Upgrade the gcc and g++ to version 12 to support Cpp20 features

dependencies/ubuntu/Dockerfile

@@ -1,14 +1,14 @@
-FROM ubuntu:20.04
+FROM ubuntu:22.04
 LABEL org.opencontainers.image.authors="Sandro Elsweijer <sandro.elsweijer@dlr.de>"
-LABEL Description="Ubuntu 20.04 with VTK, NetCDF and OpenCASCADE setup for use with t8code"
+LABEL Description="Ubuntu 22.04 with VTK, NetCDF and OpenCASCADE setup for use with t8code"
 SHELL ["/bin/bash", "-c"]
 
 ARG vtk_version=9.1.0
 ARG vtk_library_version=9.1
 
 ENV DEBIAN_FRONTEND noninteractive
-ENV LIBRARY_PATH=/usr/local/lib:$LIBRARY_PATH
-ENV LD_LIBRARY_PATH=/usr/local/lib:$LD_LIBRARY_PATH
+ENV LIBRARY_PATH=/usr/local/lib
+ENV LD_LIBRARY_PATH=/usr/local/lib
 
 #######################################################
 # Install software requirements and build tools       #
@@ -18,7 +18,7 @@ RUN apt-get update -y && apt-get upgrade -y; \
 # Prepare apt-get build-dep (https://askubuntu.com/questions/496549/error-you-must-put-some-source-uris-in-your-sources-list)
     cp /etc/apt/sources.list /etc/apt/sources.list~; \
     sed -Ei 's/^# deb-src /deb-src /' /etc/apt/sources.list; \
-    apt-get update; \
+    apt-get update && apt install build-essential; \
 # install compiler cmake and other useful stuff
     apt-get install -y sudo \
                        build-essential \
@@ -45,6 +45,7 @@ RUN apt-get update -y && apt-get upgrade -y; \
 # install NetCDF
                        libnetcdf-dev
 
+
 # clone vtk
 RUN git clone https://github.com/Kitware/VTK.git; \
     cd VTK; \

t8code/ubuntu/Dockerfile

@@ -1,6 +1,6 @@
 FROM dlramr/t8code-ubuntu:t8-dependencies
 LABEL org.opencontainers.image.authors="Sandro Elsweijer <sandro.elsweijer@dlr.de>"
-LABEL Description="Ubuntu 20.04 with VTK, NetCDF and OpenCASCADE setup and t8code"
+LABEL Description="Ubuntu 22.04 with VTK, NetCDF and OpenCASCADE setup and t8code"
 SHELL ["/bin/bash", "-c"]
 
 ARG t8code_version=1.0.0
@@ -30,6 +30,6 @@ cd t8code_build; \
                         LDFLAGS="-L/usr/lib/ -L/usr/local/lib" \
                         CPPFLAGS="-isystem/usr/include/opencascade -isystem/usr/include/vtk-${vtk_library_version}"; \
 make -j4 V=0; \
-make install -j4; \
-fi
+make install -j4;
+