Install /usr/bin/cc symlink rather than gcc package

Author: Bronek

docker/debian/Dockerfile

@@ -156,7 +156,6 @@ ARG DEBIAN_FRONTEND=noninteractive
 # Install Clang. Use the LLVM apt repository to access the latest versions. We
 # must repeat the DEBIAN_VERSION argument here, as it is not inherited from the
 # base or source images.
-# Note, gcc is needed for build dependencies.
 ARG DEBIAN_VERSION
 ARG CLANG_VERSION
 RUN <<EOF
@@ -165,13 +164,14 @@ printf "%s\n%s\n" \
   "deb [signed-by=/etc/apt/keyrings/llvm.gpg] https://apt.llvm.org/${DEBIAN_VERSION}/ llvm-toolchain-${DEBIAN_VERSION}-${CLANG_VERSION} main" \
   | tee /etc/apt/sources.list.d/llvm.list
 apt-get update
-apt-get install -y --no-install-recommends gcc
 apt-get install -t llvm-toolchain-${DEBIAN_VERSION}-${CLANG_VERSION} -y --no-install-recommends clang-${CLANG_VERSION} llvm-${CLANG_VERSION}
 apt-get clean
 rm -rf /var/lib/apt/lists/*
 EOF
 ENV CC=/usr/bin/clang-${CLANG_VERSION}
 ENV CXX=/usr/bin/clang++-${CLANG_VERSION}
+# This is required by some build dependencies
+RUN update-alternatives --install /usr/bin/cc cc $CC 999
 
 # Check that the installed Clang version matches the expected version.
 RUN <<EOF

docker/rhel/Dockerfile

@@ -52,6 +52,7 @@ dnf remove -y gcc gcc-c++
 dnf install -y --setopt=tsflags=nodocs gcc-toolset-${GCC_VERSION}-gcc gcc-toolset-${GCC_VERSION}-gcc-c++
 dnf clean -y all
 rm -rf /var/cache/dnf/*
+update-alternatives --install /usr/bin/cc cc /opt/rh/gcc-toolset-${GCC_VERSION}/root/usr/bin/gcc 999
 update-alternatives \
     --install /usr/bin/gcc gcc /opt/rh/gcc-toolset-${GCC_VERSION}/root/usr/bin/gcc ${GCC_VERSION} \
     --slave /usr/bin/g++ g++ /opt/rh/gcc-toolset-${GCC_VERSION}/root/usr/bin/g++ \
@@ -134,14 +135,15 @@ FROM base AS clang
 
 # Install Clang. Note that in the RHEL UBIs, we cannot choose the Clang version
 # to install and we get what is available.
-# Note, gcc is needed for build dependencies.
 RUN <<EOF
-dnf install -y --setopt=tsflags=nodocs clang llvm gcc
+dnf install -y --setopt=tsflags=nodocs clang llvm
 dnf clean -y all
 rm -rf /var/cache/dnf/*
 EOF
 ENV CC=/usr/bin/clang
 ENV CXX=/usr/bin/clang++
+# This is required by some build dependencies
+RUN update-alternatives --install /usr/bin/cc cc $CC 999
 
 # Check that the installed Clang version is not older than the minimum required.
 ARG MINIMUM_CLANG_VERSION=16

docker/ubuntu/Dockerfile

@@ -69,6 +69,7 @@ apt-get install -y --no-install-recommends \
     g++-${GCC_VERSION}
 apt-get clean
 rm -rf /var/lib/apt/lists/*
+update-alternatives --install /usr/bin/cc cc /usr/bin/gcc-${GCC_VERSION} 999
 update-alternatives \
     --install /usr/bin/gcc gcc /usr/bin/gcc-${GCC_VERSION} ${GCC_VERSION} \
     --slave /usr/bin/g++ g++ /usr/bin/g++-${GCC_VERSION} \
@@ -151,19 +152,20 @@ FROM base AS clang
 # This is not inherited from base image, ensure no manual interaction needed.
 ARG DEBIAN_FRONTEND=noninteractive
 
-# Install Clang. Note, gcc is needed for build dependencies
+# Install Clang.
 ARG CLANG_VERSION
 RUN <<EOF
 apt-get update
 apt-get install -y --no-install-recommends \
     clang-${CLANG_VERSION} \
-    llvm-${CLANG_VERSION} \
-    gcc
+    llvm-${CLANG_VERSION}
 apt-get clean
 rm -rf /var/lib/apt/lists/*
 EOF
 ENV CC=/usr/bin/clang-${CLANG_VERSION}
 ENV CXX=/usr/bin/clang++-${CLANG_VERSION}
+# This is required by some build dependencies
+RUN update-alternatives --install /usr/bin/cc cc $CC 999
 
 # Check that the installed Clang version matches the expected version.
 RUN <<EOF