Drop C++14 compatibility (#6403)

* Drop C++14 compatibility
Closes #6384 For reasons, see there.

* Test: build without GPU on Ubuntu 20.04

* Test 2: WITH_CUDA=OFF

* Switch tutorials CI to 24.04

Author: mvieth

.ci/azure-pipelines/azure-pipelines.yaml

@@ -50,14 +50,14 @@ stages:
               CONTAINER: env2004
               CC: gcc
               CXX: g++
-              BUILD_GPU: ON
-              CMAKE_ARGS: '-DPCL_WARNINGS_ARE_ERRORS=ON -DCMAKE_CXX_STANDARD=14 -DCMAKE_CUDA_STANDARD=14'
+              BUILD_GPU: OFF
+              CMAKE_ARGS: '-DWITH_CUDA=OFF -DPCL_WARNINGS_ARE_ERRORS=ON'
             24.04 GCC:  # latest Ubuntu
               CONTAINER: env2404
               CC: gcc
               CXX: g++
               BUILD_GPU: ON
-              CMAKE_ARGS: '-DCMAKE_CXX_STANDARD=17 -DCMAKE_CUDA_STANDARD=17'
+              CMAKE_ARGS: ''
         container: $[ variables['CONTAINER'] ]
         timeoutInMinutes: 0
         variables:

.ci/azure-pipelines/docs-pipeline.yaml

@@ -18,8 +18,8 @@ resources:
   containers:
     - container: doc # for documentation.yaml
       image: pointcloudlibrary/doc
-    - container: env2204 # for tutorials.yaml
-      image: pointcloudlibrary/env:22.04
+    - container: env2404 # for tutorials.yaml
+      image: pointcloudlibrary/env:24.04
 
 stages:
   - stage: formatting

.ci/azure-pipelines/tutorials.yaml

@@ -2,8 +2,8 @@ jobs:
   - job: tutorials
     displayName: Building Tutorials
     pool:
-      vmImage: 'ubuntu-22.04'
-    container: env2204
+      vmImage: 'ubuntu-24.04'
+    container: env2404
     timeoutInMinutes: 0
     variables:
       BUILD_DIR: '$(Agent.BuildDirectory)/build'

CMakeLists.txt

@@ -2,22 +2,18 @@
 cmake_minimum_required(VERSION 3.16.3 FATAL_ERROR)
 
 # Set target C++ standard and required compiler features
-set(CMAKE_CXX_STANDARD 17 CACHE STRING "The target C++ standard. PCL requires C++14 or higher.")
+set(CMAKE_CXX_STANDARD 17 CACHE STRING "The target C++ standard. PCL requires C++17 or higher.")
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 if("${CMAKE_CXX_STANDARD}" GREATER_EQUAL 17)
   set(PCL_CXX_COMPILE_FEATURES cxx_std_17)
   set(PCL__cplusplus 201703L)
   set(PCL_REQUIRES_MSC_VER 1912)
-elseif("${CMAKE_CXX_STANDARD}" EQUAL 14)
-  set(PCL_CXX_COMPILE_FEATURES cxx_std_14)
-  set(PCL__cplusplus 201402L)
-  set(PCL_REQUIRES_MSC_VER 1900)
 else()
-  message(FATAL_ERROR "Unknown or unsupported C++ standard specified")
+  message(FATAL_ERROR "Unknown or unsupported C++ standard specified. PCL requires C++17 or higher")
 endif()
 
-set(CMAKE_CUDA_STANDARD 17 CACHE STRING "The target CUDA/C++ standard. PCL requires CUDA/C++ 14 or higher.")
+set(CMAKE_CUDA_STANDARD 17 CACHE STRING "The target CUDA/C++ standard. PCL requires CUDA/C++ 17 or higher.")
 set(CMAKE_CUDA_STANDARD_REQUIRED ON)
 
 set(CMAKE_CONFIGURATION_TYPES "Debug;Release" CACHE STRING "possible configurations" FORCE)