Hello everybody,
now that I have found a little time, here is an updated version of
the patch, which incorporates Tobias' suggestions. Regression-tested.
OK for trunk?
Thomas
2011-08-21 Thomas Koenig <tkoe...@gcc.gnu.org>
PR fortran/47659
* expr.c (gfc_check_assign): Check for type conversions when the
right-hand side is a constant REAL/COMPLEX contstant the left-hand
side is also REAL/COMPLEX. Don't warn when a narrowing conversion
for REAL does not change the value of the constant.
2011-08-21 Thomas Koenig <tkoe...@gcc.gnu.org>
PR fortran/47659
* gfortran.dg/warn_conversion_2.f90: Also warn about conversion
of a constant resulting from simplification.
* gfortran.dg/warn_conversion_3.f90: New test.
! { dg-do compile }
! { dg-options "-Wconversion -Wconversion-extra" }
! PR 47659 - warning about conversions on assignment
! Based on test cases by Thomas Henlich and Tobias Burnus.
program main
double precision d1, d2
complex(8), parameter :: z = cmplx (0.5, 0.5) ! { dg-warning "Conversion" }
real :: r1, r2
r1 = 2.3d0 ! { dg-warning "Change of value in conversion" }
r2 = 2.5d0 ! No warning because the value does not change
d1 = .13 ! { dg-warning "Conversion" }
d2 = .13d0
d1 = z ! { dg-warning "change of value in conversion" }
end program main
Index: fortran/expr.c
===================================================================
--- fortran/expr.c (Revision 177746)
+++ fortran/expr.c (Arbeitskopie)
@@ -3190,6 +3190,53 @@
}
}
+ /* Warn about type-changing conversions for REAL or COMPLEX constants.
+ If lvalue and rvalue are mixed REAL and complex, gfc_compare_types
+ will warn anyway, so there is no need to to so here. */
+
+ if (rvalue->expr_type == EXPR_CONSTANT && lvalue->ts.type == rvalue->ts.type
+ && (lvalue->ts.type == BT_REAL || lvalue->ts.type == BT_COMPLEX))
+ {
+ if (lvalue->ts.kind < rvalue->ts.kind && gfc_option.gfc_warn_conversion)
+ {
+ /* As a special bonus, don't warn about REAL rvalues which are not
+ changed by the conversion if -Wconversion is specified. */
+ if (rvalue->ts.type == BT_REAL && mpfr_number_p (rvalue->value.real))
+ {
+ /* Calculate the difference between the constant and the rounded
+ value and check it against zero. */
+ mpfr_t rv, diff;
+ gfc_set_model_kind (lvalue->ts.kind);
+ mpfr_init (rv);
+ gfc_set_model_kind (rvalue->ts.kind);
+ mpfr_init (diff);
+
+ mpfr_set (rv, rvalue->value.real, GFC_RND_MODE);
+ mpfr_sub (diff, rv, rvalue->value.real, GFC_RND_MODE);
+
+ if (!mpfr_zero_p (diff))
+ gfc_warning ("Change of value in conversion from "
+ " %s to %s at %L", gfc_typename (&rvalue->ts),
+ gfc_typename (&lvalue->ts), &rvalue->where);
+
+ mpfr_clear (rv);
+ mpfr_clear (diff);
+ }
+ else
+ gfc_warning ("Possible change of value in conversion from %s "
+ "to %s at %L",gfc_typename (&rvalue->ts),
+ gfc_typename (&lvalue->ts), &rvalue->where);
+
+ }
+ else if (gfc_option.warn_conversion_extra
+ && lvalue->ts.kind > rvalue->ts.kind)
+ {
+ gfc_warning ("Conversion from %s to %s at %L",
+ gfc_typename (&rvalue->ts),
+ gfc_typename (&lvalue->ts), &rvalue->where);
+ }
+ }
+
if (gfc_compare_types (&lvalue->ts, &rvalue->ts))
return SUCCESS;
Index: testsuite/gfortran.dg/warn_conversion_2.f90
===================================================================
--- testsuite/gfortran.dg/warn_conversion_2.f90 (Revision 177746)
+++ testsuite/gfortran.dg/warn_conversion_2.f90 (Arbeitskopie)
@@ -7,5 +7,5 @@
x = 2.0
sqrt2 = sqrt(x) ! { dg-warning "Conversion" }
- sqrt2 = sqrt(2.0) ! no warning; simplified to a constant and range checked
+ sqrt2 = sqrt(2.0) ! { dg-warning "Conversion" }
end
