Right, no "useful common semantics" doesn't means that there aren't specific (perhaps many) cases that will work in all current browsers. It just means that it is hard to find a generalization of those specific cases that could be a useful implementable semantics that would be worth trying to spec. One might be: the enclosing function only contains a single declaration for inner function F and all references to F must be in the same block as the declaration of F and follow the declaration.
Allen On Feb 8, 2011, at 2:56 PM, Brendan Eich wrote: > On Feb 8, 2011, at 2:41 PM, Allen Wirfs-Brock wrote: > >>> The other one I know of is nested named function declarations >>> <http://wiki.ecmascript.org/doku.php?id=conventions:no_non_standard_strict_decls>. >>> And there was an ASI mis-description for "break" and "continue" that was >>> corrected between ES5 and ES5.1. >> >> There really isn't any useful common semantics for function declaration in >> blocks. See >> https://blogs.msdn.com/b/ie/archive/2010/08/25/chakra-interoperability-means-more-than-just-standards.aspx >> > > Yet we keep running into bugs where someone uses function-in-block > intersection semantics. > > Clearly it's useful, since we want it in Harmony. Of course, it's not > supported so developers counting on it are on thin ice regarding name > collisions, name leaks, etc. > > Most recent example: > > https://bugzilla.mozilla.org/show_bug.cgi?id=630851 > > See https://bugzilla.mozilla.org/show_bug.cgi?id=630851#c8 in particular. > > Nevertheless, we are banning function-in-block under Firefox 4's ES5 strict > mode implementation. > > /be >
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