Never install multiple toolchains in a task

So we'll never need to specify +$TOOLCHAIN

Author: asomers

.cirrus.yml

@@ -7,31 +7,29 @@ env:
   BUILD: build
   RUSTFLAGS: -D warnings
   RUSTDOCFLAGS: -D warnings
-  PLUS: +
   TOOL: cargo
-  # The MSRV
-  TOOLCHAIN: 1.63.0
+  MSRV: 1.63.0
   ZFLAGS:
 
 # Tests that don't require executing the build binaries
 build: &BUILD
   build_script:
     - . $HOME/.cargo/env || true
-    - $TOOL $PLUS $TOOLCHAIN -Vv
-    - rustc $PLUS $TOOLCHAIN -Vv
-    - $TOOL $PLUS $TOOLCHAIN $BUILD $ZFLAGS --target $TARGET --all-targets
-    - $TOOL $PLUS $TOOLCHAIN doc $ZFLAGS --no-deps --target $TARGET
-    - $TOOL $PLUS $TOOLCHAIN clippy $ZFLAGS --target $TARGET --all-targets -- -D warnings
+    - $TOOL -Vv
+    - rustc -Vv
+    - $TOOL $BUILD $ZFLAGS --target $TARGET --all-targets
+    - $TOOL doc $ZFLAGS --no-deps --target $TARGET
+    - $TOOL clippy $ZFLAGS --target $TARGET --all-targets -- -D warnings
     - if [ -z "$NOHACK" ]; then mkdir -p $HOME/.cargo/bin; export PATH=$HOME/.cargo/bin:$PATH; fi
     - if [ -z "$NOHACK" ]; then curl -LsSf https://github.com/taiki-e/cargo-hack/releases/latest/download/cargo-hack-${HOST:-$TARGET}.tar.gz | tar xzf - -C ~/.cargo/bin; fi
-    - if [ -z "$NOHACK" ]; then $TOOL $PLUS $TOOLCHAIN hack $ZFLAGS check --target $TARGET --each-feature; fi
+    - if [ -z "$NOHACK" ]; then $TOOL hack $ZFLAGS check --target $TARGET --each-feature; fi
 
 # Tests that do require executing the binaries
 test: &TEST
   << : *BUILD
   test_script:
     - . $HOME/.cargo/env || true
-    - $TOOL $PLUS $TOOLCHAIN test --target $TARGET
+    - $TOOL test --target $TARGET
 
 # Test FreeBSD in a full VM.  Test the i686 target too, in the
 # same VM.  The binary will be built in 32-bit mode, but will execute on a
@@ -53,10 +51,10 @@ test: &TEST
   #setup_script:
     #- kldload mqueuefs
     #- fetch https://sh.rustup.rs -o rustup.sh
-    #- sh rustup.sh -y --profile=minimal --default-toolchain $TOOLCHAIN
+    #- sh rustup.sh -y --profile=minimal --default-toolchain $MSRV
     #- . $HOME/.cargo/env
     #- rustup target add i686-unknown-freebsd
-    #- rustup component add --toolchain $TOOLCHAIN clippy
+    #- rustup component add clippy
   #<< : *TEST
   #i386_test_script:
     #- . $HOME/.cargo/env
@@ -68,20 +66,20 @@ test: &TEST
     #- if [ -z "$NOHACK" ]; then cargo hack check --each-feature --target i686-unknown-freebsd; fi
   #before_cache_script: rm -rf $CARGO_HOME/registry/index
 
-## Test macOS aarch64 in a full VM
-#task:
-  #name: macOS aarch64
-  #env:
-    #TARGET: aarch64-apple-darwin
-  #macos_instance:
-    #image: ghcr.io/cirruslabs/macos-ventura-base:latest
-  #setup_script:
-    #- curl --proto '=https' --tlsv1.2 -sSf -o rustup.sh https://sh.rustup.rs
-    #- sh rustup.sh -y --profile=minimal --default-toolchain $TOOLCHAIN
-    #- . $HOME/.cargo/env
-    #- rustup component add --toolchain $TOOLCHAIN clippy
-  #<< : *TEST
-  #before_cache_script: rm -rf $CARGO_HOME/registry/index
+# Test macOS aarch64 in a full VM
+task:
+  name: macOS aarch64
+  env:
+    TARGET: aarch64-apple-darwin
+  macos_instance:
+    image: ghcr.io/cirruslabs/macos-ventura-base:latest
+  setup_script:
+    - curl --proto '=https' --tlsv1.2 -sSf -o rustup.sh https://sh.rustup.rs
+    - sh rustup.sh -y --profile=minimal --default-toolchain $MSRV
+    - . $HOME/.cargo/env
+    - rustup component add clippy
+  << : *TEST
+  before_cache_script: rm -rf $CARGO_HOME/registry/index
 
 # Use cross for QEMU-based testing
 # cross needs to execute Docker, so we must use Cirrus's Docker Builder task.
@@ -130,7 +128,7 @@ task:
   setup_script:
     - mkdir /tmp/home
     - curl --proto '=https' --tlsv1.2 -sSf -o rustup.sh https://sh.rustup.rs
-    - sh rustup.sh -y --profile=minimal --default-toolchain $TOOLCHAIN
+    - sh rustup.sh -y --profile=minimal --default-toolchain $MSRV
     - . $HOME/.cargo/env
     - cargo install cross --version 0.2.1 # cross 0.2.2 bumped the MSRV to 1.58.1
   << : *TEST
@@ -166,8 +164,6 @@ task:
     image: rust:latest
   env:
     TARGET: x86_64-unknown-linux-gnu
-    TOOLCHAIN:
-    PLUS:
   setup_script:
     - rustup component add clippy
     - rustup toolchain list
@@ -245,28 +241,25 @@ task:
         TARGET: x86_64-unknown-netbsd
   setup_script:
     - rustup target add $TARGET
-    - rustup toolchain install $TOOLCHAIN --profile minimal --target $TARGET
-    - rustup component add --toolchain $TOOLCHAIN clippy
+    - rustup component add clippy
   << : *BUILD
   before_cache_script: rm -rf $CARGO_HOME/registry/index
 
-#task:
-  #container:
-    #image: rust:1.63.0
-  #env:
-    #BUILD: check
-  #name: Redox x86_64
-  #env:
-    #HOST: x86_64-unknown-linux-gnu
-    #TARGET: x86_64-unknown-redox
-    ## Redox's MSRV policy is unclear.  Until they define it, use nightly.
-    #TOOLCHAIN: nightly
-  #setup_script:
-    #- rustup target add $TARGET
-    #- rustup toolchain install $TOOLCHAIN --profile minimal --target $TARGET
-    #- rustup component add --toolchain $TOOLCHAIN clippy
-  #<< : *BUILD
-  #before_cache_script: rm -rf $CARGO_HOME/registry/index
+task:
+  container:
+    # Redox's MSRV policy is unclear.  Until they define it, use nightly.
+    image: rustlang/rust:nightly
+  env:
+    BUILD: check
+  name: Redox x86_64
+  env:
+    HOST: x86_64-unknown-linux-gnu
+    TARGET: x86_64-unknown-redox
+  setup_script:
+    - rustup target add $TARGET
+    - rustup component add clippy
+  << : *BUILD
+  before_cache_script: rm -rf $CARGO_HOME/registry/index
 
 ## Rust Tier 3 targets can't use Rustup
 task:
@@ -275,8 +268,6 @@ task:
   env:
     BUILD: check
     HOST: x86_64-unknown-linux-gnu
-    PLUS:
-    TOOLCHAIN: 
     ZFLAGS: -Zbuild-std
   matrix:
     - name: DragonFly BSD x86_64