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gcc.gnu.org Git - gcc.git/blob - gcc/c-convert.c
1 /* Language-level data type conversion for GNU C.
2 Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2004, 2005
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 2, or (at your option) any later
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
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, 51 Franklin Street, Fifth Floor, Boston, MA
23 /* This file contains the functions for converting C expressions
24 to different data types. The only entry point is `convert'.
25 Every language front end must have a `convert' function
26 but what kind of conversions it does will depend on the language. */
30 #include "coretypes.h"
37 #include "langhooks.h"
41 /* Change of width--truncation and extension of integers or reals--
42 is represented with NOP_EXPR. Proper functioning of many things
43 assumes that no other conversions can be NOP_EXPRs.
45 Conversion between integer and pointer is represented with CONVERT_EXPR.
46 Converting integer to real uses FLOAT_EXPR
47 and real to integer uses FIX_TRUNC_EXPR.
49 Here is a list of all the functions that assume that widening and
50 narrowing is always done with a NOP_EXPR:
51 In convert.c, convert_to_integer.
52 In c-typeck.c, build_binary_op (boolean ops), and
53 c_common_truthvalue_conversion.
54 In expr.c: expand_expr, for operands of a MULT_EXPR.
55 In fold-const.c: fold.
56 In tree.c: get_narrower and get_unwidened. */
58 /* Subroutines of `convert'. */
62 /* Create an expression whose value is that of EXPR,
63 converted to type TYPE. The TREE_TYPE of the value
64 is always TYPE. This function implements all reasonable
65 conversions; callers should filter out those that are
66 not permitted by the language being compiled. */
69 convert (tree type
, tree expr
)
72 enum tree_code code
= TREE_CODE (type
);
73 const char *invalid_conv_diag
;
75 if (type
== error_mark_node
76 || expr
== error_mark_node
77 || TREE_TYPE (expr
) == error_mark_node
)
78 return error_mark_node
;
80 if ((invalid_conv_diag
81 = targetm
.invalid_conversion (TREE_TYPE (expr
), type
)))
83 error (invalid_conv_diag
);
84 return error_mark_node
;
87 if (type
== TREE_TYPE (expr
))
90 if (TYPE_MAIN_VARIANT (type
) == TYPE_MAIN_VARIANT (TREE_TYPE (expr
)))
91 return fold_convert (type
, expr
);
92 if (TREE_CODE (TREE_TYPE (expr
)) == ERROR_MARK
)
93 return error_mark_node
;
94 if (TREE_CODE (TREE_TYPE (expr
)) == VOID_TYPE
)
96 error ("void value not ignored as it ought to be");
97 return error_mark_node
;
99 if (code
== VOID_TYPE
)
100 return fold_convert (type
, e
);
101 if (code
== INTEGER_TYPE
|| code
== ENUMERAL_TYPE
)
102 return fold (convert_to_integer (type
, e
));
103 if (code
== BOOLEAN_TYPE
)
104 return fold_convert (type
, c_objc_common_truthvalue_conversion (expr
));
105 if (code
== POINTER_TYPE
|| code
== REFERENCE_TYPE
)
106 return fold (convert_to_pointer (type
, e
));
107 if (code
== REAL_TYPE
)
108 return fold (convert_to_real (type
, e
));
109 if (code
== COMPLEX_TYPE
)
110 return fold (convert_to_complex (type
, e
));
111 if (code
== VECTOR_TYPE
)
112 return fold (convert_to_vector (type
, e
));
113 if ((code
== RECORD_TYPE
|| code
== UNION_TYPE
)
114 && lang_hooks
.types_compatible_p (type
, TREE_TYPE (expr
)))
117 error ("conversion to non-scalar type requested");
118 return error_mark_node
;
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