355801 - Incorrect "does not always return a value" strict warnings

Status: RESOLVED WONTFIX

(Core :: JavaScript Engine, defect)

Description

[Jesse Ruderman]

js> options("strict")

js> function() { do { return 3 } while(x) }
typein:4: strict warning: anonymous function does not always return a value: [...]

js> function () { return this; x; }
typein:10: strict warning: anonymous function does not always return a value: [...]

This warning is wrong.  But perhaps it should warn about "Unreachable code" instead?

Comment 1

[Brendan Eich [:brendan]]

Unreachability requires more flow analysis than SpiderMonkey's monkey-sized brain is up to.  The warning is meant to guide away from obvious bad practices such as the ones you show.  I'm not going to WONTFIX this bug, because we may end up with enough flow analysis to make a more accurate report, but this is pretty thin as bugs go :-P.

/be

Comment 2

[André Bargull [:anba]]

Strict warning "does not always return a value" was removed in http://hg.mozilla.org/mozilla-central/rev/a470d0cbe3fa (bug 1046964)