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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 --
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6 -- --
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7 -- S p e c --
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8 -- --
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145
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9 -- Copyright (C) 1992-2019, 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 --------------------------------------
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27 -- Semantic Analysis: General Model --
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28 --------------------------------------
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29
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30 -- Semantic processing involves 3 phases which are highly intertwined
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31 -- (i.e. mutually recursive):
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32
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33 -- Analysis implements the bulk of semantic analysis such as
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34 -- name analysis and type resolution for declarations,
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35 -- instructions and expressions. The main routine
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36 -- driving this process is procedure Analyze given below.
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37 -- This analysis phase is really a bottom up pass that is
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38 -- achieved during the recursive traversal performed by the
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39 -- Analyze_... procedures implemented in the sem_* packages.
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40 -- For expressions this phase determines unambiguous types
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41 -- and collects sets of possible types where the
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42 -- interpretation is potentially ambiguous.
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43
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44 -- Resolution is carried out only for expressions to finish type
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45 -- resolution that was initiated but not necessarily
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46 -- completed during analysis (because of overloading
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47 -- ambiguities). Specifically, after completing the bottom
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48 -- up pass carried out during analysis for expressions, the
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49 -- Resolve routine (see the spec of sem_res for more info)
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50 -- is called to perform a top down resolution with
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51 -- recursive calls to itself to resolve operands.
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52
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53 -- Expansion if we are not generating code this phase is a no-op.
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54 -- otherwise this phase expands, i.e. transforms, original
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55 -- declaration, expressions or instructions into simpler
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56 -- structures that can be handled by the back-end. This
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57 -- phase is also in charge of generating code which is
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58 -- implicit in the original source (for instance for
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59 -- default initializations, controlled types, etc.)
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60 -- There are two separate instances where expansion is
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61 -- invoked. For declarations and instructions, expansion is
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62 -- invoked just after analysis since no resolution needs
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63 -- to be performed. For expressions, expansion is done just
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64 -- after resolution. In both cases expansion is done from the
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65 -- bottom up just before the end of Analyze for instructions
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66 -- and declarations or the call to Resolve for expressions.
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67 -- The main routine driving expansion is Expand.
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68 -- See the spec of Expander for more details.
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69
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70 -- To summarize, in normal code generation mode we recursively traverse the
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71 -- abstract syntax tree top-down performing semantic analysis bottom
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72 -- up. For instructions and declarations, before the call to the Analyze
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73 -- routine completes we perform expansion since at that point we have all
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74 -- semantic information needed. For expression nodes, after the call to
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75 -- Analysis terminates we invoke the Resolve routine to transmit top-down
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76 -- the type that was gathered by Analyze which will resolve possible
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77 -- ambiguities in the expression. Just before the call to Resolve
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78 -- terminates, the expression can be expanded since all the semantic
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79 -- information is available at that point.
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80
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81 -- If we are not generating code then the expansion phase is a no-op
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82
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83 -- When generating code there are a number of exceptions to the basic
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84 -- Analysis-Resolution-Expansion model for expressions. The most prominent
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85 -- examples are the handling of default expressions and aggregates.
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86
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87 -----------------------------------------------------------------------
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88 -- Handling of Default and Per-Object Expressions (Spec-Expressions) --
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89 -----------------------------------------------------------------------
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90
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91 -- The default expressions in component declarations and in procedure
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92 -- specifications (but not the ones in object declarations) are quite tricky
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93 -- to handle. The problem is that some processing is required at the point
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94 -- where the expression appears:
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95
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96 -- visibility analysis (including user defined operators)
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97 -- freezing of static expressions
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98
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99 -- but other processing must be deferred until the enclosing entity (record or
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100 -- procedure specification) is frozen:
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101
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102 -- freezing of any other types in the expression expansion
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103 -- generation of code
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104
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105 -- A similar situation occurs with the argument of priority and interrupt
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106 -- priority pragmas that appear in task and protected definition specs and
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107 -- other cases of per-object expressions (see RM 3.8(18)).
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108
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109 -- Another similar case is the conditions in precondition and postcondition
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110 -- pragmas that appear with subprogram specifications rather than in the body.
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111
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112 -- Collectively we call these Spec_Expressions. The routine that performs the
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113 -- special analysis is called Analyze_Spec_Expression.
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114
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115 -- Expansion has to be deferred since you can't generate code for expressions
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116 -- that reference types that have not been frozen yet. As an example, consider
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117 -- the following:
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118
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119 -- type x is delta 0.5 range -10.0 .. +10.0;
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120 -- ...
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121 -- type q is record
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122 -- xx : x := y * z;
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123 -- end record;
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124
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125 -- for x'small use 0.25;
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126
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127 -- The expander is in charge of dealing with fixed-point, and of course the
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128 -- small declaration, which is not too late, since the declaration of type q
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129 -- does *not* freeze type x, definitely affects the expanded code.
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130
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131 -- Another reason that we cannot expand early is that expansion can generate
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132 -- range checks. These range checks need to be inserted not at the point of
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133 -- definition but at the point of use. The whole point here is that the value
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134 -- of the expression cannot be obtained at the point of declaration, only at
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135 -- the point of use.
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136
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137 -- Generally our model is to combine analysis resolution and expansion, but
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138 -- this is the one case where this model falls down. Here is how we patch
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139 -- it up without causing too much distortion to our basic model.
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140
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141 -- A switch (In_Spec_Expression) is set to show that we are in the initial
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142 -- occurrence of a default expression. The analyzer is then called on this
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143 -- expression with the switch set true. Analysis and resolution proceed almost
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144 -- as usual, except that Freeze_Expression will not freeze non-static
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145 -- expressions if this switch is set, and the call to Expand at the end of
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146 -- resolution is skipped. This also skips the code that normally sets the
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147 -- Analyzed flag to True. The result is that when we are done the tree is
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148 -- still marked as unanalyzed, but all types for static expressions are frozen
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149 -- as required, and all entities of variables have been recorded. We then turn
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150 -- off the switch, and later on reanalyze the expression with the switch off.
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151 -- The effect is that this second analysis freezes the rest of the types as
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152 -- required, and generates code but visibility analysis is not repeated since
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153 -- all the entities are marked.
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154
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155 -- The second analysis (the one that generates code) is in the context
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156 -- where the code is required. For a record field default, this is in the
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157 -- initialization procedure for the record and for a subprogram default
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158 -- parameter, it is at the point the subprogram is frozen. For a priority or
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159 -- storage size pragma it is in the context of the Init_Proc for the task or
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160 -- protected object. For a pre/postcondition pragma it is in the body when
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161 -- code for the pragma is generated.
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162
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163 ------------------
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131
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164 -- Preanalysis --
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165 ------------------
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166
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167 -- For certain kind of expressions, such as aggregates, we need to defer
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168 -- expansion of the aggregate and its inner expressions until after the whole
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169 -- set of expressions appearing inside the aggregate have been analyzed.
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170 -- Consider, for instance the following example:
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171 --
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172 -- (1 .. 100 => new Thing (Function_Call))
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173 --
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174 -- The normal Analysis-Resolution-Expansion mechanism where expansion of the
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175 -- children is performed before expansion of the parent does not work if the
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176 -- code generated for the children by the expander needs to be evaluated
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177 -- repeatedly (for instance in the above aggregate "new Thing (Function_Call)"
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178 -- needs to be called 100 times.)
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179
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180 -- The reason this mechanism does not work is that the expanded code for the
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181 -- children is typically inserted above the parent and thus when the father
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182 -- gets expanded no re-evaluation takes place. For instance in the case of
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183 -- aggregates if "new Thing (Function_Call)" is expanded before the aggregate
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184 -- the expanded code will be placed outside of the aggregate and when
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185 -- expanding the aggregate the loop from 1 to 100 will not surround the
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186 -- expanded code for "new Thing (Function_Call)".
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187
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188 -- To remedy this situation we introduce a flag that signals whether we want a
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131
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189 -- full analysis (i.e. expansion is enabled) or a preanalysis which performs
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190 -- Analysis and Resolution but no expansion.
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191
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131
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192 -- After the complete preanalysis of an expression has been carried out we
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193 -- can transform the expression and then carry out the full three stage
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194 -- (Analyze-Resolve-Expand) cycle on the transformed expression top-down so
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195 -- that the expansion of inner expressions happens inside the newly generated
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196 -- node for the parent expression.
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197
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198 -- Note that the difference between processing of default expressions and
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131
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199 -- preanalysis of other expressions is that we do carry out freezing in
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200 -- the latter but not in the former (except for static scalar expressions).
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201 -- The routine that performs preanalysis and corresponding resolution is
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202 -- called Preanalyze_And_Resolve and is in Sem_Res.
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203
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204 with Alloc;
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205 with Einfo; use Einfo;
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206 with Opt; use Opt;
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207 with Table;
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208 with Types; use Types;
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209
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210 package Sem is
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211
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212 -----------------------------
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213 -- Semantic Analysis Flags --
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214 -----------------------------
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215
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216 Full_Analysis : Boolean := True;
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131
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217 -- Switch to indicate if we are doing a full analysis or a preanalysis.
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111
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218 -- In normal analysis mode (Analysis-Expansion for instructions or
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219 -- declarations) or (Analysis-Resolution-Expansion for expressions) this
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220 -- flag is set. Note that if we are not generating code the expansion phase
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221 -- merely sets the Analyzed flag to True in this case. If we are in
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131
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222 -- Preanalysis mode (see above) this flag is set to False then the
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111
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223 -- expansion phase is skipped.
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224 --
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225 -- When this flag is False the flag Expander_Active is also False (the
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226 -- Expander_Active flag defined in the spec of package Expander tells you
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227 -- whether expansion is currently enabled). You should really regard this
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228 -- as a read only flag.
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229
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230 In_Spec_Expression : Boolean := False;
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231 -- Switch to indicate that we are in a spec-expression, as described
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232 -- above. Note that this must be recursively saved on a Semantics call
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233 -- since it is possible for the analysis of an expression to result in a
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234 -- recursive call (e.g. to get the entity for System.Address as part of the
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235 -- processing of an Address attribute reference). When this switch is True
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236 -- then Full_Analysis above must be False. You should really regard this as
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237 -- a read only flag.
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238
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239 In_Deleted_Code : Boolean := False;
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240 -- If the condition in an if-statement is statically known, the branch
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241 -- that is not taken is analyzed with expansion disabled, and the tree
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242 -- is deleted after analysis. Itypes generated in deleted code must be
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243 -- frozen from start, because the tree on which they depend will not
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244 -- be available at the freeze point.
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245
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246 In_Assertion_Expr : Nat := 0;
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247 -- This is set non-zero if we are within the expression of an assertion
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248 -- pragma or aspect. It is a counter which is incremented at the start of
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249 -- expanding such an expression, and decremented on completion of expanding
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250 -- that expression. Probably a boolean would be good enough, since we think
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251 -- that such expressions cannot nest, but that might not be true in the
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252 -- future (e.g. if let expressions are added to Ada) so we prepare for that
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253 -- future possibility by making it a counter. As with In_Spec_Expression,
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254 -- it must be recursively saved and restored for a Semantics call.
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255
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256 In_Compile_Time_Warning_Or_Error : Boolean := False;
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257 -- Switch to indicate that we are validating a pragma Compile_Time_Warning
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258 -- or Compile_Time_Error after the back end has been called (to check these
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259 -- pragmas for size and alignment appropriateness).
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260
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261 In_Default_Expr : Boolean := False;
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262 -- Switch to indicate that we are analyzing a default component expression.
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263 -- As with In_Spec_Expression, it must be recursively saved and restored
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264 -- for a Semantics call.
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265
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266 In_Inlined_Body : Boolean := False;
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267 -- Switch to indicate that we are analyzing and resolving an inlined body.
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268 -- Type checking is disabled in this context, because types are known to be
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269 -- compatible. This avoids problems with private types whose full view is
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270 -- derived from private types.
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271
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272 Inside_A_Generic : Boolean := False;
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273 -- This flag is set if we are processing a generic specification, generic
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274 -- definition, or generic body. When this flag is True the Expander_Active
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275 -- flag is False to disable any code expansion (see package Expander). Only
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276 -- the generic processing can modify the status of this flag, any other
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277 -- client should regard it as read-only.
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278
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279 Inside_Freezing_Actions : Nat := 0;
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280 -- Flag indicating whether we are within a call to Expand_N_Freeze_Actions.
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281 -- Non-zero means we are inside (it is actually a level counter to deal
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282 -- with nested calls). Used to avoid traversing the tree each time a
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283 -- subprogram call is processed to know if we must not clear all constant
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284 -- indications from entities in the current scope. Only the expansion of
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285 -- freezing nodes can modify the status of this flag, any other client
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286 -- should regard it as read-only.
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287
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131
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288 Inside_Preanalysis_Without_Freezing : Nat := 0;
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289 -- Flag indicating whether we are preanalyzing an expression performing no
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290 -- freezing. Non-zero means we are inside (it is actually a level counter
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291 -- to deal with nested calls).
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292
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293 Unloaded_Subunits : Boolean := False;
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294 -- This flag is set True if we have subunits that are not loaded. This
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295 -- occurs when the main unit is a subunit, and contains lower level
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296 -- subunits that are not loaded. We use this flag to suppress warnings
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297 -- about unused variables, since these warnings are unreliable in this
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298 -- case. We could perhaps do a more accurate job and retain some of the
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299 -- warnings, but it is quite a tricky job.
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300
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301 -----------------------------------
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302 -- Handling of Check Suppression --
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303 -----------------------------------
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304
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305 -- There are two kinds of suppress checks: scope based suppress checks,
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306 -- and entity based suppress checks.
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307
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308 -- Scope based suppress checks for the predefined checks (from initial
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309 -- command line arguments, or from Suppress pragmas not including an entity
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310 -- name) are recorded in the Sem.Scope_Suppress variable, and all that
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311 -- is necessary is to save the state of this variable on scope entry, and
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312 -- restore it on scope exit. This mechanism allows for fast checking of the
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313 -- scope suppress state without needing complex data structures.
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314
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315 -- Entity based checks, from Suppress/Unsuppress pragmas giving an
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316 -- Entity_Id and scope based checks for non-predefined checks (introduced
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317 -- using pragma Check_Name), are handled as follows. If a suppress or
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318 -- unsuppress pragma is encountered for a given entity, then the flag
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319 -- Checks_May_Be_Suppressed is set in the entity and an entry is made in
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320 -- either the Local_Entity_Suppress stack (case of pragma that appears in
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321 -- other than a package spec), or in the Global_Entity_Suppress stack (case
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322 -- of pragma that appears in a package spec, which is by the rule of RM
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323 -- 11.5(7) applicable throughout the life of the entity). Similarly, a
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324 -- Suppress/Unsuppress pragma for a non-predefined check which does not
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325 -- specify an entity is also stored in one of these stacks.
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326
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327 -- If the Checks_May_Be_Suppressed flag is set in an entity then the
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328 -- procedure is to search first the local and then the global suppress
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329 -- stacks (we search these in reverse order, top element first). The only
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330 -- other point is that we have to make sure that we have proper nested
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331 -- interaction between such specific pragmas and locally applied general
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332 -- pragmas applying to all entities. This is achieved by including in the
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333 -- Local_Entity_Suppress table dummy entries with an empty Entity field
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334 -- that are applicable to all entities. A similar search is needed for any
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335 -- non-predefined check even if no specific entity is involved.
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336
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337 Scope_Suppress : Suppress_Record;
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338 -- This variable contains the current scope based settings of the suppress
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339 -- switches. It is initialized from Suppress_Options in Gnat1drv, and then
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340 -- modified by pragma Suppress. On entry to each scope, the current setting
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341 -- is saved on the scope stack, and then restored on exit from the scope.
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342 -- This record may be rapidly checked to determine the current status of
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343 -- a check if no specific entity is involved or if the specific entity
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344 -- involved is one for which no specific Suppress/Unsuppress pragma has
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345 -- been set (as indicated by the Checks_May_Be_Suppressed flag being set).
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346
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347 -- This scheme is a little complex, but serves the purpose of enabling
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348 -- a very rapid check in the common case where no entity specific pragma
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349 -- applies, and gives the right result when such pragmas are used even
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350 -- in complex cases of nested Suppress and Unsuppress pragmas.
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351
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352 -- The Local_Entity_Suppress and Global_Entity_Suppress stacks are handled
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353 -- using dynamic allocation and linked lists. We do not often use this
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354 -- approach in the compiler (preferring to use extensible tables instead).
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355 -- The reason we do it here is that scope stack entries save a pointer to
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356 -- the current local stack top, which is also saved and restored on scope
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357 -- exit. Furthermore for processing of generics we save pointers to the
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358 -- top of the stack, so that the local stack is actually a tree of stacks
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359 -- rather than a single stack, a structure that is easy to represent using
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360 -- linked lists, but impossible to represent using a single table. Note
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|
|
361 -- that because of the generic issue, we never release entries in these
|
|
|
362 -- stacks, but that's no big deal, since we are unlikely to have a huge
|
|
|
363 -- number of Suppress/Unsuppress entries in a single compilation.
|
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364
|
|
|
365 type Suppress_Stack_Entry;
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|
|
366 type Suppress_Stack_Entry_Ptr is access all Suppress_Stack_Entry;
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367
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|
368 type Suppress_Stack_Entry is record
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|
369 Entity : Entity_Id;
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|
370 -- Entity to which the check applies, or Empty for a check that has
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|
|
371 -- no entity name (and thus applies to all entities).
|
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|
372
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|
373 Check : Check_Id;
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|
374 -- Check which is set (can be All_Checks for the All_Checks case)
|
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375
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|
376 Suppress : Boolean;
|
|
|
377 -- Set True for Suppress, and False for Unsuppress
|
|
|
378
|
|
|
379 Prev : Suppress_Stack_Entry_Ptr;
|
|
|
380 -- Pointer to previous entry on stack
|
|
|
381
|
|
|
382 Next : Suppress_Stack_Entry_Ptr;
|
|
|
383 -- All allocated Suppress_Stack_Entry records are chained together in
|
|
|
384 -- a linked list whose head is Suppress_Stack_Entries, and the Next
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|
|
385 -- field is used as a forward pointer (null ends the list). This is
|
|
|
386 -- used to free all entries in Sem.Init (which will be important if
|
|
|
387 -- we ever setup the compiler to be reused).
|
|
|
388 end record;
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|
|
389
|
|
|
390 Suppress_Stack_Entries : Suppress_Stack_Entry_Ptr := null;
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|
|
391 -- Pointer to linked list of records (see comments for Next above)
|
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|
392
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|
|
393 Local_Suppress_Stack_Top : Suppress_Stack_Entry_Ptr;
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|
|
394 -- Pointer to top element of local suppress stack. This is the entry that
|
|
|
395 -- is saved and restored in the scope stack, and also saved for generic
|
|
|
396 -- body expansion.
|
|
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397
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|
|
398 Global_Suppress_Stack_Top : Suppress_Stack_Entry_Ptr;
|
|
|
399 -- Pointer to top element of global suppress stack
|
|
|
400
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|
|
401 procedure Push_Local_Suppress_Stack_Entry
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|
402 (Entity : Entity_Id;
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|
403 Check : Check_Id;
|
|
|
404 Suppress : Boolean);
|
|
|
405 -- Push a new entry on to the top of the local suppress stack, updating
|
|
|
406 -- the value in Local_Suppress_Stack_Top;
|
|
|
407
|
|
|
408 procedure Push_Global_Suppress_Stack_Entry
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|
|
409 (Entity : Entity_Id;
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|
410 Check : Check_Id;
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|
|
411 Suppress : Boolean);
|
|
|
412 -- Push a new entry on to the top of the global suppress stack, updating
|
|
|
413 -- the value in Global_Suppress_Stack_Top;
|
|
|
414
|
|
|
415 -----------------
|
|
|
416 -- Scope Stack --
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|
|
417 -----------------
|
|
|
418
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|
|
419 -- The scope stack indicates the declarative regions that are currently
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|
|
420 -- being processed (analyzed and/or expanded). The scope stack is one of
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|
|
421 -- the basic visibility structures in the compiler: entities that are
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|
|
422 -- declared in a scope that is currently on the scope stack are immediately
|
|
|
423 -- visible (leaving aside issues of hiding and overloading).
|
|
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424
|
|
|
425 -- Initially, the scope stack only contains an entry for package Standard.
|
|
|
426 -- When a compilation unit, subprogram unit, block or declarative region
|
|
|
427 -- is being processed, the corresponding entity is pushed on the scope
|
|
|
428 -- stack. It is removed after the processing step is completed. A given
|
|
|
429 -- entity can be placed several times on the scope stack, for example
|
|
|
430 -- when processing derived type declarations, freeze nodes, etc. The top
|
|
|
431 -- of the scope stack is the innermost scope currently being processed.
|
|
|
432 -- It is obtained through function Current_Scope. After a compilation unit
|
|
|
433 -- has been processed, the scope stack must contain only Standard.
|
|
|
434 -- The predicate In_Open_Scopes specifies whether a scope is currently
|
|
|
435 -- on the scope stack.
|
|
|
436
|
|
|
437 -- This model is complicated by the need to compile units on the fly, in
|
|
|
438 -- the middle of the compilation of other units. This arises when compiling
|
|
|
439 -- instantiations, and when compiling run-time packages obtained through
|
|
|
440 -- rtsfind. Given that the scope stack is a single static and global
|
|
|
441 -- structure (not originally designed for the recursive processing required
|
|
|
442 -- by rtsfind for example) additional machinery is needed to indicate what
|
|
|
443 -- is currently being compiled. As a result, the scope stack holds several
|
|
|
444 -- contiguous sections that correspond to the compilation of a given
|
|
|
445 -- compilation unit. These sections are separated by distinct occurrences
|
|
|
446 -- of package Standard. The currently active section of the scope stack
|
|
|
447 -- goes from the current scope to the first (innermost) occurrence of
|
|
|
448 -- Standard, which is additionally marked with flag Is_Active_Stack_Base.
|
|
|
449 -- The basic visibility routine (Find_Direct_Name, in Sem_Ch8) uses this
|
|
|
450 -- contiguous section of the scope stack to determine whether a given
|
|
|
451 -- entity is or is not visible at a point. In_Open_Scopes only examines
|
|
|
452 -- the currently active section of the scope stack.
|
|
|
453
|
|
|
454 -- Similar complications arise when processing child instances. These
|
|
|
455 -- must be compiled in the context of parent instances, and therefore the
|
|
|
456 -- parents must be pushed on the stack before compiling the child, and
|
|
|
457 -- removed afterwards. Routines Save_Scope_Stack and Restore_Scope_Stack
|
|
|
458 -- are used to set/reset the visibility of entities declared in scopes
|
|
|
459 -- that are currently on the scope stack, and are used when compiling
|
|
|
460 -- instance bodies on the fly.
|
|
|
461
|
|
|
462 -- It is clear in retrospect that all semantic processing and visibility
|
|
|
463 -- structures should have been fully recursive. The rtsfind mechanism,
|
|
|
464 -- and the complexities brought about by subunits and by generic child
|
|
|
465 -- units and their instantiations, have led to a hybrid model that carries
|
|
|
466 -- more state than one would wish.
|
|
|
467
|
|
|
468 type Scope_Action_Kind is (Before, After, Cleanup);
|
|
|
469 type Scope_Actions is array (Scope_Action_Kind) of List_Id;
|
|
|
470 -- Transient blocks have three associated actions list, to be inserted
|
|
|
471 -- before and after the block's statements, and as cleanup actions.
|
|
|
472
|
|
|
473 Configuration_Component_Alignment : Component_Alignment_Kind :=
|
|
|
474 Calign_Default;
|
|
|
475 -- Used for handling the pragma Component_Alignment in the context of a
|
|
|
476 -- configuration file.
|
|
|
477
|
|
|
478 type Scope_Stack_Entry is record
|
|
|
479 Entity : Entity_Id;
|
|
|
480 -- Entity representing the scope
|
|
|
481
|
|
|
482 Last_Subprogram_Name : String_Ptr;
|
|
|
483 -- Pointer to name of last subprogram body in this scope. Used for
|
|
|
484 -- testing proper alpha ordering of subprogram bodies in scope.
|
|
|
485
|
|
|
486 Save_Scope_Suppress : Suppress_Record;
|
|
|
487 -- Save contents of Scope_Suppress on entry
|
|
|
488
|
|
|
489 Save_Local_Suppress_Stack_Top : Suppress_Stack_Entry_Ptr;
|
|
|
490 -- Save contents of Local_Suppress_Stack on entry to restore on exit
|
|
|
491
|
|
|
492 Save_Check_Policy_List : Node_Id;
|
|
|
493 -- Save contents of Check_Policy_List on entry to restore on exit. The
|
|
|
494 -- Check_Policy pragmas are chained with Check_Policy_List pointing to
|
|
|
495 -- the most recent entry. This list is searched starting here, so that
|
|
|
496 -- the search finds the most recent appicable entry. When we restore
|
|
|
497 -- Check_Policy_List on exit from the scope, the effect is to remove
|
|
|
498 -- all entries set in the scope being exited.
|
|
|
499
|
|
|
500 Save_Default_Storage_Pool : Node_Id;
|
|
|
501 -- Save contents of Default_Storage_Pool on entry to restore on exit
|
|
|
502
|
|
|
503 Save_SPARK_Mode : SPARK_Mode_Type;
|
|
|
504 -- Setting of SPARK_Mode on entry to restore on exit
|
|
|
505
|
|
|
506 Save_SPARK_Mode_Pragma : Node_Id;
|
|
|
507 -- Setting of SPARK_Mode_Pragma on entry to restore on exit
|
|
|
508
|
|
|
509 Save_No_Tagged_Streams : Node_Id;
|
|
|
510 -- Setting of No_Tagged_Streams to restore on exit
|
|
|
511
|
|
|
512 Save_Default_SSO : Character;
|
|
|
513 -- Setting of Default_SSO on entry to restore on exit
|
|
|
514
|
|
|
515 Save_Uneval_Old : Character;
|
|
|
516 -- Setting of Uneval_Old on entry to restore on exit
|
|
|
517
|
|
|
518 Is_Transient : Boolean;
|
|
|
519 -- Marks transient scopes (see Exp_Ch7 body for details)
|
|
|
520
|
|
|
521 Previous_Visibility : Boolean;
|
|
|
522 -- Used when installing the parent(s) of the current compilation unit.
|
|
|
523 -- The parent may already be visible because of an ongoing compilation,
|
|
|
524 -- and the proper visibility must be restored on exit. The flag is
|
|
|
525 -- typically needed when the context of a child unit requires
|
|
|
526 -- compilation of a sibling. In other cases the flag is set to False.
|
|
|
527 -- See Sem_Ch10 (Install_Parents, Remove_Parents).
|
|
|
528
|
|
|
529 Node_To_Be_Wrapped : Node_Id;
|
|
|
530 -- Only used in transient scopes. Records the node which will be wrapped
|
|
|
531 -- by the transient block.
|
|
|
532
|
|
|
533 Actions_To_Be_Wrapped : Scope_Actions;
|
|
|
534 -- Actions that have to be inserted at the start, at the end, or as
|
|
|
535 -- cleanup actions of a transient block. Used to temporarily hold these
|
|
|
536 -- actions until the block is created, at which time the actions are
|
|
|
537 -- moved to the block.
|
|
|
538
|
|
|
539 Pending_Freeze_Actions : List_Id;
|
|
|
540 -- Used to collect freeze entity nodes and associated actions that are
|
|
|
541 -- generated in an inner context but need to be analyzed outside, such
|
|
|
542 -- as records and initialization procedures. On exit from the scope,
|
|
|
543 -- this list of actions is inserted before the scope construct and
|
|
|
544 -- analyzed to generate the corresponding freeze processing and
|
|
|
545 -- elaboration of other associated actions.
|
|
|
546
|
|
|
547 First_Use_Clause : Node_Id;
|
|
|
548 -- Head of list of Use_Clauses in current scope. The list is built when
|
|
|
549 -- the declarations in the scope are processed. The list is traversed
|
|
|
550 -- on scope exit to undo the effect of the use clauses.
|
|
|
551
|
|
|
552 Component_Alignment_Default : Component_Alignment_Kind;
|
|
|
553 -- Component alignment to be applied to any record or array types that
|
|
|
554 -- are declared for which a specific component alignment pragma does not
|
|
|
555 -- set the alignment.
|
|
|
556
|
|
|
557 Is_Active_Stack_Base : Boolean;
|
|
|
558 -- Set to true only when entering the scope for Standard_Standard from
|
|
|
559 -- from within procedure Semantics. Indicates the base of the current
|
|
|
560 -- active set of scopes. Needed by In_Open_Scopes to handle cases where
|
|
|
561 -- Standard_Standard can be pushed anew on the scope stack to start a
|
|
|
562 -- new active section (see comment above).
|
|
|
563
|
|
|
564 Locked_Shared_Objects : Elist_Id;
|
|
|
565 -- List of shared passive protected objects that have been locked in
|
|
|
566 -- this transient scope (always No_Elist for non-transient scopes).
|
|
|
567 end record;
|
|
|
568
|
|
|
569 package Scope_Stack is new Table.Table (
|
|
|
570 Table_Component_Type => Scope_Stack_Entry,
|
|
|
571 Table_Index_Type => Int,
|
|
|
572 Table_Low_Bound => 0,
|
|
|
573 Table_Initial => Alloc.Scope_Stack_Initial,
|
|
|
574 Table_Increment => Alloc.Scope_Stack_Increment,
|
|
|
575 Table_Name => "Sem.Scope_Stack");
|
|
|
576
|
|
|
577 -----------------
|
|
|
578 -- Subprograms --
|
|
|
579 -----------------
|
|
|
580
|
|
|
581 procedure Initialize;
|
|
|
582 -- Initialize internal tables
|
|
|
583
|
|
|
584 procedure Lock;
|
|
|
585 -- Lock internal tables before calling back end
|
|
|
586
|
|
|
587 procedure Unlock;
|
|
|
588 -- Unlock internal tables
|
|
|
589
|
|
|
590 procedure Semantics (Comp_Unit : Node_Id);
|
|
|
591 -- This procedure is called to perform semantic analysis on the specified
|
|
|
592 -- node which is the N_Compilation_Unit node for the unit.
|
|
|
593
|
|
|
594 procedure Analyze (N : Node_Id);
|
|
|
595 procedure Analyze (N : Node_Id; Suppress : Check_Id);
|
|
|
596 -- This is the recursive procedure that is applied to individual nodes of
|
|
|
597 -- the tree, starting at the top level node (compilation unit node) and
|
|
|
598 -- then moving down the tree in a top down traversal. It calls individual
|
|
|
599 -- routines with names Analyze_xxx to analyze node xxx. Each of these
|
|
|
600 -- routines is responsible for calling Analyze on the components of the
|
|
|
601 -- subtree.
|
|
|
602 --
|
|
|
603 -- Note: In the case of expression components (nodes whose Nkind is in
|
|
|
604 -- N_Subexpr), the call to Analyze does not complete the semantic analysis
|
|
|
605 -- of the node, since the type resolution cannot be completed until the
|
|
|
606 -- complete context is analyzed. The completion of the type analysis occurs
|
|
|
607 -- in the corresponding Resolve routine (see Sem_Res).
|
|
|
608 --
|
|
|
609 -- Note: for integer and real literals, the analyzer sets the flag to
|
|
|
610 -- indicate that the result is a static expression. If the expander
|
|
|
611 -- generates a literal that does NOT correspond to a static expression,
|
|
|
612 -- e.g. by folding an expression whose value is known at compile time,
|
|
|
613 -- but is not technically static, then the caller should reset the
|
|
|
614 -- Is_Static_Expression flag after analyzing but before resolving.
|
|
|
615 --
|
|
|
616 -- If the Suppress argument is present, then the analysis is done
|
|
|
617 -- with the specified check suppressed (can be All_Checks to suppress
|
|
|
618 -- all checks).
|
|
|
619
|
|
|
620 procedure Analyze_List (L : List_Id);
|
|
|
621 procedure Analyze_List (L : List_Id; Suppress : Check_Id);
|
|
|
622 -- Analyzes each element of a list. If the Suppress argument is present,
|
|
|
623 -- then the analysis is done with the specified check suppressed (can
|
|
|
624 -- be All_Checks to suppress all checks).
|
|
|
625
|
|
|
626 procedure Copy_Suppress_Status
|
|
|
627 (C : Check_Id;
|
|
|
628 From : Entity_Id;
|
|
|
629 To : Entity_Id);
|
|
|
630 -- If From is an entity for which check C is explicitly suppressed
|
|
|
631 -- then also explicitly suppress the corresponding check in To.
|
|
|
632
|
|
|
633 procedure Insert_List_After_And_Analyze
|
|
|
634 (N : Node_Id; L : List_Id);
|
|
|
635 -- Inserts list L after node N using Nlists.Insert_List_After, and then,
|
|
|
636 -- after this insertion is complete, analyzes all the nodes in the list,
|
|
|
637 -- including any additional nodes generated by this analysis. If the list
|
|
|
638 -- is empty or No_List, the call has no effect.
|
|
|
639
|
|
|
640 procedure Insert_List_Before_And_Analyze
|
|
|
641 (N : Node_Id; L : List_Id);
|
|
|
642 -- Inserts list L before node N using Nlists.Insert_List_Before, and then,
|
|
|
643 -- after this insertion is complete, analyzes all the nodes in the list,
|
|
|
644 -- including any additional nodes generated by this analysis. If the list
|
|
|
645 -- is empty or No_List, the call has no effect.
|
|
|
646
|
|
|
647 procedure Insert_After_And_Analyze
|
|
|
648 (N : Node_Id; M : Node_Id);
|
|
|
649 procedure Insert_After_And_Analyze
|
|
|
650 (N : Node_Id; M : Node_Id; Suppress : Check_Id);
|
|
|
651 -- Inserts node M after node N and then after the insertion is complete,
|
|
|
652 -- analyzes the inserted node and all nodes that are generated by
|
|
|
653 -- this analysis. If the node is empty, the call has no effect. If the
|
|
|
654 -- Suppress argument is present, then the analysis is done with the
|
|
|
655 -- specified check suppressed (can be All_Checks to suppress all checks).
|
|
|
656
|
|
|
657 procedure Insert_Before_And_Analyze
|
|
|
658 (N : Node_Id; M : Node_Id);
|
|
|
659 procedure Insert_Before_And_Analyze
|
|
|
660 (N : Node_Id; M : Node_Id; Suppress : Check_Id);
|
|
|
661 -- Inserts node M before node N and then after the insertion is complete,
|
|
|
662 -- analyzes the inserted node and all nodes that could be generated by
|
|
|
663 -- this analysis. If the node is empty, the call has no effect. If the
|
|
|
664 -- Suppress argument is present, then the analysis is done with the
|
|
|
665 -- specified check suppressed (can be All_Checks to suppress all checks).
|
|
|
666
|
|
|
667 function External_Ref_In_Generic (E : Entity_Id) return Boolean;
|
|
|
668 -- Return True if we are in the context of a generic and E is
|
|
|
669 -- external (more global) to it.
|
|
|
670
|
|
|
671 procedure Enter_Generic_Scope (S : Entity_Id);
|
|
|
672 -- Called each time a Generic subprogram or package scope is entered. S is
|
|
|
673 -- the entity of the scope.
|
|
|
674 --
|
|
|
675 -- ??? At the moment, only called for package specs because this mechanism
|
|
|
676 -- is only used for avoiding freezing of external references in generics
|
|
|
677 -- and this can only be an issue if the outer generic scope is a package
|
|
|
678 -- spec (otherwise all external entities are already frozen)
|
|
|
679
|
|
|
680 procedure Exit_Generic_Scope (S : Entity_Id);
|
|
|
681 -- Called each time a Generic subprogram or package scope is exited. S is
|
|
|
682 -- the entity of the scope.
|
|
|
683 --
|
|
|
684 -- ??? At the moment, only called for package specs exit.
|
|
|
685
|
|
|
686 function Explicit_Suppress (E : Entity_Id; C : Check_Id) return Boolean;
|
|
|
687 -- This function returns True if an explicit pragma Suppress for check C
|
|
|
688 -- is present in the package defining E.
|
|
|
689
|
|
|
690 function Preanalysis_Active return Boolean;
|
|
|
691 pragma Inline (Preanalysis_Active);
|
|
|
692 -- Determine whether preanalysis is active at the point of invocation
|
|
|
693
|
|
|
694 procedure Preanalyze (N : Node_Id);
|
|
131
|
695 -- Performs a preanalysis of node N. During preanalysis no expansion is
|
|
|
696 -- carried out for N or its children. See above for more info on
|
|
|
697 -- preanalysis.
|
|
111
|
698
|
|
|
699 generic
|
|
|
700 with procedure Action (Item : Node_Id);
|
|
|
701 procedure Walk_Library_Items;
|
|
|
702 -- Primarily for use by CodePeer and GNATprove. Must be called after
|
|
|
703 -- semantic analysis (and expansion in the case of CodePeer) are complete.
|
|
|
704 -- Walks each relevant library item, calling Action for each, in an order
|
|
|
705 -- such that one will not run across forward references. Each Item passed
|
|
|
706 -- to Action is the declaration or body of a library unit, including
|
|
|
707 -- generics and renamings. The first item is the N_Package_Declaration node
|
|
|
708 -- for package Standard. Bodies are not included, except for the main unit
|
|
|
709 -- itself, which always comes last.
|
|
|
710 --
|
|
|
711 -- Item is never a subunit
|
|
|
712 --
|
|
|
713 -- Item is never an instantiation. Instead, the instance declaration is
|
|
|
714 -- passed, and (if the instantiation is the main unit), the instance body.
|
|
|
715
|
|
|
716 ------------------------
|
|
|
717 -- Debugging Routines --
|
|
|
718 ------------------------
|
|
|
719
|
|
|
720 function ss (Index : Int) return Scope_Stack_Entry;
|
|
|
721 pragma Export (Ada, ss);
|
|
|
722 -- "ss" = "scope stack"; returns the Index'th entry in the Scope_Stack
|
|
|
723
|
|
|
724 function sst return Scope_Stack_Entry;
|
|
|
725 pragma Export (Ada, sst);
|
|
|
726 -- "sst" = "scope stack top"; same as ss(Scope_Stack.Last)
|
|
|
727
|
|
|
728 end Sem;
|
