[Support] env vars with empty values on windows

An environment variable can be in one of three states:

1. undefined.
2. defined with a non-empty value.
3. defined but with an empty value.

The windows implementation did not support case 3
(it was not handling errors). The Linux implementation
is already correct.

Differential Revision: https://reviews.llvm.org/D36394

llvm-svn: 311174

1 files changed, 9 insertions, 1 deletions

diff --git a/llvm/unittests/Support/ProcessTest.cpp b/llvm/unittests/Support/ProcessTest.cpp
index 298a0a37323..37587bf4799 100644
--- a/llvm/unittests/Support/ProcessTest.cpp
+++ b/llvm/unittests/Support/ProcessTest.cpp
@@ -42,10 +42,18 @@ TEST(ProcessTest, None) {
   Optional<std::string> val(
       Process::GetEnv("__LLVM_TEST_ENVIRON_NO_SUCH_VAR__"));
   EXPECT_FALSE(val.hasValue());
-}
+} 
 #endif
 
 #ifdef LLVM_ON_WIN32
+
+TEST(ProcessTest, EmptyVal) {
+  SetEnvironmentVariableA("__LLVM_TEST_ENVIRON_VAR__", "");
+  Optional<std::string> val(Process::GetEnv("__LLVM_TEST_ENVIRON_VAR__"));
+  EXPECT_TRUE(val.hasValue());
+  EXPECT_STREQ("", val->c_str());
+}
+
 TEST(ProcessTest, Wchar) {
   SetEnvironmentVariableW(L"__LLVM_TEST_ENVIRON_VAR__", L"abcdefghijklmnopqrs");
   Optional<std::string> val(Process::GetEnv("__LLVM_TEST_ENVIRON_VAR__"));