2 files changed, 22 insertions, 0 deletions
diff --git a/validation/expand/builtin_isdigit.c b/validation/expand/builtin_isdigit.c
new file mode 100644
index 00000000..56550b38
--- /dev/null
+++ b/validation/expand/builtin_isdigit.c
@@ -0,0 +1,10 @@
+_Static_assert(__builtin_isdigit('0'));
+_Static_assert(__builtin_isdigit('9'));
+
+_Static_assert(!__builtin_isdigit(0));
+_Static_assert(!__builtin_isdigit(' '));
+_Static_assert(!__builtin_isdigit('z'));
+
+/*
+ * check-name: builtin_isdigit
+ */
diff --git a/validation/linear/builtin_isdigit.c b/validation/linear/builtin_isdigit.c
new file mode 100644
index 00000000..c1d3ea15
--- /dev/null
+++ b/validation/linear/builtin_isdigit.c
@@ -0,0 +1,12 @@
+_Bool isdigit(int c)
+{
+	return __builtin_isdigit(c) == (((unsigned) (c - '0')) <= 9);
+}
+
+/*
+ * check-name: builtin_isdigit
+ * check-command: test-linearize -Wno-decl $file
+ *
+ * check-output-ignore
+ * check-output-returns: 1
+ */