Prefer clang in all platforms

Author: Algunenano

PreLoad.cmake

@@ -60,10 +60,9 @@ execute_process(COMMAND uname -m
     COMMAND_ERROR_IS_FATAL ANY
 )
 
-# By default, prefer clang on Linux
+# We already prefer clang
 # But note, that you still may change the compiler with -DCMAKE_C_COMPILER/-DCMAKE_CXX_COMPILER.
-if (OS MATCHES "Linux"
-    AND "$ENV{CC}" STREQUAL ""
+if ("$ENV{CC}" STREQUAL ""
     AND "$ENV{CXX}" STREQUAL ""
     AND NOT DEFINED CMAKE_C_COMPILER
     AND NOT DEFINED CMAKE_CXX_COMPILER)

docs/en/development/build-osx.md

@@ -38,7 +38,7 @@ To build you must use Homebrew's Clang compiler:
 cd ClickHouse
 mkdir build
 export PATH=$(brew --prefix llvm)/bin:$PATH
-cmake -G Ninja -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_C_COMPILER=$(brew --prefix llvm)/bin/clang -DCMAKE_CXX_COMPILER=$(brew --prefix llvm)/bin/clang++ -S . -B build
+cmake -S . -B build
 cmake --build build
 # The resulting binary will be created at: build/programs/clickhouse
 ```