Make CMake find_package work for preinstalled libprotobuf on Raspbian.

CMakeLists.txt

@@ -53,6 +53,9 @@ set_property(CACHE gRPC_SSL_PROVIDER PROPERTY STRINGS "module" "package")
 set(gRPC_PROTOBUF_PROVIDER "module" CACHE STRING "Provider of protobuf library")
 set_property(CACHE gRPC_PROTOBUF_PROVIDER PROPERTY STRINGS "module" "package")
 
+set(gRPC_PROTOBUF_PACKAGE_TYPE "" CACHE STRING "Algorithm for searching protobuf package")
+set_property(CACHE gRPC_PROTOBUF_PACKAGE_TYPE PROPERTY STRINGS "CONFIG" "MODULE")
+
 set(gRPC_GFLAGS_PROVIDER "module" CACHE STRING "Provider of gflags library")
 set_property(CACHE gRPC_GFLAGS_PROVIDER PROPERTY STRINGS "module" "package")
 
@@ -183,21 +186,27 @@ if("${gRPC_PROTOBUF_PROVIDER}" STREQUAL "module")
     set(gRPC_INSTALL FALSE)
   endif()
 elseif("${gRPC_PROTOBUF_PROVIDER}" STREQUAL "package")
-  find_package(protobuf CONFIG)
+  find_package(Protobuf ${gRPC_PROTOBUF_PACKAGE_TYPE})
-  if(protobuf_FOUND)
+  if(Protobuf_FOUND OR PROTOBUF_FOUND)
     if(TARGET protobuf::${_gRPC_PROTOBUF_LIBRARY_NAME})
       set(_gRPC_PROTOBUF_LIBRARIES protobuf::${_gRPC_PROTOBUF_LIBRARY_NAME})
+    else()
+      set(_gRPC_PROTOBUF_LIBRARIES ${PROTOBUF_LIBRARIES})
     endif()
     if(TARGET protobuf::libprotoc)
       set(_gRPC_PROTOBUF_PROTOC_LIBRARIES protobuf::libprotoc)
+    else()
+      set(_gRPC_PROTOBUF_PROTOC_LIBRARIES ${PROTOBUF_PROTOC_LIBRARIES})
     endif()
     if(TARGET protobuf::protoc)
       set(_gRPC_PROTOBUF_PROTOC protobuf::protoc)
+    else()
+      set(_gRPC_PROTOBUF_PROTOC ${PROTOBUF_PROTOC_EXECUTABLE})
     endif()
-    set(_gRPC_FIND_PROTOBUF "if(NOT protobuf_FOUND)\n  find_package(protobuf CONFIG)\nendif()")
+    set(_gRPC_FIND_PROTOBUF "if(NOT Protobuf_FOUND AND NOT PROTOBUF_FOUND)\n  find_package(Protobuf ${gRPC_PROTOBUF_PACKAGE_TYPE})\nendif()")
-  else()
+  endif()
-    find_package(Protobuf MODULE)
+  if(PROTOBUF_FOUND)
-    set(_gRPC_FIND_PROTOBUF "if(NOT Protobuf_FOUND)\n  find_package(Protobuf)\nendif()")
+    include_directories(${PROTOBUF_INCLUDE_DIRS})
   endif()
   set(PROTOBUF_WELLKNOWN_IMPORT_DIR /usr/local/include)
 endif()

templates/CMakeLists.txt.template

@@ -97,6 +97,9 @@
   set(gRPC_PROTOBUF_PROVIDER "module" CACHE STRING "Provider of protobuf library")
   set_property(CACHE gRPC_PROTOBUF_PROVIDER PROPERTY STRINGS "module" "package")
 
+  set(gRPC_PROTOBUF_PACKAGE_TYPE "" CACHE STRING "Algorithm for searching protobuf package")
+  set_property(CACHE gRPC_PROTOBUF_PACKAGE_TYPE PROPERTY STRINGS "CONFIG" "MODULE")
+
   set(gRPC_GFLAGS_PROVIDER "module" CACHE STRING "Provider of gflags library")
   set_property(CACHE gRPC_GFLAGS_PROVIDER PROPERTY STRINGS "module" "package")
 
@@ -228,21 +231,27 @@
       set(gRPC_INSTALL FALSE)
     endif()
   elseif("<%text>${gRPC_PROTOBUF_PROVIDER}</%text>" STREQUAL "package")
-    find_package(protobuf CONFIG)
+    find_package(Protobuf <%text>${gRPC_PROTOBUF_PACKAGE_TYPE}</%text>)
-    if(protobuf_FOUND)
+    if(Protobuf_FOUND OR PROTOBUF_FOUND)
       if(TARGET protobuf::<%text>${_gRPC_PROTOBUF_LIBRARY_NAME}</%text>)
         set(_gRPC_PROTOBUF_LIBRARIES protobuf::<%text>${_gRPC_PROTOBUF_LIBRARY_NAME}</%text>)
+      else()
+        set(_gRPC_PROTOBUF_LIBRARIES <%text>${PROTOBUF_LIBRARIES}</%text>)
       endif()
       if(TARGET protobuf::libprotoc)
         set(_gRPC_PROTOBUF_PROTOC_LIBRARIES protobuf::libprotoc)
+      else()
+        set(_gRPC_PROTOBUF_PROTOC_LIBRARIES <%text>${PROTOBUF_PROTOC_LIBRARIES}</%text>)
       endif()
       if(TARGET protobuf::protoc)
         set(_gRPC_PROTOBUF_PROTOC protobuf::protoc)
+      else()
+        set(_gRPC_PROTOBUF_PROTOC <%text>${PROTOBUF_PROTOC_EXECUTABLE}</%text>)
       endif()
-      set(_gRPC_FIND_PROTOBUF "if(NOT protobuf_FOUND)\n  find_package(protobuf CONFIG)\nendif()")
+      set(_gRPC_FIND_PROTOBUF "if(NOT Protobuf_FOUND AND NOT PROTOBUF_FOUND)\n  find_package(Protobuf <%text>${gRPC_PROTOBUF_PACKAGE_TYPE}</%text>)\nendif()")
-    else()
+    endif()
-      find_package(Protobuf MODULE)
+    if(PROTOBUF_FOUND)
-      set(_gRPC_FIND_PROTOBUF "if(NOT Protobuf_FOUND)\n  find_package(Protobuf)\nendif()")
+      include_directories(<%text>${PROTOBUF_INCLUDE_DIRS}</%text>)
     endif()
     set(PROTOBUF_WELLKNOWN_IMPORT_DIR /usr/local/include)
   endif()