Auto merge of #122709 - onur-ozkan:use-precompiled-rustc-by-default, r=Mark-Simulacrum

use precompiled rustc for non-dist builders

Makes non-dist builders to use precompiled CI rustc by default if they are available for the target triple.

As we are going to make `rust.download-rustc=if-unchanged` default option with https://github.com/rust-lang/rust/pull/119899, we need to make sure `if-unchanged` logic never breaks and works as expected.

As an addition, this will significantly improve the build times on CI when there's no change on the compiler.

blocker for #119899

try-job: x86_64-gnu-nopt
try-job: aarch64-apple

6 files changed, 38 insertions, 1 deletions

diff --git a/src/ci/docker/host-x86_64/mingw-check/Dockerfile b/src/ci/docker/host-x86_64/mingw-check/Dockerfile
index 571378774be..467ca1dac67 100644
--- a/src/ci/docker/host-x86_64/mingw-check/Dockerfile
+++ b/src/ci/docker/host-x86_64/mingw-check/Dockerfile
@@ -46,7 +46,20 @@ ENV RUN_CHECK_WITH_PARALLEL_QUERIES 1
 # Check library crates on all tier 1 targets.
 # We disable optimized compiler built-ins because that requires a C toolchain for the target.
 # We also skip the x86_64-unknown-linux-gnu target as it is well-tested by other jobs.
-ENV SCRIPT python3 ../x.py check --stage 0 --set build.optimized-compiler-builtins=false core alloc std --target=aarch64-unknown-linux-gnu,i686-pc-windows-msvc,i686-unknown-linux-gnu,x86_64-apple-darwin,x86_64-pc-windows-gnu,x86_64-pc-windows-msvc && \
+ENV SCRIPT \
+           # `core::builder::tests::ci_rustc_if_unchanged_logic` bootstrap test covers the `rust.download-rustc=if-unchanged` logic.
+           # Here we are adding a dummy commit on compiler and running that test to ensure when there is a change on the compiler,
+           # we never download ci rustc with `rust.download-rustc=if-unchanged` option.
+           echo \"\" >> ../compiler/rustc/src/main.rs && \
+           git config --global user.email \"dummy@dummy.com\" && \
+           git config --global user.name \"dummy\" && \
+           git add ../compiler/rustc/src/main.rs && \
+           git commit -m \"test commit for rust.download-rustc=if-unchanged logic\" && \
+           DISABLE_CI_RUSTC_IF_INCOMPATIBLE=0 python3 ../x.py test bootstrap -- core::builder::tests::ci_rustc_if_unchanged_logic && \
+           # Revert the dummy commit
+           git reset --hard HEAD~1 && \
+
+           python3 ../x.py check --stage 0 --set build.optimized-compiler-builtins=false core alloc std --target=aarch64-unknown-linux-gnu,i686-pc-windows-msvc,i686-unknown-linux-gnu,x86_64-apple-darwin,x86_64-pc-windows-gnu,x86_64-pc-windows-msvc && \
            /scripts/check-default-config-profiles.sh && \
            python3 ../x.py check --target=i686-pc-windows-gnu --host=i686-pc-windows-gnu && \
            python3 ../x.py clippy bootstrap -Dwarnings && \
diff --git a/src/ci/docker/host-x86_64/x86_64-fuchsia/Dockerfile b/src/ci/docker/host-x86_64/x86_64-fuchsia/Dockerfile
index ba3e8bdb687..0cae83a85b3 100644
--- a/src/ci/docker/host-x86_64/x86_64-fuchsia/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-fuchsia/Dockerfile
@@ -58,6 +58,9 @@ RUN mkdir -p $RUST_INSTALL_DIR/etc
 # Fuchsia only supports LLVM.
 ENV CODEGEN_BACKENDS llvm
 
+# download-rustc is not allowed for `x install`
+ENV NO_DOWNLOAD_CI_RUSTC 1
+
 ENV RUST_CONFIGURE_ARGS \
   --prefix=$RUST_INSTALL_DIR \
   --sysconfdir=etc \
@@ -70,6 +73,7 @@ ENV RUST_CONFIGURE_ARGS \
   --set target.x86_64-unknown-fuchsia.ar=/usr/local/bin/llvm-ar \
   --set target.x86_64-unknown-fuchsia.ranlib=/usr/local/bin/llvm-ranlib \
   --set target.x86_64-unknown-fuchsia.linker=/usr/local/bin/ld.lld
+
 ENV SCRIPT \
     python3 ../x.py install --target $TARGETS compiler/rustc library/std clippy && \
     bash ../src/ci/docker/host-x86_64/x86_64-fuchsia/build-fuchsia.sh
diff --git a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
index 145f41f21e1..17fc1a57492 100644
--- a/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
+++ b/src/ci/docker/host-x86_64/x86_64-gnu-tools/Dockerfile
@@ -84,6 +84,7 @@ ENV RUST_CONFIGURE_ARGS \
   --enable-new-symbol-mangling
 
 ENV HOST_TARGET x86_64-unknown-linux-gnu
+ENV FORCE_CI_RUSTC 1
 
 COPY host-x86_64/dist-x86_64-linux/shared.sh /scripts/
 COPY host-x86_64/dist-x86_64-linux/build-gccjit.sh /scripts/
diff --git a/src/ci/docker/run.sh b/src/ci/docker/run.sh
index fad4b5af095..28487bce482 100755
--- a/src/ci/docker/run.sh
+++ b/src/ci/docker/run.sh
@@ -343,6 +343,7 @@ docker \
   --env PR_CI_JOB \
   --env OBJDIR_ON_HOST="$objdir" \
   --env CODEGEN_BACKENDS \
+  --env DISABLE_CI_RUSTC_IF_INCOMPATIBLE="$DISABLE_CI_RUSTC_IF_INCOMPATIBLE" \
   --init \
   --rm \
   rust-ci \
diff --git a/src/ci/github-actions/jobs.yml b/src/ci/github-actions/jobs.yml
index 6379f1ade1c..4bbebbc4697 100644
--- a/src/ci/github-actions/jobs.yml
+++ b/src/ci/github-actions/jobs.yml
@@ -85,6 +85,9 @@ envs:
 # it in each job definition.
 pr:
   - image: mingw-check
+    env:
+      # We are adding (temporarily) a dummy commit on the compiler
+      READ_ONLY_SRC: "0"
     <<: *job-linux-4c
   - image: mingw-check-tidy
     continue_on_error: true
@@ -207,6 +210,8 @@ auto:
     <<: *job-linux-8c
 
   - image: mingw-check
+    env:
+      READ_ONLY_SRC: 0
     <<: *job-linux-4c
 
   - image: test-various
diff --git a/src/ci/run.sh b/src/ci/run.sh
index c8201d9bcfd..1ce54f9ecb3 100755
--- a/src/ci/run.sh
+++ b/src/ci/run.sh
@@ -52,6 +52,13 @@ if [ "$CI" != "" ]; then
     RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set change-id=99999999"
 fi
 
+# If runner uses an incompatible option and `FORCE_CI_RUSTC` is not defined,
+# switch to in-tree rustc.
+if [ "$FORCE_CI_RUSTC" == "" ]; then
+    echo "debug: `DISABLE_CI_RUSTC_IF_INCOMPATIBLE` configured."
+    DISABLE_CI_RUSTC_IF_INCOMPATIBLE=1
+fi
+
 if ! isCI || isCiBranch auto || isCiBranch beta || isCiBranch try || isCiBranch try-perf || \
   isCiBranch automation/bors/try; then
     RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set build.print-step-timings --enable-verbose-tests"
@@ -169,10 +176,16 @@ else
   if [ "$NO_DOWNLOAD_CI_LLVM" = "" ]; then
     RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set llvm.download-ci-llvm=if-unchanged"
   else
+    # CI rustc requires CI LLVM to be enabled (see https://github.com/rust-lang/rust/issues/123586).
+    NO_DOWNLOAD_CI_RUSTC=1
     # When building for CI we want to use the static C++ Standard library
     # included with LLVM, since a dynamic libstdcpp may not be available.
     RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set llvm.static-libstdcpp"
   fi
+
+  if [ "$NO_DOWNLOAD_CI_RUSTC" = "" ]; then
+    RUST_CONFIGURE_ARGS="$RUST_CONFIGURE_ARGS --set rust.download-rustc=if-unchanged"
+  fi
 fi
 
 if [ "$ENABLE_GCC_CODEGEN" = "1" ]; then