Clang plugin by John Bartholomew for finding globals and non-const static variables, unpacked

.gitignore

warnglobals.so

ClangWarnGlobals.cpp

// -Wglobals Clang plugin
//
// Based on example plugins and searching Clang's API documentation.
// BEWARE! This is my first ever attempt at a Clang plugin.
//
// Written by John Bartholomew <jpa.bartholomew@gmail.com>

#include "clang/Frontend/FrontendPluginRegistry.h"
#include "clang/AST/AST.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/Frontend/CompilerInstance.h"

namespace {

class PrintGlobalsVisitor : public clang::RecursiveASTVisitor<PrintGlobalsVisitor> {
public:
  explicit PrintGlobalsVisitor(clang::ASTContext *Context, clang::DiagnosticsEngine *Diagnostics)
    : Context(Context), Diagnostics(Diagnostics) {}

  bool VisitVarDecl(clang::VarDecl *D) {
    const clang::SourceManager &SM = Context->getSourceManager();
    if (D->hasGlobalStorage() && !D->getType().isConstQualified()) {
      clang::FullSourceLoc loc = Context->getFullLoc(D->getLocStart());
      if (!SM.isInSystemHeader(loc)) {
        clang::DiagnosticsEngine &D = *Diagnostics;
        unsigned int id = D.getCustomDiagID(clang::DiagnosticsEngine::Warning, "global variable");
        D.Report(loc, id);
      }
    }
    return true;
  }
private:
  clang::ASTContext *Context;
  clang::DiagnosticsEngine *Diagnostics;
};

class PrintGlobalsConsumer : public clang::ASTConsumer {
public:
  explicit PrintGlobalsConsumer(clang::ASTContext *Context, clang::DiagnosticsEngine *Diagnostics)
    : Visitor(Context, Diagnostics) {}

  virtual void HandleTranslationUnit(clang::ASTContext &Context) {
    Visitor.TraverseDecl(Context.getTranslationUnitDecl());
  }
private:
  PrintGlobalsVisitor Visitor;
};

class PrintGlobalsAction : public clang::PluginASTAction {
protected:
    std::unique_ptr<clang::ASTConsumer> CreateASTConsumer(clang::CompilerInstance &CI, llvm::StringRef) {
        return std::unique_ptr<clang::ASTConsumer>(new PrintGlobalsConsumer(&CI.getASTContext(), &CI.getDiagnostics()));
  }

  bool ParseArgs(const clang::CompilerInstance &CI,
                 const std::vector<std::string>& args) {
    // To be written...
    return true;
  }
};

}

static clang::FrontendPluginRegistry::Add<PrintGlobalsAction>
X("warn-globals", "generate warnings for non-const global variables");

Makefile

warnglobals.so: ClangWarnGlobals.cpp
	clang++ -g -O0 -shared -fPIC $$(llvm-config --cflags --cxxflags --ldflags --libs support mc) -o "$@" $^ -lclang

.PHONY: run
run: warnglobals.so
	clang++ -Xclang -load -Xclang ./warnglobals.so -Xclang -add-plugin -Xclang warn-globals test.cpp

.PHONY: clean
clean:
	rm -f warnglobals.so

test.cpp

#include <iostream>

static int s_some_global = 42;
static const int s_some_const_global = 42;

static void some_function_with_a_static() {
  static int s_static_local = 42;
}

namespace some_namespace {
  namespace some_sub_namespace {
    int public_global = 42;
  }

  class some_class {
    static const int static_const_member = 42;
    static int static_member;
  };
}

int some_namespace::some_class::static_member = 42;

int main(int argc, char **argv) {
  std::cout << "global value: " << s_some_global << "\n";
  return 0;
}