[bug#47447] [PATCH] gnu: Add entt.

[Alexandru-Sergiu Marton <brown121407@posteo.ro>]

* gnu/packages/cpp.scm (entt): New variable.
(entt-fixed-tests): New variable.
---
 gnu/packages/cpp.scm | 51 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/gnu/packages/cpp.scm b/gnu/packages/cpp.scm
index 2a00d3838a..449b4c1c06 100644
--- a/gnu/packages/cpp.scm
+++ b/gnu/packages/cpp.scm
@@ -18,7 +18,7 @@
 ;;; Copyright © 2020 Brett Gilio <brettg@gnu.org>
 ;;; Copyright © 2020 Milkey Mouse <milkeymouse@meme.institute>
 ;;; Copyright © 2021 Raghav Gururajan <rg@raghavgururajan.name>
-
+;;; Copyright © 2021 Alexandru-Sergiu Marton <brown121407@posteo.ro>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -57,6 +57,7 @@
   #:use-module (gnu packages curl)
   #:use-module (gnu packages documentation)
   #:use-module (gnu packages gcc)
+  #:use-module (gnu packages graphviz)
   #:use-module (gnu packages libevent)
   #:use-module (gnu packages libunwind)
   #:use-module (gnu packages linux)
@@ -1211,3 +1212,51 @@ of reading and writing XML.")
     ;; incompatible with the GPL v2.  Refer to the file named FLOSSE for the
     ;; details.
     (license license:gpl2+)))
+
+;; TODO: Make public and remove the fix below when the next release comes and
+;; fixes the failing tests.
+(define entt
+  (package
+    (name "entt")
+    (version "3.6.0")
+    (source (origin
+              (method git-fetch)
+              (uri (git-reference
+                    (url "https://github.com/skypjack/entt")
+                    (commit (string-append "v" version))))
+              (file-name (git-file-name name version))
+              (sha256
+               (base32
+                "17w0gx6xah8j2d1kc6ly7a8jvkp4jspmn505w724hynlvlx1192x"))))
+    (build-system cmake-build-system)
+    (arguments
+     `(#:configure-flags (list "-DENTT_BUILD_TESTING=ON"
+                               "-DENTT_FIND_GTEST_PACKAGE=ON"
+                               "-DENTT_BUILD_DOCS=ON")))
+    (native-inputs
+     `(("googletest" ,googletest)
+       ("doxygen" ,doxygen)     ; These two packages are needed for
+       ("graphviz" ,graphviz))) ; generating the documentation.
+    (synopsis "Fast and reliable entity component system (ECS)")
+    (description "EnTT is a header-only, tiny and easy to use library for game
+programming and much more written in modern C++.")
+    (home-page "https://github.com/skypjack/entt")
+    (license (list license:expat        ; for the code
+                   license:cc-by4.0)))) ; for the docs
+
+(define-public entt-fixed-tests
+  ;; This commit fixes two tests that are failing on the 3.6.0 version.
+  (let ((commit "14915368c7d4fa87e944cb55ffae1bb88cc6ef4c")
+        (revision "1"))
+    (package
+      (inherit entt)
+      (name "entt")
+      (version (git-version "v3.6.0" revision commit))
+      (source (origin
+                (inherit (package-source entt))
+                (uri (git-reference
+                      (url "https://github.com/skypjack/entt")
+                      (commit commit)))
+                (sha256
+                 (base32
+                  "1amlr4amj94xnmbdz94292vfkxbl92azsr5s41vcqqjmarwkkhfh")))))))
-- 
2.31.0