Expressions currently don't support generics in paths

[seijikun]

Describe the bug
Currently, the parser does not allow generic parameters in expressions / paths.

To Reproduce

{% macro test(title = Option::<&'static str>::None) %}
    {% if let Some(title) = title %}
        Title: {{title}}
    {% endif %}
{% endmacro %}

{% call test() %}{% endcall %}

This fails to parse with:

error: failed to parse template source
         --> templates/page.jinja:1:31
       "&'static str>::None) %}\n    {% if let Some(title) = title %}\n        Title: {{ti"...
 --> src/main.rs:4:19

Askama version
a3f913a

[GuillaumeGomez]

I think the problem isn't so much that we don't allow generics rather that we don't support lifetime parsing.

[seijikun]

This doesn't have lifetimes, but doesn't work for me either:

{% macro test(title = Option::<String>::None) %}
    {% if let Some(title) = title %}
        Title: {{title}}
    {% endif %}
{% endmacro %}

{% call test() %}{% endcall %}

error: expected `)` to close macro argument list
         --> templates/page.jinja:1:28
       "::<String>::None) %}\n    {% if let Some(title) = title %}\n        Title: {{title"...
 --> src/main.rs:4:19

[GuillaumeGomez]

Oh, my bad, thought we supported it already. That's sad.

[seijikun]

I think it dislikes the turbofish - but all the parser stuff still reads like chinese to me.

[seijikun]

I've looked into this a bit now, but I don't understand enough about it. So unfortunately I have to bail on this one. Would be cool if someone else could take it on.

[GuillaumeGomez]

I was planning to, but not before sunday.

[GuillaumeGomez]

Opened #522.