Error Stack Column number

[Attila Szegedi]

Okay, I tracked this down to an incorrect optimization in code generator for when you use >>=0 to coerce to an uint32 :-( 

There is a special case for exactly this usage, where the right-hand-side operand is a literal 0, so we avoid emitting a no-op “ICONST_0; IUSHR” bytecode sequence. It unfortunately wasn’t working correctly for when the left-hand-side operand of a compound-assignment-shift-right was either a property or element access expression (either “obj.foo” or “obj[x]”)

Decomposing the compound assignment into an explicit shift and assignment would work around the problem for now:

   this.length = this.length >>> 0;  // Coerce to uint32.

I filed <https://bugs.openjdk.java.net/browse/JDK-8170594 <https://bugs.openjdk.java.net/browse/JDK-8170594>> and have a fix for it.

Attila.

> On 01 Dec 2016, at 07:44, Sundararajan Athijegannathan <sundararajan.athijegannathan at oracle.com> wrote:
> 
> We do not aim to provide complete compatibility with other JS implementations on the non-standard properties such as "stack". stack tries to mimic whatever is done for Java code (no column number for eg.). But, as you've noted there are enough information on Error objects via other properties like lineNumber, columnNumber, fileName. It should be possible to write a simple utility function to format stack string as desired for specific applications.
> 
> Thanks,
> -Sundar
> 
> On 01/12/16, 3:32 AM, Art Fiedler wrote:
>> When making an implementation of console.count([label])  part of the
>> Mozilla's developer docs
>>     https://developer.mozilla.org/en-US/docs/Web/API/Console/count
>> mentions when label is omitted, the function will count the number of times
>> count() was called
>> on that line... however, if the javascript code has been minified all lines
>> of code may be on the
>> same line... messing up all console.count() calls...
>> 
>> I was providing that implementation by using new Error().stack and parsing
>> the current file:line...
>> however I could fix the minify issue if new Error().stack output the column
>> also for instance...
>> other browser seem to be doing file:line:column in the stack trace.
>> Including nodejs see:
>>     https://nodejs.org/api/errors.html#errors_error_stack
>> 
>> Microsoft Edge's dev console outputs...
>>     new Error().stack:
>>     "Error
>>        at eval code (eval code:1:1)"
>> Firefox since FF30:
>> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error/stack
>> 
>> Currently nashorn error stacks only include the line number...
>>     public static void main(String[] args) throws Exception {
>>         NashornScriptEngineFactory factory = new
>> NashornScriptEngineFactory();
>>         ScriptEngine scriptEngine = factory.getScriptEngine();
>>         scriptEngine.put(ScriptEngine.FILENAME, "myfile.js");
>>         scriptEngine.eval("print('fileName: ' + new Error().fileName);");
>>         scriptEngine.eval("print('lineNumber: ' + new
>> Error().lineNumber);");
>>         scriptEngine.eval("print('columnNumber: ' + new
>> Error().columnNumber);");
>>         scriptEngine.eval("print('stack: ' + new Error().stack);");
>>     }
>>     /*
>>     fileName: myfile.js
>>     lineNumber: 1
>>     columnNumber: -1
>>     stack: Error
>>         at<program>  (myfile.js:1)
>>      */
>> 
>> Would be nice to add the column number to the stacks and error object in
>> nashorn.
>> 
>> Thanks,
>> Arthur Fiedler