use clang-16 on ubuntu 20.04

Author: neodix42

.github/workflows/build-ton-linux-x86-64-portable.yml

@@ -21,11 +21,11 @@ jobs:
         sudo apt-get update
         sudo apt-get install -y build-essential git cmake ninja-build libc++-dev libc++abi-dev
 
-    - if: matrix.os == 'ubuntu-20.04'
+    - if: matrix.os != 'ubuntu-24.04'
       run: |
-        sudo apt install -y manpages-dev software-properties-common
-        sudo add-apt-repository ppa:ubuntu-toolchain-r/test
-        sudo apt update && sudo apt install gcc-11 g++-11
+        wget https://apt.llvm.org/llvm.sh
+        chmod +x llvm.sh
+        sudo ./llvm.sh 16 all
 
     - name: Build TON
       run: |

assembly/native/build-ubuntu-portable.sh

@@ -101,8 +101,8 @@ else
 fi
 
 cmake -GNinja .. \
--DCMAKE_CXX_FLAGS="-stdlib=libc++" \
--DCMAKE_EXE_LINKER_FLAGS="-stdlib=libc++" \
+-DCMAKE_CXX_FLAGS="-stdlib=libc++ -I/usr/lib/llvm-16/include/c++/v1" \
+-DCMAKE_EXE_LINKER_FLAGS="-stdlib=libc++ -I/usr/lib/llvm-16/include/c++/v1" \
 -DPORTABLE=1 \
 -DCMAKE_BUILD_TYPE=Release \
 -DOPENSSL_FOUND=1 \