[C++ PATCH]: instantiation via vtable marking

https://gcc.gnu.org/ml/gcc-patches/2018-02/msg00850.html
	gcc/cp/
	* decl2.c (mark_vtable_entries): Set input_location to decl's.
	(c_parse_final_cleanups): Restore input_location after emitting
	vtables.

	gcc/testsuite/
	* g++.dg/template/instantiate5.C: Adjust required-from loc.

From-SVN: r257665

gcc/cp/ChangeLog

+2018-02-14  Nathan Sidwell  <nathan@acm.org>
+
+	* decl2.c (mark_vtable_entries): Set input_location to decl's.
+	(c_parse_final_cleanups): Restore input_location after emitting
+	vtables.
+
 2018-02-14  Paolo Carlini  <paolo.carlini@oracle.com>
 
 	* cp-tree.h (do_auto_deduction (tree, tree, tree)): Remove.

gcc/cp/decl2.c

@@ -1825,6 +1825,11 @@ mark_vtable_entries (tree decl)
 	 function, so we emit the thunks there instead.  */
       if (DECL_THUNK_P (fn))
 	use_thunk (fn, /*emit_p=*/0);
+      /* Set the location, as marking the function could cause
+         instantiation.  We do not need to preserve the incoming
+         location, as we're called from c_parse_final_cleanups, which
+         takes care of that.  */
+      input_location = DECL_SOURCE_LOCATION (fn);
       mark_used (fn);
     }
 }
@@ -4727,6 +4732,9 @@ c_parse_final_cleanups (void)
 	    reconsider = true;
 	    keyed_classes->unordered_remove (i);
 	  }
+      /* The input_location may have been changed during marking of
+	 vtable entries.  */
+      input_location = locus_at_end_of_parsing;
 
       /* Write out needed type info variables.  We have to be careful
 	 looping through unemitted decls, because emit_tinfo_decl may

gcc/testsuite/ChangeLog

+2018-02-14  Nathan Sidwell  <nathan@acm.org>
+
+	* g++.dg/template/instantiate5.C: Adjust required-from loc.
+
 2018-02-14  Will Schmidt  <will_schmidt@vnet.ibm.com>
 
 	* gcc.target/powerpc/altivec-consts.c:  Update compile stanzas.

gcc/testsuite/g++.dg/template/instantiate5.C

@@ -18,7 +18,12 @@ struct B
 
 template <typename T> struct C
 {
-  virtual void bar() const { T::foo(); } // { dg-error "no matching function" }
+  virtual void bar() const	// { dg-message "required" }
+  {
+    T::foo(); // { dg-error "no matching function" }
+  }
 };
 
-C<B> c;				// { dg-message "required" }
+C<B> c;
+
+int k;