Merge pull request #7422 from hughbe/putenv-simplify

Simplify Windows implementation of Compilation::performSimpleCommand

Author: hughbe

lib/Driver/Compilation.cpp

@@ -747,13 +747,16 @@ int Compilation::performSingleCommand(const Job *Cmd) {
 
   for (auto &envPair : Cmd->getExtraEnvironment()) {
 #if defined(_MSC_VER)
-    llvm::SmallString<256> envStr = StringRef(envPair.first);
-    envStr.append(StringRef("="));
-    envStr.append(StringRef(envPair.second));
-    _putenv(envStr.c_str());
+    int envResult =_putenv_s(envPair.first, envPair.second);
 #else
-    setenv(envPair.first, envPair.second, /*replacing=*/true);
+    int envResult = setenv(envPair.first, envPair.second, /*replacing=*/true);
 #endif
+    assert(envResult == 0 &&
+          "expected environment variable to be set successfully");
+    // Bail out early in release builds.
+    if (envResult != 0) {
+      return envResult;
+    }
   }
 
   return ExecuteInPlace(ExecPath, argv);