Handle already-set-up MSVC environments targeting AArch64/ARM. (#4625)

driver/tool.cpp

@@ -289,17 +289,33 @@ namespace {
 bool setupMsvcEnvironmentImpl(
  bool forPreprocessingOnly,
  std::vector<std::pair<std::wstring, wchar_t *>> *rollback) {
- const bool x64 = global.params.targetTriple->isArch64Bit();
+ const auto &triple = *global.params.targetTriple;
 
  if (env::has(L"VSINSTALLDIR") && !env::has(L"LDC_VSDIR_FORCE")) {
- // Assume a fully set up environment (e.g., VS native tools command prompt).
- // Skip the MSVC setup unless the environment is set up for a different
- // target architecture.
- const auto tgtArch = env::get("VSCMD_ARG_TGT_ARCH"); // VS 2017+
- if (tgtArch.empty() || tgtArch == (x64 ? "x64" : "x86"))
- return true;
+ const auto tripleArch = triple.getArch();
+ const char *expectedArch = nullptr;
+
+ if (tripleArch == llvm::Triple::ArchType::x86_64)
+ expectedArch = "x64";
+ else if (tripleArch == llvm::Triple::ArchType::x86)
+ expectedArch = "x86";
+ else if (tripleArch == llvm::Triple::ArchType::aarch64)
+ expectedArch = "arm64";
+ else if (tripleArch == llvm::Triple::ArchType::arm ||
+ tripleArch == llvm::Triple::ArchType::thumb)
+ expectedArch = "arm";
+
+ if (expectedArch) {
+ // Assume a fully set up environment (e.g., VS native tools command prompt).
+ // Skip the MSVC setup unless the environment is set up for a different
+ // target architecture.
+ const auto tgtArch = env::get("VSCMD_ARG_TGT_ARCH"); // VS 2017+
+ if (tgtArch.empty() || tgtArch == expectedArch)
+ return true;
+ }
  }
 
+ const bool x64 = triple.isArch64Bit();
  const auto begin = std::chrono::steady_clock::now();
 
  static VSOptions vsOptions; // cache, as this can be expensive