Drop the wasm32 builder

This builder tested the wasm32-unknown-emscripten target, which is tier
2 (and so not eligible for testing). In the recent beta promotion, we
ran into a problem with this target: emscripten doesn't support
passing environment variables into the std environment, so we can't
enable RUSTC_BOOTSTRAP for libtest in order to pass -Zunstable-options.

We worked around this for the beta/stable branches, but given this
problem, and its tier 2 status, just dropping the target's tests
entirely seems warranted. Downgrading to tier 3 may also be a good idea,
but that is a separate conversation not proposed here.

.github/workflows/ci.yml

@@ -264,9 +264,6 @@ jobs:
           - name: test-various
             os: ubuntu-20.04-8core-32gb
             env: {}
-          - name: wasm32
-            os: ubuntu-20.04-8core-32gb
-            env: {}
           - name: x86_64-gnu
             os: ubuntu-20.04-4core-16gb
             env: {}

src/ci/docker/host-x86_64/wasm32/Dockerfile

@@ -1,63 +0,0 @@
-FROM ubuntu:22.04
-
-ARG DEBIAN_FRONTEND=noninteractive
-RUN apt-get update && apt-get install -y --no-install-recommends \
-  g++ \
-  make \
-  ninja-build \
-  file \
-  curl \
-  ca-certificates \
-  python3 \
-  git \
-  cmake \
-  sudo \
-  gdb \
-  xz-utils \
-  libssl-dev \
-  bzip2 \
-  && rm -rf /var/lib/apt/lists/*
-
-COPY scripts/emscripten.sh /scripts/
-RUN bash /scripts/emscripten.sh
-
-COPY scripts/sccache.sh /scripts/
-RUN sh /scripts/sccache.sh
-
-# emcc seems to need python to specifically be "python" and not "python3"
-RUN ln `which python3` /usr/bin/python
-
-ENV PATH=$PATH:/emsdk-portable
-ENV PATH=$PATH:/emsdk-portable/upstream/emscripten/
-
-# Rust's build system requires NodeJS to be in the path, but the directory in
-# which emsdk stores it contains the version number. This caused breakages in
-# the past when emsdk bumped the node version causing the path to point to a
-# missing directory.
-#
-# To avoid the problem this symlinks the latest NodeJs version available to
-# "latest", and adds that to the path.
-RUN ln -s /emsdk-portable/node/$(ls /emsdk-portable/node | sort -V | tail -n 1) \
-          /emsdk-portable/node/latest
-ENV PATH=$PATH:/emsdk-portable/node/latest/bin/
-
-ENV BINARYEN_ROOT=/emsdk-portable/upstream/
-ENV EMSDK=/emsdk-portable
-ENV EM_CONFIG=/emsdk-portable/.emscripten
-ENV EM_CACHE=/emsdk-portable/upstream/emscripten/cache
-
-ENV TARGETS=wasm32-unknown-emscripten
-
-# Use -O1 optimizations in the link step to reduce time spent optimizing.
-ENV EMCC_CFLAGS=-O1
-
-COPY static/gitconfig /etc/gitconfig
-
-# Emscripten installation is user-specific
-ENV NO_CHANGE_USER=1
-RUN chown 10719 -R /emsdk-portable/
-
-# Exclude library/alloc due to OOM in benches.
-# FIXME: Fix std tests
-ENV SCRIPT python3 ../x.py test --stage 2 --host='' --target $TARGETS \
-    --skip library/alloc --skip library/std

src/ci/github-actions/ci.yml

@@ -427,9 +427,6 @@ jobs:
           - name: test-various
             <<: *job-linux-8c
 
-          - name: wasm32
-            <<: *job-linux-8c
-
           - name: x86_64-gnu
             <<: *job-linux-4c