1 files changed, 41 insertions, 0 deletions
diff --git a/clang-tools-extra/unittests/clangd/CodeCompleteTests.cpp b/clang-tools-extra/unittests/clangd/CodeCompleteTests.cpp
index 4133f946ff5..afa6f1b8d91 100644
--- a/clang-tools-extra/unittests/clangd/CodeCompleteTests.cpp
+++ b/clang-tools-extra/unittests/clangd/CodeCompleteTests.cpp
@@ -17,6 +17,7 @@
 #include "SyncAPI.h"
 #include "TestFS.h"
 #include "index/MemIndex.h"
+#include "llvm/Support/Error.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
@@ -998,6 +999,46 @@ TEST(CompletionTest, NoIndexCompletionsInsideDependentCode) {
   }
 }
 
+TEST(CompletionTest, DocumentationFromChangedFileCrash) {
+  MockFSProvider FS;
+  auto FooH = testPath("foo.h");
+  auto FooCpp = testPath("foo.cpp");
+  FS.Files[FooH] = R"cpp(
+    // this is my documentation comment.
+    int func();
+  )cpp";
+  FS.Files[FooCpp] = "";
+
+  MockCompilationDatabase CDB;
+  IgnoreDiagnostics DiagConsumer;
+  ClangdServer Server(CDB, FS, DiagConsumer, ClangdServer::optsForTest());
+
+  Annotations Source(R"cpp(
+    #include "foo.h"
+    int func() {
+      // This makes sure we have func from header in the AST.
+    }
+    int a = fun^
+  )cpp");
+  Server.addDocument(FooCpp, Source.code(), WantDiagnostics::Yes);
+  // We need to wait for preamble to build.
+  ASSERT_TRUE(Server.blockUntilIdleForTest());
+
+  // Change the header file. Completion will reuse the old preamble!
+  FS.Files[FooH] = R"cpp(
+    int func();
+  )cpp";
+
+  clangd::CodeCompleteOptions Opts;
+  Opts.IncludeComments = true;
+  CompletionList Completions =
+      cantFail(runCodeComplete(Server, FooCpp, Source.point(), Opts));
+  // We shouldn't crash. Unfortunately, current workaround is to not produce
+  // comments for symbols from headers.
+  EXPECT_THAT(Completions.items,
+              Contains(AllOf(Not(IsDocumented()), Named("func"))));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang