From: Patrick Palka <ppalka@redhat.com>
Date: Mon, 8 May 2023 13:03:35 +0000 (-0400)
Subject: c++: list CTAD and resolve_nondeduced_context [PR106214]
X-Git-Tag: basepoints/gcc-15~9561
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=06ef1583d68169d1a002f5e86189462bb748963c;p=thirdparty%2Fgcc.git

c++: list CTAD and resolve_nondeduced_context [PR106214]

This extends the PR93107 fix, which made us do resolve_nondeduced_context
on the elements of an initializer list during auto deduction, to happen for
CTAD as well.

	PR c++/106214
	PR c++/93107

gcc/cp/ChangeLog:

	* pt.cc (do_auto_deduction): Move up resolve_nondeduced_context
	calls to happen before do_class_deduction.  Add some
	error_mark_node tests.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp1z/class-deduction114.C: New test.
---

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index d400b9f3eb25..696df2bdd9f7 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -30784,7 +30784,7 @@ do_auto_deduction (tree type, tree init, tree auto_node,
 		   int flags /* = LOOKUP_NORMAL */,
 		   tree tmpl /* = NULL_TREE */)
 {
-  if (init == error_mark_node)
+  if (type == error_mark_node || init == error_mark_node)
     return error_mark_node;
 
   if (init && type_dependent_expression_p (init)
@@ -30801,6 +30801,17 @@ do_auto_deduction (tree type, tree init, tree auto_node,
      auto_node.  */
   complain &= ~tf_partial;
 
+  if (init && BRACE_ENCLOSED_INITIALIZER_P (init))
+    {
+      /* We don't recurse here because we can't deduce from a nested
+	 initializer_list.  */
+      if (CONSTRUCTOR_ELTS (init))
+	for (constructor_elt &elt : CONSTRUCTOR_ELTS (init))
+	  elt.value = resolve_nondeduced_context (elt.value, complain);
+    }
+  else if (init)
+    init = resolve_nondeduced_context (init, complain);
+
   /* In C++23, we must deduce the type to int&& for code like
        decltype(auto) f(int&& x) { return (x); }
      or
@@ -30852,24 +30863,12 @@ do_auto_deduction (tree type, tree init, tree auto_node,
 	}
     }
 
-  if (type == error_mark_node)
+  if (type == error_mark_node || init == error_mark_node)
     return error_mark_node;
 
-  if (BRACE_ENCLOSED_INITIALIZER_P (init))
-    {
-      /* We don't recurse here because we can't deduce from a nested
-	 initializer_list.  */
-      if (CONSTRUCTOR_ELTS (init))
-	for (constructor_elt &elt : CONSTRUCTOR_ELTS (init))
-	  elt.value = resolve_nondeduced_context (elt.value, complain);
-    }
-  else
-    init = resolve_nondeduced_context (init, complain);
-
   tree targs;
   if (context == adc_decomp_type
       && auto_node == type
-      && init != error_mark_node
       && TREE_CODE (TREE_TYPE (init)) == ARRAY_TYPE)
     {
       /* [dcl.struct.bind]/1 - if decomposition declaration has no ref-qualifiers
diff --git a/gcc/testsuite/g++.dg/cpp1z/class-deduction114.C b/gcc/testsuite/g++.dg/cpp1z/class-deduction114.C
new file mode 100644
index 000000000000..daf30f8d158e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction114.C
@@ -0,0 +1,28 @@
+// PR c++/106214
+// { dg-do compile { target c++17 } }
+// A version of cpp0x/initlist-deduce3.C using list CTAD instead
+// of ordinary auto deduction from an initializer list.
+
+using size_t = decltype(sizeof 0);
+
+namespace std {
+  template<typename T> struct initializer_list {
+    const T *ptr;
+    size_t n;
+    initializer_list(const T*, size_t);
+  };
+}
+
+template<typename T>
+void Task() {}
+
+template<class T>
+struct vector {
+  vector(std::initializer_list<T>);
+};
+
+vector a = &Task<int>; // { dg-error "deduction|no match" }
+vector b = { &Task<int> };
+vector e{ &Task<int> };
+vector f = { &Task<int>, &Task<int> };
+vector d = { static_cast<void(*)()>(&Task<int>) };