[foreign] road to posix

[Maurizio Cimadamore]

On 30/05/18 21:18, John Rose wrote:
>  - We might be able to use the built-in cpp expression evaluator 
> inside of clang.
On this point, few days ago I tried to do some experiments with the 
clang API point:

https://clang.llvm.org/doxygen/group__CINDEX__MISC.html#ga6be809ca82538f4a610d9a5b18a10ccb

This appeared to be useful for evaluating a clang cursor but, 
unfortunately it doesn't work on macros, not even if the 
'detailedPreprocessingRecord' flag is enabled:

https://clang.llvm.org/doxygen/group__CINDEX__TRANSLATION__UNIT.html#ggab1e4965c1ebe8e41d71e90203a723fe9a9e1dd69c4a2ff7954dca8df41a63c0e6

The problem seems to be that, by the time we get to parse the AST, the 
preprocessor has already ran, and the clang API sees just 
annotation-like thingies that are placeholders for what once used to be 
a compiler macro. So there seems to be no way to evaluate the value of a 
macro constant, other than get at the macro definition tokens, and 
defining the parsing logic manually (or jump to the C++ API, although I 
don't see a clear way to do that).

Maurizio