linking against clang/llvm 3.0 libraries - c++

Question

I've been playing around with clang/llvm 3.0, following the tutorial here
http://amnoid.de/tmp/clangtut/tut.html
The code in the tutorial is a bit outdated but after some modification, it compiles ok (both with clang++/g++, on Ubuntu):
#include <llvm/Support/raw_ostream.h>
#include <llvm/Support/Host.h>
#include <llvm/ADT/IntrusiveRefCntPtr.h>
#include <clang/Frontend/DiagnosticOptions.h>
#include <clang/Frontend/TextDiagnosticPrinter.h>
#include <clang/Frontend/CompilerInstance.h>
#include <clang/Basic/Diagnostic.h>
#include <clang/Basic/TargetOptions.h>
#include <clang/Basic/TargetInfo.h>
#include <clang/Basic/FileManager.h>
#include <clang/Lex/Preprocessor.h>
#include <clang/Lex/HeaderSearch.h>
using namespace clang;
int main()
{
DiagnosticOptions diagOpt;
TextDiagnosticPrinter *pTextDiagPrinter = new TextDiagnosticPrinter(llvm::outs(), diagOpt);
llvm::IntrusiveRefCntPtr<DiagnosticIDs> pDiagIds(new DiagnosticIDs);
DiagnosticsEngine *pDiagEng = new DiagnosticsEngine(pDiagIds, pTextDiagPrinter);
Diagnostic diag(pDiagEng);
LangOptions lang;
FileSystemOptions fmOpt;
FileManager fm(fmOpt);
SourceManager sm(*pDiagEng, fm);
HeaderSearch headers(fm);
TargetOptions tgtOpt;
tgtOpt.Triple = llvm::sys::getHostTriple();
TargetInfo *ti = TargetInfo::CreateTargetInfo(*pDiagEng, tgtOpt);
CompilerInstance comp;
Preprocessor pp(*pDiagEng, lang, ti, sm, headers, comp);
return 0;
}
The problem is linking, I guess the problem is library order, tried various combinations, some gives thousands of undefined symbols, the best I get is with this:
g++ -fno-exceptions -fno-rtti -fno-common \
-lclangParse -lclangSerialization -lclangDriver -lclangSema -lclangAnalysis -lclangAST -lclangFrontend \
-lclangLex -lclangBasic -lclang \
`llvm-config --cxxflags --ldflags --libs` -ldl tut1.cpp
which gives
tut1.cpp:(.text.startup+0xca): undefined reference to `llvm::outs()'
tut1.cpp:(.text.startup+0xef): undefined reference to `clang::TextDiagnosticPrinter::TextDiagnostic
Printer(llvm::raw_ostream&, clang::DiagnosticOptions const&, bool)'
tut1.cpp:(.text.startup+0x104): undefined reference to `clang::DiagnosticIDs::DiagnosticIDs()'
tut1.cpp:(.text.startup+0x13d): undefined reference to `clang::DiagnosticsEngine::DiagnosticsEngine
(llvm::IntrusiveRefCntPtr<clang::DiagnosticIDs> const&, clang::DiagnosticConsumer*, bool)'
tut1.cpp:(.text.startup+0x14a): undefined reference to `clang::LangOptions::LangOptions()'
tut1.cpp:(.text.startup+0x167): undefined reference to `clang::FileManager::FileManager(clang::File
SystemOptions const&)'
tut1.cpp:(.text.startup+0x17f): undefined reference to `clang::SourceManager::SourceManager(clang::
DiagnosticsEngine&, clang::FileManager&)'
tut1.cpp:(.text.startup+0x194): undefined reference to `clang::HeaderSearch::HeaderSearch(clang::Fi
leManager&)'
tut1.cpp:(.text.startup+0x1f5): undefined reference to `llvm::sys::getHostTriple()'
tut1.cpp:(.text.startup+0x227): undefined reference to `clang::TargetInfo::CreateTargetInfo(clang::
DiagnosticsEngine&, clang::TargetOptions&)'
tut1.cpp:(.text.startup+0x232): undefined reference to `clang::CompilerInstance::CompilerInstance()
'
tut1.cpp:(.text.startup+0x277): undefined reference to `clang::Preprocessor::Preprocessor(clang::Di
agnosticsEngine&, clang::LangOptions&, clang::TargetInfo const*, clang::SourceManager&, clang::Head
erSearch&, clang::ModuleLoader&, clang::IdentifierInfoLookup*, bool, bool)'
tut1.cpp:(.text.startup+0x281): undefined reference to `clang::Preprocessor::~Preprocessor()'
tut1.cpp:(.text.startup+0x289): undefined reference to `clang::CompilerInstance::~CompilerInstance(
)'
tut1.cpp:(.text.startup+0x2e4): undefined reference to `clang::HeaderSearch::~HeaderSearch()'
tut1.cpp:(.text.startup+0x2f1): undefined reference to `clang::SourceManager::~SourceManager()'
tut1.cpp:(.text.startup+0x2fe): undefined reference to `clang::FileManager::~FileManager()'
tut1.cpp:(.text.startup+0x345): undefined reference to `clang::DiagnosticIDs::~DiagnosticIDs()'
collect2: ld returned 1 exit status
I also followed this link Linking against clang-llvm
but seems it doesn't apply to clang 3.0.
Anybody knows how to successfully build the code, or better yet, some tool like some clang-config?

Answer 1

just use the LLVM flags AFTER the .o file, object file won't be linked unless
the flags are written after it. A simple makefile to show what I mean
CC=clang++
LFLAGS=`llvm-config --cppflags --ldflags --libs core`
all:
$(CC) -o out in.cc $(FLAGS)

Answer 2

clang driver itself links with:
-lclangFrontendTool -lclangFrontend -lclangDriver -lclangSerialization -lclangCodeGen -lclangParse -lclangSema -lclangStaticAnalyzerFrontend -lclangStaticAnalyzerCheckers -lclangStaticAnalyzerCore -lclangAnalysis -lclangIndex -lclangARCMigrate -lclangRewrite -lclangAST -lclangLex -lclangBasic
A little trick how to find it out: build clang, remove the clang binary, and run make -n.

Answer 3

Some linkers a sensitive to the order of -l* flags when working with static libraries. The of clang libraries seems OK, so try swapping `llvm-config --cxxflags --ldflags --libs` with clang libraries list.
If that don't help, only solution for you is what #SK-logic suggested - run make -n and look at compile command for clang target.