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Diffstat (limited to 'gcc-4.3.1/gcc/ada/sem_type.ads')
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diff --git a/gcc-4.3.1/gcc/ada/sem_type.ads b/gcc-4.3.1/gcc/ada/sem_type.ads new file mode 100644 index 000000000..a4986fc61 --- /dev/null +++ b/gcc-4.3.1/gcc/ada/sem_type.ads @@ -0,0 +1,255 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- S E M _ T Y P E -- +-- -- +-- S p e c -- +-- -- +-- Copyright (C) 1992-2007, Free Software Foundation, Inc. -- +-- -- +-- GNAT is free software; you can redistribute it and/or modify it under -- +-- terms of the GNU General Public License as published by the Free Soft- -- +-- ware Foundation; either version 3, or (at your option) any later ver- -- +-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- +-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- +-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- +-- for more details. You should have received a copy of the GNU General -- +-- Public License distributed with GNAT; see file COPYING3. If not, go to -- +-- http://www.gnu.org/licenses for a complete copy of the license. -- +-- -- +-- GNAT was originally developed by the GNAT team at New York University. -- +-- Extensive contributions were provided by Ada Core Technologies Inc. -- +-- -- +------------------------------------------------------------------------------ + +-- This unit contains the routines used to handle type determination, +-- including the routine used to support overload resolution. + +with Types; use Types; + +package Sem_Type is + + --------------------------------------------- + -- Data Structures for Overload Resolution -- + --------------------------------------------- + + -- To determine the unique meaning of an identifier, overload resolution + -- may have to be performed if the visibility rules alone identify more + -- than one possible entity as the denotation of a given identifier. When + -- the visibility rules find such a potential ambiguity, the set of + -- possible interpretations must be attached to the identifier, and + -- overload resolution must be performed over the innermost enclosing + -- complete context. At the end of the resolution, either a single + -- interpretation is found for all identifiers in the context, or else a + -- type error (invalid type or ambiguous reference) must be signalled. + + -- The set of interpretations of a given name is stored in a data structure + -- that is separate from the syntax tree, because it corresponds to + -- transient information. The interpretations themselves are stored in + -- table All_Interp. A mapping from tree nodes to sets of interpretations + -- called Interp_Map, is maintained by the overload resolution routines. + -- Both these structures are initialized at the beginning of every complete + -- context. + + -- Corresponding to the set of interpretations for a given overloadable + -- identifier, there is a set of possible types corresponding to the types + -- that the overloaded call may return. We keep a 1-to-1 correspondence + -- between interpretations and types: for user-defined subprograms the + -- type is the declared return type. For operators, the type is determined + -- by the type of the arguments. If the arguments themselves are + -- overloaded, we enter the operator name in the names table for each + -- possible result type. In most cases, arguments are not overloaded and + -- only one interpretation is present anyway. + + type Interp is record + Nam : Entity_Id; + Typ : Entity_Id; + Abstract_Op : Entity_Id := Empty; + end record; + + -- Entity Abstract_Op is set to the abstract operation which potentially + -- disables the interpretation in Ada 2005 mode. + + No_Interp : constant Interp := (Empty, Empty, Empty); + + subtype Interp_Index is Int; + + --------------------- + -- Error Reporting -- + --------------------- + + -- A common error is the use of an operator in infix notation on arguments + -- of a type that is not directly visible. Rather than diagnosing a type + -- mismatch, it is better to indicate that the type can be made use-visible + -- with the appropriate use clause. The global variable Candidate_Type is + -- set in Add_One_Interp whenever an interpretation might be legal for an + -- operator if the type were directly visible. This variable is used in + -- sem_ch4 when no legal interpretation is found. + + Candidate_Type : Entity_Id; + + ----------------- + -- Subprograms -- + ----------------- + + procedure Init_Interp_Tables; + -- Invoked by gnatf when processing multiple files + + procedure Collect_Interps (N : Node_Id); + -- Invoked when the name N has more than one visible interpretation. + -- This is the high level routine which accumulates the possible + -- interpretations of the node. The first meaning and type of N have + -- already been stored in N. If the name is an expanded name, the homonyms + -- are only those that belong to the same scope. + + function Is_Invisible_Operator + (N : Node_Id; + T : Entity_Id) + return Boolean; + -- Check whether a predefined operation with universal operands appears + -- in a context in which the operators of the expected type are not + -- visible. + + procedure List_Interps (Nam : Node_Id; Err : Node_Id); + -- List candidate interpretations of an overloaded name. Used for + -- various error reports. + + procedure Add_One_Interp + (N : Node_Id; + E : Entity_Id; + T : Entity_Id; + Opnd_Type : Entity_Id := Empty); + -- Add (E, T) to the list of interpretations of the node being resolved. + -- For calls and operators, i.e. for nodes that have a name field, + -- E is an overloadable entity, and T is its type. For constructs such + -- as indexed expressions, the caller sets E equal to T, because the + -- overloading comes from other fields, and the node itself has no name + -- to resolve. Hidden denotes whether an interpretation has been disabled + -- by an abstract operator. Add_One_Interp includes semantic processing to + -- deal with adding entries that hide one another etc. + + -- For operators, the legality of the operation depends on the visibility + -- of T and its scope. If the operator is an equality or comparison, T is + -- always Boolean, and we use Opnd_Type, which is a candidate type for one + -- of the operands of N, to check visibility. + + procedure End_Interp_List; + -- End the list of interpretations of current node + + procedure Get_First_Interp + (N : Node_Id; + I : out Interp_Index; + It : out Interp); + -- Initialize iteration over set of interpretations for Node N. The first + -- interpretation is placed in It, and I is initialized for subsequent + -- calls to Get_Next_Interp. + + procedure Get_Next_Interp (I : in out Interp_Index; It : out Interp); + -- Iteration step over set of interpretations. Using the value in I, which + -- was set by a previous call to Get_First_Interp or Get_Next_Interp, the + -- next interpretation is placed in It, and I is updated for the next call. + -- The end of the list of interpretations is signalled by It.Nam = Empty. + + procedure Remove_Interp (I : in out Interp_Index); + -- Remove an interpretation that his hidden by another, or that does not + -- match the context. The value of I on input was set by a call to either + -- Get_First_Interp or Get_Next_Interp and references the interpretation + -- to be removed. The only allowed use of the exit value of I is as input + -- to a subsequent call to Get_Next_Interp, which yields the interpretation + -- following the removed one. + + procedure Save_Interps (Old_N : Node_Id; New_N : Node_Id); + -- If an overloaded node is rewritten during semantic analysis, its + -- possible interpretations must be linked to the copy. This procedure + -- transfers the overload information from Old_N, the old node, to + -- New_N, its new copy. It has no effect in the non-overloaded case. + + function Covers (T1, T2 : Entity_Id) return Boolean; + -- This is the basic type compatibility routine. T1 is the expected + -- type, imposed by context, and T2 is the actual type. The processing + -- reflects both the definition of type coverage and the rules + -- for operand matching. + + function Disambiguate + (N : Node_Id; + I1, I2 : Interp_Index; + Typ : Entity_Id) + return Interp; + -- If more than one interpretation of a name in a call is legal, apply + -- preference rules (universal types first) and operator visibility in + -- order to remove ambiguity. I1 and I2 are the first two interpretations + -- that are compatible with the context, but there may be others. + + function Entity_Matches_Spec (Old_S, New_S : Entity_Id) return Boolean; + -- To resolve subprogram renaming and default formal subprograms in generic + -- definitions. Old_S is a possible interpretation of the entity being + -- renamed, New_S has an explicit signature. If Old_S is a subprogram, as + -- opposed to an operator, type and mode conformance are required. + + function Find_Unique_Type (L : Node_Id; R : Node_Id) return Entity_Id; + -- Used in second pass of resolution, for equality and comparison nodes. + -- L is the left operand, whose type is known to be correct, and R is + -- the right operand, which has one interpretation compatible with that + -- of L. Return the type intersection of the two. + + function Has_Compatible_Type + (N : Node_Id; + Typ : Entity_Id) + return Boolean; + -- Verify that some interpretation of the node N has a type compatible + -- with Typ. If N is not overloaded, then its unique type must be + -- compatible with Typ. Otherwise iterate through the interpretations + -- of N looking for a compatible one. + + function Hides_Op (F : Entity_Id; Op : Entity_Id) return Boolean; + -- A user-defined function hides a predefined operator if it is + -- matches the signature of the operator, and is declared in an + -- open scope, or in the scope of the result type. + + function Interface_Present_In_Ancestor + (Typ : Entity_Id; + Iface : Entity_Id) return Boolean; + -- Ada 2005 (AI-251): Typ must be a tagged record type/subtype and Iface + -- must be an abstract interface type (or a class-wide abstract interface). + -- This function is used to check if Typ or some ancestor of Typ implements + -- Iface (returning True only if so). + + function Intersect_Types (L, R : Node_Id) return Entity_Id; + -- Find the common interpretation to two analyzed nodes. If one of the + -- interpretations is universal, choose the non-universal one. If either + -- node is overloaded, find single common interpretation. + + function Is_Ancestor (T1, T2 : Entity_Id) return Boolean; + -- T1 is a tagged type (not class-wide). Verify that it is one of the + -- ancestors of type T2 (which may or not be class-wide) + + function Is_Subtype_Of (T1 : Entity_Id; T2 : Entity_Id) return Boolean; + -- Checks whether T1 is any subtype of T2 directly or indirectly. Applies + -- only to scalar subtypes ??? + + function Operator_Matches_Spec (Op, New_S : Entity_Id) return Boolean; + -- Used to resolve subprograms renaming operators, and calls to user + -- defined operators. Determines whether a given operator Op, matches + -- a specification, New_S. + + procedure Set_Abstract_Op (I : Interp_Index; V : Entity_Id); + -- Set the abstract operation field of an interpretation + + function Valid_Comparison_Arg (T : Entity_Id) return Boolean; + -- A valid argument to an ordering operator must be a discrete type, a + -- real type, or a one dimensional array with a discrete component type. + + function Valid_Boolean_Arg (T : Entity_Id) return Boolean; + -- A valid argument of a boolean operator is either some boolean type, + -- or a one-dimensional array of boolean type. + + procedure Write_Interp_Ref (Map_Ptr : Int); + -- Debugging procedure to display entry in Interp_Map. Would not be + -- needed if it were possible to debug instantiations of Table. + + procedure Write_Overloads (N : Node_Id); + -- Debugging procedure to output info on possibly overloaded entities + -- for specified node. + +end Sem_Type; |