[wwwdocs, committed] gcc-5/changes.html: Update Fortran section

[wwwdocs, committed] gcc-5/changes.html: Update Fortran section

[Tobias Burnus]

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Dear all,

I have committed the attached patch. Comment and suggestions are welcome!

See also: https://gcc.gnu.org/gcc-5/changes.html#fortran

Tobias

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Index: changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-5/changes.html,v
retrieving revision 1.7
diff -u -p -r1.7 changes.html
--- changes.html	26 Aug 2014 17:18:40 -0000	1.7
+++ changes.html	31 Aug 2014 20:34:49 -0000
@@ -91,6 +91,18 @@
 
 <h3 id="fortran">Fortran</h3>
   <ul>
+    <li>Incomplete support for colorizing diagnostics emitted by gfortran has
+      been added. The <code><a
+      href="https://gcc.gnu.org/onlinedocs/gcc/Language-Independent-Options.html#index-fdiagnostics-color-256"
+      >-fdiagnostics-color=</a>auto</code> will enable it when outputting to
+      terminals, <code>-fdiagnostics-color=always</code> unconditionally. The
+      <code>GCC_COLORS</code> environment variable can be used to customize the
+      colors or disable coloring. If <code>GCC_COLORS</code> variable is present
+      in the environment, the default is <code>-fdiagnostics-color=auto</code>,
+      otherwise <code>-fdiagnostics-color=never</code>.</li>
+    <li>The <code>-Wuse-without-only</code> option has been added to warn when a
+      <code>USE</code> statement has no <code>ONLY</code> qualifier and, thus,
+      implicitly imports all public entities of the used module.</li>
     <li><a href="https://gcc.gnu.org/wiki/Fortran2003Status">Fortran 2003</a>:
     <ul>
       <li>The intrinsic IEEE modules (<code>IEEE_FEATURES</code>,
@@ -99,11 +111,14 @@
     </ul></li>
     <li><a href="https://gcc.gnu.org/wiki/Fortran2008Status">Fortran 2008</a>:
     <ul>
-      <li>Coarrays: Full experimental support of Fortran 2008's coarrays with
+      <li><a href="https://gcc.gnu.org/wiki/Coarray">Coarrays</a>: Full
+	experimental support of Fortran 2008's coarrays with
 	<code>-fcoarray=lib</code> except for locking and allocatable/pointer
-	components of derived-type coarrays. Note that GCC currently only ships
-	with a library which only supports a single image
-	(<code>libcaf_single</code>).</li>
+	components of derived-type coarrays.  GCC currently only ships with a
+	single-image library (<code>libcaf_single</code>), but
+	mult-image support based on MPI and GASNet is provided by the libraries
+	of the <a href="http://www.opencoarrays.org/">OpenCoarrays project</a>. 
+	</li>
     </ul></li>
     <li>TS18508 Additional Parallel Features in Fortran:
     <ul>

Re: [wwwdocs, committed] gcc-5/changes.html: Update Fortran section

[Gerald Pfeifer]

On Sun, 31 Aug 2014, Tobias Burnus wrote:
> I have committed the attached patch. Comment and suggestions are welcome!

I applied the small follow-up below.

What I am struggling to understand, though, is the following piece:

   Full experimental support of Fortran 2008's coarrays with
   <code>-fcoarray=lib</code> except for locking and allocatable/pointer
   components of derived-type coarrays.

Does this mean it is only supported when -fcoarray=lib is provided?
If so, I'd say that more explicitly.

And perhaps split off the second half into something like "(Only
locking and... are not provided yet)".

What is "full experimental support", by the way?  Just "experimental"?

Gerald

Index: changes.html
===================================================================
RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-5/changes.html,v
retrieving revision 1.116
diff -u -r1.116 changes.html
--- changes.html	22 Apr 2015 12:43:34 -0000	1.116
+++ changes.html	1 May 2015 22:40:33 -0000
@@ -537,7 +537,7 @@
     </pre></li>
 
     <li>The <code>-Wuse-without-only</code> option has been added to warn when a
-      <code>USE</code> statement has no <code>ONLY</code> qualifier and, thus,
+      <code>USE</code> statement has no <code>ONLY</code> qualifier and thus
       implicitly imports all public entities of the used module.</li>
     <li>Formatted READ and WRITE statements now work correctly in locale-aware
       programs.  For more information and potential caveats, see

Re: [wwwdocs, committed] gcc-5/changes.html: Update Fortran section

[Tobias Burnus]

Hi Gerald,

Gerald Pfeifer wrote:
> On Sun, 31 Aug 2014, Tobias Burnus wrote:
>> I have committed the attached patch. Comment and suggestions are welcome!
> I applied the small follow-up below.
>
> What I am struggling to understand, though, is the following piece:
>
>     Full experimental support of Fortran 2008's coarrays with
>     <code>-fcoarray=lib</code> except for locking and allocatable/pointer
>     components of derived-type coarrays.
>
> Does this mean it is only supported when -fcoarray=lib is provided?
> If so, I'd say that more explicitly.

No, not quite. Let' me expand a bit: Coarrays permit to run programs in 
parallel following a distributed memory model. All variables which are 
coarrays have an additional (array) index designating the (remote) 
processor index ("image index"). gfortran handles this parallelization 
by generating calls to a communication library (libcaf_single, 
libcaf_mpi, libcaf_armci, ...). (The option -fcoarray=single assumes 
that only a single process exists [boring!] and requires no 
communication library.)

As just written, with -fcoarray=lib, one generates library calls for the 
communication with remote processes ("images"). However, the 
implementation is not yet complete. And the biggest omission is the 
support to access allocatable or pointer components of coarrays. Namely, 
either to pull data from a remote image/process in the form:
    lhs = coarray[remote_index]%allocatable_component
or to push data to a remote image, e.g.
    coarray[remote_index]%pointer_component = 5

As that's the main missing feature, I thought it should be listed in the 
release notes.

When accessing data for the local process, it uses the normal code and, 
hence, it automatically works with -fcoarray=single. Trying to access 
code from a remote process will give a compile-time error with a 
sorry-not-yet-implemented error.

> And perhaps split off the second half into something like "(Only
> locking and... are not provided yet)".
Locking is meanwhile supported (except for a corner case).

> What is "full experimental support", by the way?  Just "experimental"?

Well, except for some corner cases – and in particular the the listed 
one – all features are supported. Thus, there is full support of 
coarrays as defined in Fortran 2008. But it is only experimental as 
there are known and unknown bugs.


I hope, it is now clearer what was meant by the original wording.

Tobias