-
-       const auto v2 = v1.set(0, 42);
-       assert(v1[0] == 13 && v2[0] == 42);
-   }
-..
-
-  For a **complete example** check `Ewig, a simple didactic
-  text-editor <https://github.com/arximboldi/ewig>`_ built with this
-  library.  You may also wanna check `Lager, a Redux-like library
-  <https://github.com/arximboldi/lager>`_ for writting interactive
-  software in C++ using a value-oriented design.
-
-
-Why?
-----
-
-In the last few years, there has been a growing interest in immutable
-data structures, motivated by the horizontal scaling of our processing
-power and the ubiquity of highly interactive systems.  Languages like
-Clojure_ and Scala_ provide them by default, and implementations
-for JavaScript like Mori_ and Immutable.js_ are widely used,
-specially in combination with modern UI frameworks like React_.
-
-Interactivity
-    Thanks to *persistence* and *structural sharing*, new values can
-    be efficiently compared with old ones.  This enables simpler ways of
-    *reasoning about change* that sit at the core of modern
-    interactive systems programming paradigms like `reactive
-    programming`_.
-
-Concurrency
-    Passing immutable data structures by value does not need to copy
-    any data. In the absence of mutation, data can be safely read
-    from multiple concurrent processes, and enable concurrency
-    patterns like `share by communicating`_ efficiently.
-
-Parallelism
-   Some recent immutable data structures have interesting properties
-   like :math:`O(log(n))` concatenation, which enable new kinds of
-   `parallelization algorithms`_.
-
-.. _clojure: http://clojure.org/reference/data_structures
-.. _scala: http://docs.scala-lang.org/overviews/collections/overview.html
-
-.. _mori: https://swannodette.github.io/mori/
-.. _immutable.js: https://github.com/facebook/immutable-js
-.. _react: https://facebook.github.io/react/
-
-.. _reactive programming: https://en.wikipedia.org/wiki/Reactive_programming
-.. _share by communicating: https://blog.golang.org/share-memory-by-communicating
-.. _parallelization algorithms: http://docs.scala-lang.org/overviews/parallel-collections/overview.html
-
-Features
---------
-
-Idiomatic
-    This library doesn't pretend that it is written in Haskell.  It
-    leverages features from recent standards to provide an API that is
-    both efficient and natural for a C++ developer.
-
-Performant
-    You use C++ because you need this.  *Immer* implements state of
-    the art data structures with efficient cache utilization and have
-    been proven production ready in other languages.  It also includes
-    our own improvements over that are only possible because of the
-    C++'s ability to abstract over memory layout.  We monitor the
-    performance impact of every change by collecting `benchmark
-    results`_ directly from CI.
-
-.. _benchmark results: https://public.sinusoid.es/misc/immer/reports/
-
-Customizable
-    We leverage templates and `policy-based design`_ to build
-    data-structures that can be adapted to work efficiently for
-    various purposes and architectures, for example, by choosing among
-    various `memory management strategies`.  This turns
-    *immer* into a good foundation to provide immutable data
-    structures to higher level languages with a C runtime, like
-    Python_ or Guile_.
-
-.. _python: https://www.python.org/
-.. _guile: https://www.gnu.org/software/guile/
-.. _policy-based design: https://en.wikipedia.org/wiki/Policy-based_design
-.. _memory management strategies: https://sinusoid.es/immer/memory.html
-
-Dependencies
-------------
-
-This library is written in **C++14** and a compliant compiler is
-necessary.  It is `continuously tested`_ with Clang 3.8 and GCC 6, but
-it might work with other compilers and versions.
-
-No external library is necessary and there are no other requirements.
-
-.. _continuously tested: https://travis-ci.org/arximboldi/immer
-
-Usage
------
-
-This is a **header only** library.  You can just copy the ``immer``
-subfolder somewhere in your *include path*.
-
-If you are using the `Nix package manager`_ (we strongly recommend it)
-you can just::
-
-    nix-env -if https://github.com/arximboldi/immer/archive/master.tar.gz
-
-Alternatively, you can use `CMake`_ to install the library in your
-system once you have manually cloned the repository::
-
-    mkdir -p build && cd build
-    cmake .. && sudo make install
-
-.. _nix package manager: https://nixos.org/nix
-.. _cmake: https://cmake.org/
-
-Development
------------
-
-In order to develop the library, you will need to compile and run the
-examples, tests and benchmarks.  These require some additional tools.
-The easiest way to install them is by using the `Nix package
-manager`_.  At the root of the repository just type::
-
-    nix-shell
-
-This will download all required dependencies and create an isolated
-environment in which you can use these dependencies, without polluting
-your system.
-
-Then you can proceed to generate a development project using `CMake`_::
-
-    mkdir build && cd build
-    cmake ..
-
-From then on, one may build and run all tests by doing::
-
-    make check
-
-In order to build and run all benchmarks when running ``make check``,
-run ``cmake`` again with the option ``-DCHECK_BENCHMARKS=1``.  The
-results of running the benchmarks will be saved to a folder
-``reports/`` in the project root.
-
-License
--------
-
-**This software is licensed under the Boost Software License 1.0**.
-
-.. image:: https://upload.wikimedia.org/wikipedia/commons/c/cd/Boost.png
-   :alt: Boost logo
-   :target: http://boost.org/LICENSE_1_0.txt
-   :align: right
-
-The full text of the license is can be accessed `via this link
-<http://boost.org/LICENSE_1_0.txt>`_ and is also included
-in the ``LICENSE`` file of this software package.