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1 ------------------------------------------------------------------------------
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2 -- --
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3 -- GNAT COMPILER COMPONENTS --
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4 -- --
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5 -- S E M _ R E S --
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6 -- --
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7 -- S p e c --
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8 -- --
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131
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9 -- Copyright (C) 1992-2018, Free Software Foundation, Inc. --
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111
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10 -- --
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11 -- GNAT is free software; you can redistribute it and/or modify it under --
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12 -- terms of the GNU General Public License as published by the Free Soft- --
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13 -- ware Foundation; either version 3, or (at your option) any later ver- --
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14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
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17 -- for more details. You should have received a copy of the GNU General --
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18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
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19 -- http://www.gnu.org/licenses for a complete copy of the license. --
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20 -- --
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21 -- GNAT was originally developed by the GNAT team at New York University. --
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22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
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23 -- --
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24 ------------------------------------------------------------------------------
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25
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26 -- Resolution processing for all subexpression nodes. Note that the separate
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27 -- package Sem_Aggr contains the actual resolution routines for aggregates,
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28 -- which are separated off since aggregate processing is complex.
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29
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30 with Types; use Types;
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31
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32 package Sem_Res is
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33
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34 -- As described in Sem_Ch4, the type resolution proceeds in two phases.
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35 -- The first phase is a bottom up pass that is achieved during the
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36 -- recursive traversal performed by the Analyze procedures. This phase
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37 -- determines unambiguous types, and collects sets of possible types
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38 -- where the interpretation is potentially ambiguous.
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39
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40 -- On completing this bottom up pass, which corresponds to a call to
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41 -- Analyze on a complete context, the Resolve routine is called which
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42 -- performs a top down resolution with recursive calls to itself to
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43 -- resolve operands.
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44
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45 -- Since in practice a lot of semantic analysis has to be postponed until
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46 -- types are known (e.g. static folding, setting of suppress flags), the
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47 -- Resolve routines also complete the semantic analysis, and call the
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48 -- expander for possible expansion of the completely type resolved node.
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49
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50 procedure Ambiguous_Character (C : Node_Id);
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51 -- Give list of candidate interpretations when a character literal cannot
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52 -- be resolved, for example in a (useless) comparison such as 'A' = 'B'.
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53 -- In Ada 95 the literals in question can be of type Character or Wide_
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54 -- Character. In Ada 2005 Wide_Wide_Character is also a candidate. The
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55 -- node may also be overloaded with user-defined character types.
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56
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57 procedure Analyze_And_Resolve (N : Node_Id);
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58 procedure Analyze_And_Resolve (N : Node_Id; Typ : Entity_Id);
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59 procedure Analyze_And_Resolve
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60 (N : Node_Id;
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61 Typ : Entity_Id;
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62 Suppress : Check_Id);
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63 procedure Analyze_And_Resolve
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64 (N : Node_Id;
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65 Suppress : Check_Id);
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66 -- These routines combine the effect of Analyze and Resolve. If a Suppress
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67 -- argument is present, then the analysis is done with the specified check
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68 -- suppressed (can be All_Checks to suppress all checks). These checks are
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69 -- suppressed for both the analysis and resolution. If the type argument
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70 -- is not present, then the Etype of the expression after the Analyze
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71 -- call is used for the Resolve.
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72
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73 procedure Check_Parameterless_Call (N : Node_Id);
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74 -- Several forms of names can denote calls to entities without parameters.
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75 -- The context determines whether the name denotes the entity or a call to
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76 -- it. When it is a call, the node must be rebuilt accordingly and
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77 -- reanalyzed to obtain possible interpretations.
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78 --
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79 -- The name may be that of an overloadable construct, or it can be an
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80 -- explicit dereference of a prefix that denotes an access to subprogram.
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81 -- In that case, we want to convert the name into a call only if the
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82 -- context requires the return type of the subprogram. Finally, a
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83 -- parameterless protected subprogram appears as a selected component.
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84 --
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85 -- The parameter T is the Typ for the corresponding resolve call.
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86
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87 procedure Preanalyze_And_Resolve (N : Node_Id; T : Entity_Id);
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131
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88 -- Performs a preanalysis of expression node N. During preanalysis, N is
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89 -- analyzed and then resolved against type T, but no expansion is carried
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131
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90 -- out for N or its children. For more info on preanalysis read the spec
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91 -- of Sem.
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92
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93 procedure Preanalyze_And_Resolve (N : Node_Id);
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94 -- Same, but use type of node because context does not impose a single type
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95
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131
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96 procedure Preanalyze_With_Freezing_And_Resolve (N : Node_Id; T : Entity_Id);
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97 -- Same, but perform freezing of static expressions of N or its children.
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98
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99 procedure Resolve (N : Node_Id; Typ : Entity_Id);
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100 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id);
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101 -- Top-level type-checking procedure, called in a complete context. The
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102 -- construct N, which is a subexpression, has already been analyzed, and
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103 -- is required to be of type Typ given the analysis of the context (which
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104 -- uses the information gathered on the bottom-up phase in Analyze). The
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105 -- resolve routines do various other processing, e.g. static evaluation.
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106 -- If a Suppress argument is present, then the resolution is done with the
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107 -- specified check suppressed (can be All_Checks to suppress all checks).
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108
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109 procedure Resolve (N : Node_Id);
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110 -- A version of Resolve where the type to be used for resolution is taken
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111 -- from the Etype (N). This is commonly used in cases where the context
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112 -- does not add anything and the first pass of analysis found the correct
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113 -- expected type.
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114
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115 procedure Resolve_Discrete_Subtype_Indication
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116 (N : Node_Id;
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117 Typ : Entity_Id);
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118 -- Resolve subtype indications in choices (case statements and aggregates)
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119 -- and in index constraints. Note that the resulting Etype of the subtype_
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120 -- indication node is set to the Etype of the contained range (i.e. an
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121 -- Itype is not constructed for the actual subtype).
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122
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123 procedure Resolve_Entry (Entry_Name : Node_Id);
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124 -- Find name of entry being called, and resolve prefix of name with its
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125 -- own type. For now we assume that the prefix cannot be overloaded and
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126 -- the name of the entry plays no role in the resolution.
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127
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128 function Valid_Conversion
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129 (N : Node_Id;
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130 Target : Entity_Id;
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131 Operand : Node_Id;
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132 Report_Errs : Boolean := True) return Boolean;
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133 -- Verify legality rules given in 4.6 (8-23). Target is the target type
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134 -- of the conversion, which may be an implicit conversion of an actual
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135 -- parameter to an anonymous access type (in which case N denotes the
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136 -- actual parameter and N = Operand). Returns a Boolean result indicating
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137 -- whether the conversion is legal. Reports errors in the case of illegal
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138 -- conversions, unless Report_Errs is False.
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139
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140 private
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141 procedure Resolve_Implicit_Type (N : Node_Id) renames Resolve;
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142 pragma Inline (Resolve_Implicit_Type);
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143 -- We use this renaming to make the application of Inline very explicit to
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144 -- this version, since other versions of Resolve are not inlined.
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145
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146 end Sem_Res;
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