build: Add support for Windows

Author: varungandhi-src

.github/workflows/release.yml

@@ -21,7 +21,7 @@ jobs:
       matrix:
         # NOTE: GitHub-hosted runners for macOS are x86_64 only
         # https://github.com/github/roadmap/issues/528
-        platform: ['ubuntu-22.04', 'macos-12'] # , 'windows-2022']
+        platform: ['ubuntu-22.04', 'macos-12', 'windows-2022']
         config: ['dev', 'release']
         exclude:
           - platform: 'macos-12'

docs/Development.md

@@ -15,6 +15,7 @@
   - [Debugging preprocessor issues](#debugging-preprocessor-issues)
 - [Implementation notes](#implementation-notes)
 - [Notes on Clang internals](#notes-on-clang-internals)
+- [Notes on Windows](#notes-on-windows)
 
 ## Install dependencies
 
@@ -217,3 +218,41 @@ cost of assertions in Clang itself vs in our code.
 
 See [docs/SourceLocation.md](/docs/SourceLocation.md) for information
 about how source locations are handled in Clang.
+
+## Notes on Windows
+
+We have limited familiarity with Windows overall,
+so this section includes detailed steps to (try to)
+build the code on Windows.
+
+1. Spin up a Windows Server 2022 machine on GCP.
+   This generally takes a bit more time than Linux machines.
+2. Install [Microsoft Remote Desktop](https://apps.apple.com/us/app/microsoft-remote-desktop/id1295203466)
+   through the App Store.
+3. Run the GCP command: (via RDP dropdown > View gcloud command to reset password)
+   ```bash
+   gcloud compute reset-windows-password --zone "<your zone>" --project <your project>" "<instane name>"
+   ```
+   This will print a password.
+4. In the GCP UI, download the RDP file for remote login.
+5. Open the RDP file using Microsoft Remote Desktop.
+6. Enter the password from step 3.
+7. Start Powershell.exe as Admin and [install Chocolatey](https://docs.chocolatey.org/en-us/choco/setup#install-with-powershell.exe)
+8. Install [Git for Windows](https://github.com/git-for-windows/git/releases/).
+9. Run Git Bash as Admin and install Python and Bazelisk:
+   ```
+   choco install -yv bazelisk python3
+   ```
+   After this, you may need to restart Git Bash for Python to be found.
+   If after restarting, check if `python3 --version` and `python --version` work.
+   If `python3 --version` doesn't work, then copy over the binary
+   ```bash
+   cp "$(which python)" "$(dirname "$(which python)")/python3"
+   ```
+10. Before invoking Bazel, make sure to run:
+   ```bash
+   export MSYS2_ARG_CONV_EXCL="*"
+   ```
+   for correctly handling `//` in Bazel targets.
+
+After this, you should be able to run the build as usual.

indexer/os/BUILD

@@ -1,13 +1,13 @@
 # NOTE(ref: based-on-sorbet): Based on Sorbet's common/os package.
 cc_library(
     name = "os",
-    srcs = [
-        "Os.h",
-        "Os.cc",
-    ] + select({
-        "@platforms//os:linux": ["Linux.cc"],
-        "@platforms//os:macos": ["macOS.cc"],
-    }),
+    srcs = glob(
+        [
+            "*.cc",
+            "*.h",
+        ],
+        allow_empty = False,
+    ),
     hdrs = [
         "Os.h",
     ],

indexer/os/Windows.cc

@@ -0,0 +1,49 @@
+#ifdef _WIN32
+
+#include <string>
+
+#include <libloaderapi.h>
+#include <processthreadsapi.h>
+#include <windef.h>
+#include <windows.h>
+
+#include "indexer/os/Os.h"
+
+namespace scip_clang {
+
+std::string exec(std::string cmd) {
+  // FIXME(def: windows-support) Implement this if needed for addr2line
+  return "";
+}
+
+std::string addr2line(std::string_view programName, void const *const *addr,
+                      int count) {
+  // FIXME(def: windows-support)
+  return "";
+}
+
+std::string getProgramName() {
+  char buf[MAX_PATH];
+  GetModuleFileNameA(nullptr, buf, MAX_PATH);
+  return buf;
+}
+
+bool setCurrentThreadName(std::string_view name) {
+  std::wstring wstr = std::wstring(name.begin(), name.end());
+  SetThreadDescription(GetCurrentThread(), wstr.c_str());
+  return true;
+}
+
+bool amIBeingDebugged() {
+  // FIXME(def: windows-support)
+  return false;
+}
+
+bool stopInDebugger() {
+  // FIXME(def: windows-support)
+  return false;
+}
+
+} // namespace scip_clang
+
+#endif

setup_llvm.bzl

@@ -11,9 +11,10 @@ def setup_llvm_toolchain(name):
         "linux-x86_64": {"version": "15.0.6", "triple": "x86_64-linux-gnu-ubuntu-18.04", "sha256": "38bc7f5563642e73e69ac5626724e206d6d539fbef653541b34cae0ba9c3f036"},
         "darwin-arm64": {"version": "15.0.6", "triple": "arm64-apple-darwin21.0", "sha256": "32bc7b8eee3d98f72dd4e5651e6da990274ee2d28c5c19a7d8237eb817ce8d91"},
         "darwin-x86_64": {"version": "15.0.7", "triple": "x86_64-apple-darwin21.0", "sha256": "d16b6d536364c5bec6583d12dd7e6cf841b9f508c4430d9ee886726bd9983f1c"},
-        "windows": {"version": "15.0.6", "sha256": "22e2f2c38be4c44db7a1e9da5e67de2a453c5b4be9cf91e139592a63877ac0a2", "url": "https://github.com/llvm/llvm-project/releases/download/llvmorg-15.0.6/LLVM-15.0.6-win64.exe"},
+        "windows": {"version": "15.0.6", "sha256": "8c0305c569391fb842c3a1edb07e63a2c0145a2a601d5a87992ae402b437c48f", "url": "https://github.com/sourcegraph/llvm-toolchain-archives/releases/download/v0-20223-04-10/LLVM-15.0.6-win64.tar.xz"},
     }
     llvm_versions, sha256, strip_prefix, urls = {}, {}, {}, {}
+    strip_prefix["windows"] = "LLVM-15.0.6-win64"
     for (k, v) in mapping.items():
         llvm_versions[k] = v["version"]
         sha256[k] = v["sha256"]