From: Hans Johnson <hans-johnson@uiowa.edu>
Date: Wed, 16 Jan 2019 15:13:36 +0000 (-0600)
Subject: BUG:  CMake 2.8.4 does not support required features
X-Git-Tag: 1.9.9-b1~534
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b211125c7620edd1f0c138a735a14309bcd8202c;p=thirdparty%2Fzlib-ng.git

BUG:  CMake 2.8.4 does not support required features

CMake Error at CMakeLists.txt:682 (target_include_directories):
  Unknown CMake command "target_include_directories".

target_include_directories was introduced in cmake 3

C_STANDARD 99 support was added in cmake 3.1

Ubuntu 16.04 (Xenial) was distributed with cmake 3.5.1 by default.

CMake versions > 3.3 allow simplified implementations of modern
cmake compilation support.

===
For newer versions of cmake (upto a maximum validated version [3.13.2 in this case]),
use newer cmake policies available.  The newer policies often provide better
diagnostics for subtle build related issues.
---

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 67b1dc5f..a9469733 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,10 @@
-cmake_minimum_required(VERSION 2.8.4)
+cmake_minimum_required(VERSION 3.5.1)
+if(CMAKE_VERSION VERSION_LESS 3.12)
+  cmake_policy(VERSION ${CMAKE_VERSION})
+else()
+  cmake_policy(VERSION 3.5.1...3.13.2)
+endif()
+
 set(CMAKE_MACOSX_RPATH 1)
 
 project(zlib C)
@@ -20,13 +26,7 @@ include(CheckCSourceRuns)
 include(FeatureSummary)
 
 # Enable C99
-if (CMAKE_VERSION VERSION_LESS "3.1")
-    if (CMAKE_C_COMPILER_ID STREQUAL "GNU")
-        set (CMAKE_C_FLAGS "-std=c99 ${CMAKE_C_FLAGS}")
-    endif ()
-else ()
-    set (CMAKE_C_STANDARD 99)
-endif ()
+set (CMAKE_C_STANDARD 99)
 
 # make sure we use an appropriate BUILD_TYPE by default, "Release" to be exact
 # this should select the maximum generic optimisation on the current platform (i.e. -O3 for gcc/clang)