Consider `decl == NULL` case
[trivial] tweak code style
[Refactoring] Reduce use of variable 'a'
[Refactoring] Tweak token consumers

parseImport should return parsed `Import`s.
Add test for ddoc unittest feature (1)
Add test for ddoc unittest feature (2)
fix Issue 11677 - user defined attributes must be first

Parse prefix attributes in while loop of parseDeclDefs
fix Issue 11678 - user defined attributes cannot appear as postfixes
fix Issue 11679 - user defined attributes not allowed for local auto declarations
fix Issue 11680 - user defined attributes for type inference
fix Issue 9112 - Uniform construction for built-in types

Support syntax T(), T(v), and new T(v) for basic type T
Use defaultInitLiteral

It is more direct conversion than using typeDotExp(loc, t, Id::init).
And for scalar types, there is no difference. So this will just shorten
compilation pathway.
Added small parser fix
Merge back semantic result in originalType
fix Issue 12266 - Header generation produces uncompilable header
Tweak ddoc output
[Refactoring] Reduce unnecessary symtab generation
More strict error propagation on IFTI

If resolveFuncCall and functionResolve fail with "error instantiating", it should be finally translated to `ErrorExp`.
fix fix Issue 12231 - ICE on the class declaration within lambda inside template constraint
Disable optimization and inlining in debug DMD builds