[clangd] Add buildPreamble to TestTU

[kadircet]

Summary

Depends on D77644.

[sammccall]

clang-tools-extra/clangd/unittests/TestTU.h

71

or just preamble() to align with the functions below... depends whether we think build() is the special case or preamble is similar.
Up to you.

[kadircet]

• Rename buildPreamble to preamble

[kadircet]

• Rebase

[kadircet]

• Rebase

[kadircet]

• Rebase

clang-tools-extra/clangd/unittests/PreambleTests.cpp

 namespace clang {
 namespace clangd {
 namespace {
 
 MATCHER_P2(Distance, File, D, "") {
   return arg.first() == File && arg.second == D;
 }
 
-std::shared_ptr<const PreambleData>
-createPreamble(llvm::StringRef Contents = "") {
-  auto TU = TestTU::withCode(Contents);
-  // ms-compatibility changes meaning of #import, make sure it is turned off.
-  TU.ExtraArgs = {"-fno-ms-compatibility"};
-  TU.Filename = "preamble.cpp";
-  auto PI = TU.inputs();
-  IgnoreDiagnostics Diags;
-  auto CI = buildCompilerInvocation(PI, Diags);
-  if (!CI) {
-    ADD_FAILURE() << "failed to build compiler invocation";
-    return nullptr;
-  }
-  if (auto Preamble = buildPreamble(TU.Filename, *CI, PI, true, nullptr))
-    return Preamble;
-  ADD_FAILURE() << "failed to build preamble";
-  return nullptr;
-}
-
 // Builds a preamble for BaselineContents, patches it for ModifiedContents and
 // returns the includes in the patch.
 IncludeStructure
 collectPatchedIncludes(llvm::StringRef ModifiedContents,
                        llvm::StringRef BaselineContents,
                        llvm::StringRef MainFileName = "main.cpp") {
-  auto BaselinePreamble = createPreamble(BaselineContents);
-  // Create the patch.
-  auto TU = TestTU::withCode(ModifiedContents);
+  auto TU = TestTU::withCode(BaselineContents);
   TU.Filename = MainFileName.str();
+  // ms-compatibility changes meaning of #import, make sure it is turned off.
+  TU.ExtraArgs = {"-fno-ms-compatibility"};
+  auto BaselinePreamble = TU.buildPreamble();
+  // Create the patch.
+  TU = TestTU::withCode(ModifiedContents);
   auto PI = TU.inputs();
   auto PP = PreamblePatch::create(testPath(TU.Filename), PI, *BaselinePreamble);
   // Collect patch contents.
   IgnoreDiagnostics Diags;
   auto CI = buildCompilerInvocation(PI, Diags);
   PP.apply(*CI);
   // Run preprocessor over the modified contents with patched Invocation. We
   // provide a preamble and trim contents to ensure only the implicit header

clang-tools-extra/clangd/unittests/TestTU.h

struct TestTU {
   const SymbolIndex *ExternalIndex = nullptr;
 
   // Simulate a header guard of the header (using an #import directive).
   bool ImplicitHeaderGuard = true;
 
   // By default, build() will report Error diagnostics as GTest errors.
   // Suppress this behavior by adding an 'error-ok' comment to the code.
   ParsedAST build() const;
+  std::shared_ptr<const PreambleData> buildPreamble() const;
   ParseInputs inputs() const;
   SymbolSlab headerSymbols() const;
   std::unique_ptr<SymbolIndex> index() const;
 };
 
 // Look up an index symbol by qualified name, which must be unique.
 const Symbol &findSymbol(const SymbolSlab &, llvm::StringRef QName);
 // Look up an AST symbol by qualified name, which must be unique and top-level.

clang-tools-extra/clangd/unittests/TestTU.cpp

ParseInputs TestTU::inputs() const {
   Inputs.Opts.ClangTidyOpts.Checks = ClangTidyChecks;
   Inputs.Opts.ClangTidyOpts.WarningsAsErrors = ClangTidyWarningsAsErrors;
   Inputs.Index = ExternalIndex;
   if (Inputs.Index)
     Inputs.Opts.SuggestMissingIncludes = true;
   return Inputs;
 }
 
+std::shared_ptr<const PreambleData> TestTU::buildPreamble() const {
+  auto Inputs = inputs();
+  IgnoreDiagnostics Diags;
+  auto CI = buildCompilerInvocation(Inputs, Diags);
+  assert(CI && "Failed to build compilation invocation.");
+  return clang::clangd::buildPreamble(testPath(Filename), *CI, Inputs,
+                                      /*StoreInMemory=*/true,
+                                      /*PreambleCallback=*/nullptr);
+}
+
 ParsedAST TestTU::build() const {
   auto Inputs = inputs();
   StoreDiags Diags;
   auto CI = buildCompilerInvocation(Inputs, Diags);
   assert(CI && "Failed to build compilation invocation.");
-  auto Preamble =
-      buildPreamble(testPath(Filename), *CI, Inputs,
-                    /*StoreInMemory=*/true, /*PreambleCallback=*/nullptr);
+  auto Preamble = clang::clangd::buildPreamble(testPath(Filename), *CI, Inputs,
+                                               /*StoreInMemory=*/true,
+                                               /*PreambleCallback=*/nullptr);
   auto AST = ParsedAST::build(testPath(Filename), Inputs, std::move(CI),
                               Diags.take(), Preamble);
   if (!AST.hasValue()) {
     ADD_FAILURE() << "Failed to build code:\n" << Code;
     llvm_unreachable("Failed to build TestTU!");
   }
   // Check for error diagnostics and report gtest failures (unless expected).
   // This guards against accidental syntax errors silently subverting tests.