Here we're failing to communicate to cp_finish_decl from tsubst_expr
that we're in a copy-initialization context (via the LOOKUP_ONLYCONVERTING
flag), which causes do_class_deduction to always consider explicit
deduction guides when performing CTAD for a templated variable initializer.
We could fix this by passing LOOKUP_ONLYCONVERTING appropriately when
calling cp_finish_decl from tsubst_expr, but it seems do_class_deduction
can determine if we're in a copy-init context by simply inspecting the
initializer, and thus render its flags parameter unnecessary, which is
what this patch implements. (If we were to fix this in tsubst_expr
instead, I think we'd have to inspect the initializer in the same way
in order to detect a copy-init context?)
Bootstrapped and regtestd on x86_64-pc-linux-gnu, does this look OK for
trunk?
PR c++/102137
gcc/cp/ChangeLog:
* cp-tree.h (do_auto_deduction): Remove flags parameter.
* decl.cc (cp_finish_decl): Adjust call to do_auto_deduction.
* pt.cc (convert_template_argument): Likewise.
(do_class_deduction): Remove flags parameter and instead
determine if we're in a copy-init context by inspecting the
initializer.
(do_auto_deduction): Adjust call to do_class_deduction.
gcc/testsuite/ChangeLog:
* g++.dg/cpp1z/class-deduction108.C: New test.
---
gcc/cp/cp-tree.h | 3 +-
gcc/cp/decl.cc | 2 +-
gcc/cp/pt.cc | 23 +++++++------
.../g++.dg/cpp1z/class-deduction108.C | 32 +++++++++++++++++++
4 files changed, 48 insertions(+), 12 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/cpp1z/class-deduction108.C
diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index ac723901098..c2ef6544389 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7279,8 +7279,7 @@ extern tree do_auto_deduction (tree,
tree, tree,
= tf_warning_or_error,
auto_deduction_context
= adc_unspecified,
- tree = NULL_TREE,
- int = LOOKUP_NORMAL);
+ tree = NULL_TREE);
extern tree type_uses_auto (tree);
extern tree type_uses_auto_or_concept (tree);
extern void append_type_to_template_for_access_check (tree, tree, tree,
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 199ac768d43..152f657e9f2 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -8039,7 +8039,7 @@ cp_finish_decl (tree decl, tree init, bool
init_const_expr_p,
outer_targs = DECL_TI_ARGS (decl);
type = TREE_TYPE (decl) = do_auto_deduction (type, d_init, auto_node,
tf_warning_or_error, adc,
- outer_targs, flags);
+ outer_targs);
if (type == error_mark_node)
return;
if (TREE_CODE (type) == FUNCTION_TYPE)
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index d94d4538faa..66fc8cacdc6 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -8567,8 +8567,7 @@ convert_template_argument (tree parm,
can happen in the context of -fnew-ttp-matching. */;
else if (tree a = type_uses_auto (t))
{
- t = do_auto_deduction (t, arg, a, complain, adc_unify, args,
- LOOKUP_IMPLICIT);
+ t = do_auto_deduction (t, arg, a, complain, adc_unify, args);
if (t == error_mark_node)
return error_mark_node;
}
@@ -29832,8 +29831,7 @@ ctad_template_p (tree tmpl)
type. */
static tree
-do_class_deduction (tree ptype, tree tmpl, tree init,
- int flags, tsubst_flags_t complain)
+do_class_deduction (tree ptype, tree tmpl, tree init, tsubst_flags_t complain)
{
/* We should have handled this in the caller. */
if (DECL_TEMPLATE_TEMPLATE_PARM_P (tmpl))
@@ -29881,6 +29879,13 @@ do_class_deduction (tree ptype, tree tmpl, tree init,
if (type_dependent_expression_p (init))
return ptype;
+ bool copy_init_p = true;
+ if (!init
+ || TREE_CODE (init) == TREE_LIST
+ || (BRACE_ENCLOSED_INITIALIZER_P (init)
+ && CONSTRUCTOR_IS_DIRECT_INIT (init)))
+ copy_init_p = false;
+
tree type = TREE_TYPE (tmpl);
bool try_list_ctor = false;
@@ -29929,7 +29934,7 @@ do_class_deduction (tree ptype, tree tmpl, tree init,
/* Prune explicit deduction guides in copy-initialization context (but
not copy-list-initialization). */
bool elided = false;
- if (!list_init_p && (flags & LOOKUP_ONLYCONVERTING))
+ if (!list_init_p && copy_init_p)
{
for (lkp_iterator iter (cands); !elided && iter; ++iter)
if (DECL_NONCONVERTING_P (STRIP_TEMPLATE (*iter)))
@@ -30007,7 +30012,7 @@ do_class_deduction (tree ptype, tree tmpl, tree init,
}
/* [over.match.list]/1: In copy-list-initialization, if an explicit
constructor is chosen, the initialization is ill-formed. */
- else if (flags & LOOKUP_ONLYCONVERTING)
+ else if (copy_init_p)
{
if (DECL_NONCONVERTING_P (fndecl))
{
@@ -30045,7 +30050,7 @@ do_class_deduction (tree ptype, tree tmpl, tree init,
/* Replace occurrences of 'auto' in TYPE with the appropriate type deduced
from INIT. AUTO_NODE is the TEMPLATE_TYPE_PARM used for 'auto' in TYPE.
The CONTEXT determines the context in which auto deduction is performed
- and is used to control error diagnostics. FLAGS are the LOOKUP_* flags.
+ and is used to control error diagnostics.
OUTER_TARGS is used during template argument deduction (context ==
adc_unify)
to properly substitute the result. It's also used in the adc_unify and
@@ -30058,7 +30063,7 @@ do_class_deduction (tree ptype, tree tmpl, tree init,
tree
do_auto_deduction (tree type, tree init, tree auto_node,
tsubst_flags_t complain, auto_deduction_context context,
- tree outer_targs, int flags)
+ tree outer_targs)
{
if (init == error_mark_node)
return error_mark_node;
@@ -30079,7 +30084,7 @@ do_auto_deduction (tree type, tree init, tree auto_node,
if (tree tmpl = CLASS_PLACEHOLDER_TEMPLATE (auto_node))
/* C++17 class template argument deduction. */
- return do_class_deduction (type, tmpl, init, flags, complain);
+ return do_class_deduction (type, tmpl, init, complain);
if (init == NULL_TREE || TREE_TYPE (init) == NULL_TREE)
/* Nothing we can do with this, even in deduction context. */
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction108.C
b/gcc/testsuite/g++.dg/cpp1z/class-deduction108.C
new file mode 100644
index 00000000000..f76671c287a
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction108.C
@@ -0,0 +1,32 @@
+// PR c++/102137
+// { dg-do compile { target c++17 } }
+
+template<class T>
+struct A {
+ A();
+ A(int);
+};
+
+explicit A(int) -> A<int>;
+explicit A() -> A<int>;
+
+template<template<class> class T>
+void f() {
+ T x1 = 0; // { dg-error "deduction|no match" }
+ T x2 = {0}; // { dg-error "explicit deduction guide" }
+ T x3(0);
+ T x4{0};
+ T x5;
+}
+
+template<class T>
+void g(T t) {
+ A a1 = t; // { dg-error "deduction|no match" }
+ A a2 = {t}; // { dg-error "explicit deduction guide" }
+ A a3(t);
+ A a4{t};
+ A a5;
+}
+
+template void f<A>();
+template void g(int);
--
2.35.1.354.g715d08a9e5
