Simple test case: program extracomma implicit none write (*,*), 1, 2, 3 end program This compiles without error. I notice that if I compile with -std=f95, it does diagnose this as a GNU Extension. My thoughts are that a warning message should be issued, rather than quietly accepting the extension by default.
gfortran is quite in line with other compilers. ifort is also quiet by default. However, % gfc-trunk prxxx.f90 -std=f2008 prxxx.f90:4.13: write (*,*), 1, 2, 3 1 Error: GNU Extension: Comma before i/o item list at (1) % ifort prxxx.f90 -stand f08 prxxx.f90(4): warning #5198: Use of comma to separate io-access spec and io_list is non_standard. write (*,*), 1, 2, 3 -------------^ So gfortran is even stricter than ifort. Did you complain to Intel?
I didn't complain to Intel, but I can... However the compilers that did catch it by default were NAG, lahey, and Absoft. Walter
> My thoughts are that a warning message should be issued, rather than > quietly accepting the extension by default. It seems quite trivial to fix, but does it really worth the work?
> It seems quite trivial to fix, but does it really worth the work? Well, we had an instance where this accidentally slipped into our code. Later on, our nightly regression runs crashed with several non-gfortran (and non-Intel) compilers. The extension itself is pretty gratuitous. It adds nothing to the language, yet can quietly promote incompatibilities. Since g95 also accepts it, I am assuming it came into the compiler before the split.
Adding that both READ and WRITE have this issue. Interestingly, the iolength version of INQUIRE does not: inquire (iolength=i), i 1 Error: Expected expression in INQUIRE statement at (1)
(In reply to Walter Spector from comment #5) > > It seems quite trivial to fix, but does it really worth the work? > > Well, we had an instance where this accidentally slipped into our code. > Later on, our nightly regression runs crashed with several non-gfortran (and > non-Intel) compilers. If you want diagnostics of standard violations, you might consider adding -std=f2008 (e.g.) to the compile flags in your test suite. Most compilers allow "their" set of extensions by default. > The extension itself is pretty gratuitous. It adds nothing to the language, > yet can quietly promote incompatibilities. Since g95 also accepts it, I am > assuming it came into the compiler before the split.
(In reply to Walter Spector from comment #6) > Adding that both READ and WRITE have this issue. Interestingly, the > iolength version of INQUIRE does not: > > inquire (iolength=i), i > 1 > Error: Expected expression in INQUIRE statement at (1) It a g77 compatibility issue. From the g77 manual (page 190), · The commas in `READ (5), I' and `WRITE (10), J'. These commas are disallowed by FORTRAN 77, but, while strictly superfluous, are syntactically elegant, especially given that commas are required in statements such as `READ 99, I' and `PRINT *, J'. Many compilers permit the superfluous commas for this reason. This is part of GNU Fortran, which I agree a cesspool of vendor extensions. I doubt that this will be changed (too many more important things to work on). If you want strict conformance, it is probably best to add -std=f95 or -std=f2003, or -std=2008 to your command line.
Harald and Steve: I am quite aware of the std= options, thanks. My main point is that the default situation violates the Principle of Least Astonishment. I don't have a problem with gfortran offering such an extension (though I think providing it in the first place was a waste of time). But since it offers no desireable new capability, and allows gratuitous incompatibility with other compilers, it would at least be worth a warning. The ideal would be to only allow it under a -f option - but don't do that on my account. In fact the gfortran man page for the -std= argument states: "...The default value for std is gnu, which specifies a superset of the Fortran 95 standard that includes all of the extensions supported by GNU Fortran, although warnings will be given for obsolete extensions not recommended for use in new code..." I would opine that this extension is obsolete and not recommeded for use in new code. Therefore a warning should be given.
On Sun, Apr 06, 2014 at 03:45:08PM +0000, w6ws at earthlink dot net wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60751 > > --- Comment #9 from Walter Spector <w6ws at earthlink dot net> --- > Harald and Steve: I am quite aware of the std= options, thanks. > > My main point is that the default situation violates the Principle of Least > Astonishment. And my point is that the feature/bug is there solely for backwards compatibility with g77. A POLA issue back when gfortran first replaced g77 in GCC. Just last week in c.l.f there was a long thread from someone who could not use gfortran to build his legacy code, because gfortran does not support a number of g77's old -fugly-* options. In hindsight, I now regret contributing a number of patches to implement g77 compatibility and common vendor extensions. In fact, I think the default should be -std=f95+f2003+f2008. If the feature isn't in one of the standards, an error should be issued without an explicit option to permit the feature. Unfortrunately, the horse left the barn years ago.
We could just change this to a -std=legacy or a warning that would not appear with -w.
Is there an agreement to downgrade the error from GFC_STD_GNU in gcc/fortran/io.c: && !gfc_notify_std (GFC_STD_GNU, "Comma before i/o item list at %L", to GFC_STD_LEGACY? If yes, I'll submit a patch. If not, this PR should be closed as WONTFIX.
> Is there an agreement to downgrade the error from GFC_STD_GNU in > > gcc/fortran/io.c: && !gfc_notify_std (GFC_STD_GNU, "Comma before i/o > item list at %L", > > to GFC_STD_LEGACY? If yes, I'll submit a patch. If not, this PR should be > closed as WONTFIX. PING! Without answer, I'll close the PR as WONTFIX.
Hi Dominique, I am sorry I didn't see or respond to your comment from last year. Thank you for the ping. Yes, it would be fine with me to recategorize the error as GFC_STD_LEGACY. Walter
> Yes, it would be fine with me to recategorize the error as GFC_STD_LEGACY. Thanks for the answer, but the ping was intended to the gfortran maintainers (I knew your answer). If there is no objection in the coming week, I'll commit the change under the obvious rule.
*** Bug 70575 has been marked as a duplicate of this bug. ***
Note that the extra comma is used in the following tests: gfortran.dg/array_constructor_49.f90 gfortran.dg/integer_exponentiation_6.F90 gfortran.dg/graphite/pr38083.f90 Any reason to keep it?
(In reply to Dominique d'Humieres from comment #17) > Note that the extra comma is used in the following tests: > > gfortran.dg/array_constructor_49.f90 > gfortran.dg/integer_exponentiation_6.F90 > gfortran.dg/graphite/pr38083.f90 > > Any reason to keep it? No, and I am planning to fix the diagnostic on this.
Author: dominiq Date: Sat Jun 11 19:19:43 2016 New Revision: 237329 URL: https://gcc.gnu.org/viewcvs?rev=237329&root=gcc&view=rev Log: 2016-06-11 Dominique d'Humieres <dominiq@lps.ens.fr> PR fortran/60751 * io.c (gfc_resolve_dt): Replace GFC_STD_GNU with GFC_STD_LEGACY. * gfortran.dg/comma_IO_extension_1.f90: New test. * gfortran.dg/comma_IO_extension_2.f90: Likewise. * gfortran.dg/array_constructor_49.f90: Remove extra comma in WRITE statement. * gfortran.dg/graphite/pr38083.f90: Likewise. * gfortran.dg/integer_exponentiation_6.F90: Likewise and add missing format. --This line M fortran/ChangeLog M fortran/io.c M testsuite/ChangeLog M testsuite/gfortran.dg/array_constructor_49.f90 M testsuite/gfortran.dg/graphite/pr38083.f90 M testsuite/gfortran.dg/integer_exponentiation_6.F90 Modified: trunk/gcc/fortran/ChangeLog trunk/gcc/fortran/io.c trunk/gcc/testsuite/ChangeLog trunk/gcc/testsuite/gfortran.dg/array_constructor_49.f90 trunk/gcc/testsuite/gfortran.dg/graphite/pr38083.f90 trunk/gcc/testsuite/gfortran.dg/integer_exponentiation_6.F90
Author: dominiq Date: Sat Jun 11 19:21:22 2016 New Revision: 237330 URL: https://gcc.gnu.org/viewcvs?rev=237330&root=gcc&view=rev Log: 2016-06-11 Dominique d'Humieres <dominiq@lps.ens.fr> PR target/60751 * gfortran.dg/comma_IO_extension_1.f90: New test. * gfortran.dg/comma_IO_extension_2.f90: Likewise. Added: trunk/gcc/testsuite/gfortran.dg/comma_IO_extension_1.f90 trunk/gcc/testsuite/gfortran.dg/comma_IO_extension_2.f90
Author: dominiq Date: Sat Jun 11 22:36:50 2016 New Revision: 237332 URL: https://gcc.gnu.org/viewcvs?rev=237332&root=gcc&view=rev Log: 2016-06-12 Dominique d'Humieres <dominiq@lps.ens.fr> PR target/60751 * gfortran.dg/guality/pr41558.f90: Remove extra comma in WRITE statement. Modified: trunk/gcc/testsuite/ChangeLog trunk/gcc/testsuite/gfortran.dg/guality/pr41558.f90
Author: dominiq Date: Sun Jun 12 14:04:08 2016 New Revision: 237337 URL: https://gcc.gnu.org/viewcvs?rev=237337&root=gcc&view=rev Log: 2016-06-12 Dominique d'Humieres <dominiq@lps.ens.fr> PR fortran/60751 * io.c (gfc_resolve_dt): Replace GFC_STD_GNU with GFC_STD_LEGACY. * gfortran.dg/comma_IO_extension_1.f90: New test. * gfortran.dg/comma_IO_extension_2.f90: Likewise. * gfortran.dg/array_constructor_49.f90: Remove extra comma in WRITE statement. * gfortran.dg/graphite/pr38083.f90: Likewise. * gfortran.dg/guality/pr41558.f90: Likewise. * gfortran.dg/integer_exponentiation_6.F90: Likewise and add missing format. Added: branches/gcc-6-branch/gcc/testsuite/gfortran.dg/comma_IO_extension_1.f90 branches/gcc-6-branch/gcc/testsuite/gfortran.dg/comma_IO_extension_2.f90 Modified: branches/gcc-6-branch/gcc/fortran/ChangeLog branches/gcc-6-branch/gcc/fortran/io.c branches/gcc-6-branch/gcc/testsuite/ChangeLog branches/gcc-6-branch/gcc/testsuite/gfortran.dg/array_constructor_49.f90 branches/gcc-6-branch/gcc/testsuite/gfortran.dg/graphite/pr38083.f90 branches/gcc-6-branch/gcc/testsuite/gfortran.dg/guality/pr41558.f90 branches/gcc-6-branch/gcc/testsuite/gfortran.dg/integer_exponentiation_6.F90
Author: dominiq Date: Sun Jun 12 18:25:25 2016 New Revision: 237340 URL: https://gcc.gnu.org/viewcvs?rev=237340&root=gcc&view=rev Log: 2016-06-12 Dominique d'Humieres <dominiq@lps.ens.fr> PR fortran/60751 * io.c (gfc_resolve_dt): Replace GFC_STD_GNU with GFC_STD_LEGACY. * gfortran.dg/comma_IO_extension_1.f90: New test. * gfortran.dg/comma_IO_extension_2.f90: Likewise. * gfortran.dg/array_constructor_49.f90: Remove extra comma in WRITE statement. * gfortran.dg/graphite/pr38083.f90: Likewise. * gfortran.dg/guality/pr41558.f90: Likewise. * gfortran.dg/integer_exponentiation_6.F90: Likewise and add missing format. Added: branches/gcc-5-branch/gcc/testsuite/gfortran.dg/comma_IO_extension_1.f90 branches/gcc-5-branch/gcc/testsuite/gfortran.dg/comma_IO_extension_2.f90 Modified: branches/gcc-5-branch/gcc/fortran/ChangeLog branches/gcc-5-branch/gcc/fortran/io.c branches/gcc-5-branch/gcc/testsuite/ChangeLog branches/gcc-5-branch/gcc/testsuite/gfortran.dg/array_constructor_49.f90 branches/gcc-5-branch/gcc/testsuite/gfortran.dg/graphite/pr38083.f90 branches/gcc-5-branch/gcc/testsuite/gfortran.dg/guality/pr41558.f90 branches/gcc-5-branch/gcc/testsuite/gfortran.dg/integer_exponentiation_6.F90
Fixed on trunk and the gcc-5 and 6 branches. Thanks for the report. Closing.
Thank you Dominique! Walter