[SAoC 2022] Replace druntime Hooks with Templates: Milestone 1, Week 1

[Jordanne]

Your project sounds like a significant improvement to the D 
programming language's runtime efficiency and maintainability. By 
replacing the current hooks with templates, you're addressing 
several key areas:

Performance Improvement: By using templates, you're reducing the 
need for TypeInfo-related indirection, which should lead to 
faster execution at runtime. This is particularly beneficial for 
performance-critical applications.

Compiler Maintainability: Moving the lowerings to the semantic 
analysis phase simplifies the compiler's architecture. This 
change can make the compiler easier to maintain and extend in the 
future.

Function Attribute Inference: Automatically inferring attributes 
like pure and @nogc can lead to more optimized and safer code, as 
these attributes help the compiler make better optimization 
decisions and enforce memory safety.

Reduced Executable Size: By only instantiating the DRuntime 
functions that are actually used, you're minimizing the footprint 
of the compiled executables. This is especially advantageous for 
deploying applications on resource-constrained environments like 
microcontrollers.

Overall, these changes should make the D language more efficient 
and appealing for a wider range of applications, particularly in 
embedded systems. If you have any specific questions or need 
further assistance with your project, feel free to ask!