Fix having macro variables starting with an underscore

[fabpot]

Closes #4452

[stof]

What if the original name starts and ends with underscores ?

[stof]

What was the reason for the trimming anyway ?

[fabpot]

What was the reason for the trimming anyway ?

We allow people to use variables like this, context, ... So, we need to add a prefix on the PHP side, and trim it when using it in the Twig code.

[fabpot]

What if the original name starts and ends with underscores ?

Fixed

[alexislefebvre]

"\u{035C}" is used in several places, which could lead to unexpected behaviours if one instance is updated but not the others. What do you think about using a constant to define and reuse it? I could open a PR if you agree to this proposal.

[fabpot]

"\u{035C}" is used in several places, which could lead to unexpected behaviours if one instance is updated but not the others. What do you think about using a constant to define and reuse it? I could open a PR if you agree to this proposal.

That won't happen and in any case, we have tests, so I don't think we need a constant here.