Redirecting clang tooling errors

Clang Frontend Using Clang
1

Hello,

I am trying to redirect the output emitted when running a tool through clang::tooling::runToolOnCode() to a buffer or string instead of stderr (llvm::errs()). I’m using clangTooling from release 3.9.

When looking at clangTooling code and following the execution flow, I have found the following:
clang::tooling::runToolOnCode()
calls clang::tooling::runToolOnCodeWithArgs()
which calls clang::tooling::ToolInvocation::run()
which contains the following :
TextDiagnosticPrinter DiagnosticPrinter(llvm::errs(), &*DiagOpts);
DiagnosticsEngine Diagnostics(
IntrusiveRefCntPtrclang::DiagnosticIDs(new DiagnosticIDs()), &*DiagOpts,
DiagConsumer ? DiagConsumer : &DiagnosticPrinter, false);

So at this point I guess I’m stuck because everything is redirected to stderr…
Did I miss something or is there really this limitation?

I also thought of redirecting stderr to somewhere else but… I can’t see how it will fit my needs as in the end I want to call clang::tooling::runToolOnCode() on different files in parallel, all of it in the same process ; so I’ll get stderr mixed with output from several executions. The best solution would obviously being able to provide the DiagnosticConsumer but at the moment everything looks hardcoded.

Best regards,
L. Soltic

2

Considering that there is no other viable possibility, for now I have gone with the following:

using llvm::Twine;
using llvm::SmallString;
using llvm::IntrusiveRefCntPtr;
using llvm::MemoryBuffer;
using clang::FileManager;
using clang::PCHContainerOperations;
using clang::FileSystemOptions;
using clang::tooling::ToolInvocation;
using clang::tooling::FileContentMappings;

static std::vectorstd::string
getSyntaxOnlyToolArgs(const Twine &ToolName,
const std::vectorstd::string &ExtraArgs,
StringRef FileName) {
std::vectorstd::string Args;
Args.push_back(ToolName.str());
Args.push_back(“-fsyntax-only”);
Args.insert(Args.end(), ExtraArgs.begin(), ExtraArgs.end());
Args.push_back(FileName.str());
return Args;
}

bool runToolOnCode(clang::FrontendAction *ToolAction, const Twine &Code,
const Twine &FileName, clang::DiagnosticConsumer& diagConsumer)
{
const std::vectorstd::string args;
const Twine toolName = “clang-tool”;
std::shared_ptr PCHContainerOps = std::make_shared();
const FileContentMappings virtualMappedFiles = FileContentMappings();

SmallString<16> fileNameStorage;
StringRef fileNameRef = FileName.toNullTerminatedStringRef(fileNameStorage);
IntrusiveRefCntPtrclang::vfs::OverlayFileSystem OverlayFileSystem
= new clang::vfs::OverlayFileSystem(clang::vfs::getRealFileSystem());
IntrusiveRefCntPtrclang::vfs::InMemoryFileSystem inMemoryFileSystem
= new clang::vfs::InMemoryFileSystem;
OverlayFileSystem->pushOverlay(inMemoryFileSystem);
IntrusiveRefCntPtr files(new FileManager(FileSystemOptions(), OverlayFileSystem));
ToolInvocation invocation(getSyntaxOnlyToolArgs(toolName, args, fileNameRef),
ToolAction, files.get(), std::move(PCHContainerOps));
invocation.setDiagnosticConsumer(&diagConsumer);

SmallString<1024> codeStorage;
inMemoryFileSystem->addFile(fileNameRef, 0,
MemoryBuffer::getMemBuffer(Code.toNullTerminatedStringRef(codeStorage)));

for (auto &filenameWithContent : virtualMappedFiles) {
inMemoryFileSystem->addFile(filenameWithContent.first, 0,
MemoryBuffer::getMemBuffer(filenameWithContent.second));
}

return invocation.run();
}

It is basically a copy & past of runToolOnCode() but with the added parameter for diagnostic consumer. In the end it was not too much code to duplicate thanks to ToolInvocation::setDiagnosticConsumer() already existing.

Best regards,
L. Soltic