Hi Janus, > So: Ok for trunk from my side. > > However, I would prefer to disable the warning by default, but include > it in -Wall.
Here's a patch to do just that. Regression-tested (hence the changes to the existing test cases :-) OK for trunk? Once it goes in, I will also update the WWW changes. Thomas 2013-08-03 Thomas Koenig <tkoe...@gcc.gnu.org> PR fortran/56666 * gfortran.h (gfc_option_t): Add warn_zerotrip. * invoke.texi (-Wzerotrip): Document option. * lang.opt (Wzerotrip): Add. * options.c (gfc_init_options): Initialize warn_zerotrip. (set_Wall): Add handling of warn_zerotrip. (gfc_handle_option): Handle OPT_Wzerotrip. * resolve.c (gfc_resolve_iterator): Honor gfc_option.warn_zerotrip; update error message to show how to suppress the warning. 2013-08-03 Thomas Koenig <tkoe...@gcc.gnu.org> PR fortran/56666 * gfortran.dg/do_check_10.f90: New test. * gfortran.dg/array_constructor_11.f90: Add -Wzerotrip to dg-options. * gfortran.dg/array_constructor_18.f90: Likewise. * gfortran.dg/array_constructor_22.f90: Likewise. * gfortran.dg/coarray_15.f90: Likewise. * gfortran.dg/do_1.f90: Add -Wall to dg-options. * gfortran.dg/do_3.F90: Add -Wzerotrip to dg-options. * gfortran.dg/do_check_5.f90: Add -Wall to gd-options.
Index: fortran/gfortran.h =================================================================== --- fortran/gfortran.h (Revision 201448) +++ fortran/gfortran.h (Arbeitskopie) @@ -2252,6 +2252,7 @@ typedef struct int warn_align_commons; int warn_real_q_constant; int warn_unused_dummy_argument; + int warn_zerotrip; int warn_realloc_lhs; int warn_realloc_lhs_all; int warn_compare_reals; Index: fortran/invoke.texi =================================================================== --- fortran/invoke.texi (Revision 201448) +++ fortran/invoke.texi (Arbeitskopie) @@ -954,6 +954,11 @@ This option is implied by @option{-Wextra}. Warn if the pointer in a pointer assignment might be longer than the its target. This option is implied by @option{-Wall}. +@item -Wzerotrip +@opindex @code{Wzerotrip} +Warn if a @code{DO} loop is known to execute zero times at compile +time. This option is implied by @option{-Wall}. + @item -Werror @opindex @code{Werror} @cindex warnings, to errors Index: fortran/lang.opt =================================================================== --- fortran/lang.opt (Revision 201448) +++ fortran/lang.opt (Arbeitskopie) @@ -293,6 +293,10 @@ Wunused-dummy-argument Fortran Warning Warn about unused dummy arguments. +Wzerotrip +Fortran Warning +Warn about zero-trip DO loops + cpp Fortran Negative(nocpp) Enable preprocessing Index: fortran/options.c =================================================================== --- fortran/options.c (Revision 201448) +++ fortran/options.c (Arbeitskopie) @@ -109,6 +109,7 @@ gfc_init_options (unsigned int decoded_options_cou gfc_option.warn_align_commons = 1; gfc_option.warn_real_q_constant = 0; gfc_option.warn_unused_dummy_argument = 0; + gfc_option.warn_zerotrip = 0; gfc_option.warn_realloc_lhs = 0; gfc_option.warn_realloc_lhs_all = 0; gfc_option.warn_compare_reals = 0; @@ -466,6 +467,7 @@ set_Wall (int setting) gfc_option.warn_real_q_constant = setting; gfc_option.warn_unused_dummy_argument = setting; gfc_option.warn_target_lifetime = setting; + gfc_option.warn_zerotrip = setting; warn_return_type = setting; warn_uninitialized = setting; @@ -747,6 +749,10 @@ gfc_handle_option (size_t scode, const char *arg, gfc_option.warn_unused_dummy_argument = value; break; + case OPT_Wzerotrip: + gfc_option.warn_zerotrip = value; + break; + case OPT_fall_intrinsics: gfc_option.flag_all_intrinsics = 1; break; Index: fortran/resolve.c =================================================================== --- fortran/resolve.c (Revision 201448) +++ fortran/resolve.c (Arbeitskopie) @@ -6282,8 +6282,10 @@ gfc_resolve_iterator (gfc_iterator *iter, bool rea sgn = mpfr_sgn (iter->step->value.real); cmp = mpfr_cmp (iter->end->value.real, iter->start->value.real); } - if ((sgn > 0 && cmp < 0) || (sgn < 0 && cmp > 0)) - gfc_warning ("DO loop at %L will be executed zero times", + if (gfc_option.warn_zerotrip && + ((sgn > 0 && cmp < 0) || (sgn < 0 && cmp > 0))) + gfc_warning ("DO loop at %L will be executed zero times" + " (use -Wno-zerotrip to suppress)", &iter->step->where); } Index: testsuite/gfortran.dg/array_constructor_11.f90 =================================================================== --- testsuite/gfortran.dg/array_constructor_11.f90 (Revision 201448) +++ testsuite/gfortran.dg/array_constructor_11.f90 (Arbeitskopie) @@ -1,6 +1,7 @@ ! Like array_constructor_6.f90, but check iterators with non-default stride, ! including combinations which lead to zero-length vectors. ! { dg-do run } +! { dg-options "-Wzerotrip" } program main implicit none call build (77) Index: testsuite/gfortran.dg/array_constructor_18.f90 =================================================================== --- testsuite/gfortran.dg/array_constructor_18.f90 (Revision 201448) +++ testsuite/gfortran.dg/array_constructor_18.f90 (Arbeitskopie) @@ -1,4 +1,5 @@ ! { dg-do compile } +! { dg-options "-Wzerotrip" } ! Tests the fix for PR32875, in which the character length for the ! array constructor would get lost in simplification and would lead ! the error 'Not Implemented: complex character array constructor'. Index: testsuite/gfortran.dg/array_constructor_22.f90 =================================================================== --- testsuite/gfortran.dg/array_constructor_22.f90 (Revision 201448) +++ testsuite/gfortran.dg/array_constructor_22.f90 (Arbeitskopie) @@ -1,4 +1,5 @@ ! { dg-do compile } +! { dg-options "-Wzerotrip" } ! PR34990 ICE in gfc_typenode_for_spec, at fortran/trans-types.c:842 ! Test case that of the reporters. module test Index: testsuite/gfortran.dg/coarray_15.f90 =================================================================== --- testsuite/gfortran.dg/coarray_15.f90 (Revision 201448) +++ testsuite/gfortran.dg/coarray_15.f90 (Arbeitskopie) @@ -1,5 +1,5 @@ ! { dg-do run } -! { dg-options "-fcoarray=single" } +! { dg-options "-fcoarray=single -Wzerotrip" } ! ! PR fortran/18918 ! Index: testsuite/gfortran.dg/do_1.f90 =================================================================== --- testsuite/gfortran.dg/do_1.f90 (Revision 201448) +++ testsuite/gfortran.dg/do_1.f90 (Arbeitskopie) @@ -1,4 +1,5 @@ ! { dg-do run } +! { dg-options "-Wall" } ! Program to check corner cases for DO statements. program do_1 implicit none Index: testsuite/gfortran.dg/do_3.F90 =================================================================== --- testsuite/gfortran.dg/do_3.F90 (Revision 201448) +++ testsuite/gfortran.dg/do_3.F90 (Arbeitskopie) @@ -1,5 +1,5 @@ ! { dg-do run } -! { dg-options "-std=legacy -ffree-line-length-none -fno-range-check -fwrapv" } +! { dg-options "-std=legacy -ffree-line-length-none -fno-range-check -fwrapv -Wzerotrip" } program test integer :: count integer :: i Index: testsuite/gfortran.dg/do_check_5.f90 =================================================================== --- testsuite/gfortran.dg/do_check_5.f90 (Revision 201448) +++ testsuite/gfortran.dg/do_check_5.f90 (Arbeitskopie) @@ -1,5 +1,5 @@ ! { dg-do compile } -! +! { dg-options "-Wall" } ! PR/fortran 38432 ! DO-loop compile-time checks !
! { dg-do compile } ! { dg-options "-Wall -Wno-zerotrip" } program main do i=1,0 print *,i end do end program main