1 files changed, 25 insertions, 2 deletions
diff --git a/llvm/unittests/Support/DebugLogTest.cpp b/llvm/unittests/Support/DebugLogTest.cpp
index 5136999..c34d888 100644
--- a/llvm/unittests/Support/DebugLogTest.cpp
+++ b/llvm/unittests/Support/DebugLogTest.cpp
@@ -27,7 +27,7 @@ TEST(DebugLogTest, Basic) {
     std::string str;
     raw_string_ostream os(str);
     DEBUGLOG_WITH_STREAM_AND_TYPE(os, nullptr) << "NoType";
-    EXPECT_TRUE(StringRef(os.str()).starts_with('['));
+    EXPECT_FALSE(StringRef(os.str()).starts_with('['));
     EXPECT_TRUE(StringRef(os.str()).ends_with("NoType\n"));
   }
 
@@ -37,6 +37,7 @@ TEST(DebugLogTest, Basic) {
     raw_string_ostream os(str);
     DEBUGLOG_WITH_STREAM_AND_TYPE(os, "A") << "A";
     DEBUGLOG_WITH_STREAM_AND_TYPE(os, "B") << "B";
+    EXPECT_TRUE(StringRef(os.str()).starts_with('['));
     EXPECT_THAT(os.str(), AllOf(HasSubstr("A\n"), HasSubstr("B\n")));
   }
 
@@ -61,12 +62,34 @@ TEST(DebugLogTest, Basic) {
     EXPECT_THAT(count, Eq(1));
   }
 }
+
+TEST(DebugLogTest, StreamPrefix) {
+  llvm::DebugFlag = true;
+  static const char *DT[] = {"A", "B"};
+  setCurrentDebugTypes(DT, 2);
+
+  std::string str;
+  raw_string_ostream os(str);
+  std::string expected = "PrefixA 1\nPrefixA 2\nPrefixA \nPrefixB "
+                         "3\nPrefixB 4\nPrefixA 5";
+  {
+    llvm::impl::raw_ldbg_ostream ldbg_osB("PrefixB ", os);
+    llvm::impl::raw_ldbg_ostream ldbg_osA("PrefixA ", os);
+    ldbg_osA << "1\n2";
+    ldbg_osA << "\n\n";
+    ldbg_osB << "3\n4\n";
+    ldbg_osA << "5";
+    EXPECT_EQ(os.str(), expected);
+  }
+  // After destructors, there was a pending newline for stream B.
+  EXPECT_EQ(os.str(), expected + "\nPrefixB \n");
+}
 #else
 TEST(DebugLogTest, Basic) {
   // LDBG should be compiled out in NDEBUG, so just check it compiles and has
   // no effect.
   llvm::DebugFlag = true;
-  static const char *DT[] = {};
+  static const char *DT[] = {"A"};
   setCurrentDebugTypes(DT, 0);
   int count = 0;
   auto inc = [&]() { return ++count; };