[cfe-dev] PCH serialization issues (PR 34728)

[Bruno Cardoso Lopes via cfe-dev]

Hi Steve,

On Tue, Sep 26, 2017 at 6:56 PM, Steve O'Brien via cfe-dev
<cfe-dev at lists.llvm.org> wrote:
> I'm running into trouble when serializing a template function
> declaration to PCH and subsequently reading it back:
> https://bugs.llvm.org/show_bug.cgi?id=34728
>
> Small example:
>
>   header.h
>   --
>   template <int i=42, class T> int f(T const&);
>   template <int i, class T> int f(T const&) {return i;}
>
>   main.cpp
>   --
>   int main(int, char**) {return f(3.14);}
>
> An error is reported that the value for `i` could not be deduced,
> because in the AST -> PCH -> AST conversions the default value `42` is
> lost.
>
> I am just now finishing up a patch which adds one more item to the
> serialized output for these template types, indicating the decl (with
> `Record.AddDeclRef`) inherited from if present.
>
> This seems to be working: fixes the errors seen in my repro (see
> bugzilla link above for the repro patch), and the changes seem mostly
> clean.  :)
>
> Does this approach sound ok in theory?

Can't say more without looking at the patch but in theory it's ok.
Worst case we can iterate on a proper fix, please send a patch :-)

-Bruno