From f436c3d9bdc247ceccc8dad358e83e238f6eabe0 Mon Sep 17 00:00:00 2001
From: Carles Fernandez <carles.fernandez@gmail.com>
Date: Sat, 20 Apr 2019 19:11:17 +0200
Subject: [PATCH] Improve detection of Protocol Buffers in cross-compilation

---
 CMakeLists.txt | 38 ++++++++++++++++----------------------
 1 file changed, 16 insertions(+), 22 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1709219ce..320960225 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1799,7 +1799,6 @@ if(ENABLE_PROTOBUF)
         TYPE REQUIRED
     )
     if(Protobuf_FOUND AND CMAKE_CROSSCOMPILING)
-        unset(protobuf::protoc)
         find_program(PROTOC_EXECUTABLE protoc
             HINTS
             /usr/bin/
@@ -1807,7 +1806,6 @@ if(ENABLE_PROTOBUF)
             NO_SYSTEM_ENVIRONMENT_PATH
         )
         if(PROTOC_EXECUTABLE)
-            add_executable(protobuf::protoc IMPORTED)
             set_target_properties(protobuf::protoc PROPERTIES
                 IMPORTED_LINK_INTERFACE_LANGUAGES "CXX"
                 IMPORTED_LOCATION ${PROTOC_EXECUTABLE}
@@ -1831,11 +1829,6 @@ if(ENABLE_PROTOBUF)
                 ${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/bin/protoc
             )
         else()
-            if(${Protobuf_VERSION} VERSION_LESS ${GNSSSDR_PROTOBUF_MIN_VERSION})
-                unset(protobuf::libprotobuf)
-                unset(protobuf::protoc)
-            endif()
-
             if(CMAKE_VERSION VERSION_LESS 3.2)
                 ExternalProject_Add(protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}
                     PREFIX ${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}
@@ -1863,28 +1856,29 @@ if(ENABLE_PROTOBUF)
                     ${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/bin/protoc
                 )
             endif()
+
+            if(NOT TARGET protobuf::protoc)
+                add_executable(protobuf::protoc IMPORTED)
+                add_dependencies(protobuf::protoc protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION})
+            endif()
+            set_target_properties(protobuf::protoc PROPERTIES
+                IMPORTED_LINK_INTERFACE_LANGUAGES "CXX"
+                IMPORTED_LOCATION "${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/bin/protoc"
+                INTERFACE_LINK_LIBRARIES "${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/lib/${CMAKE_FIND_LIBRARY_PREFIXES}protoc${CMAKE_STATIC_LIBRARY_SUFFIX}"
+            )    
         endif()
         if(NOT TARGET protobuf::libprotobuf)
             file(MAKE_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/include)
             add_library(protobuf::libprotobuf STATIC IMPORTED)
             add_dependencies(protobuf::libprotobuf protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION})
-            set_target_properties(protobuf::libprotobuf PROPERTIES
-                IMPORTED_LINK_INTERFACE_LANGUAGES "CXX"
-                IMPORTED_LOCATION "${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/lib/${CMAKE_FIND_LIBRARY_PREFIXES}protobuf${CMAKE_STATIC_LIBRARY_SUFFIX}"
-                INTERFACE_INCLUDE_DIRECTORIES "${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/include"
-                INTERFACE_LINK_LIBRARIES "${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/lib/${CMAKE_FIND_LIBRARY_PREFIXES}protobuf${CMAKE_STATIC_LIBRARY_SUFFIX}"
-            )
         endif()
+        set_target_properties(protobuf::libprotobuf PROPERTIES
+            IMPORTED_LINK_INTERFACE_LANGUAGES "CXX"
+            IMPORTED_LOCATION "${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/lib/${CMAKE_FIND_LIBRARY_PREFIXES}protobuf${CMAKE_STATIC_LIBRARY_SUFFIX}"
+            INTERFACE_INCLUDE_DIRECTORIES "${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/include"
+            INTERFACE_LINK_LIBRARIES "${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/lib/${CMAKE_FIND_LIBRARY_PREFIXES}protobuf${CMAKE_STATIC_LIBRARY_SUFFIX}"
+        )
 
-        if(NOT TARGET protobuf::protoc)
-            add_executable(protobuf::protoc IMPORTED)
-            add_dependencies(protobuf::protoc protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION})
-            set_target_properties(protobuf::protoc PROPERTIES
-                IMPORTED_LINK_INTERFACE_LANGUAGES "CXX"
-                IMPORTED_LOCATION "${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/bin/protoc"
-                INTERFACE_LINK_LIBRARIES "${CMAKE_CURRENT_BINARY_DIR}/protobuf-${GNSSSDR_PROTOCOLBUFFERS_LOCAL_VERSION}/lib/${CMAKE_FIND_LIBRARY_PREFIXES}protoc${CMAKE_STATIC_LIBRARY_SUFFIX}"
-            )
-        endif()
         if(${Protobuf_VERSION} VERSION_LESS ${GNSSSDR_PROTOBUF_MIN_VERSION})
             set_package_properties(Protobuf PROPERTIES
                 PURPOSE "Protocol Buffers found (v${Protobuf_VERSION}) is too old (> v${GNSSSDR_PROTOBUF_MIN_VERSION} needed)."