[cfe-dev] Keeping invalid AST nodes

Eli Friedman eli.friedman at gmail.com
Mon Nov 5 10:02:19 PST 2012

On Mon, Nov 5, 2012 at 4:18 AM, Erik Verbruggen <erik.verbruggen at me.com> wrote:
> When using libclang for syntax highlighting, I noticed that no AST nodes get built for e.g. invalid expressions. For example, in the following C++ code:
> int func(int i) {
>     int j = undefinedFunction(i) + i;
>     return j;
> }
> the whole initialisation for int j gets dropped, including the (somewhat) valid references to i. I understand that this is done to keep the AST valid after parsing, but an IDE or refactoring tools cannot help out with fixing the problem in that snippet. My question: is there some way to keep the invalid AST nodes, or is somebody already working on this?

No, there's no way to keep them, and AFAIK nobody is working on this.
I'm also not sure it's worthwhile: it's a ton of work for a use case
which doesn't seem very important, given that the vast majority of
code people care about is valid.


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