The attach patch fixes PR Fortran/91960. This PR is another
one from Gerhard in 2019-10.01. A patch has been lingering
in the PR since 2023-05-30.
The patch checks that an array constructor in a parameter
statement is in fact a constant expression. I'll note
that the patch requires a special carve out to accommodate
the fix for Fortran/117070.
2026-01-11 Steven G. Kargl <[email protected]>
PR Fortran/91960
* resolve.cc (resolve_fl_parameter): Check the righthand symbol
is a constant expression.
2026-01-11 Steven G. Kargl <[email protected]>
PR Fortran/91960
* gfortran.dg/pr69962.f90: Adjust testcase to ignore new error message.
* gfortran.dg/pr91960_1.f90: New test.
* gfortran.dg/pr91960_2.f90: Ditto.
--
Steve
diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
index 2e8ce074c24..8584153c068 100644
--- a/gcc/fortran/resolve.cc
+++ b/gcc/fortran/resolve.cc
@@ -17871,6 +17871,26 @@ resolve_fl_parameter (gfc_symbol *sym)
return false;
}
+ /* Some programmers can have a typo when using an implied-do loop to
+ initialize an array constant. For example,
+ INTEGER I,J
+ INTEGER, PARAMETER :: A(3) = [(I, I = 1, 3)] ! OK
+ INTEGER, PARAMETER :: B(3) = [(A(J), I = 1, 3)] ! Not OK, J undefined
+ This check catches the typo. */
+ if (sym->attr.dimension
+ && sym->value && sym->value->expr_type == EXPR_ARRAY
+ && !gfc_is_constant_expr (sym->value))
+ {
+ /* PR fortran/117070 argues a nonconstant proc pointer can appear in
+ the array constructor of a paramater. I don't buy it, but... */
+ if (sym->value->ts.type == BT_DERIVED
+ && sym->value->ts.u.derived
+ && sym->value->ts.u.derived->attr.proc_pointer_comp)
+ return true;
+ gfc_error ("Expecting constant expression near %L", &sym->value->where);
+ return false;
+ }
+
return true;
}
diff --git a/gcc/testsuite/gfortran.dg/pr69962.f90 b/gcc/testsuite/gfortran.dg/pr69962.f90
index 2684398ee31..30aaedfdf98 100644
--- a/gcc/testsuite/gfortran.dg/pr69962.f90
+++ b/gcc/testsuite/gfortran.dg/pr69962.f90
@@ -4,3 +4,4 @@ program p
character(3), parameter :: x(2) = ['abc', 'xyz']
character(2), parameter :: y(2) = [x(2)(2:3), x(n)(1:2)] ! { dg-error "CHARACTER length must be a constant" }
end
+! { dg-prune-output "Expecting constant expression" }
diff --git a/gcc/testsuite/gfortran.dg/pr91960_1.f90 b/gcc/testsuite/gfortran.dg/pr91960_1.f90
new file mode 100644
index 00000000000..90abcaf6934
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr91960_1.f90
@@ -0,0 +1,6 @@
+! { dg-do compile }
+module m
+ integer :: i, j
+ integer, parameter :: a(3) = [1, 2, 3]
+ integer, parameter :: b(3) = [(a(j), i=1,3)] ! { dg-error "Expecting constant expression" }
+end
diff --git a/gcc/testsuite/gfortran.dg/pr91960_2.f90 b/gcc/testsuite/gfortran.dg/pr91960_2.f90
new file mode 100644
index 00000000000..a7d41d9c417
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/pr91960_2.f90
@@ -0,0 +1,8 @@
+! { dg-do compile }
+module m
+ implicit none
+ integer :: i, j
+ integer, parameter :: a(3) = [1, 2, 3]
+ integer, parameter :: c = a(j)
+ integer :: d = c ! { dg-error "initialization expression at" }
+end
