[gcc/devel/rust/master] gccrs const folding port: continue porting potential_constant_expression_1()

[Thomas Schwinge <tschwinge@gcc.gnu.org>]

https://gcc.gnu.org/g:a5b583d021a4cbbfafecc28445709afe32cdd1c8

commit a5b583d021a4cbbfafecc28445709afe32cdd1c8
Author: Faisal Abbas <90.abbasfaisal@gmail.com>
Date:   Mon Jul 11 15:59:56 2022 +0100

    gccrs const folding port: continue porting potential_constant_expression_1()
    
    Following functions are ported in this changeset:
     - next_initializable_field
     - sufficient_parms_p
     - default_ctor_p
     - user_provided_p
     - type_has_non_user_provided_default_constructor
     - default_init_uninitialized_part
     - extract_conversion_operator
     - get_class_binding_direct
     - lang_check_failed
     - skip_artificial_parms_for
     - in_class_defaulted_default_constructor
     - is_instantiation_of_constexpr
     - check_for_uninitialized_const_var
    
    Signed-off-by: Faisal Abbas <90.abbasfaisal@gmail.com>

Diff:
---
 gcc/rust/backend/rust-tree.cc | 362 ++++++++++++++++++++++++++++++++++++++++--
 gcc/rust/backend/rust-tree.h  | 161 ++++++++++++++++++-
 2 files changed, 506 insertions(+), 17 deletions(-)

diff --git a/gcc/rust/backend/rust-tree.cc b/gcc/rust/backend/rust-tree.cc
index 4439dea251e..52dae395973 100644
--- a/gcc/rust/backend/rust-tree.cc
+++ b/gcc/rust/backend/rust-tree.cc
@@ -23,6 +23,9 @@
 #include "escaped_string.h"
 #include "libiberty.h"
 #include "stor-layout.h"
+#include "hash-map.h"
+#include "diagnostic.h"
+#include "timevar.h"
 
 namespace Rust {
 
@@ -1134,9 +1137,7 @@ ovl_make (tree fn, tree next)
   if (TREE_CODE (fn) == OVERLOAD)
     OVL_NESTED_P (result) = true;
 
-  TREE_TYPE (result)
-    = (next || TREE_CODE (fn) == TEMPLATE_DECL ? unknown_type_node
-					       : TREE_TYPE (fn));
+  TREE_TYPE (result) = (next ? unknown_type_node : TREE_TYPE (fn));
   if (next && TREE_CODE (next) == OVERLOAD && OVL_DEDUP_P (next))
     OVL_DEDUP_P (result) = true;
   OVL_FUNCTION (result) = fn;
@@ -1154,13 +1155,7 @@ lookup_add (tree fns, tree lookup)
   if (fns == error_mark_node || lookup == error_mark_node)
     return error_mark_node;
 
-  if (lookup || TREE_CODE (fns) == TEMPLATE_DECL)
-    {
-      lookup = ovl_make (fns, lookup);
-      OVL_LOOKUP_P (lookup) = true;
-    }
-  else
-    lookup = fns;
+  lookup = fns;
 
   return lookup;
 }
@@ -1655,10 +1650,6 @@ called_fns_equal (tree t1, tree t2)
 	      != DECL_CONTEXT (get_first_fn (t2))))
 	return false;
 
-      if (TREE_CODE (t1) == TEMPLATE_ID_EXPR)
-	targs1 = TREE_OPERAND (t1, 1);
-      if (TREE_CODE (t2) == TEMPLATE_ID_EXPR)
-	targs2 = TREE_OPERAND (t2, 1);
       return rs_tree_equal (targs1, targs2);
     }
   else
@@ -2421,7 +2412,6 @@ rs_build_qualified_type_real (tree type, int type_quals,
   /* A restrict-qualified type must be a pointer (or reference)
      to object or incomplete type. */
   if ((type_quals & TYPE_QUAL_RESTRICT)
-      && TREE_CODE (type) != TEMPLATE_TYPE_PARM
       && TREE_CODE (type) != TYPENAME_TYPE && !INDIRECT_TYPE_P (type))
     {
       bad_quals |= TYPE_QUAL_RESTRICT;
@@ -2822,4 +2812,346 @@ comptypes (tree t1, tree t2, int strict)
     return structural_comptypes (t1, t2, strict);
 }
 
+// forked from gcc/cp/decl.cc next_initializable_field
+
+/* FIELD is an element of TYPE_FIELDS or NULL.  In the former case, the value
+   returned is the next FIELD_DECL (possibly FIELD itself) that can be
+   initialized.  If there are no more such fields, the return value
+   will be NULL.  */
+
+tree
+next_initializable_field (tree field)
+{
+  while (field
+	 && (TREE_CODE (field) != FIELD_DECL || DECL_UNNAMED_BIT_FIELD (field)
+	     || (DECL_ARTIFICIAL (field)
+		 /* Don't skip vptr fields.  We might see them when we're
+		    called from reduced_constant_expression_p.  */
+		 && !DECL_VIRTUAL_P (field))))
+    field = DECL_CHAIN (field);
+
+  return field;
+}
+
+// forked from gcc/cp/call.cc sufficient_parms_p
+
+/* Returns nonzero if PARMLIST consists of only default parms,
+   ellipsis, and/or undeduced parameter packs.  */
+
+bool
+sufficient_parms_p (const_tree parmlist)
+{
+  for (; parmlist && parmlist != void_list_node;
+       parmlist = TREE_CHAIN (parmlist))
+    if (!TREE_PURPOSE (parmlist))
+      return false;
+  return true;
+}
+
+// forked from gcc/cp/class.cc default_ctor_p
+
+/* Returns true if FN is a default constructor.  */
+
+bool
+default_ctor_p (const_tree fn)
+{
+  return (DECL_CONSTRUCTOR_P (fn)
+	  && sufficient_parms_p (FUNCTION_FIRST_USER_PARMTYPE (fn)));
+}
+
+// forked from gcc/cp/class.cc user_provided_p
+
+/* Returns true iff FN is a user-provided function, i.e. user-declared
+   and not defaulted at its first declaration.  */
+
+bool
+user_provided_p (tree fn)
+{
+  return (!DECL_ARTIFICIAL (fn)
+	  && !(DECL_INITIALIZED_IN_CLASS_P (fn)
+	       && (DECL_DEFAULTED_FN (fn) || DECL_DELETED_FN (fn))));
+}
+
+// forked from gcc/cp/class.cc type_has_non_user_provided_default_constructor
+
+/* Returns true iff class T has a non-user-provided (i.e. implicitly
+   declared or explicitly defaulted in the class body) default
+   constructor.  */
+
+bool
+type_has_non_user_provided_default_constructor (tree t)
+{
+  if (!TYPE_HAS_DEFAULT_CONSTRUCTOR (t))
+    return false;
+  if (CLASSTYPE_LAZY_DEFAULT_CTOR (t))
+    return true;
+
+  for (ovl_iterator iter (CLASSTYPE_CONSTRUCTORS (t)); iter; ++iter)
+    {
+      tree fn = *iter;
+      if (TREE_CODE (fn) == FUNCTION_DECL && default_ctor_p (fn)
+	  && !user_provided_p (fn))
+	return true;
+    }
+
+  return false;
+}
+
+// forked from gcc/cp/class.cc default_init_uninitialized_part
+
+/* If default-initialization leaves part of TYPE uninitialized, returns
+   a DECL for the field or TYPE itself (DR 253).  */
+
+tree
+default_init_uninitialized_part (tree type)
+{
+  tree t, r, binfo;
+  int i;
+
+  type = strip_array_types (type);
+  if (!CLASS_TYPE_P (type))
+    return type;
+  if (!type_has_non_user_provided_default_constructor (type))
+    return NULL_TREE;
+  for (binfo = TYPE_BINFO (type), i = 0; BINFO_BASE_ITERATE (binfo, i, t); ++i)
+    {
+      r = default_init_uninitialized_part (BINFO_TYPE (t));
+      if (r)
+	return r;
+    }
+  for (t = next_initializable_field (TYPE_FIELDS (type)); t;
+       t = next_initializable_field (DECL_CHAIN (t)))
+    if (!DECL_INITIAL (t) && !DECL_ARTIFICIAL (t))
+      {
+	r = default_init_uninitialized_part (TREE_TYPE (t));
+	if (r)
+	  return DECL_P (r) ? r : t;
+      }
+
+  return NULL_TREE;
+}
+
+// forked from gcc/cp/name-lookup.cc extract_conversion_operator
+
+/* FNS is an overload set of conversion functions.  Return the
+   overloads converting to TYPE.  */
+
+static tree
+extract_conversion_operator (tree fns, tree type)
+{
+  tree convs = NULL_TREE;
+  tree tpls = NULL_TREE;
+
+  for (ovl_iterator iter (fns); iter; ++iter)
+    {
+      if (same_type_p (DECL_CONV_FN_TYPE (*iter), type))
+	convs = lookup_add (*iter, convs);
+    }
+
+  if (!convs)
+    convs = tpls;
+
+  return convs;
+}
+
+// forked from gcc/cp/name-lookup.cc
+
+/* Look for NAME as an immediate member of KLASS (including
+   anon-members or unscoped enum member).  TYPE_OR_FNS is zero for
+   regular search.  >0 to get a type binding (if there is one) and <0
+   if you want (just) the member function binding.
+
+   Use this if you do not want lazy member creation.  */
+
+tree
+get_class_binding_direct (tree klass, tree name, bool want_type)
+{
+  gcc_checking_assert (RECORD_OR_UNION_TYPE_P (klass));
+
+  /* Conversion operators can only be found by the marker conversion
+     operator name.  */
+  bool conv_op = IDENTIFIER_CONV_OP_P (name);
+  tree lookup = conv_op ? conv_op_identifier : name;
+  tree val = NULL_TREE;
+  vec<tree, va_gc> *member_vec = CLASSTYPE_MEMBER_VEC (klass);
+
+  if (COMPLETE_TYPE_P (klass) && member_vec)
+    {
+      val = member_vec_binary_search (member_vec, lookup);
+      if (!val)
+	;
+      else if (STAT_HACK_P (val))
+	val = want_type ? STAT_TYPE (val) : STAT_DECL (val);
+      else if (want_type && !DECL_DECLARES_TYPE_P (val))
+	val = NULL_TREE;
+    }
+  else
+    {
+      if (member_vec && !want_type)
+	val = member_vec_linear_search (member_vec, lookup);
+
+      if (!val || (TREE_CODE (val) == OVERLOAD && OVL_DEDUP_P (val)))
+	/* Dependent using declarations are a 'field', make sure we
+	   return that even if we saw an overload already.  */
+	if (tree field_val = fields_linear_search (klass, lookup, want_type))
+	  {
+	    if (!val)
+	      val = field_val;
+	    else if (TREE_CODE (field_val) == USING_DECL)
+	      val = ovl_make (field_val, val);
+	  }
+    }
+
+  /* Extract the conversion operators asked for, unless the general
+     conversion operator was requested.   */
+  if (val && conv_op)
+    {
+      gcc_checking_assert (OVL_FUNCTION (val) == conv_op_marker);
+      val = OVL_CHAIN (val);
+      if (tree type = TREE_TYPE (name))
+	val = extract_conversion_operator (val, type);
+    }
+
+  return val;
+}
+
+#if defined ENABLE_TREE_CHECKING
+
+// forked from gcc/cp/tree.cc lang_check_failed
+
+/* Complain that some language-specific thing hanging off a tree
+   node has been accessed improperly.  */
+
+void
+lang_check_failed (const char *file, int line, const char *function)
+{
+  internal_error ("%<lang_*%> check: failed in %s, at %s:%d", function,
+		  trim_filename (file), line);
+}
+#endif /* ENABLE_TREE_CHECKING */
+
+// forked from gcc/cp/tree.cc skip_artificial_parms_for
+
+/* Given a FUNCTION_DECL FN and a chain LIST, skip as many elements of LIST
+   as there are artificial parms in FN.  */
+
+tree
+skip_artificial_parms_for (const_tree fn, tree list)
+{
+  if (DECL_NONSTATIC_MEMBER_FUNCTION_P (fn))
+    list = TREE_CHAIN (list);
+  else
+    return list;
+
+  if (DECL_HAS_IN_CHARGE_PARM_P (fn))
+    list = TREE_CHAIN (list);
+  if (DECL_HAS_VTT_PARM_P (fn))
+    list = TREE_CHAIN (list);
+  return list;
+}
+
+// forked from gcc/cp/class.cc in_class_defaulted_default_constructor
+
+/* Returns the defaulted constructor if T has one. Otherwise, returns
+   NULL_TREE.  */
+
+tree
+in_class_defaulted_default_constructor (tree t)
+{
+  if (!TYPE_HAS_USER_CONSTRUCTOR (t))
+    return NULL_TREE;
+
+  for (ovl_iterator iter (CLASSTYPE_CONSTRUCTORS (t)); iter; ++iter)
+    {
+      tree fn = *iter;
+
+      if (DECL_DEFAULTED_IN_CLASS_P (fn) && default_ctor_p (fn))
+	return fn;
+    }
+
+  return NULL_TREE;
+}
+
+// forked from gcc/cp/constexpr.cc
+
+/* Returns true iff FUN is an instantiation of a constexpr function
+   template or a defaulted constexpr function.  */
+
+bool
+is_instantiation_of_constexpr (tree fun)
+{
+  return ((DECL_DEFAULTED_FN (fun) && DECL_DECLARED_CONSTEXPR_P (fun)));
+}
+
+// forked from gcc/cp/decl.cc check_for_uninitialized_const_var
+
+/* Issue an error message if DECL is an uninitialized const variable.
+   CONSTEXPR_CONTEXT_P is true when the function is called in a constexpr
+   context from potential_constant_expression.  Returns true if all is well,
+   false otherwise.  */
+
+bool
+check_for_uninitialized_const_var (tree decl, bool constexpr_context_p,
+				   tsubst_flags_t complain)
+{
+  tree type = strip_array_types (TREE_TYPE (decl));
+
+  /* ``Unless explicitly declared extern, a const object does not have
+     external linkage and must be initialized. ($8.4; $12.1)'' ARM
+     7.1.6 */
+  if (VAR_P (decl) && !TYPE_REF_P (type) && (RS_TYPE_CONST_P (type))
+      && !DECL_NONTRIVIALLY_INITIALIZED_P (decl))
+    {
+      tree field = default_init_uninitialized_part (type);
+      if (!field)
+	return true;
+
+      bool show_notes = true;
+
+      if (!constexpr_context_p)
+	{
+	  if (RS_TYPE_CONST_P (type))
+	    {
+	      if (complain & tf_error)
+		show_notes = permerror (DECL_SOURCE_LOCATION (decl),
+					"uninitialized %<const %D%>", decl);
+	    }
+	  else
+	    {
+	      if (!is_instantiation_of_constexpr (current_function_decl)
+		  && (complain & tf_error))
+		error_at (DECL_SOURCE_LOCATION (decl),
+			  "uninitialized variable %qD in %<constexpr%> "
+			  "function",
+			  decl);
+	      else
+		show_notes = false;
+	    }
+	}
+      else if (complain & tf_error)
+	error_at (DECL_SOURCE_LOCATION (decl),
+		  "uninitialized variable %qD in %<constexpr%> context", decl);
+
+      if (show_notes && CLASS_TYPE_P (type) && (complain & tf_error))
+	{
+	  tree defaulted_ctor;
+
+	  inform (DECL_SOURCE_LOCATION (TYPE_MAIN_DECL (type)),
+		  "%q#T has no user-provided default constructor", type);
+	  defaulted_ctor = in_class_defaulted_default_constructor (type);
+	  if (defaulted_ctor)
+	    inform (DECL_SOURCE_LOCATION (defaulted_ctor),
+		    "constructor is not user-provided because it is "
+		    "explicitly defaulted in the class body");
+	  inform (DECL_SOURCE_LOCATION (field),
+		  "and the implicitly-defined constructor does not "
+		  "initialize %q#D",
+		  field);
+	}
+
+      return false;
+    }
+
+  return true;
+}
 } // namespace Rust
diff --git a/gcc/rust/backend/rust-tree.h b/gcc/rust/backend/rust-tree.h
index d5cc3186811..b838e402c32 100644
--- a/gcc/rust/backend/rust-tree.h
+++ b/gcc/rust/backend/rust-tree.h
@@ -763,8 +763,6 @@ extern GTY (()) tree cp_global_trees[CPTI_MAX];
    level 2.  */
 #define DECL_PARM_LEVEL(NODE) (LANG_DECL_PARM_CHECK (NODE)->level)
 
-#define LANG_DECL_PARM_CHECK(NODE) (&DECL_LANG_SPECIFIC (NODE)->u.parm)
-
 /* These flags are used by the conversion code.
    CONV_IMPLICIT   :  Perform implicit conversions (standard and user-defined).
    CONV_STATIC     :  Perform the explicit conversions for static_cast.
@@ -845,6 +843,133 @@ extern GTY (()) tree cp_global_trees[CPTI_MAX];
 /* Returns true if NODE is a pointer-to-data-member.  */
 #define TYPE_PTRDATAMEM_P(NODE) (TREE_CODE (NODE) == OFFSET_TYPE)
 
+/* Nonzero if this type is const-qualified.  */
+#define RS_TYPE_CONST_P(NODE) ((rs_type_quals (NODE) & TYPE_QUAL_CONST) != 0)
+
+/* The _DECL for this _TYPE.  */
+#define TYPE_MAIN_DECL(NODE) (TYPE_STUB_DECL (TYPE_MAIN_VARIANT (NODE)))
+
+/* Nonzero for a VAR_DECL iff an explicit initializer was provided
+   or a non-trivial constructor is called.  */
+#define DECL_NONTRIVIALLY_INITIALIZED_P(NODE)                                  \
+  (TREE_LANG_FLAG_6 (VAR_DECL_CHECK (NODE)))
+
+/* Nonzero if DECL was declared with '= default' (maybe implicitly).  */
+#define DECL_DEFAULTED_FN(DECL) (LANG_DECL_FN_CHECK (DECL)->defaulted_p)
+
+/* Nonzero for a class type means that the class type has a
+   user-declared constructor.  */
+#define TYPE_HAS_USER_CONSTRUCTOR(NODE) (TYPE_LANG_FLAG_1 (NODE))
+
+/* A FUNCTION_DECL or OVERLOAD for the constructors for NODE.  These
+   are the constructors that take an in-charge parameter.  */
+#define CLASSTYPE_CONSTRUCTORS(NODE)                                           \
+  (get_class_binding_direct (NODE, ctor_identifier))
+
+/* Nonzero if the DECL was initialized in the class definition itself,
+   rather than outside the class.  This is used for both static member
+   VAR_DECLS, and FUNCTION_DECLS that are defined in the class.  */
+#define DECL_INITIALIZED_IN_CLASS_P(DECL)                                      \
+  (DECL_LANG_SPECIFIC (VAR_OR_FUNCTION_DECL_CHECK (DECL))                      \
+     ->u.base.initialized_in_class)
+
+/* Nonzero if DECL is explicitly defaulted in the class body.  */
+#define DECL_DEFAULTED_IN_CLASS_P(DECL)                                        \
+  (DECL_DEFAULTED_FN (DECL) && DECL_INITIALIZED_IN_CLASS_P (DECL))
+
+/* Nonzero for FUNCTION_DECL means that this decl is a non-static
+   member function.  */
+#define DECL_NONSTATIC_MEMBER_FUNCTION_P(NODE)                                 \
+  (TREE_CODE (TREE_TYPE (NODE)) == METHOD_TYPE)
+
+/* For FUNCTION_DECLs: nonzero means that this function is a
+   constructor or a destructor with an extra in-charge parameter to
+   control whether or not virtual bases are constructed.  */
+#define DECL_HAS_IN_CHARGE_PARM_P(NODE)                                        \
+  (LANG_DECL_FN_CHECK (NODE)->has_in_charge_parm_p)
+
+/* Nonzero if the VTT parm has been added to NODE.  */
+#define DECL_HAS_VTT_PARM_P(NODE) (LANG_DECL_FN_CHECK (NODE)->has_vtt_parm_p)
+
+/* Given a FUNCTION_DECL, returns the first TREE_LIST out of TYPE_ARG_TYPES
+   which refers to a user-written parameter.  */
+#define FUNCTION_FIRST_USER_PARMTYPE(NODE)                                     \
+  skip_artificial_parms_for ((NODE), TYPE_ARG_TYPES (TREE_TYPE (NODE)))
+
+/* Similarly, but for DECL_ARGUMENTS.  */
+#define FUNCTION_FIRST_USER_PARM(NODE)                                         \
+  skip_artificial_parms_for ((NODE), DECL_ARGUMENTS (NODE))
+
+/* For FUNCTION_DECLs and TEMPLATE_DECLs: nonzero means that this function
+   is a constructor.  */
+#define DECL_CONSTRUCTOR_P(NODE) DECL_CXX_CONSTRUCTOR_P (NODE)
+
+/* Nonzero if DECL was declared with '= delete'.  */
+#define DECL_DELETED_FN(DECL)                                                  \
+  (LANG_DECL_FN_CHECK (DECL)->min.base.threadprivate_or_deleted_p)
+
+/* Nonzero if DECL was declared with '= default' (maybe implicitly).  */
+#define DECL_DEFAULTED_FN(DECL) (LANG_DECL_FN_CHECK (DECL)->defaulted_p)
+
+#if defined ENABLE_TREE_CHECKING
+
+#define LANG_DECL_MIN_CHECK(NODE)                                              \
+  __extension__({                                                              \
+    struct lang_decl *lt = DECL_LANG_SPECIFIC (NODE);                          \
+    if (!LANG_DECL_HAS_MIN (NODE))                                             \
+      lang_check_failed (__FILE__, __LINE__, __FUNCTION__);                    \
+    &lt->u.min;                                                                \
+  })
+
+/* We want to be able to check DECL_CONSTRUCTOR_P and such on a function
+   template, not just on a FUNCTION_DECL.  So when looking for things in
+   lang_decl_fn, look down through a TEMPLATE_DECL into its result.  */
+#define LANG_DECL_FN_CHECK(NODE)                                               \
+  __extension__({                                                              \
+    struct lang_decl *lt = DECL_LANG_SPECIFIC (NODE);                          \
+    if (!DECL_DECLARES_FUNCTION_P (NODE) || lt->u.base.selector != lds_fn)     \
+      lang_check_failed (__FILE__, __LINE__, __FUNCTION__);                    \
+    &lt->u.fn;                                                                 \
+  })
+
+#define LANG_DECL_NS_CHECK(NODE)                                               \
+  __extension__({                                                              \
+    struct lang_decl *lt = DECL_LANG_SPECIFIC (NODE);                          \
+    if (TREE_CODE (NODE) != NAMESPACE_DECL || lt->u.base.selector != lds_ns)   \
+      lang_check_failed (__FILE__, __LINE__, __FUNCTION__);                    \
+    &lt->u.ns;                                                                 \
+  })
+
+#define LANG_DECL_PARM_CHECK(NODE)                                             \
+  __extension__({                                                              \
+    struct lang_decl *lt = DECL_LANG_SPECIFIC (NODE);                          \
+    if (TREE_CODE (NODE) != PARM_DECL || lt->u.base.selector != lds_parm)      \
+      lang_check_failed (__FILE__, __LINE__, __FUNCTION__);                    \
+    &lt->u.parm;                                                               \
+  })
+
+#define LANG_DECL_DECOMP_CHECK(NODE)                                           \
+  __extension__({                                                              \
+    struct lang_decl *lt = DECL_LANG_SPECIFIC (NODE);                          \
+    if (!VAR_P (NODE) || lt->u.base.selector != lds_decomp)                    \
+      lang_check_failed (__FILE__, __LINE__, __FUNCTION__);                    \
+    &lt->u.decomp;                                                             \
+  })
+
+#else
+
+#define LANG_DECL_MIN_CHECK(NODE) (&DECL_LANG_SPECIFIC (NODE)->u.min)
+
+#define LANG_DECL_FN_CHECK(NODE) (&DECL_LANG_SPECIFIC (NODE)->u.fn)
+
+#define LANG_DECL_NS_CHECK(NODE) (&DECL_LANG_SPECIFIC (NODE)->u.ns)
+
+#define LANG_DECL_PARM_CHECK(NODE) (&DECL_LANG_SPECIFIC (NODE)->u.parm)
+
+#define LANG_DECL_DECOMP_CHECK(NODE) (&DECL_LANG_SPECIFIC (NODE)->u.decomp)
+
+#endif /* ENABLE_TREE_CHECKING */
+
 // Below macros are copied from gcc/c-family/c-common.h
 
 /* In a FIELD_DECL, nonzero if the decl was originally a bitfield.  */
@@ -1744,6 +1869,38 @@ extern bool same_type_ignoring_top_level_qualifiers_p (tree, tree);
 
 extern bool comp_ptr_ttypes_const		(tree, tree, compare_bounds_t);
 
+extern tree
+get_class_binding_direct (tree, tree, bool want_type = false);
+
+extern tree skip_artificial_parms_for (const_tree, tree);
+
+extern void
+lang_check_failed (const char *, int,
+		   const char *) ATTRIBUTE_NORETURN ATTRIBUTE_COLD;
+
+extern tree default_init_uninitialized_part (tree);
+
+extern bool type_has_non_user_provided_default_constructor (tree);
+
+extern bool default_ctor_p (const_tree);
+
+extern bool user_provided_p (tree);
+
+extern bool sufficient_parms_p (const_tree);
+
+extern tree next_initializable_field (tree);
+
+extern tree in_class_defaulted_default_constructor (tree);
+
+extern bool is_instantiation_of_constexpr (tree);
+
+extern bool
+check_for_uninitialized_const_var (tree, bool, tsubst_flags_t);
+
+extern bool reduced_constant_expression_p (tree);
+
+extern tree cv_unqualified (tree);
+
 // forked from gcc/cp/cp-tree.h
 
 enum