Auto merge of #161681 - mati865:cross-i686-mingw, r=jieyouxu

Cross-compile i686-pc-windows-gnu std from x86_64


As per rust-lang/compiler-team#1020.

We could free up the runner by building it as a part of other job, but other Windows jobs are already quite long and setup on Linux would require finding the fitting toolchain. This can be done as a followup if somebody cares.

Author: bors

src/ci/github-actions/jobs.yml

@@ -821,14 +821,14 @@ auto:
 
   - name: dist-i686-mingw
     env:
-      # Disable RISCV target because building it OOMs.
       RUST_CONFIGURE_ARGS: >-
-        --build=i686-pc-windows-gnu
-        --enable-full-tools
-        --set llvm.targets=AArch64;AMDGPU;ARM;BPF;Hexagon;LoongArch;MSP430;Mips;NVPTX;PowerPC;Sparc;SystemZ;WebAssembly;X86
+        --build=x86_64-pc-windows-gnu
+        --host=
+        --target=i686-pc-windows-gnu
+        --disable-docs
+        --set target.i686-pc-windows-gnu.linker=i686-w64-mingw32-gcc
       SCRIPT: python x.py dist bootstrap --include-default-paths
-      DIST_REQUIRE_ALL_TOOLS: 1
-      CODEGEN_BACKENDS: llvm,cranelift
+      CODEGEN_BACKENDS: llvm
     <<: *job-windows
 
   - name: dist-x86_64-mingw

src/ci/scripts/install-mingw.sh

@@ -12,7 +12,17 @@ LLVM_MINGW_ARCHIVE_AARCH64="llvm-mingw-20251104-ucrt-aarch64.zip"
 LLVM_MINGW_ARCHIVE_X86_64="llvm-mingw-20251104-ucrt-x86_64.zip"
 
 if isWindows && isKnownToBeMingwBuild; then
-    case "${CI_JOB_NAME}" in
+    toolchains=
+    # i686-pc-windows-gnu is cross-compiled from x86_64-pc-windows-gnu, so we need
+    # the both toolchains
+    if [[ "${CI_JOB_NAME}" == *i686-mingw* ]]; then
+        toolchains=("${CI_JOB_NAME}" "x86_64-mingw")
+    else
+        toolchains=("${CI_JOB_NAME}")
+    fi
+
+    for toolchain in "${toolchains[@]}"; do
+        case "${toolchain}" in
         *aarch64-llvm*)
             mingw_dir="clangarm64"
             mingw_archive="${LLVM_MINGW_ARCHIVE_AARCH64}"
@@ -81,4 +91,5 @@ if isWindows && isKnownToBeMingwBuild; then
         # (see https://github.com/actions/runner-images/issues/12600)
         /c/msys64/usr/bin/bash -lc ' '
     fi
+    done
 fi