From 8e035a7518365e4afa9c7cf079756261572029bb Mon Sep 17 00:00:00 2001
From: Azat Khuzhin <a3at.mail@gmail.com>
Date: Thu, 10 Dec 2020 21:42:53 +0300
Subject: [PATCH] build: pass the c++ standard for compiling llvm

Yes clickhosue set gnu++2a globally, but this will not work, since
default -std=c++11 will be added later, look:

    clang++ -std=gnu++2a ... -std=c++11 -Wall -Wextra contrib/llvm/...
---
 CMakeLists.txt         | 6 +++---
 contrib/CMakeLists.txt | 2 ++
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 367af2bbf9..56faf4ca2b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -225,14 +225,14 @@ endif ()
 
 if (COMPILER_GCC OR COMPILER_CLANG)
     # to make numeric_limits<__int128> works with GCC
-    set (_CXX_STANDARD "-std=gnu++2a")
+    set (_CXX_STANDARD "gnu++2a")
 else()
-    set (_CXX_STANDARD "-std=c++2a")
+    set (_CXX_STANDARD "c++2a")
 endif()
 
 # cmake < 3.12 doesn't support 20. We'll set CMAKE_CXX_FLAGS for now
 # set (CMAKE_CXX_STANDARD 20)
-set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} ${_CXX_STANDARD}")
+set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=${_CXX_STANDARD}")
 
 set (CMAKE_CXX_EXTENSIONS 0) # https://cmake.org/cmake/help/latest/prop_tgt/CXX_EXTENSIONS.html#prop_tgt:CXX_EXTENSIONS
 set (CMAKE_CXX_STANDARD_REQUIRED ON)
diff --git a/contrib/CMakeLists.txt b/contrib/CMakeLists.txt
index 48d760e754..ec7ce49634 100644
--- a/contrib/CMakeLists.txt
+++ b/contrib/CMakeLists.txt
@@ -241,6 +241,8 @@ if (USE_EMBEDDED_COMPILER AND USE_INTERNAL_LLVM_LIBRARY)
     set (LLVM_ENABLE_RTTI 1 CACHE INTERNAL "")
     set (LLVM_ENABLE_PIC 0 CACHE INTERNAL "")
     set (LLVM_TARGETS_TO_BUILD "X86;AArch64" CACHE STRING "")
+    # Yes it is set globally, but this is not enough, since llvm will add -std=c++11 after default
+    set (LLVM_CXX_STD ${_CXX_STANDARD} CACHE STRING "" FORCE)
     add_subdirectory (llvm/llvm)
     target_include_directories(LLVMSupport SYSTEM BEFORE PRIVATE ${ZLIB_INCLUDE_DIR})
 endif ()