PR c++/30897
[official-gcc.git] / gcc / c-convert.c
blob8fa68a190b6032161d09e2a7ded9847a8e23e885
1 /* Language-level data type conversion for GNU C.
2 Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2004, 2005, 2007
3 Free Software Foundation, Inc.
5 This file is part of GCC.
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 3, or (at your option) any later
10 version.
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.
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
22 /* This file contains the functions for converting C expressions
23 to different data types. The only entry point is `convert'.
24 Every language front end must have a `convert' function
25 but what kind of conversions it does will depend on the language. */
27 #include "config.h"
28 #include "system.h"
29 #include "coretypes.h"
30 #include "tm.h"
31 #include "tree.h"
32 #include "flags.h"
33 #include "convert.h"
34 #include "c-common.h"
35 #include "c-tree.h"
36 #include "langhooks.h"
37 #include "toplev.h"
38 #include "target.h"
40 /* Change of width--truncation and extension of integers or reals--
41 is represented with NOP_EXPR. Proper functioning of many things
42 assumes that no other conversions can be NOP_EXPRs.
44 Conversion between integer and pointer is represented with CONVERT_EXPR.
45 Converting integer to real uses FLOAT_EXPR
46 and real to integer uses FIX_TRUNC_EXPR.
48 Here is a list of all the functions that assume that widening and
49 narrowing is always done with a NOP_EXPR:
50 In convert.c, convert_to_integer.
51 In c-typeck.c, build_binary_op (boolean ops), and
52 c_common_truthvalue_conversion.
53 In expr.c: expand_expr, for operands of a MULT_EXPR.
54 In fold-const.c: fold.
55 In tree.c: get_narrower and get_unwidened. */
57 /* Subroutines of `convert'. */
61 /* Create an expression whose value is that of EXPR,
62 converted to type TYPE. The TREE_TYPE of the value
63 is always TYPE. This function implements all reasonable
64 conversions; callers should filter out those that are
65 not permitted by the language being compiled. */
67 tree
68 convert (tree type, tree expr)
70 tree e = expr;
71 enum tree_code code = TREE_CODE (type);
72 const char *invalid_conv_diag;
74 if (type == error_mark_node
75 || expr == error_mark_node
76 || TREE_TYPE (expr) == error_mark_node)
77 return error_mark_node;
79 if ((invalid_conv_diag
80 = targetm.invalid_conversion (TREE_TYPE (expr), type)))
82 error (invalid_conv_diag);
83 return error_mark_node;
86 if (type == TREE_TYPE (expr))
87 return expr;
89 if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)))
90 return fold_convert (type, expr);
91 if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
92 return error_mark_node;
93 if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE)
95 error ("void value not ignored as it ought to be");
96 return error_mark_node;
98 if (code == VOID_TYPE)
99 return fold_convert (type, e);
100 if (code == INTEGER_TYPE || code == ENUMERAL_TYPE)
101 return fold (convert_to_integer (type, e));
102 if (code == BOOLEAN_TYPE)
103 return fold_convert (type, c_objc_common_truthvalue_conversion (expr));
104 if (code == POINTER_TYPE || code == REFERENCE_TYPE)
105 return fold (convert_to_pointer (type, e));
106 if (code == REAL_TYPE)
107 return fold (convert_to_real (type, e));
108 if (code == FIXED_POINT_TYPE)
109 return fold (convert_to_fixed (type, e));
110 if (code == COMPLEX_TYPE)
111 return fold (convert_to_complex (type, e));
112 if (code == VECTOR_TYPE)
113 return fold (convert_to_vector (type, e));
114 if ((code == RECORD_TYPE || code == UNION_TYPE)
115 && lang_hooks.types_compatible_p (type, TREE_TYPE (expr)))
116 return e;
118 error ("conversion to non-scalar type requested");
119 return error_mark_node;