1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S E M _ R E S -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2011, Free Software Foundation, Inc. -- 10-- -- 11-- GNAT is free software; you can redistribute it and/or modify it under -- 12-- terms of the GNU General Public License as published by the Free Soft- -- 13-- ware Foundation; either version 3, or (at your option) any later ver- -- 14-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 15-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 16-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- 17-- for more details. You should have received a copy of the GNU General -- 18-- Public License distributed with GNAT; see file COPYING3. If not, go to -- 19-- http://www.gnu.org/licenses for a complete copy of the license. -- 20-- -- 21-- GNAT was originally developed by the GNAT team at New York University. -- 22-- Extensive contributions were provided by Ada Core Technologies Inc. -- 23-- -- 24------------------------------------------------------------------------------ 25 26-- Resolution processing for all subexpression nodes. Note that the separate 27-- package Sem_Aggr contains the actual resolution routines for aggregates, 28-- which are separated off since aggregate processing is complex. 29 30with Types; use Types; 31 32package Sem_Res is 33 34 -- As described in Sem_Ch4, the type resolution proceeds in two phases. 35 -- The first phase is a bottom up pass that is achieved during the 36 -- recursive traversal performed by the Analyze procedures. This phase 37 -- determines unambiguous types, and collects sets of possible types 38 -- where the interpretation is potentially ambiguous. 39 40 -- On completing this bottom up pass, which corresponds to a call to 41 -- Analyze on a complete context, the Resolve routine is called which 42 -- performs a top down resolution with recursive calls to itself to 43 -- resolve operands. 44 45 -- Since in practice a lot of semantic analysis has to be postponed until 46 -- types are known (e.g. static folding, setting of suppress flags), the 47 -- Resolve routines also complete the semantic analysis, and call the 48 -- expander for possibly expansion of the completely type resolved node. 49 50 procedure Resolve (N : Node_Id; Typ : Entity_Id); 51 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id); 52 -- Top level type-checking procedure, called in a complete context. The 53 -- construct N, which is a subexpression, has already been analyzed, and 54 -- is required to be of type Typ given the analysis of the context (which 55 -- uses the information gathered on the bottom up phase in Analyze). The 56 -- resolve routines do various other processing, e.g. static evaluation. 57 -- If a Suppress argument is present, then the resolution is done with the 58 -- specified check suppressed (can be All_Checks to suppress all checks). 59 60 procedure Resolve (N : Node_Id); 61 -- A version of Resolve where the type to be used for resolution is 62 -- taken from the Etype (N). This is commonly used in cases where the 63 -- context does not add anything and the first pass of analysis found 64 -- the correct expected type. 65 66 procedure Resolve_Discrete_Subtype_Indication 67 (N : Node_Id; 68 Typ : Entity_Id); 69 -- Resolve subtype indications in choices (case statements and 70 -- aggregates) and in index constraints. Note that the resulting Etype 71 -- of the subtype indication node is set to the Etype of the contained 72 -- range (i.e. an Itype is not constructed for the actual subtype). 73 74 procedure Resolve_Entry (Entry_Name : Node_Id); 75 -- Find name of entry being called, and resolve prefix of name with its 76 -- own type. For now we assume that the prefix cannot be overloaded and 77 -- the name of the entry plays no role in the resolution. 78 79 procedure Analyze_And_Resolve (N : Node_Id); 80 procedure Analyze_And_Resolve (N : Node_Id; Typ : Entity_Id); 81 procedure Analyze_And_Resolve 82 (N : Node_Id; 83 Typ : Entity_Id; 84 Suppress : Check_Id); 85 procedure Analyze_And_Resolve 86 (N : Node_Id; 87 Suppress : Check_Id); 88 -- These routines combine the effect of Analyze and Resolve. If a Suppress 89 -- argument is present, then the analysis is done with the specified check 90 -- suppressed (can be All_Checks to suppress all checks). These checks are 91 -- suppressed for both the analysis and resolution. If the type argument 92 -- is not present, then the Etype of the expression after the Analyze 93 -- call is used for the Resolve. 94 95 procedure Ambiguous_Character (C : Node_Id); 96 -- Give list of candidate interpretations when a character literal cannot 97 -- be resolved, for example in a (useless) comparison such as 'A' = 'B'. 98 -- In Ada 95 the literals in question can be of type Character or Wide_ 99 -- Character. In Ada 2005 Wide_Wide_Character is also a candidate. The 100 -- node may also be overloaded with user-defined character types. 101 102 procedure Check_Parameterless_Call (N : Node_Id); 103 -- Several forms of names can denote calls to entities without para- 104 -- meters. The context determines whether the name denotes the entity 105 -- or a call to it. When it is a call, the node must be rebuilt 106 -- accordingly and reanalyzed to obtain possible interpretations. 107 -- 108 -- The name may be that of an overloadable construct, or it can be an 109 -- explicit dereference of a prefix that denotes an access to subprogram. 110 -- In that case, we want to convert the name into a call only if the 111 -- context requires the return type of the subprogram. Finally, a 112 -- parameterless protected subprogram appears as a selected component. 113 -- 114 -- The parameter T is the Typ for the corresponding resolve call. 115 116 procedure Preanalyze_And_Resolve (N : Node_Id; T : Entity_Id); 117 -- Performs a pre-analysis of expression node N. During pre-analysis, 118 -- N is analyzed and then resolved against type T, but no expansion 119 -- is carried out for N or its children. For more info on pre-analysis 120 -- read the spec of Sem. 121 122 procedure Preanalyze_And_Resolve (N : Node_Id); 123 -- Same, but use type of node because context does not impose a single type 124 125 function Valid_Conversion 126 (N : Node_Id; 127 Target : Entity_Id; 128 Operand : Node_Id; 129 Report_Errs : Boolean := True) return Boolean; 130 -- Verify legality rules given in 4.6 (8-23). Target is the target type 131 -- of the conversion, which may be an implicit conversion of an actual 132 -- parameter to an anonymous access type (in which case N denotes the 133 -- actual parameter and N = Operand). Returns a Boolean result indicating 134 -- whether the conversion is legal. Reports errors in the case of illegal 135 -- conversions, unless Report_Errs is False. 136 137private 138 procedure Resolve_Implicit_Type (N : Node_Id) renames Resolve; 139 pragma Inline (Resolve_Implicit_Type); 140 -- We use this renaming to make the application of Inline very explicit 141 -- to this version, since other versions of Resolve are not inlined. 142 143end Sem_Res; 144