From db87472be99fe2acbe054aa33391b428d63f294e Mon Sep 17 00:00:00 2001
From: Martchus <martchus@gmx.net>
Date: Wed, 7 Jul 2021 20:51:57 +0200
Subject: [PATCH] Unify and improve code for finding OpenSSL

* Unify code for use_openssl and use_crypto
* Make missing OpenSSL targets a fatal error if OpenSSL is required
* Add note that possibly the devel package is missing
    * Under Tumbleweed with missing devel package I've got `OpenSSL_FOUND`
      but no imported targets because the symlink from the devel package
      was missing. This might be due to stale values within the CMake
      cache.
---
 CMakeLists.txt               |  2 +-
 cmake/modules/3rdParty.cmake | 62 ++++++++++++++++--------------------
 2 files changed, 28 insertions(+), 36 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 682e565..2d44da4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -113,7 +113,7 @@ set(META_APP_URL "https://github.com/${META_APP_AUTHOR}/${META_PROJECT_NAME}")
 set(META_APP_DESCRIPTION "Useful C++ classes and routines such as argument parser, IO and conversion utilities")
 set(META_VERSION_MAJOR 5)
 set(META_VERSION_MINOR 10)
-set(META_VERSION_PATCH 5)
+set(META_VERSION_PATCH 6)
 
 # find required 3rd party libraries
 include(3rdParty)
diff --git a/cmake/modules/3rdParty.cmake b/cmake/modules/3rdParty.cmake
index 2d71108..333358b 100644
--- a/cmake/modules/3rdParty.cmake
+++ b/cmake/modules/3rdParty.cmake
@@ -151,20 +151,29 @@ function (use_iconv)
         PARENT_SCOPE)
 endfunction ()
 
-function (use_openssl)
-    parse_arguments_for_use_functions(${ARGN})
-
+macro (_cpp_utilities_use_openssl OPENSSL_TARGETS)
     find_package(OpenSSL ${ARGS_FIND_PACKAGE})
     if (NOT OpenSSL_FOUND)
         message(STATUS "Unable to find OpenSSL")
         return()
     endif ()
-    if (NOT TARGET OpenSSL::SSL OR NOT TARGET OpenSSL::Crypto)
-        message(WARNING "Found OpenSSL but imported targets OpenSSL::SSL and/or OpenSSL::Crypto missing.")
+    foreach (OPENSSL_TARGET ${OPENSSL_TARGETS})
+        if (TARGET "${OPENSSL_TARGET}")
+            continue()
+        endif ()
+        set(MESSAGE_MODE WARNING)
+        if (REQUIRED IN_LIST ARGS_FIND_PACKAGE)
+            set(MESSAGE_MODE FATAL_ERROR)
+        endif ()
+        message(
+            "${MESSAGE_MODE}"
+            "Found OpenSSL but imported target \"${OPENSSL_TARGET}\" is missing. Possibly the devel package for OpenSSL is not installed."
+        )
         return()
-    endif ()
-    message(STATUS "Found OpenSSL")
-    set("${ARGS_LIBRARIES_VARIABLE}" "${${ARGS_LIBRARIES_VARIABLE}};OpenSSL::SSL;OpenSSL::Crypto")
+    endforeach ()
+
+    message(STATUS "Found required OpenSSL targets (${OPENSSL_TARGETS})")
+    set("${ARGS_LIBRARIES_VARIABLE}" "${${ARGS_LIBRARIES_VARIABLE}};${OPENSSL_TARGETS}")
     if (WIN32 AND OPENSSL_USE_STATIC_LIBS)
         # FIXME: preferably use pkg-config to cover this case without hardcoding OpenSSL's dependencies under Windows
         set("${ARGS_LIBRARIES_VARIABLE}" "${${ARGS_LIBRARIES_VARIABLE}};-lws2_32;-lgdi32;-lcrypt32")
@@ -175,40 +184,23 @@ function (use_openssl)
     set("${ARGS_LIBRARIES_VARIABLE}"
         "${${ARGS_LIBRARIES_VARIABLE}}"
         PARENT_SCOPE)
-    set("PKG_CONFIG_OpenSSL_SSL"
-        "libssl"
-        PARENT_SCOPE)
     set("PKG_CONFIG_OpenSSL_Crypto"
         "libcrypto"
         PARENT_SCOPE)
+endmacro ()
+
+function (use_openssl)
+    parse_arguments_for_use_functions(${ARGN})
+    _cpp_utilities_use_openssl("OpenSSL::SSL;OpenSSL::Crypto")
+    set("PKG_CONFIG_OpenSSL_SSL"
+        "libssl"
+        PARENT_SCOPE)
+
 endfunction ()
 
 function (use_crypto)
     parse_arguments_for_use_functions(${ARGN})
-
-    find_package(OpenSSL ${ARGS_FIND_PACKAGE})
-    if (NOT OpenSSL_FOUND)
-        message(STATUS "Unable to find OpenSSL")
-        return()
-    endif ()
-    if (NOT TARGET OpenSSL::Crypto)
-        message(WARNING "Found OpenSSL but imported target OpenSSL::Crypto missing.")
-        return()
-    endif ()
-    message(STATUS "Found OpenSSL")
-    set("${ARGS_LIBRARIES_VARIABLE}" "${${ARGS_LIBRARIES_VARIABLE}};OpenSSL::Crypto")
-    if (WIN32 AND OPENSSL_USE_STATIC_LIBS)
-        set("${ARGS_LIBRARIES_VARIABLE}" "${${ARGS_LIBRARIES_VARIABLE}};-lws2_32;-lgdi32;-lcrypt32")
-    endif ()
-    set("${ARGS_PACKAGES_VARIABLE}"
-        "${${ARGS_PACKAGES_VARIABLE}};OpenSSL"
-        PARENT_SCOPE)
-    set("${ARGS_LIBRARIES_VARIABLE}"
-        "${${ARGS_LIBRARIES_VARIABLE}}"
-        PARENT_SCOPE)
-    set("PKG_CONFIG_OpenSSL_Crypto"
-        "libcrypto"
-        PARENT_SCOPE)
+    _cpp_utilities_use_openssl("OpenSSL::Crypto")
 endfunction ()
 
 function (use_zlib)