https://issues.dlang.org/show_bug.cgi?id=24033
Issue ID: 24033
Summary: [compiler diagnostics] Add a way to make aliases
"strong"
Product: D
Version: D2
Hardware: All
OS: All
Status: NEW
Severity: enhancement
Priority: P1
Component: dmd
Assignee: [email protected]
Reporter: [email protected]
This is not about language semantics, but compiler diagnostics only.
Aliases are weak in the sense that error messages resolve aliases:
```d
alias ints = int[];
void f(ints xs);
pragma(msg, typeof(&f)); // void function(int[] xs)
```
The only exceptions are `string`, `wstring`, and `dstring`:
```d
void f(immutable(char)[] str);
pragma(msg, typeof(&f)); // void function(string str)
```
The string aliases aren’t like regular aliases: Their alias name is displayed
instead of the type they alias.
It might be of great pleasure to users if any alias could be marked "strong" by
the programmer, so that the alias appears in diagnostics and not the aliased
type.
Of course, for each type, there must not be multiple different "strong"
aliases.
---
There are several possibilities:
* re-use the `typedef` keyword: `typedef ints = int[];`
* introduce an @attribute: `@strong alias ints = int[];` (applicable to `alias`
only)
* introduce a pragma: `pragma(strong) alias ints = int[];` (applicable to
`alias` only)
* introduce a trait: `__traits(strong) alias ints = int[]; (applicable to
`alias` only)
This is especially useful for templates with optional parameters where users
are generally not interested in the defaults.
--
