624766 - poor error fingering for strict error about octal in unrecognized directive

Status: NEW

(Core :: JavaScript Engine, enhancement, P3)

Description

[Brendan Eich [:brendan]]

js> function f(){ "\145"; "use strict"; }
typein:1: SyntaxError: octal literals and octal escape sequences are deprecated:
typein:1: function f(){ "\145"; "use strict"; }
typein:1: ..................................^
js> function f(){
  "\145" // octal escape
  "use strict"
}
typein:5: SyntaxError: octal literals and octal escape sequences are deprecated:
typein:5: }
typein:5: ..^
js> 

Burning directives (recognized or not) into the AST could help, but then you need to suppress code generation while avoiding useless expression warnings (see bug 624199, where the current solution does not build AST for directives).

A minor polish bug, but these count and they can be fun when release pressure is (finally) off.

/be

Comment 1

[Jim Blandy :jimb]

We do retain the directive prologue in the parse tree, for functions at least. All that's missing here is some way for the scanner to indicate whether each specific token used the octal escapes.

Comment 2

[Jim Blandy :jimb]

... and a corresponding way to retain that in the parse nodes. Steal a bit!

Comment 3

[Jeff Walden [:Waldo]]

If I got more firepower behind me and convinced ECMA to make string literals containing escapes not directive prologue members, maybe we could avoid having to do any work to fix this.  ;-)

Comment 4

[Jim Blandy :jimb]

(In reply to comment #3)
> If I got more firepower behind me and convinced ECMA to make string literals
> containing escapes not directive prologue members, maybe we could avoid having
> to do any work to fix this.  ;-)

This is the better solution, yes.