Fix hylo trunk build with Swift 6.2 and LLVM 20 upgrade

Updates dependencies to match hylo trunk requirements (Swift 6.2, LLVM 20, Ubuntu 22.04) and works around the removal of Swifty-LLVM's make-pkgconfig.sh script by generating llvm.pc locally via PKG_CONFIG_PATH.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: mattgodbolt

Dockerfile.hylo

@@ -1,4 +1,4 @@
-FROM ubuntu:20.04
+FROM ubuntu:22.04
 
 ARG DEBIAN_FRONTEND=noninteractive
 
@@ -8,27 +8,27 @@ RUN apt-get install -y -q \
     curl \
     git \
     patchelf \
-    python3.9 \
-    python3.9-venv \
+    python3.10 \
+    python3.10-venv \
     python3-pip \
     ssh \
     wget \
     software-properties-common
 
 RUN wget -qO- https://apt.llvm.org/llvm-snapshot.gpg.key | tee /etc/apt/trusted.gpg.d/apt.llvm.org.asc
-RUN apt-add-repository "deb http://apt.llvm.org/focal/ llvm-toolchain-focal-15 main"
+RUN apt-add-repository "deb http://apt.llvm.org/jammy/ llvm-toolchain-jammy-20 main"
 RUN apt-get update -y -q
 
 RUN apt-get install -y -q \
-    libllvm15 \
-    llvm-15 \
-    llvm-15-dev \
-    llvm-15-runtime \
+    libllvm20 \
+    llvm-20 \
+    llvm-20-dev \
+    llvm-20-runtime \
     pkg-config \
     libzstd-dev
     # zstd
 
-RUN ln -s /usr/bin/llvm-config-15 /usr/bin/llvm-config
+RUN ln -s /usr/bin/llvm-config-20 /usr/bin/llvm-config
 
 RUN mkdir -p /opt/compiler-explorer
 RUN mkdir /root/.ssh \
@@ -37,8 +37,8 @@ RUN mkdir /root/.ssh \
 RUN git clone https://github.com/compiler-explorer/infra /opt/compiler-explorer/infra
 
 RUN cd /opt/compiler-explorer/infra && make ce
-RUN /opt/compiler-explorer/infra/bin/ce_install install 'swift 5.10'
-ENV PATH="${PATH}:/opt/compiler-explorer/swift-5.10/usr/bin"
+RUN /opt/compiler-explorer/infra/bin/ce_install install 'swift 6.2'
+ENV PATH="${PATH}:/opt/compiler-explorer/swift-6.2/usr/bin"
 
 RUN mkdir -p /root
 COPY hylo /root/

hylo/build.sh

@@ -37,7 +37,26 @@ git clone -q --depth 1 --single-branch --recursive -b "${BRANCH}" "${URL}" "hylo
 
 cd "hylo-${VERSION}"
 swift package resolve
-.build/checkouts/Swifty-LLVM/Tools/make-pkgconfig.sh /usr/local/lib/pkgconfig/llvm.pc
+
+# Create LLVM pkgconfig file locally since Swifty-LLVM no longer provides the script
+# Use PKG_CONFIG_PATH to avoid system-level changes
+PKGCONFIG_DIR="${ROOT}/pkgconfig"
+mkdir -p "${PKGCONFIG_DIR}"
+cat > "${PKGCONFIG_DIR}/llvm.pc" << EOF
+prefix=$(llvm-config --prefix)
+libdir=$(llvm-config --libdir)
+includedir=$(llvm-config --includedir)
+
+Name: LLVM
+Description: Low Level Virtual Machine
+Version: $(llvm-config --version)
+Requires:
+Libs: -L\${libdir} $(llvm-config --libs --system-libs)
+Cflags: -I\${includedir}
+EOF
+
+export PKG_CONFIG_PATH="${PKGCONFIG_DIR}:${PKG_CONFIG_PATH:-}"
+
 ./Tools/set-hc-version.sh
 swift build --static-swift-stdlib -c release --product hc