Ast visitor function for using declarations.

[schaumb]

Based on #487, it resolves #305

• Fix tests
• Add more test
• Variable template ⌧ - postponed Template variables usage #650

Manually:

• Test with multiple namespaces
• Test with multiple files with the same namespace
• Test with nested namespaces
• Using namespace with rename - OK, but namespace Cica = ::MyNamespace; fails
• Using class with rename (works as typedef)

[whisperity]

In general, I am fine with this. However, there is something I really do not understand in the tests. So, there is a function call to g() in the test function. That call should(?) resolve to the void g() {} as defined on line 21. But nowhere in the tests does the number 21 appear... I might just be seeing ghosts here because something is indexed from 0 instead of 1 (the number 20 appears as a line number in the test!), but it's nevertheless curious.

[schaumb]

In general, I am fine with this. However, there is something I really do not understand in the tests. So, there is a function call to g() in the test function. That call should(?) resolve to the void g() {} as defined on line 21. But nowhere in the tests does the number 21 appear... I might just be seeing ghosts here because something is indexed from 0 instead of 1 (the number 20 appears as a line number in the test!), but it's nevertheless curious.

Hi @whisperity ,
The test is about using, but none using directives use the global g function.
This free g function tests that using MyNamespace::g.line does not link to all g functions and the global g function call is not linked to the using line. That's why there are no explicit tests for the g function

[mcserep]

Great work @schaumb! 🏆