gcc/cp/cp-objcp-common.c

   1 /* Some code common to C++ and ObjC++ front ends.
   2    Copyright (C) 2004 Free Software Foundation, Inc.
   3    Contributed by Ziemowit Laski  <zlaski@apple.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to the Free
  19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  20 02111-1307, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "tree.h"
  27 #include "cp-tree.h"
  28 #include "c-common.h"
  29 #include "toplev.h"
  30 #include "langhooks.h"
  31 #include "langhooks-def.h"
  32 #include "diagnostic.h"
  33 #include "debug.h"
  34 #include "cxx-pretty-print.h"
  35 #include "cp-objcp-common.h"
  36
  37 /* Special routine to get the alias set for C++.  */
  38
  39 HOST_WIDE_INT
  40 cxx_get_alias_set (tree t)
  41 {
  42   if (IS_FAKE_BASE_TYPE (t))
  43     /* The base variant of a type must be in the same alias set as the
  44        complete type.  */
  45     return get_alias_set (TYPE_CONTEXT (t));
  46
  47   /* Punt on PMFs until we canonicalize functions properly.  */
  48   if (TYPE_PTRMEMFUNC_P (t))
  49     return 0;
  50
  51   return c_common_get_alias_set (t);
  52 }
  53
  54 /* Called from check_global_declarations.  */
  55
  56 bool
  57 cxx_warn_unused_global_decl (tree decl)
  58 {
  59   if (TREE_CODE (decl) == FUNCTION_DECL && DECL_DECLARED_INLINE_P (decl))
  60     return false;
  61   if (DECL_IN_SYSTEM_HEADER (decl))
  62     return false;
  63
  64   /* Const variables take the place of #defines in C++.  */
  65   if (TREE_CODE (decl) == VAR_DECL && TREE_READONLY (decl))
  66     return false;
  67
  68   return true;
  69 }
  70
  71 /* Langhook for expr_size: Tell the backend that the value of an expression
  72    of non-POD class type does not include any tail padding; a derived class
  73    might have allocated something there.  */
  74
  75 tree
  76 cp_expr_size (tree exp)
  77 {
  78   tree type = TREE_TYPE (exp);
  79
  80   if (CLASS_TYPE_P (type))
  81     {
  82       /* The backend should not be interested in the size of an expression
  83          of a type with both of these set; all copies of such types must go
  84          through a constructor or assignment op.  */
  85       gcc_assert (!TYPE_HAS_COMPLEX_INIT_REF (type)
  86                   || !TYPE_HAS_COMPLEX_ASSIGN_REF (type)
  87                   /* But storing a CONSTRUCTOR isn't a copy.  */
  88                   || TREE_CODE (exp) == CONSTRUCTOR
  89                   /* And, the gimplifier will sometimes make a copy of
  90                      an aggregate.  In particular, for a case like:
  91
  92                         struct S { S(); };
  93                         struct X { int a; S s; };
  94                         X x = { 0 };
  95
  96                      the gimplifier will create a temporary with
  97                      static storage duration, perform static
  98                      initialization of the temporary, and then copy
  99                      the result.  Since the "s" subobject is never
 100                      constructed, this is a valid transformation.  */
 101                   || CP_AGGREGATE_TYPE_P (type));
 102
 103       /* This would be wrong for a type with virtual bases, but they are
 104          caught by the assert above.  */
 105       return (is_empty_class (type)
 106               ? size_zero_node
 107               : CLASSTYPE_SIZE_UNIT (type));
 108     }
 109   else
 110     /* Use the default code.  */
 111     return lhd_expr_size (exp);
 112 }
 113
 114 /* Langhook for tree_size: determine size of our 'x' and 'c' nodes.  */
 115 size_t
 116 cp_tree_size (enum tree_code code)
 117 {
 118   switch (code)
 119     {
 120     case TINST_LEVEL:           return sizeof (struct tinst_level_s);
 121     case PTRMEM_CST:            return sizeof (struct ptrmem_cst);
 122     case BASELINK:              return sizeof (struct tree_baselink);
 123     case TEMPLATE_PARM_INDEX:   return sizeof (template_parm_index);
 124     case DEFAULT_ARG:           return sizeof (struct tree_default_arg);
 125     case OVERLOAD:              return sizeof (struct tree_overload);
 126     default:
 127       gcc_unreachable ();
 128     }
 129   /* NOTREACHED */
 130 }
 131
 132 /* Returns true if T is a variably modified type, in the sense of C99.
 133    FN is as passed to variably_modified_p.
 134    This routine needs only check cases that cannot be handled by the
 135    language-independent logic in tree.c.  */
 136
 137 bool
 138 cp_var_mod_type_p (tree type, tree fn)
 139 {
 140   /* If TYPE is a pointer-to-member, it is variably modified if either
 141      the class or the member are variably modified.  */
 142   if (TYPE_PTR_TO_MEMBER_P (type))
 143     return (variably_modified_type_p (TYPE_PTRMEM_CLASS_TYPE (type), fn)
 144             || variably_modified_type_p (TYPE_PTRMEM_POINTED_TO_TYPE (type),
 145                                          fn));
 146
 147   /* All other types are not variably modified.  */
 148   return false;
 149 }
 150
 151 /* Construct a C++-aware pretty-printer for CONTEXT.  It is assumed
 152    that CONTEXT->printer is an already constructed basic pretty_printer.  */
 153 void
 154 cxx_initialize_diagnostics (diagnostic_context *context)
 155 {
 156   pretty_printer *base = context->printer;
 157   cxx_pretty_printer *pp = xmalloc (sizeof (cxx_pretty_printer));
 158   memcpy (pp_base (pp), base, sizeof (pretty_printer));
 159   pp_cxx_pretty_printer_init (pp);
 160   context->printer = (pretty_printer *) pp;
 161
 162   /* It is safe to free this object because it was previously malloc()'d.  */
 163   free (base);
 164 }
 165
 166 /* This compares two types for equivalence ("compatible" in C-based languages).
 167    This routine should only return 1 if it is sure.  It should not be used
 168    in contexts where erroneously returning 0 causes problems.  */
 169
 170 int
 171 cxx_types_compatible_p (tree x, tree y)
 172 {
 173   if (same_type_ignoring_top_level_qualifiers_p (x, y))
 174     return 1;
 175
 176   /* Once we get to the middle-end, references and pointers are
 177      interchangeable.  FIXME should we try to replace all references with
 178      pointers?  */
 179   if (POINTER_TYPE_P (x) && POINTER_TYPE_P (y)
 180       && TYPE_MODE (x) == TYPE_MODE (y)
 181       && TYPE_REF_CAN_ALIAS_ALL (x) == TYPE_REF_CAN_ALIAS_ALL (y)
 182       && same_type_p (TREE_TYPE (x), TREE_TYPE (y)))
 183     return 1;
 184
 185   return 0;
 186 }
 187
 188 /* Stubs to keep c-opts.c happy.  */
 189 void
 190 push_file_scope (void)
 191 {
 192 }
 193
 194 void
 195 pop_file_scope (void)
 196 {
 197 }
 198
 199 /* c-pragma.c needs to query whether a decl has extern "C" linkage.  */
 200 bool
 201 has_c_linkage (tree decl)
 202 {
 203   return DECL_EXTERN_C_P (decl);
 204 }