Segmentation fault when accessing a token


I’m trying to acces to the SourceLocation of a token (a comma, specifically) in a declaration of this type:

class A{
int a, b;

For this, I’m using this function:

SourceLocation findTokenAfterLocation(SourceLocation loc, ASTContext* Ctx, char c) {
SourceManager &SM = Ctx->getSourceManager();
if (loc.isMacroID())
if (!Lexer::isAtEndOfMacroExpansion(loc, SM,Ctx->getLangOpts(), &loc))
return SourceLocation();
loc = Lexer::getLocForEndOfToken(loc, /Offset=/0, SM, Ctx->getLangOpts());

// Break down the source location.
std::pair<FileID, unsigned> locInfo = SM.getDecomposedLoc(loc);

// Try to load the file buffer.
bool invalidTemp = false;
StringRef file = SM.getBufferData(locInfo.first, &invalidTemp);
if (invalidTemp)
return SourceLocation();

const char *tokenBegin = + locInfo.second;

// Lex from the start of the given location.
Lexer lexer(SM.getLocForStartOfFile(locInfo.first), Ctx->getLangOpts(), file.begin(), tokenBegin, file.end());
Token tok;

case ‘;’: if (tok.isNot(tok::semi))
return findTokenAfterLocation(tok.getLocation(), Ctx, c);
case ‘,’: if (tok.isNot(tok::comma))
return findTokenAfterLocation(tok.getLocation(), Ctx, c);
default: return SourceLocation();

return tok.getLocation();

Which is adapted from “findLocationAfterSemi” from clang/lib/ARCMigrate/Transforms.cpp in order to find several tokens and it works fine in others programs in which is used. But I get a segmentation fault when I try this:

SourceLocation comma = findSymbolAfterLocation(f1->getLocation(), Context,‘,’);

being f1 a FieldDecl*.
What can be happenning?