fix linkage with freetype/icu twice on linux

On linux Qt library depend on icu and freetype,
so OMaps linked with freetype/icu twice:
- static libraries 3rdparty/icu|freetype
- dynamic dependencies from libQtCore/libQtWidgets

this is undefined behavior because of one-definition-rule violation
comment #395

Signed-off-by: Evgeniy A. Dushistov <dushistov@mail.ru>

3party/freetype/CMakeLists.txt

@@ -6,3 +6,4 @@ target_include_directories(freetype
     $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>
     $<INSTALL_INTERFACE:include/freetype2>
 )
+add_library(Freetype::Freetype ALIAS freetype)

3party/icu/CMakeLists.txt

@@ -1,6 +1,6 @@
 project(icu)
 
-set(SRC
+add_library(icuuc
   uconfig_local.h
   icu/icu4c/source/common/appendable.cpp
   icu/icu4c/source/common/bmpset.cpp
@@ -170,6 +170,20 @@ set(SRC
   icu/icu4c/source/common/uvectr32.cpp
   icu/icu4c/source/common/uvectr64.h
   icu/icu4c/source/common/wintz.h
+)
+add_library(ICU::uc ALIAS icuuc)
+
+target_include_directories(icuuc
+  PUBLIC
+    ./
+    icu/icu4c/source/common
+)
+
+target_compile_definitions(icuuc PUBLIC UCONFIG_USE_LOCAL)
+
+set_target_properties(icuuc PROPERTIES UNITY_BUILD OFF)
+
+add_library(icui18n
   icu/icu4c/source/i18n/anytrans.cpp
   icu/icu4c/source/i18n/anytrans.h
   icu/icu4c/source/i18n/astro.h
@@ -374,19 +388,18 @@ set(SRC
   icu/icu4c/source/i18n/ztrans.h
   icu/icu4c/source/stubdata/stubdata.cpp
 )
+add_library(ICU::i18n ALIAS icui18n)
 
-add_library(${PROJECT_NAME} ${SRC})
+target_compile_definitions(icui18n PUBLIC UCONFIG_USE_LOCAL)
 
-target_compile_definitions(${PROJECT_NAME}
-  PUBLIC
-    UCONFIG_USE_LOCAL
-)
-
-target_include_directories(${PROJECT_NAME}
+target_include_directories(icui18n
   PUBLIC
     ./
-    icu/icu4c/source/common
     icu/icu4c/source/i18n
+  PRIVATE
+    icu/icu4c/source/common
 )
 
-set_target_properties(${PROJECT_NAME} PROPERTIES UNITY_BUILD OFF)
+target_link_libraries(icui18n PRIVATE icuuc)
+
+set_target_properties(icui18n PROPERTIES UNITY_BUILD OFF)

CMakeLists.txt

@@ -310,9 +310,14 @@ set(EXPAT_SHARED_LIBS OFF)
 add_subdirectory(3party/expat/expat)
 add_subdirectory(3party/agg)
 add_subdirectory(3party/bsdiff-courgette)
-add_subdirectory(3party/freetype)
 add_subdirectory(3party/gflags)
-add_subdirectory(3party/icu)
+if (CMAKE_SYSTEM_NAME MATCHES "Linux")
+  find_package(ICU COMPONENTS uc i18n data REQUIRED)
+  find_package(Freetype REQUIRED)
+else()
+  add_subdirectory(3party/freetype)
+  add_subdirectory(3party/icu)
+endif()
 add_subdirectory(3party/jansson)
 add_subdirectory(3party/liboauthcpp)
 add_subdirectory(3party/minizip)

coding/CMakeLists.txt

@@ -93,11 +93,14 @@ set(SRC
 omim_add_library(${PROJECT_NAME} ${SRC})
 
 target_link_libraries(${PROJECT_NAME}
+PUBLIC
+  ICU::uc
+  ICU::i18n # For transliteration.
+PRIVATE
   base
   expat
   jansson
   succinct
-  icu       # For transliteration.
   oauthcpp  # For base64_encode and base64_decode
   minizip
   ${LIBZ}

coding/transliteration.hpp

@@ -6,11 +6,11 @@
 #include <memory>
 #include <mutex>
 #include <string>
+#include <unicode/uversion.h>
 
-namespace icu
-{
+U_NAMESPACE_BEGIN
 class UnicodeString;
-}  // namespace icu
+U_NAMESPACE_END
 
 class Transliteration
 {

drape/CMakeLists.txt

@@ -164,16 +164,18 @@ if (PLATFORM_LINUX)
 endif()
 
 target_link_libraries(${PROJECT_NAME}
+PUBLIC
+  Freetype::Freetype
+  vulkan_wrapper
+PRIVATE
   indexer
   platform
   geometry
   coding
   base
-  freetype
-  vulkan_wrapper
   stb_image
   sdf_image
-  icu
+  ICU::i18n
   expat
   $<$<BOOL:${PLATFORM_MAC}>:-framework\ OpenGL>
   $<$<BOOL:${PLATFORM_LINUX}>:OpenGL::GL>

generator/pygen/CMakeLists.txt

@@ -29,7 +29,7 @@ omim_link_libraries(
   opening_hours
   freetype
   expat
-  icu
+  ICU::i18n
   jansson
   protobuf
   bsdiff

kml/pykmlib/CMakeLists.txt

@@ -19,7 +19,7 @@ omim_link_libraries(
   coding
   geometry
   base
-  icu
+  ICU::i18n
   jansson
   oauthcpp
   protobuf

search/pysearch/CMakeLists.txt

@@ -24,7 +24,7 @@ omim_link_libraries(
   coding
   base
   bsdiff
-  icu
+  ICU::i18n
   jansson
   oauthcpp
   opening_hours

traffic/pytraffic/CMakeLists.txt

@@ -42,7 +42,7 @@ omim_link_libraries(
   pugixml
   opening_hours
   succinct
-  icu
+  ICU::i18n
   ${Boost_LIBRARIES}
   ${LIBZ}
 )