--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/gcc.dg/Wstringop-overflow-31.c	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,40 @@
+/* PR middle-end/93646 - confusing -Wstringop-truncation on strncat where
+   -Wstringop-overflow is expected
+   { dg-do compile }
+   { dg-options "-O2 -Wall" } */
+
+extern __SIZE_TYPE__ strlen (const char*);
+extern char* strncat (char*, const char*, __SIZE_TYPE__);
+
+
+char a[4];
+
+
+void f0 (char *d, const char *s)
+{
+  strncat (d, s, strlen (s));   // { dg-warning "specified bound depends on the length of the source argument" }
+  /* { dg-message "function 'f0'.*inlined from 'f1'" "inlining stack" { target *-*-* } 0 }  */
+
+  // Prevent f0 from being replaced by g0.
+  *d = 'f';
+}
+
+void f1 (const char *s)
+{
+  f0 (a, s);
+}
+
+
+static void g0 (char *d, const char *s)
+{
+  strncat (d, s, strlen (s));   // { dg-warning "specified bound 3 equals source length" }
+  /* { dg-message "function 'g0'.*inlined from 'g1'" "inlining stack" { target *-*-* } 0 }  */
+
+  // Prevent g0 from being replaced by f0.
+  *d = 'g';
+}
+
+void g1 (void)
+{
+  g0 (a, "123");
+}