h2tp: "$a" is converted to $a

[jesseschalken]

HHVM Version

HipHop VM 3.16.0-dev (rel)
Compiler: heads/master-0-ge9eb3fc414fbae9b2c999a4f11390e23050b23b7
Repo schema: 9cc0ebe15bc9d2ba3609c5e4458deeef9ed86dcc

Standalone code, or other way to reproduce the problem

<?hh

$a = 1;
print \is_string("$a");

Run h2tp on file.

Expected result

<?php
require_once ($GLOBALS["HACKLIB_ROOT"]);
$a = 1;
echo (\is_string("$a"));

Actual result

<?php
require_once ($GLOBALS["HACKLIB_ROOT"]);
$a = 1;
echo (\is_string($a));

The conversion to a string via variable interpolation is lost.

[jesseschalken]

Since "{$a}foo" is converted to $a."foo", my guess is that it converts interpolated variables to a list of expressions to be concatenated together, and if that list of expressions contains 1 element, it emits it directly since it has nothing to concat it with. A special case would be needed for an expr list of 1 element so it is emitted as $a."".

[paulbiss]

Just to set some expectations here, there isn't anyone who's currently maintaining h2tp. If you or someone else from the community would like to fix this we'd gladly take a pull request but it's unlikely any of us will have the bandwidth to look at h2tp related issues right now.

[paulbiss]

Aha, I just saw #7427

[SiebelsTim]

h2tp is dead. This can be closed I guess.

[Pacerier]

Re "there isn't anyone who's currently maintaining h2tp", #2236 (comment)

[fredemmott]

If someone in the community wants to build a replacement, https://github.com/hhvm/hhast could be a good starting point.

[fredemmott]

We won't be revisiting our decision to drop support for H2TP; we expect Hack and PHP to continue to diverge, to the point where targeting PHP for cross-compilation won't make more sense than any other language.