do more compile-time checks of values.

This is only for the modules "delay", "attr_filter", and "exec".
Tho "exec" hasn't been updated yet, as it takes attributes.

These modules should arguably be moved to the call_env framework.

src/lib/server/cf_parse.c

@@ -262,6 +262,25 @@ int cf_pair_parse_value(TALLOC_CTX *ctx, void *out, UNUSED void *base, CONF_ITEM
 		}
 		fr_assert(vpt);
 
+		/*
+		 *	The caller told us what data type was expected.  If we do have data, then try to cast
+		 *	it to the requested type.
+		 */
+		if ((rule->type != FR_TYPE_VOID) && tmpl_contains_data(vpt)) {
+			slen = 0;					// for errors
+
+			if (tmpl_is_data_unresolved(vpt)) {
+				tmpl_cast_set(vpt, rule->type);
+
+				if (tmpl_resolve(vpt, NULL) < 0) goto tmpl_error;
+
+			} else if (rule->type != tmpl_value_type(vpt)) {
+				fr_assert(tmpl_is_data(vpt));
+
+				if (tmpl_cast_in_place(vpt, rule->type, NULL) < 0) goto tmpl_error;
+			}
+		}
+
 		*(tmpl_t **)out = vpt;
 		goto finish;
 	}

src/lib/server/cf_parse.h

@@ -244,6 +244,22 @@ _Generic(&(_ct), \
 	.flags = (_flags), \
 	.offset = FR_CONF_FLAG_CHECK((_type), (_flags), &(((_struct *)NULL)->_field), offsetof(_struct, _field))
 
+/** conf_parser_t which parses a single CONF_PAIR, writing the result to a field in a struct
+ *
+ * This variant takes output hint type.  If the type is a bare word, it MUST be of the relevant data type.
+ *
+ * @param[in] _name		of the CONF_PAIR to search for.
+ * @param[in] _type		to parse the CONF_PAIR as.
+ * @param[in] _flags		controlling parsing behaviour.
+ * @param[in] _struct		containing the field to write the result to.
+ * @param[in] _field		to write the result to.
+ */
+#  define FR_CONF_OFFSET_HINT_TYPE(_name, _type, _struct, _field) \
+	.name1 = _name, \
+	.type = (_type), \
+	.flags = CONF_FLAG_TMPL, \
+	.offset = FR_CONF_FLAG_CHECK(FR_TYPE_VOID, CONF_FLAG_TMPL, &(((_struct *)NULL)->_field), offsetof(_struct, _field))
+
 /** conf_parser_t which parses a single CONF_PAIR, writing the result to a field in a struct
  *
  * This variant takes additional flags, and will add CONF_FLAG_MULTI automatically if the field is an array.

src/lib/server/tmpl.h

@@ -226,10 +226,12 @@ typedef enum tmpl_type_e {
 #define tmpl_is_regex_xlat_unresolved(vpt) 	((vpt)->type == TMPL_TYPE_REGEX_XLAT_UNRESOLVED)
 
 #define tmpl_needs_resolving(vpt)		((vpt)->type & TMPL_FLAG_UNRESOLVED)
+#define tmpl_contains_data(vpt)			((vpt)->type & TMPL_TYPE_DATA)
 #define tmpl_contains_attr(vpt)			((vpt)->type & TMPL_FLAG_ATTR)
 #define tmpl_contains_regex(vpt)		((vpt)->type & TMPL_FLAG_REGEX)
 #define tmpl_contains_xlat(vpt)			((vpt)->type & TMPL_FLAG_XLAT)
 
+
 extern fr_table_num_ordered_t const tmpl_type_table[];
 extern size_t tmpl_type_table_len;