fixed Ubuntu build

.github/workflows/build-ubuntu.yml

@@ -11,6 +11,6 @@ jobs:
         uses: actions/checkout@v2
         with:
           fetch-depth: 0
-      - name: Build Ubuntu-20.10
+      - name: Build Ubuntu-20.04
         run: |
-          docker build -f Docker/Test-Build-Ubuntu-20.10.docker .
+          docker build -f Docker/Test-Build-Ubuntu-20.04.docker .

Docker/Test-Build-Ubuntu-20.04.docker

@@ -0,0 +1,34 @@
+FROM ubuntu:20.04
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt update -y
+
+# Apparently wget is not installed by default
+RUN apt-get install -y wget
+
+# Add llvm pub key
+RUN wget -qO- https://apt.llvm.org/llvm-snapshot.gpg.key | tee /etc/apt/trusted.gpg.d/apt.llvm.org.asc
+
+# Install add-apt-repository
+RUN apt-get install -y software-properties-common
+
+# Add llvm 18 repository with sources
+RUN add-apt-repository -s -y "deb http://apt.llvm.org/focal/ llvm-toolchain-focal-18 main"
+
+RUN echo apt-get update && apt-get install -y llvm-18 clang-18 libclang-18-dev libclang-cpp18-dev python3-pip
+
+# Easiest way to get sufficiently new cmake appears to be using pip - Ubuntu 20.10 version is too old
+RUN pip3 install --upgrade cmake
+
+# Copy the source into the Docker container
+RUN mkdir -p /c2ffi
+COPY / /c2ffi
+WORKDIR /c2ffi
+
+# Build c2ffi
+RUN cd /c2ffi && \
+        rm -rf build && mkdir -p build && cd build && \
+        cmake -DBUILD_CONFIG=Release .. && make
+
+# As a sanity check, make sure the binary we built can be executed
+RUN /c2ffi/build/bin/c2ffi --help