[SAOC 2025] Improving D error messages Weekly Update #2

[Iskaban10]

# [SAOC 2025] Improving D error messages Weekly Update #2

This week I focused on trying to improve the diagnostic quality 
of dmd by including the function or constructor name in error 
messages i.e. providing the logical location of errors like the 
C++ compiler does.

For example -
```
hello.cpp: In function main()
```

## Explored the dmd error working pipeline
+ Studied errors.d, specially printDiagnostic() and 
vreportDiagnostic(), where error messages are formatted and 
displayed.
+ Reviewed the role of DiagnosticContext and experimented with it 
to carry contextual information like the current function name.
+ Explored semantic3.d and funcsem.d to understand the semantic 
processing of function bodies.
## Globals and function tracking
+ Experimented with adding a currentFuncName field in globals.d 
for globally tracking the active function during analysis.
+ Experimented with using .error() member functions on 
FuncDeclaration and other Dsymbol-derived classes to simplify 
error reporting.
## Challenges / Issues Encountered
+ **Import cycles**: Adding FuncDeclaration references in 
globals.d caused cyclic imports.
+ **Infinite recursion / silent compiler**: Incorrect placement 
of function name tracking in semantic3() temporarily suppressed 
error output, likely due to recursion.

The git branch I am working on is : 
https://github.com/Iskaban10/dmd/tree/improve-error-msg