From f21cc62832a9d5c521d10da9177b075bfed43f2f Mon Sep 17 00:00:00 2001
From: Cristian Morales Vega <cristian@samknows.com>
Date: Thu, 19 Nov 2020 07:54:09 +0000
Subject: cmake: make CURL_ZLIB a tri-state variable

By differentiating between ON and AUTO it can make a missing zlib
library a hard error when CURL_ZLIB=ON is used.

Reviewed-by: Jakub Zakrzewski
Closes #6221
Fixes #6173
---
 CMake/Macros.cmake | 11 +++++++++++
 1 file changed, 11 insertions(+)

(limited to 'CMake')

diff --git a/CMake/Macros.cmake b/CMake/Macros.cmake
index 6c29856c4..d57dd6ad5 100644
--- a/CMake/Macros.cmake
+++ b/CMake/Macros.cmake
@@ -107,3 +107,14 @@ macro(curl_nroff_check)
     message(WARNING "Found no *nroff program")
   endif()
 endmacro()
+
+macro(optional_dependency DEPENDENCY)
+  set(CURL_${DEPENDENCY} AUTO CACHE STRING "Build curl with ${DEPENDENCY} support (AUTO, ON or OFF)")
+  set_property(CACHE CURL_${DEPENDENCY} PROPERTY STRINGS AUTO ON OFF)
+
+  if(CURL_${DEPENDENCY} STREQUAL AUTO)
+    find_package(${DEPENDENCY})
+  elseif(CURL_${DEPENDENCY})
+    find_package(${DEPENDENCY} REQUIRED)
+  endif()
+endmacro()
-- 
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