[Bug fortran/119836] [15 Regression] Elemental intrinsic treated as IMPURE within BLOCK within DO CONCURRENT

[kargls at comcast dot net via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119836

--- Comment #4 from kargls at comcast dot net ---
All intrinsic functions are simple, and therefore pure.  The following
patch should fix the issue with functions.  A similar fix is needed for
subroutine, but only a few intrinsic subroutine are pure or simple.  I
don't have the time today to poke at subroutines.

diff --git a/gcc/fortran/resolve.cc b/gcc/fortran/resolve.cc
index cdf043b6411..f4e029bdda1 100644
--- a/gcc/fortran/resolve.cc
+++ b/gcc/fortran/resolve.cc
@@ -3243,7 +3243,8 @@ pure_stmt_function (gfc_expr *e, gfc_symbol *sym)

 /* Check if an impure function is allowed in the current context. */

-static bool check_pure_function (gfc_expr *e)
+static bool
+check_pure_function (gfc_expr *e)
 {
   const char *name = NULL;
   code_stack *stack;
@@ -3258,9 +3259,16 @@ static bool check_pure_function (gfc_expr *e)
       if (stack->current->op == EXEC_BLOCK) saw_block = true;
       if (saw_block && stack->current->op == EXEC_DO_CONCURRENT)
        {
-         gfc_error ("Reference to impure function at %L inside a "
-                    "DO CONCURRENT", &e->where);
-         return false;
+         bool is_pure = e->value.function.isym
+                        || (e->value.function.esym
+                            && (e->value.function.esym->attr.pure
+                                || e->value.function.esym->attr.elemental));
+         if (!is_pure)
+           {
+             gfc_error ("Reference to impure function at %L inside a "
+                        "DO CONCURRENT", &e->where);
+             return false;
+           }
        }
     }