[cfe-dev] Stmt::getLocEnd() behaviour

[Robert Ankeney]

I've been playing with Clang to see what it can do, and thinking of
writing a Rewriter tutorial.  I was thinking of rewriting statements
of the form:
   if (expr)
     stmt;
to:
   if (expr)
   {
      stmt;
   }
as a way to enforce some coding standards I've seen.  I coupled a
RecursiveASTVisitor with a rewriter, and when visiting an IfStmt, I
expected getLocEnd() to point at the end of the if statement.  What I
get instead is somewhere inside the stmt.  Is that expected behaviour?
 For example with the following input file test1.c:
int i = 4;
int j = 0;

int main()
{
  if (i < 4)
     j++;

  while (i < 6)
     i++;

  return 0;
}

I get the output:
int i = 4;
int j = 0;

int main()
{
  <Start If>if (i < 4)
     j<End If>++;

  <Start While>while (i < 6)
     i<End While>++;

  return 0;
}

so that the getLocEnd points to before the ++ operator.
The code I used was:
#include <iostream>

#include "llvm/Support/Host.h"
#include "llvm/Support/raw_ostream.h"

#include "clang/Frontend/CompilerInstance.h"
#include "clang/Basic/TargetOptions.h"
#include "clang/Basic/TargetInfo.h"
#include "clang/Basic/FileManager.h"
#include "clang/Basic/SourceManager.h"
#include "clang/Lex/Preprocessor.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/AST/RecursiveASTVisitor.h"
#include "clang/AST/ASTConsumer.h"
#include "clang/Parse/ParseAST.h"
#include "clang/Rewrite/Rewriters.h"
#include "clang/Rewrite/Rewriter.h"

clang::Rewriter Rewrite;

// RecursiveASTVisitor is is the big-kahuna visitor that traverses
// everything in the AST.
class MyRecursiveASTVisitor
    : public clang::RecursiveASTVisitor<MyRecursiveASTVisitor>
{
 public:
  bool VisitStmt(clang::Stmt *s);
};


// Override Statements which includes expressions and more
bool MyRecursiveASTVisitor::VisitStmt(clang::Stmt *s)
{
  if (clang::isa<clang::IfStmt>(s))
  {
    Rewrite.InsertText(s->getLocStart(), "<Start If>", true, true);
    Rewrite.InsertText(s->getLocEnd(), "<End If>", true, true);
  }
  else
  if (clang::isa<clang::WhileStmt>(s))
  {
    Rewrite.InsertText(s->getLocStart(), "<Start While>", true, true);
    Rewrite.InsertText(s->getLocEnd(), "<End While>", true, true);
  }

  return true; // returning false aborts the traversal
}

class MyASTConsumer : public clang::ASTConsumer
{
 public:
    virtual bool HandleTopLevelDecl(clang::DeclGroupRef d);
};


bool MyASTConsumer::HandleTopLevelDecl(clang::DeclGroupRef d)
{
  MyRecursiveASTVisitor rv;
  typedef clang::DeclGroupRef::iterator iter;

  for (iter b = d.begin(), e = d.end(); b != e; ++b) {
    rv.TraverseDecl(*b);
  }

  return true; // keep going
}


int main()
{
  using clang::CompilerInstance;
  using clang::TargetOptions;
  using clang::TargetInfo;
  using clang::FileEntry;

  CompilerInstance ci;
  ci.createDiagnostics(0,NULL);

  TargetOptions to;
  to.Triple = llvm::sys::getDefaultTargetTriple();
  TargetInfo *pti = TargetInfo::CreateTargetInfo(ci.getDiagnostics(), to);
  ci.setTarget(pti);

  ci.createFileManager();
  ci.createSourceManager(ci.getFileManager());
  ci.createPreprocessor();
  ci.getPreprocessorOpts().UsePredefines = false;
  MyASTConsumer *astConsumer = new MyASTConsumer();
  ci.setASTConsumer(astConsumer);

  ci.createASTContext();

  // Initialize rewriter
  Rewrite.setSourceMgr(ci.getSourceManager(), ci.getLangOpts());

  const FileEntry *pFile = ci.getFileManager().getFile("test1.c");
  ci.getSourceManager().createMainFileID(pFile);
  ci.getDiagnosticClient().BeginSourceFile(ci.getLangOpts(),
                                           &ci.getPreprocessor());
  clang::ParseAST(ci.getPreprocessor(), astConsumer, ci.getASTContext());
  ci.getDiagnosticClient().EndSourceFile();

  // Now output rewritten source code
  const clang::RewriteBuffer *RewriteBuf =
           Rewrite.getRewriteBufferFor(ci.getSourceManager().getMainFileID());
  llvm::errs() << std::string(RewriteBuf->begin(), RewriteBuf->end());

  return 0;
}


A few more questions:
How do I find the points inside the if statement to insert braces?
(after the expression and after the statement)
How best to check if the statement within the if is a CompoundStmt?

Thanks!
Robert Ankeney