* [PATCH] c++: Fix P0846 (ADL and function templates) in template [PR97010]
@ 2020-09-10 22:15 Marek Polacek
2020-09-18 20:05 ` Marek Polacek
2020-10-07 21:07 ` Jason Merrill
0 siblings, 2 replies; 4+ messages in thread
From: Marek Polacek @ 2020-09-10 22:15 UTC (permalink / raw)
To: Jason Merrill, GCC Patches
To quickly recap, P0846 says that 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.
In a template, when parsing a function call that has type-dependent
arguments, we can't perform ADL right away so we set KOENIG_LOOKUP_P in
the call to remember to do it when instantiating the call
(tsubst_copy_and_build/CALL_EXPR). When the called function is a
function template, we represent the call with a TEMPLATE_ID_EXPR;
usually the operand is an OVERLOAD.
In the P0846 case though, the operand can be an IDENTIFIER_NODE, when
name lookup found nothing when parsing the template name. But we
weren't handling this correctly in tsubst_copy_and_build. First
we need to pass the FUNCTION_P argument from <case TEMPLATE_ID_EXPR> to
<case IDENTIFIER_NODE>, otherwise we give a bogus error. And then in
<case CALL_EXPR> we need to perform ADL. The rest of the changes is to
give better errors when ADL didn't find anything.
Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
I think I'd like to backport to 10 too.
gcc/cp/ChangeLog:
PR c++/97010
* pt.c (tsubst_copy_and_build) <case TEMPLATE_ID_EXPR>: Call
tsubst_copy_and_build explicitly instead of using the RECUR macro.
Handle a TEMPLATE_ID_EXPR with an IDENTIFIER_NODE as its operand.
<case CALL_EXPR>: Perform ADL for a TEMPLATE_ID_EXPR with an
IDENTIFIER_NODE as its operand.
gcc/testsuite/ChangeLog:
PR c++/97010
* g++.dg/cpp2a/fn-template21.C: New test.
* g++.dg/cpp2a/fn-template22.C: New test.
---
gcc/cp/pt.c | 37 ++++++++++++++++------
gcc/testsuite/g++.dg/cpp2a/fn-template21.C | 24 ++++++++++++++
gcc/testsuite/g++.dg/cpp2a/fn-template22.C | 25 +++++++++++++++
3 files changed, 77 insertions(+), 9 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/fn-template21.C
create mode 100644 gcc/testsuite/g++.dg/cpp2a/fn-template22.C
diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 30c6735dede..566e24f9bf3 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -19241,7 +19241,8 @@ out:
}
/* Like tsubst but deals with expressions and performs semantic
- analysis. FUNCTION_P is true if T is the "F" in "F (ARGS)". */
+ analysis. FUNCTION_P is true if T is the "F" in "F (ARGS)" or
+ "F<TARGS> (ARGS)". */
tree
tsubst_copy_and_build (tree t,
@@ -19323,7 +19324,10 @@ tsubst_copy_and_build (tree t,
case TEMPLATE_ID_EXPR:
{
tree object;
- tree templ = RECUR (TREE_OPERAND (t, 0));
+ tree templ = tsubst_copy_and_build (TREE_OPERAND (t, 0), args,
+ complain, in_decl,
+ function_p,
+ integral_constant_expression_p);
tree targs = TREE_OPERAND (t, 1);
if (targs)
@@ -19370,13 +19374,21 @@ tsubst_copy_and_build (tree t,
}
else
object = NULL_TREE;
- templ = lookup_template_function (templ, targs);
+
+ tree tid = lookup_template_function (templ, targs);
if (object)
- RETURN (build3 (COMPONENT_REF, TREE_TYPE (templ),
- object, templ, NULL_TREE));
+ RETURN (build3 (COMPONENT_REF, TREE_TYPE (tid),
+ object, tid, NULL_TREE));
+ else if (identifier_p (templ))
+ {
+ /* C++20 P0846: we can encounter an IDENTIFIER_NODE here when
+ name lookup found nothing when parsing the template name. */
+ gcc_assert (cxx_dialect >= cxx20 || seen_error ());
+ RETURN (tid);
+ }
else
- RETURN (baselink_for_fns (templ));
+ RETURN (baselink_for_fns (tid));
}
case INDIRECT_REF:
@@ -19967,14 +19979,17 @@ tsubst_copy_and_build (tree t,
/* We do not perform argument-dependent lookup if normal
lookup finds a non-function, in accordance with the
- expected resolution of DR 218. */
+ resolution of DR 218. */
if (koenig_p
&& ((is_overloaded_fn (function)
/* If lookup found a member function, the Koenig lookup is
not appropriate, even if an unqualified-name was used
to denote the function. */
&& !DECL_FUNCTION_MEMBER_P (get_first_fn (function)))
- || identifier_p (function))
+ || identifier_p (function)
+ /* C++20 P0846: Lookup found nothing. */
+ || (TREE_CODE (function) == TEMPLATE_ID_EXPR
+ && identifier_p (TREE_OPERAND (function, 0))))
/* Only do this when substitution turns a dependent call
into a non-dependent call. */
&& type_dependent_expression_p_push (t)
@@ -19982,9 +19997,13 @@ tsubst_copy_and_build (tree t,
function = perform_koenig_lookup (function, call_args, tf_none);
if (function != NULL_TREE
- && identifier_p (function)
+ && (identifier_p (function)
+ || (TREE_CODE (function) == TEMPLATE_ID_EXPR
+ && identifier_p (TREE_OPERAND (function, 0))))
&& !any_type_dependent_arguments_p (call_args))
{
+ if (TREE_CODE (function) == TEMPLATE_ID_EXPR)
+ function = TREE_OPERAND (function, 0);
if (koenig_p && (complain & tf_warning_or_error))
{
/* For backwards compatibility and good diagnostics, try
diff --git a/gcc/testsuite/g++.dg/cpp2a/fn-template21.C b/gcc/testsuite/g++.dg/cpp2a/fn-template21.C
new file mode 100644
index 00000000000..7b3f26bbfa0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/fn-template21.C
@@ -0,0 +1,24 @@
+// PR c++/97010
+// { dg-do compile { target c++20 } }
+
+namespace M {
+ struct S { int x; };
+ S foo ();
+
+ template<typename>
+ void get (S);
+}
+
+template<typename T>
+void bar (const T& t)
+{
+ get<int>(t);
+}
+
+int
+main ()
+{
+ auto a = M::foo ();
+ get<int>(a);
+ bar (a);
+}
diff --git a/gcc/testsuite/g++.dg/cpp2a/fn-template22.C b/gcc/testsuite/g++.dg/cpp2a/fn-template22.C
new file mode 100644
index 00000000000..62cc81db0c7
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/fn-template22.C
@@ -0,0 +1,25 @@
+// PR c++/97010
+// { dg-do compile { target c++20 } }
+
+namespace M {
+ struct S { int x; };
+ S foo ();
+
+// Test not-found-by-ADL scenario.
+// template<typename>
+// void get (S);
+}
+
+template<typename T>
+void bar (const T& t)
+{
+ get<int>(t); // { dg-error ".get. was not declared in this scope" }
+}
+
+int
+main ()
+{
+ auto a = M::foo ();
+ get<int>(a); // { dg-error ".get. was not declared in this scope" }
+ bar (a);
+}
base-commit: af47a2035a4882e6d4506e3d00b5a42414e3ee2b
--
2.26.2
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] c++: Fix P0846 (ADL and function templates) in template [PR97010]
2020-09-10 22:15 [PATCH] c++: Fix P0846 (ADL and function templates) in template [PR97010] Marek Polacek
@ 2020-09-18 20:05 ` Marek Polacek
2020-09-29 20:24 ` Marek Polacek
2020-10-07 21:07 ` Jason Merrill
1 sibling, 1 reply; 4+ messages in thread
From: Marek Polacek @ 2020-09-18 20:05 UTC (permalink / raw)
To: Jason Merrill, GCC Patches
Ping.
On Thu, Sep 10, 2020 at 06:15:24PM -0400, Marek Polacek via Gcc-patches wrote:
> To quickly recap, P0846 says that 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.
>
> In a template, when parsing a function call that has type-dependent
> arguments, we can't perform ADL right away so we set KOENIG_LOOKUP_P in
> the call to remember to do it when instantiating the call
> (tsubst_copy_and_build/CALL_EXPR). When the called function is a
> function template, we represent the call with a TEMPLATE_ID_EXPR;
> usually the operand is an OVERLOAD.
>
> In the P0846 case though, the operand can be an IDENTIFIER_NODE, when
> name lookup found nothing when parsing the template name. But we
> weren't handling this correctly in tsubst_copy_and_build. First
> we need to pass the FUNCTION_P argument from <case TEMPLATE_ID_EXPR> to
> <case IDENTIFIER_NODE>, otherwise we give a bogus error. And then in
> <case CALL_EXPR> we need to perform ADL. The rest of the changes is to
> give better errors when ADL didn't find anything.
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> I think I'd like to backport to 10 too.
>
> gcc/cp/ChangeLog:
>
> PR c++/97010
> * pt.c (tsubst_copy_and_build) <case TEMPLATE_ID_EXPR>: Call
> tsubst_copy_and_build explicitly instead of using the RECUR macro.
> Handle a TEMPLATE_ID_EXPR with an IDENTIFIER_NODE as its operand.
> <case CALL_EXPR>: Perform ADL for a TEMPLATE_ID_EXPR with an
> IDENTIFIER_NODE as its operand.
>
> gcc/testsuite/ChangeLog:
>
> PR c++/97010
> * g++.dg/cpp2a/fn-template21.C: New test.
> * g++.dg/cpp2a/fn-template22.C: New test.
> ---
> gcc/cp/pt.c | 37 ++++++++++++++++------
> gcc/testsuite/g++.dg/cpp2a/fn-template21.C | 24 ++++++++++++++
> gcc/testsuite/g++.dg/cpp2a/fn-template22.C | 25 +++++++++++++++
> 3 files changed, 77 insertions(+), 9 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/fn-template21.C
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/fn-template22.C
>
> diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
> index 30c6735dede..566e24f9bf3 100644
> --- a/gcc/cp/pt.c
> +++ b/gcc/cp/pt.c
> @@ -19241,7 +19241,8 @@ out:
> }
>
> /* Like tsubst but deals with expressions and performs semantic
> - analysis. FUNCTION_P is true if T is the "F" in "F (ARGS)". */
> + analysis. FUNCTION_P is true if T is the "F" in "F (ARGS)" or
> + "F<TARGS> (ARGS)". */
>
> tree
> tsubst_copy_and_build (tree t,
> @@ -19323,7 +19324,10 @@ tsubst_copy_and_build (tree t,
> case TEMPLATE_ID_EXPR:
> {
> tree object;
> - tree templ = RECUR (TREE_OPERAND (t, 0));
> + tree templ = tsubst_copy_and_build (TREE_OPERAND (t, 0), args,
> + complain, in_decl,
> + function_p,
> + integral_constant_expression_p);
> tree targs = TREE_OPERAND (t, 1);
>
> if (targs)
> @@ -19370,13 +19374,21 @@ tsubst_copy_and_build (tree t,
> }
> else
> object = NULL_TREE;
> - templ = lookup_template_function (templ, targs);
> +
> + tree tid = lookup_template_function (templ, targs);
>
> if (object)
> - RETURN (build3 (COMPONENT_REF, TREE_TYPE (templ),
> - object, templ, NULL_TREE));
> + RETURN (build3 (COMPONENT_REF, TREE_TYPE (tid),
> + object, tid, NULL_TREE));
> + else if (identifier_p (templ))
> + {
> + /* C++20 P0846: we can encounter an IDENTIFIER_NODE here when
> + name lookup found nothing when parsing the template name. */
> + gcc_assert (cxx_dialect >= cxx20 || seen_error ());
> + RETURN (tid);
> + }
> else
> - RETURN (baselink_for_fns (templ));
> + RETURN (baselink_for_fns (tid));
> }
>
> case INDIRECT_REF:
> @@ -19967,14 +19979,17 @@ tsubst_copy_and_build (tree t,
>
> /* We do not perform argument-dependent lookup if normal
> lookup finds a non-function, in accordance with the
> - expected resolution of DR 218. */
> + resolution of DR 218. */
> if (koenig_p
> && ((is_overloaded_fn (function)
> /* If lookup found a member function, the Koenig lookup is
> not appropriate, even if an unqualified-name was used
> to denote the function. */
> && !DECL_FUNCTION_MEMBER_P (get_first_fn (function)))
> - || identifier_p (function))
> + || identifier_p (function)
> + /* C++20 P0846: Lookup found nothing. */
> + || (TREE_CODE (function) == TEMPLATE_ID_EXPR
> + && identifier_p (TREE_OPERAND (function, 0))))
> /* Only do this when substitution turns a dependent call
> into a non-dependent call. */
> && type_dependent_expression_p_push (t)
> @@ -19982,9 +19997,13 @@ tsubst_copy_and_build (tree t,
> function = perform_koenig_lookup (function, call_args, tf_none);
>
> if (function != NULL_TREE
> - && identifier_p (function)
> + && (identifier_p (function)
> + || (TREE_CODE (function) == TEMPLATE_ID_EXPR
> + && identifier_p (TREE_OPERAND (function, 0))))
> && !any_type_dependent_arguments_p (call_args))
> {
> + if (TREE_CODE (function) == TEMPLATE_ID_EXPR)
> + function = TREE_OPERAND (function, 0);
> if (koenig_p && (complain & tf_warning_or_error))
> {
> /* For backwards compatibility and good diagnostics, try
> diff --git a/gcc/testsuite/g++.dg/cpp2a/fn-template21.C b/gcc/testsuite/g++.dg/cpp2a/fn-template21.C
> new file mode 100644
> index 00000000000..7b3f26bbfa0
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/fn-template21.C
> @@ -0,0 +1,24 @@
> +// PR c++/97010
> +// { dg-do compile { target c++20 } }
> +
> +namespace M {
> + struct S { int x; };
> + S foo ();
> +
> + template<typename>
> + void get (S);
> +}
> +
> +template<typename T>
> +void bar (const T& t)
> +{
> + get<int>(t);
> +}
> +
> +int
> +main ()
> +{
> + auto a = M::foo ();
> + get<int>(a);
> + bar (a);
> +}
> diff --git a/gcc/testsuite/g++.dg/cpp2a/fn-template22.C b/gcc/testsuite/g++.dg/cpp2a/fn-template22.C
> new file mode 100644
> index 00000000000..62cc81db0c7
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/fn-template22.C
> @@ -0,0 +1,25 @@
> +// PR c++/97010
> +// { dg-do compile { target c++20 } }
> +
> +namespace M {
> + struct S { int x; };
> + S foo ();
> +
> +// Test not-found-by-ADL scenario.
> +// template<typename>
> +// void get (S);
> +}
> +
> +template<typename T>
> +void bar (const T& t)
> +{
> + get<int>(t); // { dg-error ".get. was not declared in this scope" }
> +}
> +
> +int
> +main ()
> +{
> + auto a = M::foo ();
> + get<int>(a); // { dg-error ".get. was not declared in this scope" }
> + bar (a);
> +}
>
> base-commit: af47a2035a4882e6d4506e3d00b5a42414e3ee2b
> --
> 2.26.2
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] c++: Fix P0846 (ADL and function templates) in template [PR97010]
2020-09-18 20:05 ` Marek Polacek
@ 2020-09-29 20:24 ` Marek Polacek
0 siblings, 0 replies; 4+ messages in thread
From: Marek Polacek @ 2020-09-29 20:24 UTC (permalink / raw)
To: Jason Merrill, GCC Patches
Ping.
On Fri, Sep 18, 2020 at 04:05:16PM -0400, Marek Polacek via Gcc-patches wrote:
> Ping.
>
> On Thu, Sep 10, 2020 at 06:15:24PM -0400, Marek Polacek via Gcc-patches wrote:
> > To quickly recap, P0846 says that 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.
> >
> > In a template, when parsing a function call that has type-dependent
> > arguments, we can't perform ADL right away so we set KOENIG_LOOKUP_P in
> > the call to remember to do it when instantiating the call
> > (tsubst_copy_and_build/CALL_EXPR). When the called function is a
> > function template, we represent the call with a TEMPLATE_ID_EXPR;
> > usually the operand is an OVERLOAD.
> >
> > In the P0846 case though, the operand can be an IDENTIFIER_NODE, when
> > name lookup found nothing when parsing the template name. But we
> > weren't handling this correctly in tsubst_copy_and_build. First
> > we need to pass the FUNCTION_P argument from <case TEMPLATE_ID_EXPR> to
> > <case IDENTIFIER_NODE>, otherwise we give a bogus error. And then in
> > <case CALL_EXPR> we need to perform ADL. The rest of the changes is to
> > give better errors when ADL didn't find anything.
> >
> > Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> > I think I'd like to backport to 10 too.
> >
> > gcc/cp/ChangeLog:
> >
> > PR c++/97010
> > * pt.c (tsubst_copy_and_build) <case TEMPLATE_ID_EXPR>: Call
> > tsubst_copy_and_build explicitly instead of using the RECUR macro.
> > Handle a TEMPLATE_ID_EXPR with an IDENTIFIER_NODE as its operand.
> > <case CALL_EXPR>: Perform ADL for a TEMPLATE_ID_EXPR with an
> > IDENTIFIER_NODE as its operand.
> >
> > gcc/testsuite/ChangeLog:
> >
> > PR c++/97010
> > * g++.dg/cpp2a/fn-template21.C: New test.
> > * g++.dg/cpp2a/fn-template22.C: New test.
> > ---
> > gcc/cp/pt.c | 37 ++++++++++++++++------
> > gcc/testsuite/g++.dg/cpp2a/fn-template21.C | 24 ++++++++++++++
> > gcc/testsuite/g++.dg/cpp2a/fn-template22.C | 25 +++++++++++++++
> > 3 files changed, 77 insertions(+), 9 deletions(-)
> > create mode 100644 gcc/testsuite/g++.dg/cpp2a/fn-template21.C
> > create mode 100644 gcc/testsuite/g++.dg/cpp2a/fn-template22.C
> >
> > diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
> > index 30c6735dede..566e24f9bf3 100644
> > --- a/gcc/cp/pt.c
> > +++ b/gcc/cp/pt.c
> > @@ -19241,7 +19241,8 @@ out:
> > }
> >
> > /* Like tsubst but deals with expressions and performs semantic
> > - analysis. FUNCTION_P is true if T is the "F" in "F (ARGS)". */
> > + analysis. FUNCTION_P is true if T is the "F" in "F (ARGS)" or
> > + "F<TARGS> (ARGS)". */
> >
> > tree
> > tsubst_copy_and_build (tree t,
> > @@ -19323,7 +19324,10 @@ tsubst_copy_and_build (tree t,
> > case TEMPLATE_ID_EXPR:
> > {
> > tree object;
> > - tree templ = RECUR (TREE_OPERAND (t, 0));
> > + tree templ = tsubst_copy_and_build (TREE_OPERAND (t, 0), args,
> > + complain, in_decl,
> > + function_p,
> > + integral_constant_expression_p);
> > tree targs = TREE_OPERAND (t, 1);
> >
> > if (targs)
> > @@ -19370,13 +19374,21 @@ tsubst_copy_and_build (tree t,
> > }
> > else
> > object = NULL_TREE;
> > - templ = lookup_template_function (templ, targs);
> > +
> > + tree tid = lookup_template_function (templ, targs);
> >
> > if (object)
> > - RETURN (build3 (COMPONENT_REF, TREE_TYPE (templ),
> > - object, templ, NULL_TREE));
> > + RETURN (build3 (COMPONENT_REF, TREE_TYPE (tid),
> > + object, tid, NULL_TREE));
> > + else if (identifier_p (templ))
> > + {
> > + /* C++20 P0846: we can encounter an IDENTIFIER_NODE here when
> > + name lookup found nothing when parsing the template name. */
> > + gcc_assert (cxx_dialect >= cxx20 || seen_error ());
> > + RETURN (tid);
> > + }
> > else
> > - RETURN (baselink_for_fns (templ));
> > + RETURN (baselink_for_fns (tid));
> > }
> >
> > case INDIRECT_REF:
> > @@ -19967,14 +19979,17 @@ tsubst_copy_and_build (tree t,
> >
> > /* We do not perform argument-dependent lookup if normal
> > lookup finds a non-function, in accordance with the
> > - expected resolution of DR 218. */
> > + resolution of DR 218. */
> > if (koenig_p
> > && ((is_overloaded_fn (function)
> > /* If lookup found a member function, the Koenig lookup is
> > not appropriate, even if an unqualified-name was used
> > to denote the function. */
> > && !DECL_FUNCTION_MEMBER_P (get_first_fn (function)))
> > - || identifier_p (function))
> > + || identifier_p (function)
> > + /* C++20 P0846: Lookup found nothing. */
> > + || (TREE_CODE (function) == TEMPLATE_ID_EXPR
> > + && identifier_p (TREE_OPERAND (function, 0))))
> > /* Only do this when substitution turns a dependent call
> > into a non-dependent call. */
> > && type_dependent_expression_p_push (t)
> > @@ -19982,9 +19997,13 @@ tsubst_copy_and_build (tree t,
> > function = perform_koenig_lookup (function, call_args, tf_none);
> >
> > if (function != NULL_TREE
> > - && identifier_p (function)
> > + && (identifier_p (function)
> > + || (TREE_CODE (function) == TEMPLATE_ID_EXPR
> > + && identifier_p (TREE_OPERAND (function, 0))))
> > && !any_type_dependent_arguments_p (call_args))
> > {
> > + if (TREE_CODE (function) == TEMPLATE_ID_EXPR)
> > + function = TREE_OPERAND (function, 0);
> > if (koenig_p && (complain & tf_warning_or_error))
> > {
> > /* For backwards compatibility and good diagnostics, try
> > diff --git a/gcc/testsuite/g++.dg/cpp2a/fn-template21.C b/gcc/testsuite/g++.dg/cpp2a/fn-template21.C
> > new file mode 100644
> > index 00000000000..7b3f26bbfa0
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/cpp2a/fn-template21.C
> > @@ -0,0 +1,24 @@
> > +// PR c++/97010
> > +// { dg-do compile { target c++20 } }
> > +
> > +namespace M {
> > + struct S { int x; };
> > + S foo ();
> > +
> > + template<typename>
> > + void get (S);
> > +}
> > +
> > +template<typename T>
> > +void bar (const T& t)
> > +{
> > + get<int>(t);
> > +}
> > +
> > +int
> > +main ()
> > +{
> > + auto a = M::foo ();
> > + get<int>(a);
> > + bar (a);
> > +}
> > diff --git a/gcc/testsuite/g++.dg/cpp2a/fn-template22.C b/gcc/testsuite/g++.dg/cpp2a/fn-template22.C
> > new file mode 100644
> > index 00000000000..62cc81db0c7
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/cpp2a/fn-template22.C
> > @@ -0,0 +1,25 @@
> > +// PR c++/97010
> > +// { dg-do compile { target c++20 } }
> > +
> > +namespace M {
> > + struct S { int x; };
> > + S foo ();
> > +
> > +// Test not-found-by-ADL scenario.
> > +// template<typename>
> > +// void get (S);
> > +}
> > +
> > +template<typename T>
> > +void bar (const T& t)
> > +{
> > + get<int>(t); // { dg-error ".get. was not declared in this scope" }
> > +}
> > +
> > +int
> > +main ()
> > +{
> > + auto a = M::foo ();
> > + get<int>(a); // { dg-error ".get. was not declared in this scope" }
> > + bar (a);
> > +}
> >
> > base-commit: af47a2035a4882e6d4506e3d00b5a42414e3ee2b
> > --
> > 2.26.2
> >
>
Marek
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] c++: Fix P0846 (ADL and function templates) in template [PR97010]
2020-09-10 22:15 [PATCH] c++: Fix P0846 (ADL and function templates) in template [PR97010] Marek Polacek
2020-09-18 20:05 ` Marek Polacek
@ 2020-10-07 21:07 ` Jason Merrill
1 sibling, 0 replies; 4+ messages in thread
From: Jason Merrill @ 2020-10-07 21:07 UTC (permalink / raw)
To: Marek Polacek, GCC Patches
On 9/10/20 6:15 PM, Marek Polacek wrote:
> To quickly recap, P0846 says that 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.
>
> In a template, when parsing a function call that has type-dependent
> arguments, we can't perform ADL right away so we set KOENIG_LOOKUP_P in
> the call to remember to do it when instantiating the call
> (tsubst_copy_and_build/CALL_EXPR). When the called function is a
> function template, we represent the call with a TEMPLATE_ID_EXPR;
> usually the operand is an OVERLOAD.
>
> In the P0846 case though, the operand can be an IDENTIFIER_NODE, when
> name lookup found nothing when parsing the template name. But we
> weren't handling this correctly in tsubst_copy_and_build. First
> we need to pass the FUNCTION_P argument from <case TEMPLATE_ID_EXPR> to
> <case IDENTIFIER_NODE>, otherwise we give a bogus error. And then in
> <case CALL_EXPR> we need to perform ADL. The rest of the changes is to
> give better errors when ADL didn't find anything.
>
> Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?
> I think I'd like to backport to 10 too.
OK for both.
> gcc/cp/ChangeLog:
>
> PR c++/97010
> * pt.c (tsubst_copy_and_build) <case TEMPLATE_ID_EXPR>: Call
> tsubst_copy_and_build explicitly instead of using the RECUR macro.
> Handle a TEMPLATE_ID_EXPR with an IDENTIFIER_NODE as its operand.
> <case CALL_EXPR>: Perform ADL for a TEMPLATE_ID_EXPR with an
> IDENTIFIER_NODE as its operand.
>
> gcc/testsuite/ChangeLog:
>
> PR c++/97010
> * g++.dg/cpp2a/fn-template21.C: New test.
> * g++.dg/cpp2a/fn-template22.C: New test.
> ---
> gcc/cp/pt.c | 37 ++++++++++++++++------
> gcc/testsuite/g++.dg/cpp2a/fn-template21.C | 24 ++++++++++++++
> gcc/testsuite/g++.dg/cpp2a/fn-template22.C | 25 +++++++++++++++
> 3 files changed, 77 insertions(+), 9 deletions(-)
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/fn-template21.C
> create mode 100644 gcc/testsuite/g++.dg/cpp2a/fn-template22.C
>
> diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
> index 30c6735dede..566e24f9bf3 100644
> --- a/gcc/cp/pt.c
> +++ b/gcc/cp/pt.c
> @@ -19241,7 +19241,8 @@ out:
> }
>
> /* Like tsubst but deals with expressions and performs semantic
> - analysis. FUNCTION_P is true if T is the "F" in "F (ARGS)". */
> + analysis. FUNCTION_P is true if T is the "F" in "F (ARGS)" or
> + "F<TARGS> (ARGS)". */
>
> tree
> tsubst_copy_and_build (tree t,
> @@ -19323,7 +19324,10 @@ tsubst_copy_and_build (tree t,
> case TEMPLATE_ID_EXPR:
> {
> tree object;
> - tree templ = RECUR (TREE_OPERAND (t, 0));
> + tree templ = tsubst_copy_and_build (TREE_OPERAND (t, 0), args,
> + complain, in_decl,
> + function_p,
> + integral_constant_expression_p);
> tree targs = TREE_OPERAND (t, 1);
>
> if (targs)
> @@ -19370,13 +19374,21 @@ tsubst_copy_and_build (tree t,
> }
> else
> object = NULL_TREE;
> - templ = lookup_template_function (templ, targs);
> +
> + tree tid = lookup_template_function (templ, targs);
>
> if (object)
> - RETURN (build3 (COMPONENT_REF, TREE_TYPE (templ),
> - object, templ, NULL_TREE));
> + RETURN (build3 (COMPONENT_REF, TREE_TYPE (tid),
> + object, tid, NULL_TREE));
> + else if (identifier_p (templ))
> + {
> + /* C++20 P0846: we can encounter an IDENTIFIER_NODE here when
> + name lookup found nothing when parsing the template name. */
> + gcc_assert (cxx_dialect >= cxx20 || seen_error ());
> + RETURN (tid);
> + }
> else
> - RETURN (baselink_for_fns (templ));
> + RETURN (baselink_for_fns (tid));
> }
>
> case INDIRECT_REF:
> @@ -19967,14 +19979,17 @@ tsubst_copy_and_build (tree t,
>
> /* We do not perform argument-dependent lookup if normal
> lookup finds a non-function, in accordance with the
> - expected resolution of DR 218. */
> + resolution of DR 218. */
> if (koenig_p
> && ((is_overloaded_fn (function)
> /* If lookup found a member function, the Koenig lookup is
> not appropriate, even if an unqualified-name was used
> to denote the function. */
> && !DECL_FUNCTION_MEMBER_P (get_first_fn (function)))
> - || identifier_p (function))
> + || identifier_p (function)
> + /* C++20 P0846: Lookup found nothing. */
> + || (TREE_CODE (function) == TEMPLATE_ID_EXPR
> + && identifier_p (TREE_OPERAND (function, 0))))
> /* Only do this when substitution turns a dependent call
> into a non-dependent call. */
> && type_dependent_expression_p_push (t)
> @@ -19982,9 +19997,13 @@ tsubst_copy_and_build (tree t,
> function = perform_koenig_lookup (function, call_args, tf_none);
>
> if (function != NULL_TREE
> - && identifier_p (function)
> + && (identifier_p (function)
> + || (TREE_CODE (function) == TEMPLATE_ID_EXPR
> + && identifier_p (TREE_OPERAND (function, 0))))
> && !any_type_dependent_arguments_p (call_args))
> {
> + if (TREE_CODE (function) == TEMPLATE_ID_EXPR)
> + function = TREE_OPERAND (function, 0);
> if (koenig_p && (complain & tf_warning_or_error))
> {
> /* For backwards compatibility and good diagnostics, try
> diff --git a/gcc/testsuite/g++.dg/cpp2a/fn-template21.C b/gcc/testsuite/g++.dg/cpp2a/fn-template21.C
> new file mode 100644
> index 00000000000..7b3f26bbfa0
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/fn-template21.C
> @@ -0,0 +1,24 @@
> +// PR c++/97010
> +// { dg-do compile { target c++20 } }
> +
> +namespace M {
> + struct S { int x; };
> + S foo ();
> +
> + template<typename>
> + void get (S);
> +}
> +
> +template<typename T>
> +void bar (const T& t)
> +{
> + get<int>(t);
> +}
> +
> +int
> +main ()
> +{
> + auto a = M::foo ();
> + get<int>(a);
> + bar (a);
> +}
> diff --git a/gcc/testsuite/g++.dg/cpp2a/fn-template22.C b/gcc/testsuite/g++.dg/cpp2a/fn-template22.C
> new file mode 100644
> index 00000000000..62cc81db0c7
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/fn-template22.C
> @@ -0,0 +1,25 @@
> +// PR c++/97010
> +// { dg-do compile { target c++20 } }
> +
> +namespace M {
> + struct S { int x; };
> + S foo ();
> +
> +// Test not-found-by-ADL scenario.
> +// template<typename>
> +// void get (S);
> +}
> +
> +template<typename T>
> +void bar (const T& t)
> +{
> + get<int>(t); // { dg-error ".get. was not declared in this scope" }
> +}
> +
> +int
> +main ()
> +{
> + auto a = M::foo ();
> + get<int>(a); // { dg-error ".get. was not declared in this scope" }
> + bar (a);
> +}
>
> base-commit: af47a2035a4882e6d4506e3d00b5a42414e3ee2b
>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2020-09-10 22:15 [PATCH] c++: Fix P0846 (ADL and function templates) in template [PR97010] Marek Polacek
2020-09-18 20:05 ` Marek Polacek
2020-09-29 20:24 ` Marek Polacek
2020-10-07 21:07 ` Jason Merrill
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