[clangd] Don't treat top-level decls as "local" if they are from the preamble.

[sammccall]

Summary

These get passed to HandleTopLevelDecl() if they happen to have been
deserialized for any reason. We don't want to treat them as part of the
main file.

[ilya-biryukov]

LGTM!

unittests/clangd/ClangdUnitTests.cpp

268

NIT: maybe use ASSEET_THAT(AST.getLocalTopLevelDecls(), ElementsAre(...))

Unless that's too hard for some reason.

clangd/ClangdUnit.cpp

 
 class DeclTrackingASTConsumer : public ASTConsumer {
 public:
   DeclTrackingASTConsumer(std::vector<Decl *> &TopLevelDecls)
       : TopLevelDecls(TopLevelDecls) {}
 
   bool HandleTopLevelDecl(DeclGroupRef DG) override {
     for (Decl *D : DG) {
+      if (D->isFromASTFile())
+        continue;
+
       // ObjCMethodDecl are not actually top-level decls.
       if (isa<ObjCMethodDecl>(D))
         continue;
 
       TopLevelDecls.push_back(D);
     }
     return true;
   }

unittests/clangd/ClangdUnitTests.cpp

SourceLocation Actual = getBeginningOfIdentifier(
         AST, TestCase.points().back(), SourceMgr.getMainFileID());
     Position ActualPos = offsetToPosition(
         TestCase.code(),
         SourceMgr.getFileOffset(SourceMgr.getSpellingLoc(Actual)));
     EXPECT_EQ(TestCase.points().front(), ActualPos) << Text;
   }
 }
 
+MATCHER_P(DeclNamed, Name, "") {
+  if (NamedDecl *ND = dyn_cast<NamedDecl>(arg))
+    if (ND->getName() == Name)
+      return true;
+  if (auto *Stream = result_listener->stream()) {
+    llvm::raw_os_ostream OS(*Stream);
+    arg->dump(OS);
+  }
+  return false;
+}
+
+TEST(ClangdUnitTest, TopLevelDecls) {
+  TestTU TU;
+  TU.HeaderCode = R"(
+    int header1();
+    int header2;
+  )";
+  TU.Code = "int main();";
+  auto AST = TU.build();
+  EXPECT_THAT(AST.getLocalTopLevelDecls(), ElementsAre(DeclNamed("main")));
+}
+
 } // namespace
 } // namespace clangd
 } // namespace clang