[GSoC] 'Replace Runtime Hooks with Templates' progress and update thread

[Dan Printzell]

On Wednesday, 17 July 2019 at 20:47:02 UTC, Olivier FAURE wrote:
> On Wednesday, 17 July 2019 at 17:04:45 UTC, Dan Printzell wrote:
>> It does this by getting getting the `FuncDeclaration` which in 
>> this case
>> is `HookTraceImpl` function, goes to its parent the 
>> `HookTraceImpl`
>> template, takes the second template parameters, and uses to 
>> rewrite the
>> `CallExp` and replace the `FuncDeclaration` that is used to do 
>> the CTFE
>> interception.
>
> Out of curiosity, what is CTFE interception?

Basically I rewrite the expression `arr.length = len;` into a 
function
call to the templated runtime function `_d_arraysetlengthT(arr,
len);`. But because of this the CTFE can no longer recognize that 
the
code is trying to change the size of `arr`, only that it is 
calling a
function called `_d_arraysetlengthT`.
The CTFE intercept is basically intercepting all the function call
that the CTFE would run and checks if it is trying to call the
`_d_arraysetlengthT`, and if it is it will rewrite the expression 
back
to `arr.length = len` and then interpret that expression instead 
of
the function call.

This is needed as the CTFE way of resizing arrays is not the same 
as
how regular code resizes arrays.