--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/warn/Wstringop-truncation-1.C	Thu Oct 25 07:37:49 2018 +0900
@@ -0,0 +1,126 @@
+/* PR/tree-optimization/84480 - bogus -Wstringop-truncation despite
+   assignment with an inlined string literal
+   { dg-do compile }
+   { dg-options "-O2 -Wstringop-truncation" }  */
+
+#include <string.h>
+
+template <size_t N>
+class GoodString
+{
+public:
+  GoodString (const char *s, size_t slen = N)
+  {
+    if (slen > N)
+      slen = N;
+
+    strncpy (str, s, slen);
+
+    str[slen] = '\0';
+  }
+
+private:
+  char str[N + 1];
+};
+
+void sink (void*);
+
+void good_nowarn_size_m2 ()
+{
+  GoodString<3> str ("12");
+  sink (&str);
+}
+
+void good_nowarn_size_m1 ()
+{
+  GoodString<3> str ("123");    // { dg-bogus "\\\[-Wstringop-truncation]" }
+  sink (&str);
+}
+
+static void good_nowarn_size_m1_var (const char* s)
+{
+  GoodString<3> str (s);        // { dg-bogus "\\\[-Wstringop-truncation]" }
+  sink (&str);
+}
+
+void call_good_nowarn_size_m1_var ()
+{
+  good_nowarn_size_m1_var ("456");
+}
+
+
+template <size_t N>
+class BadString1
+{
+public:
+  BadString1 (const char *s, size_t slen = N)
+  {
+    if (slen > N)
+      slen = N;
+
+    strncpy (str, s, slen);
+  }
+
+private:
+  char str[N + 1];
+};
+
+void bad1_nowarn_size_m2 ()
+{
+  BadString1<3> str ("12");
+  sink (&str);
+}
+
+
+template <size_t N>
+class BadString2
+{
+public:
+  BadString2 (const char *s, size_t slen = N)
+  {
+    if (slen > N)
+      slen = N;
+
+    strncpy (str, s, slen);     // { dg-warning "\\\[-Wstringop-truncation]" }
+  }
+
+private:
+  char str[N + 1];
+};
+
+void bad2_warn_size_m1 ()
+{
+  BadString2<3> str ("123");
+  sink (&str);
+}
+
+// { dg-message "inlined from .void bad2_warn_size_m1." "" { target *-*-* } 0 }
+
+template <size_t N>
+class BadString3
+{
+public:
+  BadString3 (const char *s, size_t slen = N)
+  {
+    if (slen > N)
+      slen = N;
+
+    strncpy (str, s, slen);     // { dg-warning "\\\[-Wstringop-truncation]" }
+  }
+
+private:
+  char str[N + 1];
+};
+
+static void bad3_warn_size_m1_var (const char *s)
+{
+  BadString3<3> str (s);
+  sink (&str);
+}
+
+void call_bad3_warn_size_m1_var ()
+{
+  bad3_warn_size_m1_var ("456");
+}
+
+// { dg-message "inlined from .void call_bad3_warn_size_m1_var." "" { target *-*-* } 0 }