interpreter-directive-comments.md

Various command line applications use an Interpreter Directive to define how they should be run.

#! js -m foo

#! node foo

#! eshost foo

I propose we add this as a top level syntax to ECMA262 as a comment that can occur before a DirectivePrologue.

Early Errors

None

Evaluation

None

Grammar

Module := HashBang (opt) ...
Script := HashBang (opt) ...
HashBang := "#!" SingleLineCommentChars (opt)

DirectivePrologue Change

DirectivePrologue text should be changed to explicitly allow HashBang to occur in front of it.

Stage 1?

@bmeck I would call this Shebang instead of InterpreterDirective (to avoid the word "directive") and it should just be the first non-terminal in Script and Module. Something like

Shebang :: #! SingleLineCommentChars(opt)
Script : Shebang(opt) ScriptBody(opt)
Module : Shebang(opt) ModuleBody(opt)

@bmeck Directive prologues are unrelated to this proposal. You should remove the mention. Remember, directive prologues may be present in function bodies, a location where we definitely don't want to allow shebangs.

@michaelficarra DirectivePrologue is affected by the initial statement list, we need to be sure that HashBang doesn't prevent the DirectivePrologue.