Re: [PATCH 2/4] PR c++/62314: add fixit hint for "expected ';' after class definition"

[David Malcolm <dmalcolm at redhat dot com>]

On Mon, 2016-05-02 at 12:40 +0200, Bernd Schmidt wrote:
> On 04/28/2016 04:28 PM, David Malcolm wrote:
> > whereas clang reportedly emits:
> > 
> > test.c:2:12: error: expected ';' after struct
> >   struct a {}
> >              ^
> >              ;
> > 
> > (note the offset of the location, and the fix-it hint)
> > 
> > The following patch gives us the latter, more readable output.
> 
> Huh. Only the non-C++ parts remain to be reviewed, and I have no 
> technical objections, but do people really want this? To me that
> looks 
> like unnecessary visual clutter that eats up vertical space for no 
> reason. I know what a semicolon looks like without the compiler
> telling 
> me twice.

My own opinion is that it's worth spending the extra line to get the
semicolon under the caret, as (IMHO) it makes things slightly clearer.

A better argument is that as of r237712 we now have -fdiagnostics
-parseable-fixits.  This allows for an IDE to offer to automatically
apply a fix-it hint.  Hence by providing a fix-it here, an IDE can
potentially insert the semicolon itself:

$ ./xgcc -B. ../../src/gcc/testsuite/g++.dg/pr62314-2.C \
   -fdiagnostics-parseable-fixits

../../src/gcc/testsuite/g++.dg/pr62314-2.C:4:11: error: expected â;â after class definition
 class a {} // { dg-error "11: expected .;. after class definition" }
           ^
           ;
fix-it:"../../src/gcc/testsuite/g++.dg/pr62314-2.C":{4:11-4:11}:";"
../../src/gcc/testsuite/g++.dg/pr62314-2.C:8:2: error: expected â;â after struct definition
 } // { dg-error "2: expected .;. after struct definition" }
  ^
  ;
fix-it:"../../src/gcc/testsuite/g++.dg/pr62314-2.C":{8:2-8:2}:";"


I believe that on building this within a sufficiently recent version of
Xcode that Xcode can offer to insert the semicolon directly.
I'm hoping someone implements this for Emacs.

In that light, is the patch OK?

Thanks
Dave