hg: panama/dev: Summary: Add libclang version check and option to select version

[Jorn Vernee]

Yes this is desired. We don't support libclang 8 and 9 currently, but we 
know 7 works, so we set that as a default. It's a way of saying "please 
use 7, because we know it works". But there could be reasons why people 
want to use other versions, for instance to experiment, so there's still 
an option to change the version using --with-libclang-version.

> Anything else should be optional to accommodate	special cases.

So yeah, anything but version 7 would be considered a special case at 
this point.

If you're using another version that also works, we could add that as a 
default supported version as well, e.g. for 6:

```
diff -r 819585c6b8e3 make/autoconf/lib-clang.m4
--- a/make/autoconf/lib-clang.m4        Tue May 07 18:51:44 2019 +0200
+++ b/make/autoconf/lib-clang.m4        Thu May 09 11:48:51 2019 +0200
@@ -61,7 +61,7 @@
        LIBCLANG_VERSION="$with_libclang_version"
        AC_MSG_RESULT([$LIBCLANG_VERSION (manually specified)])
      else
-      LIBCLANG_VERSION="7"
+      LIBCLANG_VERSION="[67]"
        AC_MSG_RESULT([$LIBCLANG_VERSION (default)])
      fi

```

Since we use grep to do the filtering.

Jorn

Henry Jen schreef op 2019-05-09 08:11:
> This change force me to use —with-libclang-version unless I am using
> 7, is this desired?
> 
> Normally, —with-libclang should be enough and there would be only one
> version as the bundle is one single version.
> 
> Anything else should be optional to accommodate	special cases.
> 
> Cheers,
> Henry
> 
> 
>> On May 7, 2019, at 10:55 AM, jbvernee at xs4all.nl wrote:
>> 
>> Changeset: 819585c6b8e3
>> Author:    jvernee
>> Date:      2019-05-07 18:51 +0200
>> URL:       http://hg.openjdk.java.net/panama/dev/rev/819585c6b8e3
>> 
>> Summary: Add libclang version check and option to select version
>> Reviewed-by: mcimadamore
>> 
>> ! make/autoconf/lib-clang.m4
>>