RFR: 8210742: Compound var declaration splitting seems broken
maurizio.cimadamore at oracle.com
Fri Nov 16 19:48:23 UTC 2018
One thing that I don't 100% get is what is the set of requirements we
need to preserve; in this case we have a parser error, meaning that the
input source file is wrong according to the grammar; javac ends up
creating a variable tree node anyway, and then this node gets eventually
type-checked, and what we are talking about here is that, when this
type-checking happens (on this tree that is the result of a javac error
recovery step), we are observing a type checking difference from 10 to 11.
Now, it seems like NB would like to have 'var' be applied in all
branches of the compound assignment, and have all types be inferred.
But, as you said, for a variable type such as 'var x' we can't do
much, so we will report an error and we will, I think, create an AST of
type 'var' which will be left untouched, I believe, by type-checking.
So, I guess what I'm really asking for is some explanation of what the
desired behavior should be, and why - so that we can make sure that,
moving forward, we create the right kind of synthetic recovery trees in
(of course none of this is an issue for javac which will shut down
immediately after discovering a parser error w/o even attempting
On 15/11/2018 15:22, srinivas wrote:
> Hi Maurizio,
> Thanks for the review.
> Yes - Initially I thought of making this code common to all branches.
> Below are the reasons for not doing that.
> 1) the reported issue from NB team is for simple 'var x' types but not
> for arrays.
> 2) I don't have enough data to preserve the type for arrays or not and
> I want to avoid breaking any assumption related to arrays error cases
> both from NB team and javac tests.
> Please let me know if I should include array case as well and refactor
> the fix.
> On 15/11/18 5:13 PM, Maurizio Cimadamore wrote:
>> I think what you are doing is ok, but I have some comments:
>> 1) it seems like this code:
>> startPos = TreeInfo.getStartPos(mods);
>> if (startPos == Position.NOPOS)
>> startPos = TreeInfo.getStartPos(type);
>> should probably be lifted outside the 'if' - e.g. should apply to all
>> cases after the check for "isRestrictedLocalVarTypeName"
>> 2) A similar argument applies, kind of, to setting type to 'null'.
>> With your patch we do that in 2/3 branches; the branch that is left
>> out is when you have a var declaration like this:
>> var foo = ...
>> In this case the parser will still attempt to create a var tree with
>> 'var' as its type. If we are worried about how the AST would look in
>> erroneous cases, then I think this is a problem too.
>> On 15/11/2018 10:31, srinivas wrote:
>>> Please review http://cr.openjdk.java.net/~sdama/8210742/webrev.00/
>>> for https://bugs.openjdk.java.net/browse/JDK-8210742.
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