I think what is being referred to Richard Stallman's rejection of AST-dumping support in gcc (which some have requested for IDE support of refactoring, etc.) on

I think what is being referred to Richard Stallman's rejection of AST-dumping support in gcc (which some have requested for IDE support of refactoring, etc.) on the grounds that such support could theoretically also aid proprietary tools that could avoid the GPL by just taking the AST output.