Add support for the conan C/C++ package manager

* Don't overwrite the CMAKE_MODULE_PATH
* Allow linking libsodium statically with MSVC
* Allow finding libsodium the normal way on MSVC
* Allow using pthreads4w for pthreads on MSVC
* Fall back to find_package if pkg_find_module fails
* Don't pass incompatible compile flags to MSVC
* Also try to find Opus and libvpx using their canonical names
* Support building using conan
* Allow pkg_use_module to take a list of libraries to look for
* Build for Windows on Appveyor using conan

1 files changed, 33 insertions, 15 deletions

diff --git a/cmake/ModulePackage.cmake b/cmake/ModulePackage.cmake
index 9cc21863..04dbf16d 100644
--- a/cmake/ModulePackage.cmake
+++ b/cmake/ModulePackage.cmake
@@ -21,21 +21,39 @@ endif()
 
 find_package(PkgConfig)
 
-function(pkg_use_module mod pkg)
-  if(PKG_CONFIG_FOUND)
-    pkg_search_module(${mod} ${pkg})
-  endif()
-  if(${mod}_FOUND)
-    link_directories(${${mod}_LIBRARY_DIRS})
-    include_directories(${${mod}_INCLUDE_DIRS})
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${${mod}_CFLAGS_OTHER}" PARENT_SCOPE)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${${mod}_CFLAGS_OTHER}" PARENT_SCOPE)
-
-    foreach(dir ${${mod}_INCLUDE_DIRS})
-      set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -isystem ${dir}" PARENT_SCOPE)
-      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -isystem ${dir}" PARENT_SCOPE)
-    endforeach()
-  endif()
+function(pkg_use_module mod pkgs)
+  foreach(pkg IN ITEMS ${pkgs})
+    if(PKG_CONFIG_FOUND)
+      pkg_search_module(${mod} ${pkg})
+    endif()
+    if(NOT ${mod}_FOUND)
+      find_package(${pkg} QUIET)
+      # This is very very ugly, but the variables are sometimes used in this scope
+      # and sometimes in the parent scope, so we have to set them to both places.
+      set(${mod}_FOUND ${${pkg}_FOUND})
+      set(${mod}_FOUND ${${pkg}_FOUND} PARENT_SCOPE)
+      set(${mod}_LIBRARIES ${${pkg}_LIBS})
+      set(${mod}_LIBRARIES ${${pkg}_LIBS} PARENT_SCOPE)
+      set(${mod}_LIBRARY_DIRS ${${pkg}_LIBRARY_DIRS})
+      set(${mod}_LIBRARY_DIRS ${${pkg}_LIBRARY_DIRS} PARENT_SCOPE)
+      set(${mod}_INCLUDE_DIRS ${${pkg}_INCLUDE_DIRS})
+      set(${mod}_INCLUDE_DIRS ${${pkg}_INCLUDE_DIRS} PARENT_SCOPE)
+    endif()
+    if(${mod}_FOUND)
+      link_directories(${${mod}_LIBRARY_DIRS})
+      include_directories(${${mod}_INCLUDE_DIRS})
+      set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} ${${mod}_CFLAGS_OTHER}" PARENT_SCOPE)
+      set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${${mod}_CFLAGS_OTHER}" PARENT_SCOPE)
+
+      if(NOT MSVC)
+        foreach(dir ${${mod}_INCLUDE_DIRS})
+          set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -isystem ${dir}" PARENT_SCOPE)
+          set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -isystem ${dir}" PARENT_SCOPE)
+        endforeach()
+      endif()
+      break()
+    endif()
+  endforeach()
 endfunction()
 
 function(add_module lib)