1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S E M _ R E S -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1992-2019, 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 possible expansion of the completely type resolved node. 49 50 procedure Ambiguous_Character (C : Node_Id); 51 -- Give list of candidate interpretations when a character literal cannot 52 -- be resolved, for example in a (useless) comparison such as 'A' = 'B'. 53 -- In Ada 95 the literals in question can be of type Character or Wide_ 54 -- Character. In Ada 2005 Wide_Wide_Character is also a candidate. The 55 -- node may also be overloaded with user-defined character types. 56 57 procedure Analyze_And_Resolve (N : Node_Id); 58 procedure Analyze_And_Resolve (N : Node_Id; Typ : Entity_Id); 59 procedure Analyze_And_Resolve 60 (N : Node_Id; 61 Typ : Entity_Id; 62 Suppress : Check_Id); 63 procedure Analyze_And_Resolve 64 (N : Node_Id; 65 Suppress : Check_Id); 66 -- These routines combine the effect of Analyze and Resolve. If a Suppress 67 -- argument is present, then the analysis is done with the specified check 68 -- suppressed (can be All_Checks to suppress all checks). These checks are 69 -- suppressed for both the analysis and resolution. If the type argument 70 -- is not present, then the Etype of the expression after the Analyze 71 -- call is used for the Resolve. 72 73 procedure Check_Parameterless_Call (N : Node_Id); 74 -- Several forms of names can denote calls to entities without parameters. 75 -- The context determines whether the name denotes the entity or a call to 76 -- it. When it is a call, the node must be rebuilt accordingly and 77 -- reanalyzed to obtain possible interpretations. 78 -- 79 -- The name may be that of an overloadable construct, or it can be an 80 -- explicit dereference of a prefix that denotes an access to subprogram. 81 -- In that case, we want to convert the name into a call only if the 82 -- context requires the return type of the subprogram. Finally, a 83 -- parameterless protected subprogram appears as a selected component. 84 -- 85 -- The parameter T is the Typ for the corresponding resolve call. 86 87 procedure Preanalyze_And_Resolve (N : Node_Id; T : Entity_Id); 88 -- Performs a preanalysis of expression node N. During preanalysis, N is 89 -- analyzed and then resolved against type T, but no expansion is carried 90 -- out for N or its children. For more info on preanalysis read the spec 91 -- of Sem. 92 93 procedure Preanalyze_And_Resolve (N : Node_Id); 94 -- Same, but use type of node because context does not impose a single type 95 96 procedure Preanalyze_With_Freezing_And_Resolve (N : Node_Id; T : Entity_Id); 97 -- Same, but perform freezing of static expressions of N or its children. 98 99 procedure Resolve (N : Node_Id; Typ : Entity_Id); 100 procedure Resolve (N : Node_Id; Typ : Entity_Id; Suppress : Check_Id); 101 -- Top-level type-checking procedure, called in a complete context. The 102 -- construct N, which is a subexpression, has already been analyzed, and 103 -- is required to be of type Typ given the analysis of the context (which 104 -- uses the information gathered on the bottom-up phase in Analyze). The 105 -- resolve routines do various other processing, e.g. static evaluation. 106 -- If a Suppress argument is present, then the resolution is done with the 107 -- specified check suppressed (can be All_Checks to suppress all checks). 108 109 procedure Resolve (N : Node_Id); 110 -- A version of Resolve where the type to be used for resolution is taken 111 -- from the Etype (N). This is commonly used in cases where the context 112 -- does not add anything and the first pass of analysis found the correct 113 -- expected type. 114 115 procedure Resolve_Discrete_Subtype_Indication 116 (N : Node_Id; 117 Typ : Entity_Id); 118 -- Resolve subtype indications in choices (case statements and aggregates) 119 -- and in index constraints. Note that the resulting Etype of the subtype_ 120 -- indication node is set to the Etype of the contained range (i.e. an 121 -- Itype is not constructed for the actual subtype). 122 123 procedure Resolve_Entry (Entry_Name : Node_Id); 124 -- Find name of entry being called, and resolve prefix of name with its 125 -- own type. For now we assume that the prefix cannot be overloaded and 126 -- the name of the entry plays no role in the resolution. 127 128 function Valid_Conversion 129 (N : Node_Id; 130 Target : Entity_Id; 131 Operand : Node_Id; 132 Report_Errs : Boolean := True) return Boolean; 133 -- Verify legality rules given in 4.6 (8-23). Target is the target type 134 -- of the conversion, which may be an implicit conversion of an actual 135 -- parameter to an anonymous access type (in which case N denotes the 136 -- actual parameter and N = Operand). Returns a Boolean result indicating 137 -- whether the conversion is legal. Reports errors in the case of illegal 138 -- conversions, unless Report_Errs is False. 139 140private 141 procedure Resolve_Implicit_Type (N : Node_Id) renames Resolve; 142 pragma Inline (Resolve_Implicit_Type); 143 -- We use this renaming to make the application of Inline very explicit to 144 -- this version, since other versions of Resolve are not inlined. 145 146end Sem_Res; 147