https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107874
--- Comment #4 from anlauf at gcc dot gnu.org ---
The following patch fixes comment#3:
diff --git a/gcc/fortran/simplify.cc b/gcc/fortran/simplify.cc
index 9c2fea8c5f2..2f69c4369ab 100644
--- a/gcc/fortran/simplify.cc
+++ b/gcc/fortran/simplify.cc
@@ -4913,6 +4914,11 @@ gfc_simplify_merge (gfc_expr *tsource, gfc_expr
*fsource, gfc_expr *mask)
if (mask->expr_type == EXPR_CONSTANT)
{
+ /* The standard requires evaluation of all function arguments.
+ Simplify only when TSOURCE, FSOURCE are constant expressions. */
+ if (!gfc_is_constant_expr (tsource) || !gfc_is_constant_expr (fsource))
+ return NULL;
+
result = gfc_copy_expr (mask->value.logical ? tsource : fsource);
/* Parenthesis is needed to get lower bounds of 1. */
result = gfc_get_parentheses (result);
This leads to a "regression" for gfortran.dg/merge_init_expr_2.f90,
which is due to the pattern matching the old, faulty simplification result.
That's trivial to fix, though.
