1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2015, Free Software Foundation, Inc. --
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. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
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.
30 with Types; use Types;
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.
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
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.
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).
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.
66 procedure Resolve_Discrete_Subtype_Indication
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).
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.
79 procedure Analyze_And_Resolve (N : Node_Id);
80 procedure Analyze_And_Resolve (N : Node_Id; Typ : Entity_Id);
81 procedure Analyze_And_Resolve
85 procedure Analyze_And_Resolve
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.
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.
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.
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.
114 -- The parameter T is the Typ for the corresponding resolve call.
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.
122 procedure Preanalyze_And_Resolve (N : Node_Id);
123 -- Same, but use type of node because context does not impose a single type
125 function Valid_Conversion
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.
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.