1 files changed, 41 insertions, 2 deletions
diff --git a/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp b/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
index 8f9386e802a..d94d1c9f52b 100644
--- a/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
+++ b/clang-tools-extra/clangd/unittests/SourceCodeTests.cpp
@@ -312,6 +312,45 @@ TEST(SourceCodeTests, SourceLocationInMainFile) {
   }
 }
 
+TEST(ClangdUnitTest, GetBeginningOfIdentifier) {
+  std::string Preamble = R"cpp(
+struct Bar { int func(); };
+#define MACRO(X) void f() { X; }
+Bar* bar;
+  )cpp";
+  // First ^ is the expected beginning, last is the search position.
+  for (std::string Text : std::vector<std::string>{
+           "int ^f^oo();", // inside identifier
+           "int ^foo();",  // beginning of identifier
+           "int ^foo^();", // end of identifier
+           "int foo(^);",  // non-identifier
+           "^int foo();",  // beginning of file (can't back up)
+           "int ^f0^0();", // after a digit (lexing at N-1 is wrong)
+           "int ^λλ^λ();", // UTF-8 handled properly when backing up
+
+           // identifier in macro arg
+           "MACRO(bar->^func())",  // beginning of identifier
+           "MACRO(bar->^fun^c())", // inside identifier
+           "MACRO(bar->^func^())", // end of identifier
+           "MACRO(^bar->func())",  // begin identifier
+           "MACRO(^bar^->func())", // end identifier
+           "^MACRO(bar->func())",  // beginning of macro name
+           "^MAC^RO(bar->func())", // inside macro name
+           "^MACRO^(bar->func())", // end of macro name
+       }) {
+    std::string WithPreamble = Preamble + Text;
+    Annotations TestCase(WithPreamble);
+    auto AST = TestTU::withCode(TestCase.code()).build();
+    const auto &SourceMgr = AST.getSourceManager();
+    SourceLocation Actual = getBeginningOfIdentifier(
+        TestCase.points().back(), SourceMgr, AST.getASTContext().getLangOpts());
+    Position ActualPos = offsetToPosition(
+        TestCase.code(),
+        SourceMgr.getFileOffset(SourceMgr.getSpellingLoc(Actual)));
+    EXPECT_EQ(TestCase.points().front(), ActualPos) << Text;
+  }
+}
+
 TEST(SourceCodeTests, CollectIdentifiers) {
   auto Style = format::getLLVMStyle();
   auto IDs = collectIdentifiers(R"cpp(
@@ -417,8 +456,8 @@ TEST(SourceCodeTests, GetMacros) {
    )cpp");
   TestTU TU = TestTU::withCode(Code.code());
   auto AST = TU.build();
-  auto Loc = getBeginningOfIdentifier(AST, Code.point(),
-                                      AST.getSourceManager().getMainFileID());
+  auto Loc = getBeginningOfIdentifier(Code.point(), AST.getSourceManager(),
+                                      AST.getASTContext().getLangOpts());
   auto Result = locateMacroAt(Loc, AST.getPreprocessor());
   ASSERT_TRUE(Result);
   EXPECT_THAT(*Result, MacroName("MACRO"));