[RFC] c++: Print function template parms when relevant (was: [PATCH v4] c++: Add gnu::diagnose_as attribute)

[Matthias Kretz]

On Tuesday, 16 November 2021 21:25:33 CET Jason Merrill wrote:
> On 11/8/21 15:00, Matthias Kretz wrote:
> > I forgot to mention why I tagged it [RFC]: I needed one more bit of
> > information on the template args TREE_VEC to encode
> > EXPLICIT_TEMPLATE_ARGS_P. Its TREE_CHAIN already points to an integer
> > constant denoting the number of non-default arguments, so I couldn't
> > trivially replace that. Therefore, I used the sign of that integer. I was
> > hoping to find a cleaner solution, though.
> It seems that we aren't using any TREE_LANG_FLAG_n on TREE_VEC, so that
> would be a cleaner solution.

I tried that first but realized that TREE_VEC doesn't allow any 
TREE_LANG_FLAGs (it uses those bits for the length IIRC). And setting the 
TREE_LANG_FLAGs on the TREE_CHAIN of the TREE_VEC can't work either (since the 
int constants are shared between many trees).

Should I maybe turn the TREE_CHAIN into a TREE_LIST using TREE_PURPOSE and 
TREE_VALUE for EXPLICIT_TEMPLATE_ARGS_P and non-default arguments, 
respectively? (And where would I document this?)

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 Dr. Matthias Kretz                           https://mattkretz.github.io
 GSI Helmholtz Centre for Heavy Ion Research               https://gsi.de
 stdₓ::simd
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