Make invalid LHSs that are calls late errors

Make invalid LHSs that are calls late errors

Necessary for web legacy compatibility.

Also fold in additional strict mode checks into LHS checks.
Minor constness clean-ups on the way.

R=marja@chromium.org
BUG=chromium:358346
LOG=Y

Committed: https://code.google.com/p/v8/source/detail?r=20428

[marja, 2014-04-01 16:13:47]

lgtm modulo comments...

https://codereview.chromium.org/217823003/diff/1/src/parser.cc
File src/parser.cc (right):

https://codereview.chromium.org/217823003/diff/1/src/parser.cc#newcode3031
src/parser.cc:3031: if (expression == NULL) {
I don't think that expression can be NULL here. Afaics the parsing functions
such as ParseExpression only return NULL if they also set ok to false, and we
check that above.

(Parser contains these checks here and there. Probably some historical reason,
maybe from times when we didn't have the "ok" boolean but used a NULL return
value to signal error.)

https://codereview.chromium.org/217823003/diff/1/src/preparser.h
File src/preparser.h (right):

https://codereview.chromium.org/217823003/diff/1/src/preparser.h#newcode428
src/preparser.h:428: // Rewrite an expression that denotes a reference value.
The comment is a bit vague if the reader doesn't know already what this is
doing.

How about e.g.:

Checks if the expression is a valid left hand side (takes into account strict
mode), and produces the corresponding errors. Exception: calls are allowed as
left hand sides for web compatibility, and they are rewritten to throw
expressions to produce run time errors.

And the name, how about <Something>LeftHandSideExpression?
CheckLeftHandSideExpression?

[rossberg, 2014-04-01 17:20:05]

https://codereview.chromium.org/217823003/diff/1/src/parser.cc
File src/parser.cc (right):

https://codereview.chromium.org/217823003/diff/1/src/parser.cc#newcode3031
src/parser.cc:3031: if (expression == NULL) {
On 2014/04/01 16:13:47, marja wrote:
> I don't think that expression can be NULL here. Afaics the parsing functions
> such as ParseExpression only return NULL if they also set ok to false, and we
> check that above.
> 
> (Parser contains these checks here and there. Probably some historical reason,
> maybe from times when we didn't have the "ok" boolean but used a NULL return
> value to signal error.)

Good to know. :) Removed.

https://codereview.chromium.org/217823003/diff/1/src/preparser.h
File src/preparser.h (right):

https://codereview.chromium.org/217823003/diff/1/src/preparser.h#newcode428
src/preparser.h:428: // Rewrite an expression that denotes a reference value.
On 2014/04/01 16:13:47, marja wrote:
> The comment is a bit vague if the reader doesn't know already what this is
> doing.
> 
> How about e.g.:
> 
> Checks if the expression is a valid left hand side (takes into account strict
> mode), and produces the corresponding errors. Exception: calls are allowed as
> left hand sides for web compatibility, and they are rewritten to throw
> expressions to produce run time errors.

Done.

> And the name, how about <Something>LeftHandSideExpression?
> CheckLeftHandSideExpression?

Renamed to CheckAndRewriteReferenceExpression. I think it is incorrect to speak
of LeftHandSideExpr here, since that is an independent syntactic category --
this function is applied in places that are not syntactically LHSexprs (e.g. for
++/--). "Reference" is spec terminology for the respective semantic property. I
renamed the IsValidLeftHandSide predicate to match that.

[marja, 2014-04-02 10:42:41]

(still lgtm)

[rossberg, 2014-04-02 11:03:20]

Committed patchset #2 manually as r20428 (presubmit successful).