Auto merge of #110242 - cuviper:vanilla-llvm-16, r=Mark-Simulacrum

ci: add a runner for vanilla LLVM 16

Like #107044, this will let us track compatibility with LLVM 16 going
forward, especially after we eventually upgrade our own to the next.

This also drops `tidy` here and in `x86_64-gnu-llvm-15`, syncing with
that change in #106085.

3 files changed, 68 insertions, 7 deletions

diff --git a/src/ci/docker/host-x86_64/dist-x86_64-illumos/Dockerfile b/src/ci/docker/host-x86_64/dist-x86_64-illumos/Dockerfile
index 2089bf38716..55fefd2b725 100644
--- a/src/ci/docker/host-x86_64/dist-x86_64-illumos/Dockerfile
+++ b/src/ci/docker/host-x86_64/dist-x86_64-illumos/Dockerfile
@@ -6,12 +6,13 @@ RUN sed -i 's/^# deb-src/deb-src/' /etc/apt/sources.list
 COPY scripts/cross-apt-packages.sh /tmp/
 RUN bash /tmp/cross-apt-packages.sh
 
-# Required for cross-build gcc
+# Required for cross-build gcc, and we install python2 to test general compatibility.
 RUN apt-get update && \
     apt-get install -y --no-install-recommends \
     libgmp-dev \
     libmpfr-dev \
     libmpc-dev \
+    python2.7 \
     && rm -rf /var/lib/apt/lists/*
 
 COPY scripts/illumos-toolchain.sh /tmp/
@@ -35,4 +36,4 @@ ENV \
 ENV HOSTS=x86_64-unknown-illumos
 
 ENV RUST_CONFIGURE_ARGS --enable-extended --disable-docs
-ENV SCRIPT python3 ../x.py dist --host $HOSTS --target $HOSTS
+ENV SCRIPT python2.7 ../x.py dist --host $HOSTS --target $HOSTS
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-15/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-15/Dockerfile
index fb5037e3b97..c471843b853 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-15/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-15/Dockerfile
@@ -2,7 +2,6 @@ FROM ubuntu:22.10
 
 ARG DEBIAN_FRONTEND=noninteractive
 
-# NOTE: intentionally installs both python2 and python3 so we can test support for both.
 RUN apt-get update && apt-get install -y --no-install-recommends \
   g++ \
   gcc-multilib \
@@ -11,7 +10,6 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   file \
   curl \
   ca-certificates \
-  python2.7 \
   python3 \
   git \
   cmake \
@@ -63,6 +61,4 @@ ENV SCRIPT ../x.py --stage 2 test --exclude src/tools/tidy && \
            # work.
            #
            ../x.ps1 --stage 2 test tests/ui --pass=check \
-                             --host='' --target=i686-unknown-linux-gnu && \
-           # Run tidy at the very end, after all the other tests.
-           python2.7 ../x.py --stage 2 test src/tools/tidy
+                             --host='' --target=i686-unknown-linux-gnu
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-llvm-16/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-16/Dockerfile
new file mode 100644
index 00000000000..7c75d0df590
--- /dev/null
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-llvm-16/Dockerfile
@@ -0,0 +1,64 @@
+FROM ubuntu:23.04
+
+ARG DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+  g++ \
+  gcc-multilib \
+  make \
+  ninja-build \
+  file \
+  curl \
+  ca-certificates \
+  python3 \
+  git \
+  cmake \
+  sudo \
+  gdb \
+  llvm-16-tools \
+  llvm-16-dev \
+  libedit-dev \
+  libssl-dev \
+  pkg-config \
+  zlib1g-dev \
+  xz-utils \
+  nodejs \
+  mingw-w64 \
+  && rm -rf /var/lib/apt/lists/*
+
+# Install powershell (universal package) so we can test x.ps1 on Linux
+RUN curl -sL "https://github.com/PowerShell/PowerShell/releases/download/v7.3.1/powershell_7.3.1-1.deb_amd64.deb" > powershell.deb && \
+    dpkg -i powershell.deb && \
+    rm -f powershell.deb
+
+COPY scripts/sccache.sh /scripts/
+RUN sh /scripts/sccache.sh
+
+# We are disabling CI LLVM since this builder is intentionally using a host
+# LLVM, rather than the typical src/llvm-project LLVM.
+ENV NO_DOWNLOAD_CI_LLVM 1
+
+# Using llvm-link-shared due to libffi issues -- see #34486
+ENV RUST_CONFIGURE_ARGS \
+      --build=x86_64-unknown-linux-gnu \
+      --llvm-root=/usr/lib/llvm-16 \
+      --enable-llvm-link-shared \
+      --set rust.thin-lto-import-instr-limit=10
+
+# NOTE: intentionally uses all of `x.py`, `x`, and `x.ps1` to make sure they all work on Linux.
+ENV SCRIPT ../x.py --stage 2 test --exclude src/tools/tidy && \
+           # Run the `mir-opt` tests again but this time for a 32-bit target.
+           # This enforces that tests using `// EMIT_MIR_FOR_EACH_BIT_WIDTH` have
+           # both 32-bit and 64-bit outputs updated by the PR author, before
+           # the PR is approved and tested for merging.
+           # It will also detect tests lacking `// EMIT_MIR_FOR_EACH_BIT_WIDTH`,
+           # despite having different output on 32-bit vs 64-bit targets.
+           ../x --stage 2 test tests/mir-opt \
+                             --host='' --target=i686-unknown-linux-gnu && \
+           # Run the UI test suite again, but in `--pass=check` mode
+           #
+           # This is intended to make sure that both `--pass=check` continues to
+           # work.
+           #
+           ../x.ps1 --stage 2 test tests/ui --pass=check \
+                             --host='' --target=i686-unknown-linux-gnu