Address @robinlinden comments.

Improve the Bazel build. Attempt to fix previous errors recorded while
trying to publish ftxui in the Bazel Central Registry:
- https://github.com/bazelbuild/bazel-central-registry/pull/4485
- https://buildkite.com/bazel/bcr-presubmit/builds/13601#01968b61-f5b2-4d16-94d0-c87a03a1a23b

Test against "recent" platforms
-------------------------------

Previously, I got the error:
```
gcc: error: unrecognized command line option '-std-c++20'; did you mean '-std-c++2a'?
```
This was due to using old distribution like ubuntu 2004. Test against
newer platforms only to avoid GCC version<-9.x.y

Downgrade gtest version.
------------------------

I suspect this caused the Bazel Central Registry error:
```
file:///workdir/modules/googletest/1.15.2/MODULE.bazel:68:20: name 'use_repo_rule' is not defined
```
I hoped using a lower version will fix the issue.

Tag gtest as dev_dependency
---------------------------

Presumably, this should avoid dependants to fetch it?

Enable --features-layering_check
--------------------------------

Aka clang `-Wprivate-header`. Fix the encountered errors.

Use clang in the CI
-------------------

The CI was defining clang/gcc in the matrix, but was not using it. Fix
the bug.

.bazelrc

@@ -1,7 +1,2 @@
 build --features=layering_check
 build --enable_bzlmod
-
-build --enable_platform_specific_config
-build:linux --cxxopt=-std=c++20
-build:macos --cxxopt=-std=c++20
-build:windows --cxxopt=-std:c++20

.bcr/presubmit.yml

@@ -1,36 +1,26 @@
 matrix:
-  bazel:
-    - 7.x
-    - 8.x
-    - rolling
-  unix_platform:
+  # Note that gcc 9 and earlier aren't supported due to using --std=c++2a
+  # instead of --std=c++20
+  platform:
   - debian11
   - ubuntu2204
   - macos
-    - macos_arm64
-  win_platform:
+  - macos-arm64
   - windows
-
+  bazel:
+  #- 6.x -> Build fails with bazel 6.x
+  - 7.x
+  - 8.x
 tasks:
-
-  unix_test:
-    name: Verify build targets on Unix
-    platform: ${{ unix_platform }}
+  verify_targets:
+    name: Build and test.
+    platform: ${{ platform }}
     bazel: ${{ bazel }}
-    build_flags:
-    - --cxxopt=-std=c++20
     build_targets:
+    - '@ftxui//:ftxui'
+    - '@ftxui//:screen'
     - '@ftxui//:dom'
     - '@ftxui//:component'
-    - '@ftxui//:screen'
+    test_targets:
+    - '@ftxui//:tests'
 
-  windows_test:
-    name: Verify build targets
-    platform: ${{ win_platform }}
-    bazel: ${{ bazel }}
-    build_flags:
-    - --cxxopt=/std:c++20
-    build_targets:
-    - '@ftxui//:dom'
-    - '@ftxui//:component'
-    - '@ftxui//:screen'

BUILD.bazel

@@ -12,6 +12,7 @@
 load("@rules_cc//cc:defs.bzl", "cc_binary", "cc_library", "cc_test")
 load(":bazel/ftxui.bzl", "ftxui_cc_library")
 load(":bazel/ftxui.bzl", "generate_examples")
+load(":bazel/ftxui.bzl", "cpp20")
 load(":bazel/ftxui.bzl", "windows_copts")
 load(":bazel/ftxui.bzl", "pthread_linkopts")
 
@@ -257,7 +258,7 @@ cc_test(
         "include",
         "src",
     ],
-    copts = windows_copts(),
+    copts = cpp20() + windows_copts(),
     deps = [
         ":screen",
         ":dom",

CHANGELOG.md

@@ -1,20 +1,9 @@
 Changelog
 =========
 
-6.1.9 (2025-05-07)
+Future release
 ------------
 
-### Build
-If all goes well (pending), ftxui should appear in the Bazel central repository.
-It can be imported into your project using the following lines:
-
-**MODULE.bazel**
-```bazel
-bazel_dep(name = "ftxui", version = "6.1.9")
-```
-
-Thanks @robinlinden and @kcc for the reviews.
-
 ### dom
 - Bugfix: Restore the `dbox` behavior from ftxui 5.0.0. To apply bgcolor
   blending between the two layers, a new `dboxBlend` will be added.
@@ -25,6 +14,13 @@ Thanks @robinlinden and @kcc for the reviews.
 ### Build
 - Feature: Support `bazel` build system. See #1032.
   Proposed by Kostya Serebryany @kcc
+  If all goes well (pending), it should appear in the Bazel central repository.
+  It can be imported into your project using the following lines:
+
+  **MODULE.bazel**
+  ```bazel
+  bazel_dep(name = "ftxui", version = "6.1.8")
+  ```
 
   **BUILD.bazel**
   ```bazel

CMakeLists.txt

@@ -2,7 +2,7 @@ cmake_minimum_required(VERSION 3.12)
 
 project(ftxui
   LANGUAGES CXX
-  VERSION 6.1.9
+  VERSION 6.1.8
   DESCRIPTION "C++ Functional Terminal User Interface."
 )
 

MODULE.bazel

@@ -1,7 +1,7 @@
 # FTXUI module.
 module(
     name = "ftxui",
-    version = "6.1.9",
+    version = "6.1.8",
     compatibility_level = 6,
 )
 

README.md

@@ -348,7 +348,6 @@ Feel free to add your projects here:
 - [terminal-rain](https://github.com/Oakamoore/terminal-rain)
 - [keywords](https://github.com/Oakamoore/keywords) ([Play web version :heart:](https://oakamoore.itch.io/keywords))
 - [FTB - tertminal file browser](https://github.com/Cyxuan0311/FTB)
-- [SHOOT!](https://github.com/ShingZhanho/ENGG1340-Project-25Spring)
 
 ### [cpp-best-practices/game_jam](https://github.com/cpp-best-practices/game_jam)
 
@@ -373,7 +372,7 @@ include(FetchContent)
 
 FetchContent_Declare(ftxui
   GIT_REPOSITORY https://github.com/ArthurSonzogni/ftxui
-  GIT_TAG v6.1.9
+  GIT_TAG v6.1.8
 )
 
 FetchContent_GetProperties(ftxui)

bazel/ftxui.bzl

@@ -3,6 +3,24 @@
 load("@rules_cc//cc:defs.bzl", "cc_library")
 load("@rules_cc//cc:defs.bzl", "cc_binary")
 
+def cpp17():
+    return select({
+        "@rules_cc//cc/compiler:msvc-cl": ["/std:c++17"],
+        "@rules_cc//cc/compiler:clang-cl": ["/std:c++17"],
+        "@rules_cc//cc/compiler:clang": ["-std=c++17"],
+        "@rules_cc//cc/compiler:gcc": ["-std=c++17"],
+        "//conditions:default": ["-std=c++17"],
+    })
+
+def cpp20():
+    return select({
+        "@rules_cc//cc/compiler:msvc-cl": ["/std:c++20"],
+        "@rules_cc//cc/compiler:clang-cl": ["/std:c++20"],
+        "@rules_cc//cc/compiler:clang": ["-std=c++20"],
+        "@rules_cc//cc/compiler:gcc": ["-std=c++20"],
+        "//conditions:default": ["-std=c++20"],
+    })
+
 # Microsoft terminal is a bit buggy ¯\_(ツ)_/¯ and MSVC uses bad defaults.
 def windows_copts():
     MSVC_COPTS = [
@@ -72,7 +90,7 @@ def ftxui_cc_library(
             "include",
             "src",
         ],
-        copts = windows_copts(),
+        copts = cpp17() + windows_copts(),
         visibility = ["//visibility:public"],
     )
 
@@ -100,5 +118,5 @@ def generate_examples():
               ":dom",
               ":screen",
             ],
-            copts = windows_copts(),
+            copts = cpp20() + windows_copts(),
         )

tools/test_bazel.sh

@@ -1,8 +1,14 @@
 # This script tests the project with different versions of Bazel and compilers
 # locally. This avoids waiting on the CI to run the tests.
 
+# Version
+# -------
+# - Version >= 7 are supported
+# - Version <= 6 fail with the error:
+#   Error:
+#     external/googletest~1.14.0.bcr.1/googletest/include/gtest/internal/gtest-port.h:279:2:
+#     error: #error C++ versions less than C++14 are not supported.
 for ver in \
-  "6.0.0" \
   "7.0.0" \
   "8.0.0"
 do