Reapply r359778: [clangd] Fix code completion of macros defined in the preamble region of the main file.

The bad assert has been removed, and updateOutOfDateIdentifier has been guarded.
This reverts commit r359796.

llvm-svn: 359799

1 files changed, 15 insertions, 6 deletions

diff --git a/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp b/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
index 97f9124e714..c0ec8dd1a37 100644
--- a/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
+++ b/clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp
@@ -2073,19 +2073,28 @@ TEST(CompletionTest, MergeMacrosFromIndexAndSema) {
               UnorderedElementsAre(Named("Clangd_Macro_Test")));
 }
 
-TEST(CompletionTest, NoMacroFromPreambleIfIndexIsSet) {
+TEST(CompletionTest, MacroFromPreamble) {
+  MockFSProvider FS;
+  MockCompilationDatabase CDB;
+  std::string FooHeader = testPath("foo.h");
+  FS.Files[FooHeader] = "#define CLANGD_PREAMBLE_HEADER x\n";
+  IgnoreDiagnostics DiagConsumer;
+  ClangdServer Server(CDB, FS, DiagConsumer, ClangdServer::optsForTest());
   auto Results = completions(
-      R"cpp(#define CLANGD_PREAMBLE x
+      R"cpp(#include "foo.h"
+          #define CLANGD_PREAMBLE_MAIN x
 
           int x = 0;
           #define CLANGD_MAIN x
           void f() { CLANGD_^ }
       )cpp",
       {func("CLANGD_INDEX")});
-  // Index is overriden in code completion options, so the preamble symbol is
-  // not seen.
-  EXPECT_THAT(Results.Completions, UnorderedElementsAre(Named("CLANGD_MAIN"),
-                                                        Named("CLANGD_INDEX")));
+  // We should get results from the main file, including the preamble section.
+  // However no results from included files (the index should cover them).
+  EXPECT_THAT(Results.Completions,
+              UnorderedElementsAre(Named("CLANGD_PREAMBLE_MAIN"),
+                                   Named("CLANGD_MAIN"),
+                                   Named("CLANGD_INDEX")));
 }
 
 TEST(CompletionTest, DeprecatedResults) {