[cfe-dev] Rewriter::InsertText

[Сергей Филиппов]

Thanks

Sergey

5 августа 2010 г. 14:17 пользователь Douglas Gregor <dgregor at apple.com>написал:

>
> On Aug 5, 2010, at 12:04 PM, Сергей Филиппов wrote:
>
> > Hi,
> > I'm facing strange bug with Rewriter::InsertText.
> > Here is the code:
> >
> > void RewritingPass::Initialize(ASTContext &context)
> > {
> >     this->context = &context;
> >     SourceLocation L;
> >     mainFileId = context.getSourceManager().getMainFileID();
> >     rewriter = new Rewriter(context.getSourceManager(),
> context.getLangOptions());
> >     const llvm::StringRef preamble(getPreamble());
> >     if (preamble.size() > 0)
> >
> rewriter->InsertText(context.getSourceManager().getLocForStartOfFile(mainFileId),
> preamble, true);
> > }
>
>
> StringRef is a reference to a string that exists somewhere in memory; it
> doesn't copy the contents of the string. In this case, getPreamble() returns
> a temporary, and the preamble StringRef refers to that temporary's storage.
> When the temporary is destroyed, the storage goes away... and you get
> strange behavior. Capture the result of getPreamble() in a local string,
> then pass that along to InsertText.
>
> It's generally not a good idea to have a StringRef variable.
>
>        - Doug
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