Fix for issue 23908 - error message reports the exact error when a native extension fails to load.

Fix for issue 23908 - error message reports the exact error when a native extension fails to load.

BUG=23908
R=sgjesse@google.com

Committed: https://github.com/dart-lang/sdk/commit/e1ff27e7619cf962dcd7cc8fda52b5b0152e8a61

[siva, 2015-10-13 21:13:14]

asiva@google.com changed reviewers:
+ sgjesse@google.com

[Søren Gjesse, 2015-10-14 07:00:25]

lgtm

https://codereview.chromium.org/1403683007/diff/20001/runtime/bin/extensions_...
File runtime/bin/extensions_android.cc (right):

https://codereview.chromium.org/1403683007/diff/20001/runtime/bin/extensions_...
runtime/bin/extensions_android.cc:36: return Dart_NewApiError(err_str);
Drop the temp err_str like above?

[siva, 2015-10-14 18:13:19]

https://codereview.chromium.org/1403683007/diff/20001/runtime/bin/extensions_...
File runtime/bin/extensions_android.cc (right):

https://codereview.chromium.org/1403683007/diff/20001/runtime/bin/extensions_...
runtime/bin/extensions_android.cc:36: return Dart_NewApiError(err_str);
On 2015/10/14 07:00:25, Søren Gjesse wrote:
> Drop the temp err_str like above?

It is not possible to drop the temp err_str, see comment from man pages "Since
the value of the symbol could actually be NULL (so that a NULL return  from 
dlsym()  need  not indicate  an  error),  the  correct way to test for an error
is to call dlerror() to clear any old error conditions,  then  call  dlsym(), 
and then call dlerror() again, saving its return value into a variable, and
check whether this saved value is not NULL"

[siva, 2015-10-14 18:16:26]

Committed patchset #4 (id:60001) manually as
e1ff27e7619cf962dcd7cc8fda52b5b0152e8a61 (presubmit successful).

[jamesr, 2015-10-14 23:55:38]

jamesr@chromium.org changed reviewers:
+ jamesr@chromium.org

[jamesr, 2015-10-14 23:55:39]

https://codereview.chromium.org/1403683007/diff/60001/runtime/bin/extensions_...
File runtime/bin/extensions_android.cc (right):

https://codereview.chromium.org/1403683007/diff/60001/runtime/bin/extensions_...
runtime/bin/extensions_android.cc:35: char* err_str = dlerror();
This produces the following error in the Flutter build:

../../dart/runtime/bin/extensions_android.cc: In static member function 'static
_Dart_Handle* dart::bin::Extensions::ResolveSymbol(void*, const char*, void**)':
../../dart/runtime/bin/extensions_android.cc:39:27: error: invalid conversion
from 'const char*' to 'char*' [-fpermissive]
   char* err_str = dlerror();

the fix is to make this 'const char* err_str'.  Would it be possible for the
dart build with a higher warning level?

[siva, 2015-10-15 00:27:45]

https://codereview.chromium.org/1403683007/diff/60001/runtime/bin/extensions_...
File runtime/bin/extensions_android.cc (right):

https://codereview.chromium.org/1403683007/diff/60001/runtime/bin/extensions_...
runtime/bin/extensions_android.cc:35: char* err_str = dlerror();
On 2015/10/14 23:55:39, jamesr wrote:
> This produces the following error in the Flutter build:
> 
> ../../dart/runtime/bin/extensions_android.cc: In static member function
'static
> _Dart_Handle* dart::bin::Extensions::ResolveSymbol(void*, const char*,
void**)':
> ../../dart/runtime/bin/extensions_android.cc:39:27: error: invalid conversion
> from 'const char*' to 'char*' [-fpermissive]
>    char* err_str = dlerror();
> 
> the fix is to make this 'const char* err_str'.  Would it be possible for the
> dart build with a higher warning level?

Will fix this in the Dart repo, I thought our warnings are at the highest level
let me check that.