Merge remote-tracking branch 'origin/main' into jsgette/fix-windows-cpython-install-runfiles

Author: JSGette

.bazelrc

@@ -81,7 +81,6 @@ common:windows --repo_env=PIP_CACHE_DIR # https://pip.pypa.io/en/stable/topics/c
 common:windows --repo_env=SYSTEMDRIVE # needed by vswhere to locate the VS installer instance database
 common:windows --repo_env=SYSTEMROOT # used by COM to load system DLLs, needed by vswhere
 common:windows --repo_env=USERPROFILE # used by MSYS2 bash to emulate HOME, needed by git to fetch repositories
-common:windows --repo_env=VSTUDIO_ROOT # visual_studio(path_variable) in MODULE.bazel; MSBuild-only
 common:windows --run_env=__COMPAT_LAYER=RunAsInvoker # install*.exe may otherwise fail claiming unneeded admin elevation
 common:windows --test_env=__COMPAT_LAYER=RunAsInvoker # same, for bazel test
 common:windows --shell_executable=C:/tools/msys64/usr/bin/bash.exe

MODULE.bazel

@@ -218,8 +218,6 @@ register_toolchains(
     dev_dependency = True,
 )
 
-visual_studio = use_repo_rule("//bazel/rules:visual_studio.bzl", "visual_studio")
-
 ######################################
 ## LLVM BPF toolchain for eBPF    ##
 ####################################
@@ -378,8 +376,9 @@ winlibs_mingw_repository(
     url = "https://github.com/brechtsanders/winlibs_mingw/releases/download/14.2.0posix-19.1.7-12.0.0-msvcrt-r3/winlibs-x86_64-posix-seh-gcc-14.2.0-mingw-w64msvcrt-12.0.0-r3.zip",
 )
 
-# Hermetic MSVC + Windows SDK for rules_cc (cl/link), and MSBuild for CPython
-# (see deps/cpython/build_python.bat). MinGW stays the default Windows cc_toolchain.
+# Hermetic MSVC + Windows SDK + MSBuild for CPython and DatadogInterop
+# (see deps/cpython/build_python.bat, tools/windows/DatadogInterop). MinGW stays
+# the default Windows cc_toolchain.
 msvc_toolchain = use_extension("@toolchains_msvc//:extensions.bzl", "toolchain")
 msvc_toolchain.toolchain_set(
     name = "default",
@@ -402,13 +401,6 @@ register_toolchains(
     "@llvm_toolchain//:all",  # last to avoid taking precedence over GCC toolchains
 )
 
-# Host MSBuild for the DatadogInterop vcxproj only; CPython uses the hermetic
-# @msvc_toolchains//msbuild instead.
-visual_studio(
-    name = "visual_studio",
-    path_variable = "VSTUDIO_ROOT",
-)
-
 # =========================================
 # Python dependencies
 # =========================================

bazel/AGENTS.md

@@ -892,6 +892,14 @@ over constructing paths under `*.runfiles`.
 **No sandbox.** Windows uses `--strategy=standalone`. Builds are less hermetic by default — undeclared dependencies that
 happen to be present locally will succeed locally and fail in CI or RBE.
 
+**Hermetic MSVC / MSBuild.** MinGW is the default Windows `cc_toolchain`. Hermetic `cl.exe`,
+Windows SDK, and MSBuild come from `@msvc_toolchains` (staged by
+`bazel/patches/toolchains_msvc/`). Drive MSVC-only sources (C++/WinRT, etc.) with
+`run_binary` + hermetic MSBuild — see `tools/windows/DatadogInterop/BUILD.bazel` and
+`deps/cpython.BUILD.bazel` (`python_win`) — so the rest of the Windows tree stays on MinGW.
+Only do this for a library the Go side loads over a C ABI: MSVC and MinGW objects must not
+be linked into the same binary.
+
 **Path separators.** Bazel stores paths with `/` internally. When constructing command lines or environment variables
 for actions, replace `/` with `\` for Windows tools that don't accept forward slashes:
 

bazel/rules/visual_studio.bzl

@@ -21,7 +21,7 @@ tar_md5sums = rule(
             mandatory = True,
         ),
         "_tool": attr.label(
-            default = "//tools/tar_checksums:tar_checksums",
+            default = "//bazel/tools/tar_checksums:tar_checksums",
             executable = True,
             cfg = "exec",
         ),