gnu: msgpack: Deprecate with msgpack-c.

* gnu/packages/serialization.scm (msgpack-c): New variable.
(msgpack-cxx): New variable.
(msgpack): Rename to...
(msgpack-3): ... this, and inherit from msgpack-c.
* gnu/packages/vim.scm (eovim) [arguments]: Add help-cmake-find-msgpack-c
phase.
[inputs]: Replace msgpack with msgpack-c.
* gnu/packages/terminals.scm (tmate)
[inputs]: Replace msgpack with msgpack-3.
* gnu/packages/networking.scm (opendht)
[propagated-inputs]: Replace msgpack with msgpack-cxx.
* gnu/packages/chemistry.scm (mmtf-cpp) [propagated-inputs]: Likewise.

gnu/packages/chemistry.scm

@@ -263,7 +263,7 @@ molecules.")
     (arguments '(#:tests? #f))
     ;; There is no support for modern msgpack versions yet (see:
     ;; https://github.com/rcsb/mmtf-cpp/issues/44).
-    (propagated-inputs (list msgpack))  ;included by mmtf/structure_data.hpp
+    (propagated-inputs (list msgpack-3)) ;included by mmtf/structure_data.hpp
     (home-page "https://mmtf.rcsb.org/")
     (synopsis "C++ API for the Macromolecular Transmission Format")
     (description "This package is a library for the

gnu/packages/networking.scm

@@ -3888,7 +3888,7 @@ and targeted primarily for asynchronous processing of HTTP-requests.")
            fmt
            readline))
     (propagated-inputs
-     (list msgpack                      ;included in several installed headers
+     (list msgpack-cxx                  ;included in several installed headers
            restinio-0.6                 ;included in opendht/http.h
            ;; The following are listed in the 'Requires.private' field of
            ;; opendht.pc:

gnu/packages/serialization.scm

@@ -15,6 +15,7 @@
 ;;; Copyright © 2023 Alexey Abramov <levenson@mmer.org>
 ;;; Copyright © 2023 Sharlatan Hellseher <sharlatanus@gmail.com>
 ;;; Copyright © 2023 Vinicius Monego <monego@posteo.net>
+;;; Copyright © 2023 Maxim Cournoyer <maxim.cournoyer@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -219,8 +220,60 @@ such as compact binary encodings, XML, or JSON.")
      (list doxygen gcc-10
            (package-source cereal)))))
 
-(define-public msgpack
+(define-public msgpack-c
   (package
+    (name "msgpack-c")
+    (version "6.0.0")
+    (source
+     (origin
+       (method url-fetch)
+       (uri
+        (string-append
+         "https://github.com/msgpack/msgpack-c/releases/download/"
+         "c-" version "/" name "-" version ".tar.gz"))
+       (sha256
+        (base32 "1fmf08babfsjq5qkgw034wk2nw6mayxp1qlkm7h55p2jqvigam1n"))
+       (snippet
+        '(let ((p (open-file "msgpack-c.pc.in" "a")))
+           (display "Requires: zlib\n" p)
+           (close-output-port p)))))
+    (build-system cmake-build-system)
+    (arguments (list #:configure-flags #~(list "-DMSGPACK_BUILD_TESTS=ON")))
+    (native-inputs (list googletest))
+    (propagated-inputs (list zlib))  ;zbuffer.h includes zlib.h
+    (home-page "https://www.msgpack.org")
+    (synopsis "Binary serialization library")
+    (description "Msgpack is a library for C that implements binary
+serialization.")
+    (license license:boost1.0)))
+
+(define-public msgpack-cxx
+  (package
+    (inherit msgpack-c)
+    (name "msgpack-cxx")
+    (version "6.1.0")
+    (source
+     (origin
+       (method url-fetch)
+       (uri
+        (string-append
+         "https://github.com/msgpack/msgpack-c/releases/download/"
+         "cpp-" version "/" name "-" version ".tar.gz"))
+       (sha256
+        (base32 "1rrrf3nskcv994z3pbq6a5z2021piz118rccmm1y7zlf7klygv93"))))
+    (build-system cmake-build-system)
+    (propagated-inputs (list boost zlib)) ;included in headers
+    (description "Msgpack is a library for C++ that implements binary
+serialization.")))
+
+;;; The msgpack package was split into msgpack-c and msgpack-cxx starting from
+;;; version 4.0.0.
+(define-public msgpack
+  (deprecated-package "msgpack" msgpack-c))
+
+(define-public msgpack-3
+  (package
+    (inherit msgpack-c)
     (name "msgpack")
     (version "3.3.0")
     (source
@@ -234,23 +287,13 @@ such as compact binary encodings, XML, or JSON.")
         '(let ((p (open-file "msgpack.pc.in" "a")))
            (display
             (string-append "Requires: " "zlib" "\n") p)
-           (close-output-port p)
-           #t))
+           (close-output-port p)))
        (sha256
         (base32 "0yzhq50ijvwrfkr97knhvn54lj3f4hr3zy39yq8wpf6xll94s4bf"))))
-    (build-system cmake-build-system)
-    (native-inputs
-     (list googletest-1.8 pkg-config))
-    (propagated-inputs
-     (list zlib)) ;; Msgpack installs two headers (zbuffer.h,
-    ;; zbuffer.hpp) which #include <zlib.h>.  However, 'guix gc --references'
-    ;; does not detect a store reference to zlib since these headers are not
-    ;; compiled.
-    (home-page "https://www.msgpack.org")
-    (synopsis "Binary serialization library")
+    (native-inputs (list googletest-1.8))
     (description "Msgpack is a library for C/C++ that implements binary
-serialization.")
-    (license license:boost1.0)))
+serialization.  This is the legacy version that predates the split into C and
+C++ specific packages.")))
 
 (define-public libmpack
   (package

gnu/packages/terminals.scm

@@ -1289,10 +1289,8 @@ that can be displayed terminal.")
         (base32
          "0x5c31yq7ansmiy20a0qf59wagba9v3pq97mlkxrqxn4n1gcc6vi"))))
     (build-system gnu-build-system)
-    (inputs
-     (list libevent libssh msgpack ncurses))
-    (native-inputs
-     (list autoconf automake pkg-config))
+    (inputs (list libevent libssh msgpack-3 ncurses))
+    (native-inputs (list autoconf automake pkg-config))
     (home-page "https://tmate.io/")
     (synopsis "Terminal sharing application")
     (description "tmate is a terminal sharing application that allows you to

gnu/packages/vim.scm

@@ -884,6 +884,14 @@ refactor Vim in order to:
      '(#:tests? #false ;no tests
        #:phases
        (modify-phases %standard-phases
+         (add-after 'unpack 'help-cmake-find-msgpack-c
+           (lambda _
+             ;; Patch the build system so that it can find the modern
+             ;; 'msgpack-c' named pkg-config file (see:
+             ;; https://github.com/jeanguyomarch/eovim/issues/73).
+             (substitute* "cmake/Modules/FindMsgPack.cmake"
+               (("MSGPACK QUIET msgpack")
+                "MSGPACK QUIET msgpack-c msgpack"))))
          (add-after 'configure 'reference-nvim
            (lambda* (#:key inputs #:allow-other-keys)
              (let ((nvim (search-input-file inputs "/bin/nvim")))
@@ -894,10 +902,8 @@ refactor Vim in order to:
                   (string-append start nvim))))))
          (add-before 'build 'set-home
            (lambda _ (setenv "HOME" "/tmp"))))))
-    (native-inputs
-     (list pkg-config))
-    (inputs
-     (list efl msgpack neovim))
+    (native-inputs (list pkg-config))
+    (inputs (list efl msgpack-c neovim))
     (home-page "https://github.com/jeanguyomarch/eovim/")
     (synopsis "EFL GUI for Neovim")
     (description "Graphical Neovim interface based on the @acronym{EFL, Enlightenment