[Frontend] SetUpDiagnosticLog should handle unowned diagnostic consumer

in the compiler

The function SetUpDiagnosticLog that was called from createDiagnostics didn't
handle the case where the diagnostics engine didn't own the diagnostics consumer.
This is a potential problem for a clang tool, in particular some of the follow-up
patches for clang-scan-deps will need this fix.

Differential Revision: https://reviews.llvm.org/D63101

llvm-svn: 363009

2 files changed, 25 insertions, 3 deletions

diff --git a/clang/lib/Frontend/CompilerInstance.cpp b/clang/lib/Frontend/CompilerInstance.cpp
index 9c70a70ed7e..fd33b85b31d 100644
--- a/clang/lib/Frontend/CompilerInstance.cpp
+++ b/clang/lib/Frontend/CompilerInstance.cpp
@@ -232,9 +232,13 @@ static void SetUpDiagnosticLog(DiagnosticOptions *DiagOpts,
                                                         std::move(StreamOwner));
   if (CodeGenOpts)
     Logger->setDwarfDebugFlags(CodeGenOpts->DwarfDebugFlags);
-  assert(Diags.ownsClient());
-  Diags.setClient(
-      new ChainedDiagnosticConsumer(Diags.takeClient(), std::move(Logger)));
+  if (Diags.ownsClient()) {
+    Diags.setClient(
+        new ChainedDiagnosticConsumer(Diags.takeClient(), std::move(Logger)));
+  } else {
+    Diags.setClient(
+        new ChainedDiagnosticConsumer(Diags.getClient(), std::move(Logger)));
+  }
 }
 
 static void SetupSerializedDiagnostics(DiagnosticOptions *DiagOpts,
diff --git a/clang/unittests/Frontend/CompilerInstanceTest.cpp b/clang/unittests/Frontend/CompilerInstanceTest.cpp
index 1c3803289b9..3ef13d32ca4 100644
--- a/clang/unittests/Frontend/CompilerInstanceTest.cpp
+++ b/clang/unittests/Frontend/CompilerInstanceTest.cpp
@@ -8,6 +8,7 @@
 
 #include "clang/Frontend/CompilerInstance.h"
 #include "clang/Frontend/CompilerInvocation.h"
+#include "clang/Frontend/TextDiagnosticPrinter.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/ToolOutputFile.h"
@@ -70,4 +71,21 @@ TEST(CompilerInstance, DefaultVFSOverlayFromInvocation) {
   ASSERT_TRUE(Instance.getFileManager().getFile("vfs-virtual.file"));
 }
 
+TEST(CompilerInstance, AllowDiagnosticLogWithUnownedDiagnosticConsumer) {
+  auto DiagOpts = new DiagnosticOptions();
+  DiagOpts->DiagnosticLogFile = "log.diags";
+
+  // Create the diagnostic engine with unowned consumer.
+  std::string DiagnosticOutput;
+  llvm::raw_string_ostream DiagnosticsOS(DiagnosticOutput);
+  auto DiagPrinter = llvm::make_unique<TextDiagnosticPrinter>(
+      DiagnosticsOS, new DiagnosticOptions());
+  CompilerInstance Instance;
+  IntrusiveRefCntPtr<DiagnosticsEngine> Diags = Instance.createDiagnostics(
+      DiagOpts, DiagPrinter.get(), /*ShouldOwnClient=*/false);
+
+  Diags->Report(diag::err_expected) << "no crash";
+  ASSERT_EQ(DiagnosticsOS.str(), "error: expected no crash\n");
+}
+
 } // anonymous namespace