I tried running CMake version 3.5.1 to build the latest Curl release (7.87.0).
Since CMakeLists.txt contains the line cmake_minimum_required(VERSION 3.2...3.16 FATAL_ERROR) I didn't expect the command to fail with my version of CMake. Unfortunately the usage of GREATER_EQUAL and GREATER_EQUAL that became available only in CMake 3.7 led to the following error:
CMake Error at CMakeLists.txt:1093 (if):
if given arguments:
"NOT" "MSVC" "OR" "(" "MSVC_VERSION" "GREATER_EQUAL" "1900" ")"
Unknown arguments specified
Called from:  /curl-7.87.0/CMakeLists.txt
-- Configuring incomplete, errors occurred!
If I knew cmake, I would move that version number check into the C code that needs to be built and linked to check for the symbol to avoid having cmake do it. But as I don't know how to, I propose we instead raise the lowest accepted cmake version to 3.7. Released in November 2016.