Hi all,
Fortran 2023 added restrictions on integer arguments to SYSTEM_CLOCK.
The attached patch implements these.
I was struggling with the way we should handle features that are sort-of
deleted in a new standard, but not described as such in the standard,
which is why we do not have GFC_STD_F2023_DEL. As -std=gnu should not
apply this restriction, I came up with the solution in the patch.
While playing, I hit a gcc_unreachable in notify_std_msg due to a
missing case, also fixed.
Interestingly, the standard now has a recommendation:
16.9.202 SYSTEM_CLOCK
It it recommended that all references to SYSTEM_CLOCK use integer
arguments with a decimal exponent range of at least 18. ...
In case the user chooses integer(4), shall we emit a warning
e.g. under -pedantic, or some other flag? This is not done
in the patch, but could be added.
Regtested on x86_64-pc-linux-gnu. OK for mainline?
Thanks,
Harald
From 44814d9436b2e0be14b76b137602e40f3fdaf805 Mon Sep 17 00:00:00 2001
From: Harald Anlauf
Date: Sat, 18 Nov 2023 22:51:35 +0100
Subject: [PATCH] Fortran: restrictions on integer arguments to SYSTEM_CLOCK
[PR112609]
Fortran 2023 added restrictions on integer arguments to SYSTEM_CLOCK to
have a decimal exponent range at least as large as a default integer,
and that all integer arguments have the same kind type parameter.
gcc/fortran/ChangeLog:
PR fortran/112609
* check.cc (gfc_check_system_clock): Add checks on integer arguments
to SYSTEM_CLOCK specific to F2023.
* error.cc (notify_std_msg): Adjust to handle new features added
in F2023.
gcc/testsuite/ChangeLog:
PR fortran/112609
* gfortran.dg/system_clock_4.f90: New test.
---
gcc/fortran/check.cc | 57
gcc/fortran/error.cc | 4 +-
gcc/testsuite/gfortran.dg/system_clock_4.f90 | 24 +
3 files changed, 84 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/gfortran.dg/system_clock_4.f90
diff --git a/gcc/fortran/check.cc b/gcc/fortran/check.cc
index 6c45e6542f0..8c2534ae1c9 100644
--- a/gcc/fortran/check.cc
+++ b/gcc/fortran/check.cc
@@ -6774,6 +6774,10 @@ bool
gfc_check_system_clock (gfc_expr *count, gfc_expr *count_rate,
gfc_expr *count_max)
{
+ int first_int_kind = -1;
+ bool f2023 = ((gfc_option.allow_std & GFC_STD_F2023) != 0
+ && (gfc_option.allow_std & GFC_STD_GNU) == 0);
+
if (count != NULL)
{
if (!scalar_check (count, 0))
@@ -6788,8 +6792,18 @@ gfc_check_system_clock (gfc_expr *count, gfc_expr *count_rate,
&count->where))
return false;
+ if (f2023 && count->ts.kind < gfc_default_integer_kind)
+ {
+ gfc_error ("Fortran 2023: COUNT argument to SYSTEM_CLOCK "
+ "at %L must have kind of at least default integer",
+ &count->where);
+ return false;
+ }
+
if (!variable_check (count, 0, false))
return false;
+
+ first_int_kind = count->ts.kind;
}
if (count_rate != NULL)
@@ -6816,6 +6830,17 @@ gfc_check_system_clock (gfc_expr *count, gfc_expr *count_rate,
"SYSTEM_CLOCK at %L has non-default kind",
&count_rate->where))
return false;
+
+ if (f2023 && count_rate->ts.kind < gfc_default_integer_kind)
+ {
+ gfc_error ("Fortran 2023: COUNT_RATE argument to SYSTEM_CLOCK "
+ "at %L must have kind of at least default integer",
+ &count_rate->where);
+ return false;
+ }
+
+ if (first_int_kind < 0)
+ first_int_kind = count_rate->ts.kind;
}
}
@@ -6836,6 +6861,38 @@ gfc_check_system_clock (gfc_expr *count, gfc_expr *count_rate,
if (!variable_check (count_max, 2, false))
return false;
+
+ if (f2023 && count_max->ts.kind < gfc_default_integer_kind)
+ {
+ gfc_error ("Fortran 2023: COUNT_MAX argument to SYSTEM_CLOCK "
+ "at %L must have kind of at least default integer",
+ &count_max->where);
+ return false;
+ }
+
+ if (first_int_kind < 0)
+ first_int_kind = count_max->ts.kind;
+}
+
+ if (f2023 && first_int_kind > 0)
+{
+ if (count_rate
+ && count_rate->ts.type == BT_INTEGER
+ && count_rate->ts.kind != first_int_kind)
+ {
+ gfc_error ("Fortran 2023: all integer arguments to SYSTEM_CLOCK "
+ "at %L must have the same kind",
+ &count_rate->where);
+ return false;
+ }
+
+ if (count_max && count_max->ts.kind != first_int_kind)
+ {
+ gfc_error ("Fortran 2023: all integer arguments to SYSTEM_CLOCK "
+ "at %L must have the same kind",
+ &count_max->where);
+ return false;
+ }
}
return true;
diff --git a/gcc/fortran/error.cc b/gcc/fortran/error.cc
index 2ac51e95e4d..b8b36c0cd7c 100644
--- a/gcc/fortran/error.cc
+++ b/gcc/fortran/error.cc
@@ -980,7 +980,9 @@ char const*
notify_std_msg(int std)
{
- if (std & GFC_STD_F2018_DEL)
+ if (std & GFC_STD_F2023)
+return _("Fortran 2023:");
+ else if (std & GFC_STD_F2018_DEL)
return _("Fortran 2018 deleted feature:");
else if (std & GFC_STD_F2018_OBS)
return _("Fortran 2018 obsolesc
