RFR: Improve missing symbols handling

[Maurizio Cimadamore]

If I understand what you are saying, you just want to make explicit the 
fact that if -l has been set, _some_ library will always be set, either 
explicitly (via -L) or implicitly (inferred from java.library.path).

If so, this seems like a good change.

Maurizio

On 03/05/2019 18:12, Henry Jen wrote:
> The current implementation behave correctly as expected, but reading LibraryLookupFilter feels wrong. It depends on the fact that linkCheckPaths is initialized to java.library.path when -l is specified but not -L in Main.java.
>
> At least we can do is to add following change,
>
> --- a/src/jdk.jextract/share/classes/com/sun/tools/jextract/LibraryLookupFilter.java
> +++ b/src/jdk.jextract/share/classes/com/sun/tools/jextract/LibraryLookupFilter.java
> @@ -86,8 +86,9 @@
>       }
>
>       private void initSymChecker(List<String> linkCheckPaths) {
> -        if (!libraryNames.isEmpty() && !linkCheckPaths.isEmpty()) {
> +        if (!libraryNames.isEmpty()) {
>               try {
> +                assert !linkCheckPaths.isEmpty();
>                   Library[] libs = loadLibraries(MethodHandles.lookup(),
>                           linkCheckPaths.toArray(new String[0]),
>                           libraryNames.toArray(new String[0]));
>
> Cheers,
> Henry
>
>> On May 3, 2019, at 10:02 AM, Henry Jen <henry.jen at oracle.com> wrote:
>>
>> Correct.
>>
>> Cheers,
>> Henry
>>
>>
>>> On May 3, 2019, at 10:00 AM, Maurizio Cimadamore <maurizio.cimadamore at oracle.com> wrote:
>>>
>>> Seems like an useful follow up. Just to make sure I understand, if -l is specified, we get same behavior as before. If -l is NOT specified, then the behavior would differ (as we now do the check), and therefore we need the 'ignore' option explicitly, if we want to suppress logging. Right?
>>>
>>> Maurizio
>>>
>>>
>>>
>>>
>>>
>>> On 03/05/2019 17:43, Henry Jen wrote:
>>>> Hi,
>>>>
>>>> Please review a webrev[1] that add the missing —missing-symbols warn support, and turn on symbol checking against default library by default.
>>>>
>>>> This is kind of a follow up to JDK-8223247, as that simply assume we are using the default libraries within JVM if no -l option is provided. This webrev now will
>>>>
>>>> - Same behavior as before if both -l and -L are provided.
>>>> - Symbol check is turned on always. If there is no -l provided, jextract will check symbols against the default library.
>>>> - Default is to issue warnings without -l, exclude with explicit -l. This is mostly backward compatible as it doesn’t change generated code/classes, but show warnings to inform user about potential missing libraries.
>>>>
>>>> To be 100% compatible with before, use '—missing-symbols ignore’
>>>>
>>>> Thoughts?
>>>>
>>>> Cheers,
>>>> Henry
>>>>
>>>> [1] http://cr.openjdk.java.net/~henryjen/panama/missingSymbols/webrev/