HHVM+Hacklang: errors/warnings output into browser

Question

Is there any way to tell HHVM to output Hacklang warnings and errors into the browser? Something like PHP does with enabled display_errors, display_startup_errors and error_reporting set to E_ALL

HHVM version:

$ php -v

HipHop VM 3.1.0-dev+2014.04.09 (rel)
Compiler: heads/master-0-g4fc811c64c23a3686f66a2bea80ba47f3eaf9f3d
Repo schema: 79197c935790c0b9c9cb13566c3e727ace368117

I've tried the following config:

$ cat /etc/hhvm/php.ini
; php options
display_startup_errors = On
error_reporting = E_ALL
display_errors = On

; hhvm specific 
hhvm.log.level = Warning
hhvm.log.always_log_unhandled_exceptions = true
hhvm.log.runtime_error_reporting_level = 8191
hhvm.mysql.typed_results = false

And :

$ cat /etc/hhvm/server.ini 

; php options
pid = /var/run/hhvm/pid

; hhvm specific 
hhvm.server.port = 9000
hhvm.server.type = fastcgi
hhvm.server.default_document = index.php
hhvm.log.level = Warning
hhvm.log.always_log_unhandled_exceptions = true
hhvm.log.runtime_error_reporting_level = 8191
hhvm.log.use_log_file = true
hhvm.log.file = /var/log/hhvm/error.log
hhvm.repo.central.path = /var/run/hhvm/hhvm.hhbc
hhvm.mysql.typed_results = false
hhvm.debug.full_backtrace = true
hhvm.debug.server_stack_trace = true
hhvm.debug.server_error_message = true
hhvm.debug.translate_source = true

Answer 1

tl;dr: You can't.

The thing to keep in mind here is that the typechecker does a static analysis of your code while the PHP errors you talk about show up at runtime. If this was C++, you could compare the Hack typechecker errors with the errors during the compile step - so Hack tells you things that are wrong before the code even runs.

The trick is to use either the vim or emacs plugins which warn you of errors as you save the file, or use hh_client from the terminal, or build a plugin for your favorite IDE (feel free to send pull requests!). hh_client --json gives an easy to parse output if you want to build a plugin for Sublime Text, or Eclipse or whatever you want.

Note that some errors are runtime errors, while some aren't. Function args as well as return types should throw exceptions at runtime for the latest HHVM build for example. The problem there is that you only see those errors when you hit a certain code-path. The beauty of Hack is that it errors for all the problems in your code, even if it's a code-path you may not test at runtime.