This patch implements P0846R0: ADL and Function Templates that are not Visible
<http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0846r0.html>
whereby a name for which a normal lookup produces either no result or finds one
or more functions and that is followed by a "<" would be treated as if a
function
template name had been found and would cause ADL to be performed. Thus e.g.
namespace N {
struct S { };
template<int X> void f(S);
}
void
bar (N::S s)
{
f<3>(s);
}
will now compile; ADL will find N::f. The gist of the approach I took is in
cp_parser_template_name and setting TEMPLATE_ID_TRY_ADL_P.
One of the side effects is that a function name followed by a < means that the
< is
always taken as the delimiter of a template-argument-list, rendering e.g. this
fun-ptr < a;
ill-formed.
There's something I'm not clear on; the proposal talks about an
unqualified-id followed by a <, which is also the case for
a.foo < 1;
which is "postfix-expression . unqualified-id <", but treating "foo" as a
template name would break valid programs. I don't think this proposal should
be in effect for class member accesses, so I've disabled it by using scoped_p
below. See fn-template8.C for a complete testcase for this scenario.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2018-10-28 Marek Polacek <pola...@redhat.com>
Implement P0846R0, ADL and function templates.
* cp-tree.h (TEMPLATE_ID_TRY_ADL_P): New macro.
* decl.c (grokfndecl): Allow FUNCTION_DECL in assert.
* parser.c (cp_parser_postfix_expression): Also perform ADL for
template-id that is TEMPLATE_ID_TRY_ADL_P.
(cp_parser_template_id): Adjust a call to cp_parser_template_name.
Allow FUNCTION_DECL in assert. Return error node if parsing the
template argument list didn't go well. Set TEMPLATE_ID_TRY_ADL_P
on the template-id.
(cp_parser_template_name): Add a new parameter. Consider a name to
refer to a template if it is an unqualified-id followed by <.
(cp_parser_constructor_declarator_p): Adjust a call to
cp_parser_template_name.
* g++.dg/addr_builtin-1.C: Adjust dg-error.
* g++.dg/cpp2a/fn-template1.C: New test.
* g++.dg/cpp2a/fn-template10.C: New test.
* g++.dg/cpp2a/fn-template11.C: New test.
* g++.dg/cpp2a/fn-template12.C: New test.
* g++.dg/cpp2a/fn-template13.C: New test.
* g++.dg/cpp2a/fn-template2.C: New test.
* g++.dg/cpp2a/fn-template3.C: New test.
* g++.dg/cpp2a/fn-template4.C: New test.
* g++.dg/cpp2a/fn-template5.C: New test.
* g++.dg/cpp2a/fn-template6.C: New test.
* g++.dg/cpp2a/fn-template7.C: New test.
* g++.dg/cpp2a/fn-template8.C: New test.
* g++.dg/cpp2a/fn-template9.C: New test.
* g++.dg/parse/fn-template1.C: New test.
* g++.dg/parse/fn-template2.C: New test.
* g++.dg/template/pr61745.C: Add target to dg-error.
diff --git gcc/cp/cp-tree.h gcc/cp/cp-tree.h
index 26ded3a9214..aa7ddb0830c 100644
--- gcc/cp/cp-tree.h
+++ gcc/cp/cp-tree.h
@@ -409,6 +409,7 @@ extern GTY(()) tree cp_global_trees[CPTI_MAX];
SWITCH_STMT_ALL_CASES_P (in SWITCH_STMT)
REINTERPRET_CAST_P (in NOP_EXPR)
ALIGNOF_EXPR_STD_P (in ALIGNOF_EXPR)
+ TEMPLATE_ID_TRY_ADL_P (in TEMPLATE_ID_EXPR)
1: IDENTIFIER_KIND_BIT_1 (in IDENTIFIER_NODE)
TI_PENDING_TEMPLATE_FLAG.
TEMPLATE_PARMS_FOR_INLINE.
@@ -4987,6 +4988,11 @@ more_aggr_init_expr_args_p (const
aggr_init_expr_arg_iterator *iter)
#define ALIGNOF_EXPR_STD_P(NODE) \
TREE_LANG_FLAG_0 (ALIGNOF_EXPR_CHECK (NODE))
+/* True iff this template-id uses an unqualified-id that should
+ be considered to refer to a template-name, as per P0846R0. */
+#define TEMPLATE_ID_TRY_ADL_P(NODE) \
+ (TREE_LANG_FLAG_0 (TEMPLATE_ID_EXPR_CHECK (NODE)))
+
/* An enumeration of the kind of tags that C++ accepts. */
enum tag_types {
none_type = 0, /* Not a tag type. */
diff --git gcc/cp/decl.c gcc/cp/decl.c
index 5ebfaaf85e6..e63743f8a6f 100644
--- gcc/cp/decl.c
+++ gcc/cp/decl.c
@@ -8827,7 +8827,9 @@ grokfndecl (tree ctype,
the information in the TEMPLATE_ID_EXPR. */
SET_DECL_IMPLICIT_INSTANTIATION (decl);
- gcc_assert (identifier_p (fns) || TREE_CODE (fns) == OVERLOAD);
+ gcc_assert (identifier_p (fns)
+ || TREE_CODE (fns) == OVERLOAD
+ || TREE_CODE (fns) == FUNCTION_DECL);
DECL_TEMPLATE_INFO (decl) = build_template_info (fns, args);
for (t = TYPE_ARG_TYPES (TREE_TYPE (decl)); t; t = TREE_CHAIN (t))
diff --git gcc/cp/parser.c gcc/cp/parser.c
index ebe326eb923..a99bde334fb 100644
--- gcc/cp/parser.c
+++ gcc/cp/parser.c
@@ -2323,7 +2323,7 @@ static tree cp_parser_type_parameter
static tree cp_parser_template_id
(cp_parser *, bool, bool, enum tag_types, bool);
static tree cp_parser_template_name
- (cp_parser *, bool, bool, bool, enum tag_types, bool *);
+ (cp_parser *, bool, bool, bool, enum tag_types, bool *, bool *);
static tree cp_parser_template_argument_list
(cp_parser *);
static tree cp_parser_template_argument
@@ -7165,7 +7165,9 @@ cp_parser_postfix_expression (cp_parser *parser, bool
address_p, bool cast_p,
if (idk == CP_ID_KIND_UNQUALIFIED
|| idk == CP_ID_KIND_TEMPLATE_ID)
{
- if (identifier_p (postfix_expression))
+ if (identifier_p (postfix_expression)
+ || (TREE_CODE (postfix_expression) == TEMPLATE_ID_EXPR
+ && TEMPLATE_ID_TRY_ADL_P (postfix_expression)))
{
if (!args->is_empty ())
{
@@ -7175,9 +7177,13 @@ cp_parser_postfix_expression (cp_parser *parser, bool
address_p, bool cast_p,
= perform_koenig_lookup (postfix_expression, args,
complain);
}
- else
+ else if (identifier_p (postfix_expression))
postfix_expression
= unqualified_fn_lookup_error (postfix_expression);
+ else
+ postfix_expression
+ = unqualified_fn_lookup_error (TREE_OPERAND
+ (postfix_expression, 0));
}
/* We do not perform argument-dependent lookup if
normal lookup finds a non-function, in accordance
@@ -15848,7 +15854,6 @@ cp_parser_template_id (cp_parser *parser,
tree template_id;
cp_token_position start_of_id = 0;
cp_token *next_token = NULL, *next_token_2 = NULL;
- bool is_identifier;
/* If the next token corresponds to a template-id, there is no need
to reparse it. */
@@ -15877,12 +15882,14 @@ cp_parser_template_id (cp_parser *parser,
push_deferring_access_checks (dk_deferred);
/* Parse the template-name. */
- is_identifier = false;
+ bool is_identifier = false;
+ bool id_as_tmpl_name = false;
templ = cp_parser_template_name (parser, template_keyword_p,
check_dependency_p,
is_declaration,
tag_type,
- &is_identifier);
+ &is_identifier,
+ &id_as_tmpl_name);
if (templ == error_mark_node || is_identifier)
{
pop_deferring_access_checks ();
@@ -15951,6 +15958,35 @@ cp_parser_template_id (cp_parser *parser,
}
/* Parse the arguments. */
arguments = cp_parser_enclosed_template_argument_list (parser);
+
+ if (id_as_tmpl_name
+ && (cp_parser_error_occurred (parser)
+ || cp_lexer_next_token_is_not (parser->lexer, CPP_OPEN_PAREN)))
+ {
+ /* This didn't go well. */
+ if (TREE_CODE (templ) == FUNCTION_DECL)
+ {
+ /* C++2A says that "function-name < a;" is now ill-formed. */
+ if (cp_parser_error_occurred (parser))
+ {
+ error_at (token->location, "invalid template-argument-list");
+ inform (token->location, "function name as the left hand "
+ "operand of %<<%> is ill-formed in C++2a; wrap the "
+ "function name in %<()%>");
+ }
+ else
+ /* We expect "f<targs>" to be followed by "(args)". */
+ error_at (cp_lexer_peek_token (parser->lexer)->location,
+ "expected %<(%> after template-argument-list");
+ if (start_of_id)
+ /* Purge all subsequent tokens. */
+ cp_lexer_purge_tokens_after (parser->lexer, start_of_id);
+ }
+ else
+ cp_parser_simulate_error (parser);
+ pop_deferring_access_checks ();
+ return error_mark_node;
+ }
}
/* Set the location to be of the form:
@@ -15973,9 +16009,12 @@ cp_parser_template_id (cp_parser *parser,
template_id = error_mark_node;
/* Build a representation of the specialization. */
else if (identifier_p (templ))
- template_id = build_min_nt_loc (combined_loc,
- TEMPLATE_ID_EXPR,
- templ, arguments);
+ {
+ template_id = build_min_nt_loc (combined_loc,
+ TEMPLATE_ID_EXPR,
+ templ, arguments);
+ TEMPLATE_ID_TRY_ADL_P (template_id) = id_as_tmpl_name;
+ }
else if (DECL_TYPE_TEMPLATE_P (templ)
|| DECL_TEMPLATE_TEMPLATE_PARM_P (templ))
{
@@ -16007,6 +16046,7 @@ cp_parser_template_id (cp_parser *parser,
a function-template. */
gcc_assert ((DECL_FUNCTION_TEMPLATE_P (templ)
|| TREE_CODE (templ) == OVERLOAD
+ || TREE_CODE (templ) == FUNCTION_DECL
|| BASELINK_P (templ)));
template_id = lookup_template_function (templ, arguments);
@@ -16088,7 +16128,9 @@ cp_parser_template_id (cp_parser *parser,
name refers to a set of overloaded functions, at least one of which
is a template, or an IDENTIFIER_NODE with the name of the template,
if TEMPLATE_KEYWORD_P is true. If CHECK_DEPENDENCY_P is FALSE,
- names are looked up inside uninstantiated templates. */
+ names are looked up inside uninstantiated templates.
+ ID_AS_TMPL_NAME will be set if we should consider the unqualified-id
+ as a template-name. */
static tree
cp_parser_template_name (cp_parser* parser,
@@ -16096,7 +16138,8 @@ cp_parser_template_name (cp_parser* parser,
bool check_dependency_p,
bool is_declaration,
enum tag_types tag_type,
- bool *is_identifier)
+ bool *is_identifier,
+ bool *id_as_tmpl_name)
{
tree identifier;
tree decl;
@@ -16209,6 +16252,10 @@ cp_parser_template_name (cp_parser* parser,
}
}
+ /* cp_parser_lookup_name clears OBJECT_TYPE. */
+ const bool scoped_p = ((parser->scope ? parser->scope
+ : parser->context->object_type) != NULL_TREE);
+
/* Look up the name. */
decl = cp_parser_lookup_name (parser, identifier,
tag_type,
@@ -16241,6 +16288,33 @@ cp_parser_template_name (cp_parser* parser,
if (TREE_CODE (*iter) == TEMPLATE_DECL)
found = true;
+ if (!found
+ && (cxx_dialect > cxx17)
+ && !scoped_p
+ && cp_lexer_next_token_is (parser->lexer, CPP_LESS))
+ {
+ /* [temp.names] says "A name is also considered to refer to a template
+ if it is an unqualified-id followed by a < and name lookup finds
+ either one or more functions or finds nothing." */
+
+ /* The "more functions" case. Just use the OVERLOAD as normally. */
+ if (TREE_CODE (decl) == OVERLOAD
+ /* Name lookup found one function. */
+ || TREE_CODE (decl) == FUNCTION_DECL)
+ {
+ if (id_as_tmpl_name)
+ *id_as_tmpl_name = true;
+ found = true;
+ }
+ /* Name lookup found nothing. */
+ else if (decl == error_mark_node)
+ {
+ if (id_as_tmpl_name)
+ *id_as_tmpl_name = true;
+ return identifier;
+ }
+ }
+
if (!found)
{
/* The name does not name a template. */
@@ -26736,7 +26810,8 @@ cp_parser_constructor_declarator_p (cp_parser *parser,
bool friend_p)
/*check_dependency_p*/false,
/*is_declaration*/false,
none_type,
- /*is_identifier*/NULL);
+ /*is_identifier*/NULL,
+ /*id_as_tmpl_name*/NULL);
if (DECL_CLASS_TEMPLATE_P (tmpl)
|| DECL_TEMPLATE_TEMPLATE_PARM_P (tmpl))
/* It's a deduction guide, return true. */;
diff --git gcc/testsuite/g++.dg/addr_builtin-1.C
gcc/testsuite/g++.dg/addr_builtin-1.C
index e8ba31f994c..0c282b1f8cd 100644
--- gcc/testsuite/g++.dg/addr_builtin-1.C
+++ gcc/testsuite/g++.dg/addr_builtin-1.C
@@ -108,7 +108,7 @@ static F* test_taking_address_of_gcc_builtin ()
a = p - __builtin_trap; // { dg-error "built-in" }
// Relational operators. Ill-formed but allowed with -fpermissive.
- a = __builtin_trap < p; // { dg-error "built-in" }
+ a = __builtin_trap < p; // { dg-error "built-in|invalid
template-argument-list" }
a = p < __builtin_trap; // { dg-error "built-in" }
a = __builtin_trap <= p; // { dg-error "built-in" }
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template1.C
gcc/testsuite/g++.dg/cpp2a/fn-template1.C
index e69de29bb2d..2492d9df7d5 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template1.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template1.C
@@ -0,0 +1,37 @@
+// P0846R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+int h;
+void g();
+void e();
+void e(int);
+void e(int, int);
+
+namespace N {
+ struct A { };
+ template <class T> int f(T);
+ template <class T> int g(T);
+ template <class T> int h(T);
+ template <class T> int e(T);
+}
+
+int v = e<N::A>(N::A());
+int x = f<N::A>(N::A());
+int y = g<N::A>(N::A());
+int z = h<N::A>(N::A()); // { dg-error "expected" }
+
+template<class>
+void fn ()
+{
+ int v = e<N::A>(N::A());
+ int x = f<N::A>(N::A());
+ int y = g<N::A>(N::A());
+ int z = h<N::A>(N::A()); // { dg-error "expected" }
+}
+
+void
+test ()
+{
+ fn<int>();
+}
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template10.C
gcc/testsuite/g++.dg/cpp2a/fn-template10.C
index e69de29bb2d..c69d48fa9b2 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template10.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template10.C
@@ -0,0 +1,22 @@
+// P0846R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+int h;
+void g();
+void e();
+void e(int);
+void e(int, int);
+
+namespace N {
+ struct A { };
+ template <class T> static int f(T) { return 1; }
+ template <class T> static int g(T) { return 2; }
+ template <class T> static int h(T);
+ template <class T> static int e(T) { return 3; }
+}
+
+int v = e<N::A>(N::A());
+int x = f<N::A>(N::A());
+int y = g<N::A>(N::A());
+int z = h<N::A>(N::A()); // { dg-error "expected" }
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template11.C
gcc/testsuite/g++.dg/cpp2a/fn-template11.C
index e69de29bb2d..1a6b6882900 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template11.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template11.C
@@ -0,0 +1,11 @@
+// P0846R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+int nonconst ();
+
+int foo ()
+{
+ return blah < // { dg-error "not declared" }
+ nonconst (), nonconst (); // { dg-error "call to non-.constexpr. function"
}
+}
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template12.C
gcc/testsuite/g++.dg/cpp2a/fn-template12.C
index e69de29bb2d..fc72fd00584 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template12.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template12.C
@@ -0,0 +1,33 @@
+// P0846R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+struct S {
+ template<typename T> int foo(T);
+ template<typename T> int foo(T, T);
+ template<typename T> int foo(T, T, T);
+};
+
+template<typename T>
+struct W {
+ template<typename U> T foo(U);
+ template<typename U> T foo(U, U);
+ template<typename U> T foo(U, U, U);
+};
+
+void
+test ()
+{
+ S s;
+ s.foo<int>(1);
+ s.foo<int>(1, 2);
+ s.foo<int>(1, 2, 3);
+
+ W<int> w;
+ w.foo<int>(1);
+ w.foo<int>(1, 2);
+ w.foo<int>(1, 2, 3);
+
+ w.nothere<int>(1); // { dg-error "has no member|expected" }
+ s.nothere<int>(1); // { dg-error "has no member|expected" }
+}
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template13.C
gcc/testsuite/g++.dg/cpp2a/fn-template13.C
index e69de29bb2d..ece6d152601 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template13.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template13.C
@@ -0,0 +1,32 @@
+// P0846R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+struct A {
+ template<typename T>
+ int foo (T a, T b) { return a + b; }
+};
+
+int
+bar (A* pa, int (A::*pm)(int, int))
+{
+ return (pa->*pm)(1, 2);
+}
+
+int
+baz (A pa, int (A::*pm)(int, int))
+{
+ return (pa.*pm)(1, 2);
+}
+
+int
+main ()
+{
+ A a;
+ int i = bar (&a, &A::foo<int>);
+ if (i != 3)
+ __builtin_abort ();
+ i = baz (a, &A::foo<int>);
+ if (i != 3)
+ __builtin_abort ();
+}
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template2.C
gcc/testsuite/g++.dg/cpp2a/fn-template2.C
index e69de29bb2d..f974c8c2cf9 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template2.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template2.C
@@ -0,0 +1,16 @@
+// P0846R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+struct A { };
+bool operator <(void (*fp)(), A) { return false; }
+void f() {}
+
+int
+main ()
+{
+ A a;
+ f < a; // { dg-error "invalid" }
+ bool b = f < a; // { dg-error "invalid" }
+ (f) < a;
+}
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template3.C
gcc/testsuite/g++.dg/cpp2a/fn-template3.C
index e69de29bb2d..f801625ab3d 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template3.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template3.C
@@ -0,0 +1,29 @@
+// P0846R0
+// { dg-do run }
+// { dg-options "-std=c++2a" }
+
+void g();
+void e();
+void e(int);
+void e(int, int);
+
+namespace N {
+ struct A { };
+ template <class T> int f(T) { return 1; }
+ template <class T> int g(T) { return 2; }
+ template <class T> int e(T) { return 3; }
+}
+
+int
+main ()
+{
+ int v = e<N::A>(N::A());
+ if (v != 3)
+ __builtin_abort ();
+ int x = f<N::A>(N::A());
+ if (x != 1)
+ __builtin_abort ();
+ int y = g<N::A>(N::A());
+ if (y != 2)
+ __builtin_abort ();
+}
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template4.C
gcc/testsuite/g++.dg/cpp2a/fn-template4.C
index e69de29bb2d..9259c2ebf23 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template4.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template4.C
@@ -0,0 +1,11 @@
+// P0846R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+template <typename T> void foo() { }
+template <typename T> void bar(int) { }
+int main()
+{
+ foo<float>();
+ bar<int>(1);
+}
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template5.C
gcc/testsuite/g++.dg/cpp2a/fn-template5.C
index e69de29bb2d..33477c96746 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template5.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template5.C
@@ -0,0 +1,32 @@
+// P0846R0
+// { dg-do run }
+// { dg-options "-std=c++2a" }
+
+int g() { return 11; }
+int e() { return 12; }
+int e(int) { return 13; }
+int e(int, int) { return 14; }
+
+namespace N {
+ struct A { };
+ template <class T> int f(T) { return 1; }
+ template <class T> int g(T) { return 2; }
+ template <class T> int e(T) { return 3; }
+}
+
+int
+main ()
+{
+ int v = e(1);
+ if (v != 13)
+ __builtin_abort ();
+ int x = e(1, 2);
+ if (x != 14)
+ __builtin_abort ();
+ int y = g();
+ if (y != 11)
+ __builtin_abort ();
+ int z = e();
+ if (z != 12)
+ __builtin_abort ();
+}
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template6.C
gcc/testsuite/g++.dg/cpp2a/fn-template6.C
index e69de29bb2d..63b2377bc6e 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template6.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template6.C
@@ -0,0 +1,16 @@
+// P0846R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+template<class>
+struct X {
+ int first = 0;
+};
+
+int
+f ()
+{
+ X<int> x, y;
+ bool b = x.first < y.first;
+ return b;
+}
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template7.C
gcc/testsuite/g++.dg/cpp2a/fn-template7.C
index e69de29bb2d..d048606c0d6 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template7.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template7.C
@@ -0,0 +1,18 @@
+// P0846R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+struct undeclared<int> { }; // { dg-error "not a class template" }
+
+int
+main ()
+{
+ int foo ();
+ int a, b = 10;
+ a = foo<; // { dg-error "invalid template-argument-list|invalid" }
+ a = foo < b; // { dg-error "invalid template-argument-list|invalid" }
+ a = foo<b>; // { dg-error "after template-argument-list|invalid" }
+ a = foo<b>(; // { dg-error "expected" }
+ a = foo<b>(1; // { dg-error "expected" }
+ a = foo<b>(1); // { dg-error "no matching" }
+}
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template8.C
gcc/testsuite/g++.dg/cpp2a/fn-template8.C
index e69de29bb2d..9cd28eed5d0 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template8.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template8.C
@@ -0,0 +1,34 @@
+// P0846R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+const unsigned long arr[10] = { 2 };
+template<class T> struct S { int n; };
+
+template <class T>
+int fn1 (S<T>* s)
+{
+ int i = 1;
+ return s->n < arr[i + 1];
+}
+
+template <class T>
+int fn2 (S<T> s)
+{
+ int i = 1;
+ return s.n < arr[i + 1];
+}
+
+template <class T>
+int fn3 (S<T>* s)
+{
+ int i = 1;
+ return s->template n < 1; // { dg-error "parse error in template argument
list" }
+}
+
+template <class T>
+int fn4 (S<T> s)
+{
+ int i = 1;
+ return s.template n < 1; // { dg-error "parse error in template argument
list" }
+}
diff --git gcc/testsuite/g++.dg/cpp2a/fn-template9.C
gcc/testsuite/g++.dg/cpp2a/fn-template9.C
index e69de29bb2d..19c960cc936 100644
--- gcc/testsuite/g++.dg/cpp2a/fn-template9.C
+++ gcc/testsuite/g++.dg/cpp2a/fn-template9.C
@@ -0,0 +1,21 @@
+// P0846R0
+// { dg-do compile }
+// { dg-options "-std=c++2a" }
+
+namespace N1 {
+ struct S {};
+ template<int X> void f(S);
+}
+
+namespace N2 {
+ template<class T> void f(T t);
+}
+
+void
+g (N1::S s)
+{
+ f<3>(s);
+
+ using N2::f;
+ f<3>(s);
+}
diff --git gcc/testsuite/g++.dg/parse/fn-template1.C
gcc/testsuite/g++.dg/parse/fn-template1.C
index e69de29bb2d..00f8b4920e1 100644
--- gcc/testsuite/g++.dg/parse/fn-template1.C
+++ gcc/testsuite/g++.dg/parse/fn-template1.C
@@ -0,0 +1,15 @@
+// P0846R0
+// { dg-do compile }
+
+struct A { };
+bool operator <(void (*fp)(), A) { return false; }
+void f() {}
+
+int
+main ()
+{
+ A a;
+ f < a; // { dg-error "invalid" "" { target c++2a } }
+ bool b = f < a; // { dg-error "invalid" "" { target c++2a } }
+ (f) < a;
+}
diff --git gcc/testsuite/g++.dg/parse/fn-template2.C
gcc/testsuite/g++.dg/parse/fn-template2.C
index e69de29bb2d..c56694efb92 100644
--- gcc/testsuite/g++.dg/parse/fn-template2.C
+++ gcc/testsuite/g++.dg/parse/fn-template2.C
@@ -0,0 +1,17 @@
+// P0846R0
+// { dg-do compile }
+
+namespace N1 {
+ struct S {};
+ template<int X> void f(S);
+}
+
+namespace N2 {
+ template<class T> void f(T t);
+}
+
+void
+g (N1::S s)
+{
+ f<3>(s); // { dg-error "was not declared" "" { target c++17_down } }
+}
diff --git gcc/testsuite/g++.dg/template/pr61745.C
gcc/testsuite/g++.dg/template/pr61745.C
index 0f7c280e52a..da5973e3867 100644
--- gcc/testsuite/g++.dg/template/pr61745.C
+++ gcc/testsuite/g++.dg/template/pr61745.C
@@ -18,5 +18,7 @@ public:
// this compiles only if the following definition is moved
// AFTER the friend declaration
Zp operator-() const { return Zp(p-val); }
- friend Zp<INT,P> operator- <>(const Zp<INT,P>& a, const Zp<INT,P>& b); // {
dg-error "declaration|expected" }
+ // In C++2A, we have an unqualified-id (operator-) followed by
+ // '<', and name lookup found a function.
+ friend Zp<INT,P> operator- <>(const Zp<INT,P>& a, const Zp<INT,P>& b); // {
dg-error "declaration|expected" "" { target c++17_down } }
};
