From 1df539fd197ef2427bdfa27156b92d2a857af949 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Wed, 3 Nov 2021 09:29:47 -0400
Subject: [PATCH] c++: remember pointer-to-member location

Jakub recently mentioned that a PTRMEM_CST has no location; let's give it a
location wrapper.

gcc/cp/ChangeLog:

	* typeck.c (build_x_unary_op): Set address location.
	(convert_member_func_to_ptr): Handle location wrapper.
	* pt.c (convert_nontype_argument): Likewise.

gcc/testsuite/ChangeLog:

	* g++.dg/template/crash106.C: Adjust.
	* g++.dg/diagnostic/ptrtomem3.C: New test.
---
 gcc/cp/pt.c                                 |  2 ++
 gcc/cp/typeck.c                             | 15 +++++++++++++--
 gcc/testsuite/g++.dg/diagnostic/ptrtomem3.C | 14 ++++++++++++++
 gcc/testsuite/g++.dg/template/crash106.C    |  4 ++--
 4 files changed, 31 insertions(+), 4 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/diagnostic/ptrtomem3.C

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index c73e035d8b8..288625e3e93 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -7267,6 +7267,8 @@ convert_nontype_argument (tree type, tree expr, tsubst_flags_t complain)
   const bool val_dep_p = value_dependent_expression_p (expr);
   if (val_dep_p)
     expr = canonicalize_expr_argument (expr, complain);
+  else
+    STRIP_ANY_LOCATION_WRAPPER (expr);
 
   /* 14.3.2/5: The null pointer{,-to-member} conversion is applied
      to a non-type argument of "nullptr".  */
diff --git a/gcc/cp/typeck.c b/gcc/cp/typeck.c
index 63a0eaef2da..84dcb6f014f 100644
--- a/gcc/cp/typeck.c
+++ b/gcc/cp/typeck.c
@@ -6492,6 +6492,11 @@ build_x_unary_op (location_t loc, enum tree_code code, cp_expr xarg,
 	}
 
       exp = cp_build_addr_expr_strict (xarg, complain);
+
+      if (TREE_CODE (exp) == PTRMEM_CST)
+	exp = maybe_wrap_with_location (exp, loc);
+      else
+	protected_set_expr_location (exp, loc);
     }
 
   if (processing_template_decl && exp != error_mark_node)
@@ -8179,10 +8184,14 @@ convert_member_func_to_ptr (tree type, tree expr, tsubst_flags_t complain)
   if (!(complain & tf_warning_or_error))
     return error_mark_node;
 
+  location_t loc = cp_expr_loc_or_input_loc (expr);
+
   if (pedantic || warn_pmf2ptr)
-    pedwarn (input_location, pedantic ? OPT_Wpedantic : OPT_Wpmf_conversions,
+    pedwarn (loc, pedantic ? OPT_Wpedantic : OPT_Wpmf_conversions,
 	     "converting from %qH to %qI", intype, type);
 
+  STRIP_ANY_LOCATION_WRAPPER (expr);
+
   if (TREE_CODE (intype) == METHOD_TYPE)
     expr = build_addr_func (expr, complain);
   else if (TREE_CODE (expr) == PTRMEM_CST)
@@ -8197,7 +8206,9 @@ convert_member_func_to_ptr (tree type, tree expr, tsubst_flags_t complain)
   if (expr == error_mark_node)
     return error_mark_node;
 
-  return build_nop (type, expr);
+  expr = build_nop (type, expr);
+  SET_EXPR_LOCATION (expr, loc);
+  return expr;
 }
 
 /* Build a NOP_EXPR to TYPE, but mark it as a reinterpret_cast so that
diff --git a/gcc/testsuite/g++.dg/diagnostic/ptrtomem3.C b/gcc/testsuite/g++.dg/diagnostic/ptrtomem3.C
new file mode 100644
index 00000000000..6096a98f708
--- /dev/null
+++ b/gcc/testsuite/g++.dg/diagnostic/ptrtomem3.C
@@ -0,0 +1,14 @@
+// Check that the diagnostic for a pointer-to-member expression has the caret
+// at the &.
+
+struct A
+{
+  int i;
+};
+
+void f();
+
+int main()
+{
+  return &A::i; 		// { dg-error "10:cannot convert" }
+}
diff --git a/gcc/testsuite/g++.dg/template/crash106.C b/gcc/testsuite/g++.dg/template/crash106.C
index f904bd4dc9b..35cedb55b0b 100644
--- a/gcc/testsuite/g++.dg/template/crash106.C
+++ b/gcc/testsuite/g++.dg/template/crash106.C
@@ -7,6 +7,6 @@ struct A
   template<T> void foo(); // { dg-error "type" "" { target c++17_down } }
 };
 
-template<T N = 0.0, void (A::*)() = &A::foo<N> > struct B {}; // { dg-error "type|declared" "" { target c++17_down } }
+template<T N = 0.0, void (A::*)() = &A::foo<N> > struct B {}; // { dg-error "type|declared|could not convert" "" { target c++17_down } }
 
-B<> b; // { dg-error "(could not convert|no matches)" "" { target c++17_down } }
+B<> b; // { dg-message "" "" { target c++17_down } }