[SAOC 2024] Separate Semantic Routines from AST Nodes. - Weekly Update #6

[Dennis]

## Tasks for the week(Oct.21th-Oct.27th)

### Tasks Accomplished
- I started this week by figuring out which of the `include` 
visitor methods was problematic. I used the strategy which I 
mentioned in last week’s report. After the debugging I figured 
out that the StaticIfDeclaration was problematic because there 
was an incorrect cast to the ConditionalDeclaration.

**Initial snippet**
```
Dsymbols* d = include(cast(ConditionalDeclaration)sif, 
sif._scope);
```
This is what happens here, the cast is ignored when calling 
include because include expects an AttribDeclaration. It then 
uses a visitor pattern to reach the appropriate visit override, 
but this results in the StaticIfDeclaration override being called 
instead of ConditionalDeclaration. So to effect the change the 
original scope (sc) was saved into saved_scope  temporalily, the 
scope was then changed to sif._scope, which represents the scope 
of the sif (StaticIfDeclaration). It processes the sif_scope by 
treating it like a `ConditionalDeclaration`  stores the result in 
the `symbols` and restores the original scope without altering 
any behaviour.

https://github.com/dlang/dmd/pull/16970/files/ed00ce2cfcd85eb0ff2dff45357e8c94c8013cd5#diff-862192b33df815981dcb4a8a49bc7dc572506b444a7dc034fde3643f887e2982

**Refactored snippet**
```
Scope* saved_scope = sc;
  sc = sif._scope;
  visit(cast(ConditionalDeclaration) sif);
  Dsymbols* d = symbols;
  sc = saved_scope;
```




- To make the unittest and CI pass successfully, I did the 
following things
      - Updated the `cxxfrontend.cc` with a refactored free 
function call.
      - Updated `frontend.h` using this Command `./build.d 
cxx-headers-test AUTO_UPDATE=1`
      - Updates `dsymbol.h` with the include signature `Dsymbols 
*include(Dsymbol *d, Scope *sc);`
      - Added a Wrapper for the include method in cxxfrontend.d to 
reflect the update in dmd namespace block in `dsymbol.h`
**Merged PR** = 
[https://github.com/dlang/dmd/pull/16970](https://github.com/dlang/dmd/pull/16970)

### Summary
It was a week full of debugging and learning. Next will be, to 
fix the prepare, lowerNonArrayAggregate and lowerArrayAggregate 
methods in statementsem to pass the test suite and then move all 
semantics methods from `dclass.d` to their appropriate modules.