Index: gcc/testsuite/g++.dg/cpp1y/auto-fn47.C
===================================================================
--- gcc/testsuite/g++.dg/cpp1y/auto-fn47.C	(nonexistent)
+++ gcc/testsuite/g++.dg/cpp1y/auto-fn47.C	(revision 257630)
@@ -0,0 +1,6 @@
+// PR c++/84080
+// { dg-do compile { target c++14 } }
+
+template <int i, typename T> T foo();
+
+template <> auto foo<0>() { return 42; } // { dg-error "does not match" }
Index: gcc/cp/pt.c
===================================================================
--- gcc/cp/pt.c	(revision 257629)
+++ gcc/cp/pt.c	(revision 257630)
@@ -2203,6 +2203,11 @@
 	       specialize TMPL will produce DECL.  */
 	    continue;
 
+	  if (uses_template_parms (targs))
+	    /* We deduced something involving 'auto', which isn't a valid
+	       template argument.  */
+	    continue;
+
           /* Remove, from the set of candidates, all those functions
              whose constraints are not satisfied. */
           if (flag_concepts && !constraints_satisfied_p (fn, targs))