chores(cmake): bump version to 3.21.0 (pingcap#4162)

close pingcap#4138

CMakeLists.txt

@@ -13,7 +13,7 @@
 # limitations under the License.
 
 project (TiFlash)
-cmake_minimum_required (VERSION 2.8)
+cmake_minimum_required (VERSION 3.21)
 
 set(CMAKE_SKIP_INSTALL_ALL_DEPENDENCY true)
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${TiFlash_SOURCE_DIR}/cmake/Modules/")

README.md

@@ -29,7 +29,7 @@ git clone --recursive https://github.com/pingcap/tiflash.git
 ### Prerequisites
 
 The following packages are needed for all platforms:
-- CMake 3.13.2+
+- CMake 3.21.0+
 - Rust
   ```bash
   curl https://sh.rustup.rs -sSf | sh -s -- -y --profile minimal --default-toolchain nightly

dbms/CMakeLists.txt

@@ -219,8 +219,10 @@ if (Poco_Data_FOUND AND NOT USE_INTERNAL_POCO_LIBRARY)
     target_include_directories (dbms PRIVATE ${Poco_Data_INCLUDE_DIRS})
 endif()
 
+# NetSSL headers are exposed in clickhouse_common_io's headers.
+# We mark it public to make the headers available.
 if (Poco_NetSSL_FOUND)
-    target_link_libraries (clickhouse_common_io PRIVATE ${Poco_NetSSL_LIBRARY})
+    target_link_libraries (clickhouse_common_io PUBLIC ${Poco_NetSSL_LIBRARY})
 endif()
 
 target_link_libraries (dbms ${Poco_Foundation_LIBRARY})

libs/libcommon/CMakeLists.txt

@@ -136,6 +136,8 @@ target_include_directories (common PUBLIC ${COMMON_INCLUDE_DIR})
 
 target_include_directories (common BEFORE PUBLIC ${Boost_INCLUDE_DIRS})
 
+# `libcommon` provides a bridge for many other libs.
+# We expose the linkage to public because we want headers to be inherited.
 target_link_libraries (
     common
     PUBLIC
@@ -153,7 +155,7 @@ target_link_libraries (
 )
 
 if (RT_LIBRARY)
-    target_link_libraries (common ${RT_LIBRARY})
+    target_link_libraries (common PUBLIC ${RT_LIBRARY})
 endif ()
 
 if (ENABLE_TESTS)