[Clang][Tooling] Accept preprocessed input files

[jryans]

Summary

This restores the tooling library's ability to accept invocations that take a
preprocessed file as the primary input.

Regressed by https://reviews.llvm.org/D105695
Fixes https://github.com/llvm/llvm-project/issues/63941

[jryans]

• Fixed formatting
• Rebased

[dexonsmith]

LGTM.

clang/lib/Tooling/Tooling.cpp

auto IsSrcFile = [](const driver::InputInfo &II) {
     return isSrcFile(II.getType());
   };
 
   llvm::SmallVector<const driver::Command *, 1> CC1Jobs;
   for (const driver::Command &Job : Jobs)
     if (IsCC1Command(Job) && llvm::all_of(Job.getInputInfos(), IsSrcFile))
       CC1Jobs.push_back(&Job);
 
+  // If there are no jobs for source files, try checking again for a single job
+  // with any file type. This accepts a preprocessed file as input.
+  if (CC1Jobs.empty())
+    for (const driver::Command &Job : Jobs)
+      if (IsCC1Command(Job))
+        CC1Jobs.push_back(&Job);
+
   if (CC1Jobs.empty() ||
       (CC1Jobs.size() > 1 && !ignoreExtraCC1Commands(Compilation))) {
     SmallString<256> error_msg;
     llvm::raw_svector_ostream error_stream(error_msg);
     Jobs.Print(error_stream, "; ", true);
     Diagnostics->Report(diag::err_fe_expected_compiler_job)
         << error_stream.str();
     return nullptr;

clang/unittests/Tooling/ToolingTest.cpp

 
 TEST_F(CommandLineExtractorTest, AcceptSaveTemps) {
   addFile("test.c", "int main() {}\n");
   const char *Args[] = {"clang", "-target",     "arm64-apple-macosx11.0.0",
                         "-c",    "-save-temps", "test.c"};
   EXPECT_NE(extractCC1Arguments(Args), nullptr);
 }
 
+TEST_F(CommandLineExtractorTest, AcceptPreprocessedInputFile) {
+  addFile("test.i", "int main() {}\n");
+  const char *Args[] = {"clang", "-target", "arm64-apple-macosx11.0.0", "-c",
+                        "test.i"};
+  EXPECT_NE(extractCC1Arguments(Args), nullptr);
+}
+
 TEST_F(CommandLineExtractorTest, RejectMultipleArchitectures) {
   addFile("test.c", "int main() {}\n");
   const char *Args[] = {"clang", "-target", "arm64-apple-macosx11.0.0",
                         "-arch", "x86_64",  "-arch",
                         "arm64", "-c",      "test.c"};
   EXPECT_EQ(extractCC1Arguments(Args), nullptr);
 }