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Diffstat (limited to 'gcc-4.4.0/gcc/ada/sem_ch7.adb')
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diff --git a/gcc-4.4.0/gcc/ada/sem_ch7.adb b/gcc-4.4.0/gcc/ada/sem_ch7.adb new file mode 100644 index 000000000..46cd93839 --- /dev/null +++ b/gcc-4.4.0/gcc/ada/sem_ch7.adb @@ -0,0 +1,2395 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- S E M . C H 7 -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 1992-2008, 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 package contains the routines to process package specifications and +-- bodies. The most important semantic aspects of package processing are the +-- handling of private and full declarations, and the construction of +-- dispatch tables for tagged types. + +with Atree; use Atree; +with Debug; use Debug; +with Einfo; use Einfo; +with Elists; use Elists; +with Errout; use Errout; +with Exp_Disp; use Exp_Disp; +with Exp_Dist; use Exp_Dist; +with Exp_Dbug; use Exp_Dbug; +with Lib; use Lib; +with Lib.Xref; use Lib.Xref; +with Namet; use Namet; +with Nmake; use Nmake; +with Nlists; use Nlists; +with Opt; use Opt; +with Output; use Output; +with Sem; use Sem; +with Sem_Cat; use Sem_Cat; +with Sem_Ch3; use Sem_Ch3; +with Sem_Ch6; use Sem_Ch6; +with Sem_Ch8; use Sem_Ch8; +with Sem_Ch10; use Sem_Ch10; +with Sem_Ch12; use Sem_Ch12; +with Sem_Disp; use Sem_Disp; +with Sem_Prag; use Sem_Prag; +with Sem_Util; use Sem_Util; +with Sem_Warn; use Sem_Warn; +with Snames; use Snames; +with Stand; use Stand; +with Sinfo; use Sinfo; +with Sinput; use Sinput; +with Style; +with Uintp; use Uintp; + +package body Sem_Ch7 is + + ----------------------------------- + -- Handling private declarations -- + ----------------------------------- + + -- The principle that each entity has a single defining occurrence clashes + -- with the presence of two separate definitions for private types: the + -- first is the private type declaration, and the second is the full type + -- declaration. It is important that all references to the type point to + -- the same defining occurrence, namely the first one. To enforce the two + -- separate views of the entity, the corresponding information is swapped + -- between the two declarations. Outside of the package, the defining + -- occurrence only contains the private declaration information, while in + -- the private part and the body of the package the defining occurrence + -- contains the full declaration. To simplify the swap, the defining + -- occurrence that currently holds the private declaration points to the + -- full declaration. During semantic processing the defining occurrence + -- also points to a list of private dependents, that is to say access types + -- or composite types whose designated types or component types are + -- subtypes or derived types of the private type in question. After the + -- full declaration has been seen, the private dependents are updated to + -- indicate that they have full definitions. + + ----------------------- + -- Local Subprograms -- + ----------------------- + + procedure Check_Anonymous_Access_Types + (Spec_Id : Entity_Id; + P_Body : Node_Id); + -- If the spec of a package has a limited_with_clause, it may declare + -- anonymous access types whose designated type is a limited view, such an + -- anonymous access return type for a function. This access type cannot be + -- elaborated in the spec itself, but it may need an itype reference if it + -- is used within a nested scope. In that case the itype reference is + -- created at the beginning of the corresponding package body and inserted + -- before other body declarations. + + procedure Install_Package_Entity (Id : Entity_Id); + -- Supporting procedure for Install_{Visible,Private}_Declarations. + -- Places one entity on its visibility chain, and recurses on the visible + -- part if the entity is an inner package. + + function Is_Private_Base_Type (E : Entity_Id) return Boolean; + -- True for a private type that is not a subtype + + function Is_Visible_Dependent (Dep : Entity_Id) return Boolean; + -- If the private dependent is a private type whose full view is derived + -- from the parent type, its full properties are revealed only if we are in + -- the immediate scope of the private dependent. Should this predicate be + -- tightened further??? + + procedure Declare_Inherited_Private_Subprograms (Id : Entity_Id); + -- Called upon entering the private part of a public child package and the + -- body of a nested package, to potentially declare certain inherited + -- subprograms that were inherited by types in the visible part, but whose + -- declaration was deferred because the parent operation was private and + -- not visible at that point. These subprograms are located by traversing + -- the visible part declarations looking for non-private type extensions + -- and then examining each of the primitive operations of such types to + -- find those that were inherited but declared with a special internal + -- name. Each such operation is now declared as an operation with a normal + -- name (using the name of the parent operation) and replaces the previous + -- implicit operation in the primitive operations list of the type. If the + -- inherited private operation has been overridden, then it's replaced by + -- the overriding operation. + + -------------------------- + -- Analyze_Package_Body -- + -------------------------- + + procedure Analyze_Package_Body (N : Node_Id) is + Loc : constant Source_Ptr := Sloc (N); + HSS : Node_Id; + Body_Id : Entity_Id; + Spec_Id : Entity_Id; + Last_Spec_Entity : Entity_Id; + New_N : Node_Id; + Pack_Decl : Node_Id; + + procedure Install_Composite_Operations (P : Entity_Id); + -- Composite types declared in the current scope may depend on + -- types that were private at the point of declaration, and whose + -- full view is now in scope. Indicate that the corresponding + -- operations on the composite type are available. + + ---------------------------------- + -- Install_Composite_Operations -- + ---------------------------------- + + procedure Install_Composite_Operations (P : Entity_Id) is + Id : Entity_Id; + + begin + Id := First_Entity (P); + while Present (Id) loop + if Is_Type (Id) + and then (Is_Limited_Composite (Id) + or else Is_Private_Composite (Id)) + and then No (Private_Component (Id)) + then + Set_Is_Limited_Composite (Id, False); + Set_Is_Private_Composite (Id, False); + end if; + + Next_Entity (Id); + end loop; + end Install_Composite_Operations; + + -- Start of processing for Analyze_Package_Body + + begin + -- Find corresponding package specification, and establish the + -- current scope. The visible defining entity for the package is the + -- defining occurrence in the spec. On exit from the package body, all + -- body declarations are attached to the defining entity for the body, + -- but the later is never used for name resolution. In this fashion + -- there is only one visible entity that denotes the package. + + if Debug_Flag_C then + Write_Str ("==== Compiling package body "); + Write_Name (Chars (Defining_Entity (N))); + Write_Str (" from "); + Write_Location (Loc); + Write_Eol; + end if; + + -- Set Body_Id. Note that this Will be reset to point to the + -- generic copy later on in the generic case. + + Body_Id := Defining_Entity (N); + + if Present (Corresponding_Spec (N)) then + + -- Body is body of package instantiation. Corresponding spec + -- has already been set. + + Spec_Id := Corresponding_Spec (N); + Pack_Decl := Unit_Declaration_Node (Spec_Id); + + else + Spec_Id := Current_Entity_In_Scope (Defining_Entity (N)); + + if Present (Spec_Id) + and then Is_Package_Or_Generic_Package (Spec_Id) + then + Pack_Decl := Unit_Declaration_Node (Spec_Id); + + if Nkind (Pack_Decl) = N_Package_Renaming_Declaration then + Error_Msg_N ("cannot supply body for package renaming", N); + return; + + elsif Present (Corresponding_Body (Pack_Decl)) then + Error_Msg_N ("redefinition of package body", N); + return; + end if; + + else + Error_Msg_N ("missing specification for package body", N); + return; + end if; + + if Is_Package_Or_Generic_Package (Spec_Id) + and then + (Scope (Spec_Id) = Standard_Standard + or else Is_Child_Unit (Spec_Id)) + and then not Unit_Requires_Body (Spec_Id) + then + if Ada_Version = Ada_83 then + Error_Msg_N + ("optional package body (not allowed in Ada 95)?", N); + else + Error_Msg_N + ("spec of this package does not allow a body", N); + end if; + end if; + end if; + + Set_Is_Compilation_Unit (Body_Id, Is_Compilation_Unit (Spec_Id)); + Style.Check_Identifier (Body_Id, Spec_Id); + + if Is_Child_Unit (Spec_Id) then + if Nkind (Parent (N)) /= N_Compilation_Unit then + Error_Msg_NE + ("body of child unit& cannot be an inner package", N, Spec_Id); + end if; + + Set_Is_Child_Unit (Body_Id); + end if; + + -- Generic package case + + if Ekind (Spec_Id) = E_Generic_Package then + + -- Disable expansion and perform semantic analysis on copy. + -- The unannotated body will be used in all instantiations. + + Body_Id := Defining_Entity (N); + Set_Ekind (Body_Id, E_Package_Body); + Set_Scope (Body_Id, Scope (Spec_Id)); + Set_Is_Obsolescent (Body_Id, Is_Obsolescent (Spec_Id)); + Set_Body_Entity (Spec_Id, Body_Id); + Set_Spec_Entity (Body_Id, Spec_Id); + + New_N := Copy_Generic_Node (N, Empty, Instantiating => False); + Rewrite (N, New_N); + + -- Update Body_Id to point to the copied node for the remainder + -- of the processing. + + Body_Id := Defining_Entity (N); + Start_Generic; + end if; + + -- The Body_Id is that of the copied node in the generic case, the + -- current node otherwise. Note that N was rewritten above, so we + -- must be sure to get the latest Body_Id value. + + Set_Ekind (Body_Id, E_Package_Body); + Set_Body_Entity (Spec_Id, Body_Id); + Set_Spec_Entity (Body_Id, Spec_Id); + + -- Defining name for the package body is not a visible entity: Only + -- the defining name for the declaration is visible. + + Set_Etype (Body_Id, Standard_Void_Type); + Set_Scope (Body_Id, Scope (Spec_Id)); + Set_Corresponding_Spec (N, Spec_Id); + Set_Corresponding_Body (Pack_Decl, Body_Id); + + -- The body entity is not used for semantics or code generation, but + -- it is attached to the entity list of the enclosing scope to simplify + -- the listing of back-annotations for the types it main contain. + + if Scope (Spec_Id) /= Standard_Standard then + Append_Entity (Body_Id, Scope (Spec_Id)); + end if; + + -- Indicate that we are currently compiling the body of the package + + Set_In_Package_Body (Spec_Id); + Set_Has_Completion (Spec_Id); + Last_Spec_Entity := Last_Entity (Spec_Id); + + Push_Scope (Spec_Id); + + Set_Categorization_From_Pragmas (N); + + Install_Visible_Declarations (Spec_Id); + Install_Private_Declarations (Spec_Id); + Install_Private_With_Clauses (Spec_Id); + Install_Composite_Operations (Spec_Id); + + Check_Anonymous_Access_Types (Spec_Id, N); + + if Ekind (Spec_Id) = E_Generic_Package then + Set_Use (Generic_Formal_Declarations (Pack_Decl)); + end if; + + Set_Use (Visible_Declarations (Specification (Pack_Decl))); + Set_Use (Private_Declarations (Specification (Pack_Decl))); + + -- This is a nested package, so it may be necessary to declare certain + -- inherited subprograms that are not yet visible because the parent + -- type's subprograms are now visible. + + if Ekind (Scope (Spec_Id)) = E_Package + and then Scope (Spec_Id) /= Standard_Standard + then + Declare_Inherited_Private_Subprograms (Spec_Id); + end if; + + if Present (Declarations (N)) then + Analyze_Declarations (Declarations (N)); + Inspect_Deferred_Constant_Completion (Declarations (N)); + end if; + + -- Analyze_Declarations has caused freezing of all types; now generate + -- bodies for RACW primitives and stream attributes, if any. + + if Ekind (Spec_Id) = E_Package and then Has_RACW (Spec_Id) then + + -- Attach subprogram bodies to support RACWs declared in spec + + Append_RACW_Bodies (Declarations (N), Spec_Id); + Analyze_List (Declarations (N)); + end if; + + HSS := Handled_Statement_Sequence (N); + + if Present (HSS) then + Process_End_Label (HSS, 't', Spec_Id); + Analyze (HSS); + + -- Check that elaboration code in a preelaborable package body is + -- empty other than null statements and labels (RM 10.2.1(6)). + + Validate_Null_Statement_Sequence (N); + end if; + + Validate_Categorization_Dependency (N, Spec_Id); + Check_Completion (Body_Id); + + -- Generate start of body reference. Note that we do this fairly late, + -- because the call will use In_Extended_Main_Source_Unit as a check, + -- and we want to make sure that Corresponding_Stub links are set + + Generate_Reference (Spec_Id, Body_Id, 'b', Set_Ref => False); + + -- For a generic package, collect global references and mark them on + -- the original body so that they are not resolved again at the point + -- of instantiation. + + if Ekind (Spec_Id) /= E_Package then + Save_Global_References (Original_Node (N)); + End_Generic; + end if; + + -- The entities of the package body have so far been chained onto the + -- declaration chain for the spec. That's been fine while we were in the + -- body, since we wanted them to be visible, but now that we are leaving + -- the package body, they are no longer visible, so we remove them from + -- the entity chain of the package spec entity, and copy them to the + -- entity chain of the package body entity, where they will never again + -- be visible. + + if Present (Last_Spec_Entity) then + Set_First_Entity (Body_Id, Next_Entity (Last_Spec_Entity)); + Set_Next_Entity (Last_Spec_Entity, Empty); + Set_Last_Entity (Body_Id, Last_Entity (Spec_Id)); + Set_Last_Entity (Spec_Id, Last_Spec_Entity); + + else + Set_First_Entity (Body_Id, First_Entity (Spec_Id)); + Set_Last_Entity (Body_Id, Last_Entity (Spec_Id)); + Set_First_Entity (Spec_Id, Empty); + Set_Last_Entity (Spec_Id, Empty); + end if; + + End_Package_Scope (Spec_Id); + + -- All entities declared in body are not visible + + declare + E : Entity_Id; + + begin + E := First_Entity (Body_Id); + while Present (E) loop + Set_Is_Immediately_Visible (E, False); + Set_Is_Potentially_Use_Visible (E, False); + Set_Is_Hidden (E); + + -- Child units may appear on the entity list (for example if + -- they appear in the context of a subunit) but they are not + -- body entities. + + if not Is_Child_Unit (E) then + Set_Is_Package_Body_Entity (E); + end if; + + Next_Entity (E); + end loop; + end; + + Check_References (Body_Id); + + -- For a generic unit, check that the formal parameters are referenced, + -- and that local variables are used, as for regular packages. + + if Ekind (Spec_Id) = E_Generic_Package then + Check_References (Spec_Id); + end if; + + -- The processing so far has made all entities of the package body + -- public (i.e. externally visible to the linker). This is in general + -- necessary, since inlined or generic bodies, for which code is + -- generated in other units, may need to see these entities. The + -- following loop runs backwards from the end of the entities of the + -- package body making these entities invisible until we reach a + -- referencer, i.e. a declaration that could reference a previous + -- declaration, a generic body or an inlined body, or a stub (which + -- may contain either of these). This is of course an approximation, + -- but it is conservative and definitely correct. + + -- We only do this at the outer (library) level non-generic packages. + -- The reason is simply to cut down on the number of external symbols + -- generated, so this is simply an optimization of the efficiency + -- of the compilation process. It has no other effect. + + if (Scope (Spec_Id) = Standard_Standard or else Is_Child_Unit (Spec_Id)) + and then not Is_Generic_Unit (Spec_Id) + and then Present (Declarations (N)) + then + Make_Non_Public_Where_Possible : declare + + function Has_Referencer + (L : List_Id; + Outer : Boolean) + return Boolean; + -- Traverse the given list of declarations in reverse order. + -- Return True as soon as a referencer is reached. Return + -- False if none is found. The Outer parameter is True for + -- the outer level call, and False for inner level calls for + -- nested packages. If Outer is True, then any entities up + -- to the point of hitting a referencer get their Is_Public + -- flag cleared, so that the entities will be treated as + -- static entities in the C sense, and need not have fully + -- qualified names. For inner levels, we need all names to + -- be fully qualified to deal with the same name appearing + -- in parallel packages (right now this is tied to their + -- being external). + + -------------------- + -- Has_Referencer -- + -------------------- + + function Has_Referencer + (L : List_Id; + Outer : Boolean) + return Boolean + is + D : Node_Id; + E : Entity_Id; + K : Node_Kind; + S : Entity_Id; + + begin + if No (L) then + return False; + end if; + + D := Last (L); + while Present (D) loop + K := Nkind (D); + + if K in N_Body_Stub then + return True; + + elsif K = N_Subprogram_Body then + if Acts_As_Spec (D) then + E := Defining_Entity (D); + + -- An inlined body acts as a referencer. Note also + -- that we never reset Is_Public for an inlined + -- subprogram. Gigi requires Is_Public to be set. + + -- Note that we test Has_Pragma_Inline here rather + -- than Is_Inlined. We are compiling this for a + -- client, and it is the client who will decide + -- if actual inlining should occur, so we need to + -- assume that the procedure could be inlined for + -- the purpose of accessing global entities. + + if Has_Pragma_Inline (E) then + return True; + else + Set_Is_Public (E, False); + end if; + + else + E := Corresponding_Spec (D); + + if Present (E) + and then (Is_Generic_Unit (E) + or else Has_Pragma_Inline (E) + or else Is_Inlined (E)) + then + return True; + end if; + end if; + + -- Processing for package bodies + + elsif K = N_Package_Body + and then Present (Corresponding_Spec (D)) + then + E := Corresponding_Spec (D); + + -- Generic package body is a referencer. It would + -- seem that we only have to consider generics that + -- can be exported, i.e. where the corresponding spec + -- is the spec of the current package, but because of + -- nested instantiations, a fully private generic + -- body may export other private body entities. + + if Is_Generic_Unit (E) then + return True; + + -- For non-generic package body, recurse into body + -- unless this is an instance, we ignore instances + -- since they cannot have references that affect + -- outer entities. + + elsif not Is_Generic_Instance (E) then + if Has_Referencer + (Declarations (D), Outer => False) + then + return True; + end if; + end if; + + -- Processing for package specs, recurse into declarations. + -- Again we skip this for the case of generic instances. + + elsif K = N_Package_Declaration then + S := Specification (D); + + if not Is_Generic_Unit (Defining_Entity (S)) then + if Has_Referencer + (Private_Declarations (S), Outer => False) + then + return True; + elsif Has_Referencer + (Visible_Declarations (S), Outer => False) + then + return True; + end if; + end if; + + -- Objects and exceptions need not be public if we have + -- not encountered a referencer so far. We only reset + -- the flag for outer level entities that are not + -- imported/exported, and which have no interface name. + + elsif Nkind_In (K, N_Object_Declaration, + N_Exception_Declaration, + N_Subprogram_Declaration) + then + E := Defining_Entity (D); + + if Outer + and then not Is_Imported (E) + and then not Is_Exported (E) + and then No (Interface_Name (E)) + then + Set_Is_Public (E, False); + end if; + end if; + + Prev (D); + end loop; + + return False; + end Has_Referencer; + + -- Start of processing for Make_Non_Public_Where_Possible + + begin + declare + Discard : Boolean; + pragma Warnings (Off, Discard); + + begin + Discard := Has_Referencer (Declarations (N), Outer => True); + end; + end Make_Non_Public_Where_Possible; + end if; + + -- If expander is not active, then here is where we turn off the + -- In_Package_Body flag, otherwise it is turned off at the end of + -- the corresponding expansion routine. If this is an instance body, + -- we need to qualify names of local entities, because the body may + -- have been compiled as a preliminary to another instantiation. + + if not Expander_Active then + Set_In_Package_Body (Spec_Id, False); + + if Is_Generic_Instance (Spec_Id) + and then Operating_Mode = Generate_Code + then + Qualify_Entity_Names (N); + end if; + end if; + end Analyze_Package_Body; + + --------------------------------- + -- Analyze_Package_Declaration -- + --------------------------------- + + procedure Analyze_Package_Declaration (N : Node_Id) is + Id : constant Node_Id := Defining_Entity (N); + + PF : Boolean; + -- True when in the context of a declared pure library unit + + Body_Required : Boolean; + -- True when this package declaration requires a corresponding body + + Comp_Unit : Boolean; + -- True when this package declaration is not a nested declaration + + begin + -- Ada 2005 (AI-217): Check if the package has been erroneously named + -- in a limited-with clause of its own context. In this case the error + -- has been previously notified by Analyze_Context. + + -- limited with Pkg; -- ERROR + -- package Pkg is ... + + if From_With_Type (Id) then + return; + end if; + + Generate_Definition (Id); + Enter_Name (Id); + Set_Ekind (Id, E_Package); + Set_Etype (Id, Standard_Void_Type); + + Push_Scope (Id); + + PF := Is_Pure (Enclosing_Lib_Unit_Entity); + Set_Is_Pure (Id, PF); + + Set_Categorization_From_Pragmas (N); + + if Debug_Flag_C then + Write_Str ("==== Compiling package spec "); + Write_Name (Chars (Id)); + Write_Str (" from "); + Write_Location (Sloc (N)); + Write_Eol; + end if; + + Analyze (Specification (N)); + Validate_Categorization_Dependency (N, Id); + + Body_Required := Unit_Requires_Body (Id); + + -- When this spec does not require an explicit body, we know that + -- there are no entities requiring completion in the language sense; + -- we call Check_Completion here only to ensure that any nested package + -- declaration that requires an implicit body gets one. (In the case + -- where a body is required, Check_Completion is called at the end of + -- the body's declarative part.) + + if not Body_Required then + Check_Completion; + end if; + + Comp_Unit := Nkind (Parent (N)) = N_Compilation_Unit; + if Comp_Unit then + + -- Set Body_Required indication on the compilation unit node, and + -- determine whether elaboration warnings may be meaningful on it. + + Set_Body_Required (Parent (N), Body_Required); + + if not Body_Required then + Set_Suppress_Elaboration_Warnings (Id); + end if; + + end if; + + End_Package_Scope (Id); + + -- For the declaration of a library unit that is a remote types package, + -- check legality rules regarding availability of stream attributes for + -- types that contain non-remote access values. This subprogram performs + -- visibility tests that rely on the fact that we have exited the scope + -- of Id. + + if Comp_Unit then + Validate_RT_RAT_Component (N); + end if; + end Analyze_Package_Declaration; + + ----------------------------------- + -- Analyze_Package_Specification -- + ----------------------------------- + + -- Note that this code is shared for the analysis of generic package + -- specs (see Sem_Ch12.Analyze_Generic_Package_Declaration for details). + + procedure Analyze_Package_Specification (N : Node_Id) is + Id : constant Entity_Id := Defining_Entity (N); + Orig_Decl : constant Node_Id := Original_Node (Parent (N)); + Vis_Decls : constant List_Id := Visible_Declarations (N); + Priv_Decls : constant List_Id := Private_Declarations (N); + E : Entity_Id; + L : Entity_Id; + Public_Child : Boolean; + + Private_With_Clauses_Installed : Boolean := False; + -- In Ada 2005, private with_clauses are visible in the private part + -- of a nested package, even if it appears in the public part of the + -- enclosing package. This requires a separate step to install these + -- private_with_clauses, and remove them at the end of the nested + -- package. + + procedure Analyze_PPCs (Decls : List_Id); + -- Given a list of declarations, go through looking for subprogram + -- specs, and for each one found, analyze any pre/postconditions that + -- are chained to the spec. This is the implementation of the late + -- visibility analysis for preconditions and postconditions in specs. + + procedure Clear_Constants (Id : Entity_Id; FE : Entity_Id); + -- Clears constant indications (Never_Set_In_Source, Constant_Value, + -- and Is_True_Constant) on all variables that are entities of Id, + -- and on the chain whose first element is FE. A recursive call is + -- made for all packages and generic packages. + + procedure Generate_Parent_References; + -- For a child unit, generate references to parent units, for + -- GPS navigation purposes. + + function Is_Public_Child (Child, Unit : Entity_Id) return Boolean; + -- Child and Unit are entities of compilation units. True if Child + -- is a public child of Parent as defined in 10.1.1 + + procedure Inspect_Unchecked_Union_Completion (Decls : List_Id); + -- Detects all incomplete or private type declarations having a known + -- discriminant part that are completed by an Unchecked_Union. Emits + -- the error message "Unchecked_Union may not complete discriminated + -- partial view". + + procedure Install_Parent_Private_Declarations (Inst_Id : Entity_Id); + -- Given the package entity of a generic package instantiation or + -- formal package whose corresponding generic is a child unit, installs + -- the private declarations of each of the child unit's parents. + -- This has to be done at the point of entering the instance package's + -- private part rather than being done in Sem_Ch12.Install_Parent + -- (which is where the parents' visible declarations are installed). + + ------------------ + -- Analyze_PPCs -- + ------------------ + + procedure Analyze_PPCs (Decls : List_Id) is + Decl : Node_Id; + Spec : Node_Id; + Sent : Entity_Id; + Prag : Node_Id; + + begin + Decl := First (Decls); + while Present (Decl) loop + if Nkind (Original_Node (Decl)) = N_Subprogram_Declaration then + Spec := Specification (Original_Node (Decl)); + Sent := Defining_Unit_Name (Spec); + Prag := Spec_PPC_List (Sent); + while Present (Prag) loop + Analyze_PPC_In_Decl_Part (Prag, Sent); + Prag := Next_Pragma (Prag); + end loop; + end if; + + Next (Decl); + end loop; + end Analyze_PPCs; + + --------------------- + -- Clear_Constants -- + --------------------- + + procedure Clear_Constants (Id : Entity_Id; FE : Entity_Id) is + E : Entity_Id; + + begin + -- Ignore package renamings, not interesting and they can + -- cause self referential loops in the code below. + + if Nkind (Parent (Id)) = N_Package_Renaming_Declaration then + return; + end if; + + -- Note: in the loop below, the check for Next_Entity pointing + -- back to the package entity may seem odd, but it is needed, + -- because a package can contain a renaming declaration to itself, + -- and such renamings are generated automatically within package + -- instances. + + E := FE; + while Present (E) and then E /= Id loop + if Is_Assignable (E) then + Set_Never_Set_In_Source (E, False); + Set_Is_True_Constant (E, False); + Set_Current_Value (E, Empty); + Set_Is_Known_Null (E, False); + Set_Last_Assignment (E, Empty); + + if not Can_Never_Be_Null (E) then + Set_Is_Known_Non_Null (E, False); + end if; + + elsif Is_Package_Or_Generic_Package (E) then + Clear_Constants (E, First_Entity (E)); + Clear_Constants (E, First_Private_Entity (E)); + end if; + + Next_Entity (E); + end loop; + end Clear_Constants; + + -------------------------------- + -- Generate_Parent_References -- + -------------------------------- + + procedure Generate_Parent_References is + Decl : constant Node_Id := Parent (N); + + begin + if Id = Cunit_Entity (Main_Unit) + or else Parent (Decl) = Library_Unit (Cunit (Main_Unit)) + then + Generate_Reference (Id, Scope (Id), 'k', False); + + elsif not Nkind_In (Unit (Cunit (Main_Unit)), N_Subprogram_Body, + N_Subunit) + then + -- If current unit is an ancestor of main unit, generate + -- a reference to its own parent. + + declare + U : Node_Id; + Main_Spec : Node_Id := Unit (Cunit (Main_Unit)); + + begin + if Nkind (Main_Spec) = N_Package_Body then + Main_Spec := Unit (Library_Unit (Cunit (Main_Unit))); + end if; + + U := Parent_Spec (Main_Spec); + while Present (U) loop + if U = Parent (Decl) then + Generate_Reference (Id, Scope (Id), 'k', False); + exit; + + elsif Nkind (Unit (U)) = N_Package_Body then + exit; + + else + U := Parent_Spec (Unit (U)); + end if; + end loop; + end; + end if; + end Generate_Parent_References; + + --------------------- + -- Is_Public_Child -- + --------------------- + + function Is_Public_Child (Child, Unit : Entity_Id) return Boolean is + begin + if not Is_Private_Descendant (Child) then + return True; + else + if Child = Unit then + return not Private_Present ( + Parent (Unit_Declaration_Node (Child))); + else + return Is_Public_Child (Scope (Child), Unit); + end if; + end if; + end Is_Public_Child; + + ---------------------------------------- + -- Inspect_Unchecked_Union_Completion -- + ---------------------------------------- + + procedure Inspect_Unchecked_Union_Completion (Decls : List_Id) is + Decl : Node_Id; + + begin + Decl := First (Decls); + while Present (Decl) loop + + -- We are looking at an incomplete or private type declaration + -- with a known_discriminant_part whose full view is an + -- Unchecked_Union. + + if Nkind_In (Decl, N_Incomplete_Type_Declaration, + N_Private_Type_Declaration) + and then Has_Discriminants (Defining_Identifier (Decl)) + and then Present (Full_View (Defining_Identifier (Decl))) + and then + Is_Unchecked_Union (Full_View (Defining_Identifier (Decl))) + then + Error_Msg_N + ("completion of discriminated partial view " + & "cannot be an Unchecked_Union", + Full_View (Defining_Identifier (Decl))); + end if; + + Next (Decl); + end loop; + end Inspect_Unchecked_Union_Completion; + + ----------------------------------------- + -- Install_Parent_Private_Declarations -- + ----------------------------------------- + + procedure Install_Parent_Private_Declarations (Inst_Id : Entity_Id) is + Inst_Par : Entity_Id; + Gen_Par : Entity_Id; + Inst_Node : Node_Id; + + begin + Inst_Par := Inst_Id; + + Gen_Par := + Generic_Parent (Specification (Unit_Declaration_Node (Inst_Par))); + while Present (Gen_Par) and then Is_Child_Unit (Gen_Par) loop + Inst_Node := Get_Package_Instantiation_Node (Inst_Par); + + if Nkind_In (Inst_Node, N_Package_Instantiation, + N_Formal_Package_Declaration) + and then Nkind (Name (Inst_Node)) = N_Expanded_Name + then + Inst_Par := Entity (Prefix (Name (Inst_Node))); + + if Present (Renamed_Entity (Inst_Par)) then + Inst_Par := Renamed_Entity (Inst_Par); + end if; + + Gen_Par := + Generic_Parent + (Specification (Unit_Declaration_Node (Inst_Par))); + + -- Install the private declarations and private use clauses + -- of a parent instance of the child instance, unless the + -- parent instance private declarations have already been + -- installed earlier in Analyze_Package_Specification, which + -- happens when a generic child is instantiated, and the + -- instance is a child of the parent instance. + + -- Installing the use clauses of the parent instance twice + -- is both unnecessary and wrong, because it would cause the + -- clauses to be chained to themselves in the use clauses + -- list of the scope stack entry. That in turn would cause + -- an endless loop from End_Use_Clauses upon scope exit. + + -- The parent is now fully visible. It may be a hidden open + -- scope if we are currently compiling some child instance + -- declared within it, but while the current instance is being + -- compiled the parent is immediately visible. In particular + -- its entities must remain visible if a stack save/restore + -- takes place through a call to Rtsfind. + + if Present (Gen_Par) then + if not In_Private_Part (Inst_Par) then + Install_Private_Declarations (Inst_Par); + Set_Use (Private_Declarations + (Specification + (Unit_Declaration_Node (Inst_Par)))); + Set_Is_Hidden_Open_Scope (Inst_Par, False); + end if; + + -- If we've reached the end of the generic instance parents, + -- then finish off by looping through the nongeneric parents + -- and installing their private declarations. + + else + while Present (Inst_Par) + and then Inst_Par /= Standard_Standard + and then (not In_Open_Scopes (Inst_Par) + or else not In_Private_Part (Inst_Par)) + loop + Install_Private_Declarations (Inst_Par); + Set_Use (Private_Declarations + (Specification + (Unit_Declaration_Node (Inst_Par)))); + Inst_Par := Scope (Inst_Par); + end loop; + + exit; + end if; + + else + exit; + end if; + end loop; + end Install_Parent_Private_Declarations; + + -- Start of processing for Analyze_Package_Specification + + begin + if Present (Vis_Decls) then + Analyze_Declarations (Vis_Decls); + Analyze_PPCs (Vis_Decls); + end if; + + -- Verify that incomplete types have received full declarations + + E := First_Entity (Id); + while Present (E) loop + if Ekind (E) = E_Incomplete_Type + and then No (Full_View (E)) + then + Error_Msg_N ("no declaration in visible part for incomplete}", E); + end if; + + Next_Entity (E); + end loop; + + if Is_Remote_Call_Interface (Id) + and then Nkind (Parent (Parent (N))) = N_Compilation_Unit + then + Validate_RCI_Declarations (Id); + end if; + + -- Save global references in the visible declarations, before + -- installing private declarations of parent unit if there is one, + -- because the privacy status of types defined in the parent will + -- change. This is only relevant for generic child units, but is + -- done in all cases for uniformity. + + if Ekind (Id) = E_Generic_Package + and then Nkind (Orig_Decl) = N_Generic_Package_Declaration + then + declare + Orig_Spec : constant Node_Id := Specification (Orig_Decl); + Save_Priv : constant List_Id := Private_Declarations (Orig_Spec); + + begin + Set_Private_Declarations (Orig_Spec, Empty_List); + Save_Global_References (Orig_Decl); + Set_Private_Declarations (Orig_Spec, Save_Priv); + end; + end if; + + -- If package is a public child unit, then make the private declarations + -- of the parent visible. + + Public_Child := False; + + declare + Par : Entity_Id; + Pack_Decl : Node_Id; + Par_Spec : Node_Id; + + begin + Par := Id; + Par_Spec := Parent_Spec (Parent (N)); + + -- If the package is formal package of an enclosing generic, it is + -- transformed into a local generic declaration, and compiled to make + -- its spec available. We need to retrieve the original generic to + -- determine whether it is a child unit, and install its parents. + + if No (Par_Spec) + and then + Nkind (Original_Node (Parent (N))) = N_Formal_Package_Declaration + then + Par := Entity (Name (Original_Node (Parent (N)))); + Par_Spec := Parent_Spec (Unit_Declaration_Node (Par)); + end if; + + if Present (Par_Spec) then + Generate_Parent_References; + + while Scope (Par) /= Standard_Standard + and then Is_Public_Child (Id, Par) + and then In_Open_Scopes (Par) + loop + Public_Child := True; + Par := Scope (Par); + Install_Private_Declarations (Par); + Install_Private_With_Clauses (Par); + Pack_Decl := Unit_Declaration_Node (Par); + Set_Use (Private_Declarations (Specification (Pack_Decl))); + end loop; + end if; + end; + + if Is_Compilation_Unit (Id) then + Install_Private_With_Clauses (Id); + else + + -- The current compilation unit may include private with_clauses, + -- which are visible in the private part of the current nested + -- package, and have to be installed now. This is not done for + -- nested instantiations, where the private with_clauses of the + -- enclosing unit have no effect once the instantiation info is + -- established and we start analyzing the package declaration. + + declare + Comp_Unit : constant Entity_Id := Cunit_Entity (Current_Sem_Unit); + begin + if Is_Package_Or_Generic_Package (Comp_Unit) + and then not In_Private_Part (Comp_Unit) + and then not In_Instance + then + Install_Private_With_Clauses (Comp_Unit); + Private_With_Clauses_Installed := True; + end if; + end; + end if; + + -- If this is a package associated with a generic instance or formal + -- package, then the private declarations of each of the generic's + -- parents must be installed at this point. + + if Is_Generic_Instance (Id) then + Install_Parent_Private_Declarations (Id); + end if; + + -- Analyze private part if present. The flag In_Private_Part is reset + -- in End_Package_Scope. + + L := Last_Entity (Id); + + if Present (Priv_Decls) then + Set_In_Private_Part (Id); + + -- Upon entering a public child's private part, it may be necessary + -- to declare subprograms that were derived in the package's visible + -- part but not yet made visible. + + if Public_Child then + Declare_Inherited_Private_Subprograms (Id); + end if; + + Analyze_Declarations (Priv_Decls); + Analyze_PPCs (Priv_Decls); + + -- Check the private declarations for incomplete deferred constants + + Inspect_Deferred_Constant_Completion (Priv_Decls); + + -- The first private entity is the immediate follower of the last + -- visible entity, if there was one. + + if Present (L) then + Set_First_Private_Entity (Id, Next_Entity (L)); + else + Set_First_Private_Entity (Id, First_Entity (Id)); + end if; + + -- There may be inherited private subprograms that need to be declared, + -- even in the absence of an explicit private part. If there are any + -- public declarations in the package and the package is a public child + -- unit, then an implicit private part is assumed. + + elsif Present (L) and then Public_Child then + Set_In_Private_Part (Id); + Declare_Inherited_Private_Subprograms (Id); + Set_First_Private_Entity (Id, Next_Entity (L)); + end if; + + E := First_Entity (Id); + while Present (E) loop + + -- Check rule of 3.6(11), which in general requires waiting till all + -- full types have been seen. + + if Ekind (E) = E_Record_Type or else Ekind (E) = E_Array_Type then + Check_Aliased_Component_Types (E); + end if; + + -- Check preelaborable initialization for full type completing a + -- private type for which pragma Preelaborable_Initialization given. + + if Is_Type (E) + and then Must_Have_Preelab_Init (E) + and then not Has_Preelaborable_Initialization (E) + then + Error_Msg_N + ("full view of & does not have preelaborable initialization", E); + end if; + + Next_Entity (E); + end loop; + + -- Ada 2005 (AI-216): The completion of an incomplete or private type + -- declaration having a known_discriminant_part shall not be an + -- Unchecked_Union type. + + if Present (Vis_Decls) then + Inspect_Unchecked_Union_Completion (Vis_Decls); + end if; + + if Present (Priv_Decls) then + Inspect_Unchecked_Union_Completion (Priv_Decls); + end if; + + if Ekind (Id) = E_Generic_Package + and then Nkind (Orig_Decl) = N_Generic_Package_Declaration + and then Present (Priv_Decls) + then + -- Save global references in private declarations, ignoring the + -- visible declarations that were processed earlier. + + declare + Orig_Spec : constant Node_Id := Specification (Orig_Decl); + Save_Vis : constant List_Id := Visible_Declarations (Orig_Spec); + Save_Form : constant List_Id := + Generic_Formal_Declarations (Orig_Decl); + + begin + Set_Visible_Declarations (Orig_Spec, Empty_List); + Set_Generic_Formal_Declarations (Orig_Decl, Empty_List); + Save_Global_References (Orig_Decl); + Set_Generic_Formal_Declarations (Orig_Decl, Save_Form); + Set_Visible_Declarations (Orig_Spec, Save_Vis); + end; + end if; + + Process_End_Label (N, 'e', Id); + + -- Remove private_with_clauses of enclosing compilation unit, if they + -- were installed. + + if Private_With_Clauses_Installed then + Remove_Private_With_Clauses (Cunit (Current_Sem_Unit)); + end if; + + -- For the case of a library level package, we must go through all the + -- entities clearing the indications that the value may be constant and + -- not modified. Why? Because any client of this package may modify + -- these values freely from anywhere. This also applies to any nested + -- packages or generic packages. + + -- For now we unconditionally clear constants for packages that are + -- instances of generic packages. The reason is that we do not have the + -- body yet, and we otherwise think things are unreferenced when they + -- are not. This should be fixed sometime (the effect is not terrible, + -- we just lose some warnings, and also some cases of value propagation) + -- ??? + + if Is_Library_Level_Entity (Id) + or else Is_Generic_Instance (Id) + then + Clear_Constants (Id, First_Entity (Id)); + Clear_Constants (Id, First_Private_Entity (Id)); + end if; + end Analyze_Package_Specification; + + -------------------------------------- + -- Analyze_Private_Type_Declaration -- + -------------------------------------- + + procedure Analyze_Private_Type_Declaration (N : Node_Id) is + PF : constant Boolean := Is_Pure (Enclosing_Lib_Unit_Entity); + Id : constant Entity_Id := Defining_Identifier (N); + + begin + Generate_Definition (Id); + Set_Is_Pure (Id, PF); + Init_Size_Align (Id); + + if not Is_Package_Or_Generic_Package (Current_Scope) + or else In_Private_Part (Current_Scope) + then + Error_Msg_N ("invalid context for private declaration", N); + end if; + + New_Private_Type (N, Id, N); + Set_Depends_On_Private (Id); + end Analyze_Private_Type_Declaration; + + ---------------------------------- + -- Check_Anonymous_Access_Types -- + ---------------------------------- + + procedure Check_Anonymous_Access_Types + (Spec_Id : Entity_Id; + P_Body : Node_Id) + is + E : Entity_Id; + IR : Node_Id; + + begin + -- Itype references are only needed by gigi, to force elaboration of + -- itypes. In the absence of code generation, they are not needed. + + if not Expander_Active then + return; + end if; + + E := First_Entity (Spec_Id); + while Present (E) loop + if Ekind (E) = E_Anonymous_Access_Type + and then From_With_Type (E) + then + IR := Make_Itype_Reference (Sloc (P_Body)); + Set_Itype (IR, E); + + if No (Declarations (P_Body)) then + Set_Declarations (P_Body, New_List (IR)); + else + Prepend (IR, Declarations (P_Body)); + end if; + end if; + + Next_Entity (E); + end loop; + end Check_Anonymous_Access_Types; + + ------------------------------------------- + -- Declare_Inherited_Private_Subprograms -- + ------------------------------------------- + + procedure Declare_Inherited_Private_Subprograms (Id : Entity_Id) is + + function Is_Primitive_Of (T : Entity_Id; S : Entity_Id) return Boolean; + -- Check whether an inherited subprogram is an operation of an + -- untagged derived type. + + --------------------- + -- Is_Primitive_Of -- + --------------------- + + function Is_Primitive_Of (T : Entity_Id; S : Entity_Id) return Boolean is + Formal : Entity_Id; + + begin + -- If the full view is a scalar type, the type is the anonymous + -- base type, but the operation mentions the first subtype, so + -- check the signature against the base type. + + if Base_Type (Etype (S)) = Base_Type (T) then + return True; + + else + Formal := First_Formal (S); + while Present (Formal) loop + if Base_Type (Etype (Formal)) = Base_Type (T) then + return True; + end if; + + Next_Formal (Formal); + end loop; + + return False; + end if; + end Is_Primitive_Of; + + -- Local variables + + E : Entity_Id; + Op_List : Elist_Id; + Op_Elmt : Elmt_Id; + Op_Elmt_2 : Elmt_Id; + Prim_Op : Entity_Id; + New_Op : Entity_Id := Empty; + Parent_Subp : Entity_Id; + Tag : Entity_Id; + + -- Start of processing for Declare_Inherited_Private_Subprograms + + begin + E := First_Entity (Id); + while Present (E) loop + + -- If the entity is a nonprivate type extension whose parent + -- type is declared in an open scope, then the type may have + -- inherited operations that now need to be made visible. + -- Ditto if the entity is a formal derived type in a child unit. + + if ((Is_Derived_Type (E) and then not Is_Private_Type (E)) + or else + (Nkind (Parent (E)) = N_Private_Extension_Declaration + and then Is_Generic_Type (E))) + and then In_Open_Scopes (Scope (Etype (E))) + and then E = Base_Type (E) + then + if Is_Tagged_Type (E) then + Op_List := Primitive_Operations (E); + New_Op := Empty; + Tag := First_Tag_Component (E); + + Op_Elmt := First_Elmt (Op_List); + while Present (Op_Elmt) loop + Prim_Op := Node (Op_Elmt); + + -- Search primitives that are implicit operations with an + -- internal name whose parent operation has a normal name. + + if Present (Alias (Prim_Op)) + and then Find_Dispatching_Type (Alias (Prim_Op)) /= E + and then not Comes_From_Source (Prim_Op) + and then Is_Internal_Name (Chars (Prim_Op)) + and then not Is_Internal_Name (Chars (Alias (Prim_Op))) + then + Parent_Subp := Alias (Prim_Op); + + -- Case 1: Check if the type has also an explicit + -- overriding for this primitive. + + Op_Elmt_2 := Next_Elmt (Op_Elmt); + while Present (Op_Elmt_2) loop + if Chars (Node (Op_Elmt_2)) = Chars (Parent_Subp) + and then Type_Conformant (Prim_Op, Node (Op_Elmt_2)) + then + -- The private inherited operation has been + -- overridden by an explicit subprogram: replace + -- the former by the latter. + + New_Op := Node (Op_Elmt_2); + Replace_Elmt (Op_Elmt, New_Op); + Remove_Elmt (Op_List, Op_Elmt_2); + Set_Is_Overriding_Operation (New_Op); + Set_Overridden_Operation (New_Op, Parent_Subp); + + -- We don't need to inherit its dispatching slot. + -- Set_All_DT_Position has previously ensured that + -- the same slot was assigned to the two primitives + + if Present (Tag) + and then Present (DTC_Entity (New_Op)) + and then Present (DTC_Entity (Prim_Op)) + then + pragma Assert (DT_Position (New_Op) + = DT_Position (Prim_Op)); + null; + end if; + + goto Next_Primitive; + end if; + + Next_Elmt (Op_Elmt_2); + end loop; + + -- Case 2: We have not found any explicit overriding and + -- hence we need to declare the operation (i.e., make it + -- visible). + + Derive_Subprogram (New_Op, Alias (Prim_Op), E, Etype (E)); + + -- Inherit the dispatching slot if E is already frozen + + if Is_Frozen (E) + and then Present (DTC_Entity (Alias (Prim_Op))) + then + Set_DTC_Entity_Value (E, New_Op); + Set_DT_Position (New_Op, + DT_Position (Alias (Prim_Op))); + end if; + + pragma Assert + (Is_Dispatching_Operation (New_Op) + and then Node (Last_Elmt (Op_List)) = New_Op); + + -- Substitute the new operation for the old one + -- in the type's primitive operations list. Since + -- the new operation was also just added to the end + -- of list, the last element must be removed. + + -- (Question: is there a simpler way of declaring + -- the operation, say by just replacing the name + -- of the earlier operation, reentering it in the + -- in the symbol table (how?), and marking it as + -- private???) + + Replace_Elmt (Op_Elmt, New_Op); + Remove_Last_Elmt (Op_List); + end if; + + <<Next_Primitive>> + Next_Elmt (Op_Elmt); + end loop; + + -- Generate listing showing the contents of the dispatch table + + if Debug_Flag_ZZ then + Write_DT (E); + end if; + + else + -- Non-tagged type, scan forward to locate + -- inherited hidden operations. + + Prim_Op := Next_Entity (E); + while Present (Prim_Op) loop + if Is_Subprogram (Prim_Op) + and then Present (Alias (Prim_Op)) + and then not Comes_From_Source (Prim_Op) + and then Is_Internal_Name (Chars (Prim_Op)) + and then not Is_Internal_Name (Chars (Alias (Prim_Op))) + and then Is_Primitive_Of (E, Prim_Op) + then + Derive_Subprogram (New_Op, Alias (Prim_Op), E, Etype (E)); + end if; + + Next_Entity (Prim_Op); + end loop; + end if; + end if; + + Next_Entity (E); + end loop; + end Declare_Inherited_Private_Subprograms; + + ----------------------- + -- End_Package_Scope -- + ----------------------- + + procedure End_Package_Scope (P : Entity_Id) is + begin + Uninstall_Declarations (P); + Pop_Scope; + end End_Package_Scope; + + --------------------------- + -- Exchange_Declarations -- + --------------------------- + + procedure Exchange_Declarations (Id : Entity_Id) is + Full_Id : constant Entity_Id := Full_View (Id); + H1 : constant Entity_Id := Homonym (Id); + Next1 : constant Entity_Id := Next_Entity (Id); + H2 : Entity_Id; + Next2 : Entity_Id; + + begin + -- If missing full declaration for type, nothing to exchange + + if No (Full_Id) then + return; + end if; + + -- Otherwise complete the exchange, and preserve semantic links + + Next2 := Next_Entity (Full_Id); + H2 := Homonym (Full_Id); + + -- Reset full declaration pointer to reflect the switched entities + -- and readjust the next entity chains. + + Exchange_Entities (Id, Full_Id); + + Set_Next_Entity (Id, Next1); + Set_Homonym (Id, H1); + + Set_Full_View (Full_Id, Id); + Set_Next_Entity (Full_Id, Next2); + Set_Homonym (Full_Id, H2); + end Exchange_Declarations; + + ---------------------------- + -- Install_Package_Entity -- + ---------------------------- + + procedure Install_Package_Entity (Id : Entity_Id) is + begin + if not Is_Internal (Id) then + if Debug_Flag_E then + Write_Str ("Install: "); + Write_Name (Chars (Id)); + Write_Eol; + end if; + + if not Is_Child_Unit (Id) then + Set_Is_Immediately_Visible (Id); + end if; + + end if; + end Install_Package_Entity; + + ---------------------------------- + -- Install_Private_Declarations -- + ---------------------------------- + + procedure Install_Private_Declarations (P : Entity_Id) is + Id : Entity_Id; + Priv_Elmt : Elmt_Id; + Priv : Entity_Id; + Full : Entity_Id; + + begin + -- First exchange declarations for private types, so that the + -- full declaration is visible. For each private type, we check + -- its Private_Dependents list and also exchange any subtypes of + -- or derived types from it. Finally, if this is a Taft amendment + -- type, the incomplete declaration is irrelevant, and we want to + -- link the eventual full declaration with the original private + -- one so we also skip the exchange. + + Id := First_Entity (P); + while Present (Id) and then Id /= First_Private_Entity (P) loop + if Is_Private_Base_Type (Id) + and then Comes_From_Source (Full_View (Id)) + and then Present (Full_View (Id)) + and then Scope (Full_View (Id)) = Scope (Id) + and then Ekind (Full_View (Id)) /= E_Incomplete_Type + then + -- If there is a use-type clause on the private type, set the + -- full view accordingly. + + Set_In_Use (Full_View (Id), In_Use (Id)); + Full := Full_View (Id); + + if Is_Private_Base_Type (Full) + and then Has_Private_Declaration (Full) + and then Nkind (Parent (Full)) = N_Full_Type_Declaration + and then In_Open_Scopes (Scope (Etype (Full))) + and then In_Package_Body (Current_Scope) + and then not Is_Private_Type (Etype (Full)) + then + -- This is the completion of a private type by a derivation + -- from another private type which is not private anymore. This + -- can only happen in a package nested within a child package, + -- when the parent type is defined in the parent unit. At this + -- point the current type is not private either, and we have to + -- install the underlying full view, which is now visible. + -- Save the current full view as well, so that all views can + -- be restored on exit. It may seem that after compiling the + -- child body there are not environments to restore, but the + -- back-end expects those links to be valid, and freeze nodes + -- depend on them. + + if No (Full_View (Full)) + and then Present (Underlying_Full_View (Full)) + then + Set_Full_View (Id, Underlying_Full_View (Full)); + Set_Underlying_Full_View (Id, Full); + + Set_Underlying_Full_View (Full, Empty); + Set_Is_Frozen (Full_View (Id)); + end if; + end if; + + Priv_Elmt := First_Elmt (Private_Dependents (Id)); + + Exchange_Declarations (Id); + Set_Is_Immediately_Visible (Id); + + while Present (Priv_Elmt) loop + Priv := Node (Priv_Elmt); + + -- Before the exchange, verify that the presence of the + -- Full_View field. It will be empty if the entity + -- has already been installed due to a previous call. + + if Present (Full_View (Priv)) + and then Is_Visible_Dependent (Priv) + then + + -- For each subtype that is swapped, we also swap the + -- reference to it in Private_Dependents, to allow access + -- to it when we swap them out in End_Package_Scope. + + Replace_Elmt (Priv_Elmt, Full_View (Priv)); + Exchange_Declarations (Priv); + Set_Is_Immediately_Visible + (Priv, In_Open_Scopes (Scope (Priv))); + Set_Is_Potentially_Use_Visible + (Priv, Is_Potentially_Use_Visible (Node (Priv_Elmt))); + end if; + + Next_Elmt (Priv_Elmt); + end loop; + end if; + + Next_Entity (Id); + end loop; + + -- Next make other declarations in the private part visible as well + + Id := First_Private_Entity (P); + while Present (Id) loop + Install_Package_Entity (Id); + Set_Is_Hidden (Id, False); + Next_Entity (Id); + end loop; + + -- Indicate that the private part is currently visible, so it can be + -- properly reset on exit. + + Set_In_Private_Part (P); + end Install_Private_Declarations; + + ---------------------------------- + -- Install_Visible_Declarations -- + ---------------------------------- + + procedure Install_Visible_Declarations (P : Entity_Id) is + Id : Entity_Id; + Last_Entity : Entity_Id; + + begin + pragma Assert + (Is_Package_Or_Generic_Package (P) or else Is_Record_Type (P)); + + if Is_Package_Or_Generic_Package (P) then + Last_Entity := First_Private_Entity (P); + else + Last_Entity := Empty; + end if; + + Id := First_Entity (P); + while Present (Id) and then Id /= Last_Entity loop + Install_Package_Entity (Id); + Next_Entity (Id); + end loop; + end Install_Visible_Declarations; + + -------------------------- + -- Is_Private_Base_Type -- + -------------------------- + + function Is_Private_Base_Type (E : Entity_Id) return Boolean is + begin + return Ekind (E) = E_Private_Type + or else Ekind (E) = E_Limited_Private_Type + or else Ekind (E) = E_Record_Type_With_Private; + end Is_Private_Base_Type; + + -------------------------- + -- Is_Visible_Dependent -- + -------------------------- + + function Is_Visible_Dependent (Dep : Entity_Id) return Boolean + is + S : constant Entity_Id := Scope (Dep); + + begin + -- Renamings created for actual types have the visibility of the + -- actual. + + if Ekind (S) = E_Package + and then Is_Generic_Instance (S) + and then (Is_Generic_Actual_Type (Dep) + or else Is_Generic_Actual_Type (Full_View (Dep))) + then + return True; + + elsif not (Is_Derived_Type (Dep)) + and then Is_Derived_Type (Full_View (Dep)) + then + -- When instantiating a package body, the scope stack is empty, + -- so check instead whether the dependent type is defined in + -- the same scope as the instance itself. + + return In_Open_Scopes (S) + or else (Is_Generic_Instance (Current_Scope) + and then Scope (Dep) = Scope (Current_Scope)); + else + return True; + end if; + end Is_Visible_Dependent; + + ---------------------------- + -- May_Need_Implicit_Body -- + ---------------------------- + + procedure May_Need_Implicit_Body (E : Entity_Id) is + P : constant Node_Id := Unit_Declaration_Node (E); + S : constant Node_Id := Parent (P); + B : Node_Id; + Decls : List_Id; + + begin + if not Has_Completion (E) + and then Nkind (P) = N_Package_Declaration + and then (Present (Activation_Chain_Entity (P)) or else Has_RACW (E)) + then + B := + Make_Package_Body (Sloc (E), + Defining_Unit_Name => Make_Defining_Identifier (Sloc (E), + Chars => Chars (E)), + Declarations => New_List); + + if Nkind (S) = N_Package_Specification then + if Present (Private_Declarations (S)) then + Decls := Private_Declarations (S); + else + Decls := Visible_Declarations (S); + end if; + else + Decls := Declarations (S); + end if; + + Append (B, Decls); + Analyze (B); + end if; + end May_Need_Implicit_Body; + + ---------------------- + -- New_Private_Type -- + ---------------------- + + procedure New_Private_Type (N : Node_Id; Id : Entity_Id; Def : Node_Id) is + begin + Enter_Name (Id); + + if Limited_Present (Def) then + Set_Ekind (Id, E_Limited_Private_Type); + else + Set_Ekind (Id, E_Private_Type); + end if; + + Set_Etype (Id, Id); + Set_Has_Delayed_Freeze (Id); + Set_Is_First_Subtype (Id); + Init_Size_Align (Id); + + Set_Is_Constrained (Id, + No (Discriminant_Specifications (N)) + and then not Unknown_Discriminants_Present (N)); + + -- Set tagged flag before processing discriminants, to catch + -- illegal usage. + + Set_Is_Tagged_Type (Id, Tagged_Present (Def)); + + Set_Discriminant_Constraint (Id, No_Elist); + Set_Stored_Constraint (Id, No_Elist); + + if Present (Discriminant_Specifications (N)) then + Push_Scope (Id); + Process_Discriminants (N); + End_Scope; + + elsif Unknown_Discriminants_Present (N) then + Set_Has_Unknown_Discriminants (Id); + end if; + + Set_Private_Dependents (Id, New_Elmt_List); + + if Tagged_Present (Def) then + Set_Ekind (Id, E_Record_Type_With_Private); + Make_Class_Wide_Type (Id); + Set_Primitive_Operations (Id, New_Elmt_List); + Set_Is_Abstract_Type (Id, Abstract_Present (Def)); + Set_Is_Limited_Record (Id, Limited_Present (Def)); + Set_Has_Delayed_Freeze (Id, True); + + elsif Abstract_Present (Def) then + Error_Msg_N ("only a tagged type can be abstract", N); + end if; + end New_Private_Type; + + ---------------------------- + -- Uninstall_Declarations -- + ---------------------------- + + procedure Uninstall_Declarations (P : Entity_Id) is + Decl : constant Node_Id := Unit_Declaration_Node (P); + Id : Entity_Id; + Full : Entity_Id; + Priv_Elmt : Elmt_Id; + Priv_Sub : Entity_Id; + + procedure Preserve_Full_Attributes (Priv, Full : Entity_Id); + -- Copy to the private declaration the attributes of the full view + -- that need to be available for the partial view also. + + function Type_In_Use (T : Entity_Id) return Boolean; + -- Check whether type or base type appear in an active use_type clause + + ------------------------------ + -- Preserve_Full_Attributes -- + ------------------------------ + + procedure Preserve_Full_Attributes (Priv, Full : Entity_Id) is + Priv_Is_Base_Type : constant Boolean := Priv = Base_Type (Priv); + + begin + Set_Size_Info (Priv, (Full)); + Set_RM_Size (Priv, RM_Size (Full)); + Set_Size_Known_At_Compile_Time + (Priv, Size_Known_At_Compile_Time (Full)); + Set_Is_Volatile (Priv, Is_Volatile (Full)); + Set_Treat_As_Volatile (Priv, Treat_As_Volatile (Full)); + Set_Is_Ada_2005_Only (Priv, Is_Ada_2005_Only (Full)); + Set_Has_Pragma_Unreferenced (Priv, Has_Pragma_Unreferenced (Full)); + Set_Has_Pragma_Unreferenced_Objects + (Priv, Has_Pragma_Unreferenced_Objects + (Full)); + if Is_Unchecked_Union (Full) then + Set_Is_Unchecked_Union (Base_Type (Priv)); + end if; + -- Why is atomic not copied here ??? + + if Referenced (Full) then + Set_Referenced (Priv); + end if; + + if Priv_Is_Base_Type then + Set_Is_Controlled (Priv, Is_Controlled (Base_Type (Full))); + Set_Finalize_Storage_Only (Priv, Finalize_Storage_Only + (Base_Type (Full))); + Set_Has_Task (Priv, Has_Task (Base_Type (Full))); + Set_Has_Controlled_Component (Priv, Has_Controlled_Component + (Base_Type (Full))); + end if; + + Set_Freeze_Node (Priv, Freeze_Node (Full)); + + if Is_Tagged_Type (Priv) + and then Is_Tagged_Type (Full) + and then not Error_Posted (Full) + then + if Priv_Is_Base_Type then + + -- Ada 2005 (AI-345): The full view of a type implementing + -- an interface can be a task type. + + -- type T is new I with private; + -- private + -- task type T is new I with ... + + if Is_Interface (Etype (Priv)) + and then Is_Concurrent_Type (Base_Type (Full)) + then + -- Protect the frontend against previous errors + + if Present (Corresponding_Record_Type + (Base_Type (Full))) + then + Set_Access_Disp_Table + (Priv, Access_Disp_Table + (Corresponding_Record_Type (Base_Type (Full)))); + + -- Generic context, or previous errors + + else + null; + end if; + + else + Set_Access_Disp_Table + (Priv, Access_Disp_Table (Base_Type (Full))); + end if; + end if; + + if Is_Tagged_Type (Priv) then + + -- If the type is tagged, the tag itself must be available + -- on the partial view, for expansion purposes. + + Set_First_Entity (Priv, First_Entity (Full)); + + -- If there are discriminants in the partial view, these remain + -- visible. Otherwise only the tag itself is visible, and there + -- are no nameable components in the partial view. + + if No (Last_Entity (Priv)) then + Set_Last_Entity (Priv, First_Entity (Priv)); + end if; + end if; + + Set_Has_Discriminants (Priv, Has_Discriminants (Full)); + end if; + end Preserve_Full_Attributes; + + ----------------- + -- Type_In_Use -- + ----------------- + + function Type_In_Use (T : Entity_Id) return Boolean is + begin + return Scope (Base_Type (T)) = P + and then (In_Use (T) or else In_Use (Base_Type (T))); + end Type_In_Use; + + -- Start of processing for Uninstall_Declarations + + begin + Id := First_Entity (P); + while Present (Id) and then Id /= First_Private_Entity (P) loop + if Debug_Flag_E then + Write_Str ("unlinking visible entity "); + Write_Int (Int (Id)); + Write_Eol; + end if; + + -- On exit from the package scope, we must preserve the visibility + -- established by use clauses in the current scope. Two cases: + + -- a) If the entity is an operator, it may be a primitive operator of + -- a type for which there is a visible use-type clause. + + -- b) for other entities, their use-visibility is determined by a + -- visible use clause for the package itself. For a generic instance, + -- the instantiation of the formals appears in the visible part, + -- but the formals are private and remain so. + + if Ekind (Id) = E_Function + and then Is_Operator_Symbol_Name (Chars (Id)) + and then not Is_Hidden (Id) + and then not Error_Posted (Id) + then + Set_Is_Potentially_Use_Visible (Id, + In_Use (P) + or else Type_In_Use (Etype (Id)) + or else Type_In_Use (Etype (First_Formal (Id))) + or else (Present (Next_Formal (First_Formal (Id))) + and then + Type_In_Use + (Etype (Next_Formal (First_Formal (Id)))))); + else + if In_Use (P) and then not Is_Hidden (Id) then + + -- A child unit of a use-visible package remains use-visible + -- only if it is itself a visible child unit. Otherwise it + -- would remain visible in other contexts where P is use- + -- visible, because once compiled it stays in the entity list + -- of its parent unit. + + if Is_Child_Unit (Id) then + Set_Is_Potentially_Use_Visible (Id, + Is_Visible_Child_Unit (Id)); + else + Set_Is_Potentially_Use_Visible (Id); + end if; + + else + Set_Is_Potentially_Use_Visible (Id, False); + end if; + end if; + + -- Local entities are not immediately visible outside of the package + + Set_Is_Immediately_Visible (Id, False); + + -- If this is a private type with a full view (for example a local + -- subtype of a private type declared elsewhere), ensure that the + -- full view is also removed from visibility: it may be exposed when + -- swapping views in an instantiation. + + if Is_Type (Id) + and then Present (Full_View (Id)) + then + Set_Is_Immediately_Visible (Full_View (Id), False); + end if; + + if Is_Tagged_Type (Id) and then Ekind (Id) = E_Record_Type then + Check_Abstract_Overriding (Id); + Check_Conventions (Id); + end if; + + if (Ekind (Id) = E_Private_Type + or else Ekind (Id) = E_Limited_Private_Type) + and then No (Full_View (Id)) + and then not Is_Generic_Type (Id) + and then not Is_Derived_Type (Id) + then + Error_Msg_N ("missing full declaration for private type&", Id); + + elsif Ekind (Id) = E_Record_Type_With_Private + and then not Is_Generic_Type (Id) + and then No (Full_View (Id)) + then + if Nkind (Parent (Id)) = N_Private_Type_Declaration then + Error_Msg_N ("missing full declaration for private type&", Id); + else + Error_Msg_N + ("missing full declaration for private extension", Id); + end if; + + elsif Ekind (Id) = E_Constant + and then No (Constant_Value (Id)) + and then No (Full_View (Id)) + and then not Is_Imported (Id) + and then (Nkind (Parent (Id)) /= N_Object_Declaration + or else not No_Initialization (Parent (Id))) + then + if not Has_Private_Declaration (Etype (Id)) then + + -- We assume that the user did not intend a deferred + -- constant declaration, and the expression is just missing. + + Error_Msg_N + ("constant declaration requires initialization expression", + Parent (Id)); + + if Is_Limited_Type (Etype (Id)) then + Error_Msg_N + ("\if variable intended, remove CONSTANT from declaration", + Parent (Id)); + end if; + + else + Error_Msg_N + ("missing full declaration for deferred constant (RM 7.4)", + Id); + + if Is_Limited_Type (Etype (Id)) then + Error_Msg_N + ("\if variable intended, remove CONSTANT from declaration", + Parent (Id)); + end if; + end if; + end if; + + Next_Entity (Id); + end loop; + + -- If the specification was installed as the parent of a public child + -- unit, the private declarations were not installed, and there is + -- nothing to do. + + if not In_Private_Part (P) then + return; + else + Set_In_Private_Part (P, False); + end if; + + -- Make private entities invisible and exchange full and private + -- declarations for private types. Id is now the first private + -- entity in the package. + + while Present (Id) loop + if Debug_Flag_E then + Write_Str ("unlinking private entity "); + Write_Int (Int (Id)); + Write_Eol; + end if; + + if Is_Tagged_Type (Id) and then Ekind (Id) = E_Record_Type then + Check_Abstract_Overriding (Id); + Check_Conventions (Id); + end if; + + Set_Is_Immediately_Visible (Id, False); + + if Is_Private_Base_Type (Id) + and then Present (Full_View (Id)) + then + Full := Full_View (Id); + + -- If the partial view is not declared in the visible part + -- of the package (as is the case when it is a type derived + -- from some other private type in the private part of the + -- current package), no exchange takes place. + + if No (Parent (Id)) + or else List_Containing (Parent (Id)) + /= Visible_Declarations (Specification (Decl)) + then + goto Next_Id; + end if; + + -- The entry in the private part points to the full declaration, + -- which is currently visible. Exchange them so only the private + -- type declaration remains accessible, and link private and + -- full declaration in the opposite direction. Before the actual + -- exchange, we copy back attributes of the full view that + -- must be available to the partial view too. + + Preserve_Full_Attributes (Id, Full); + + Set_Is_Potentially_Use_Visible (Id, In_Use (P)); + + if Is_Indefinite_Subtype (Full) + and then not Is_Indefinite_Subtype (Id) + then + Error_Msg_N + ("full view of type must be definite subtype", Full); + end if; + + Priv_Elmt := First_Elmt (Private_Dependents (Id)); + + -- Swap out the subtypes and derived types of Id that were + -- compiled in this scope, or installed previously by + -- Install_Private_Declarations. + -- Before we do the swap, we verify the presence of the + -- Full_View field which may be empty due to a swap by + -- a previous call to End_Package_Scope (e.g. from the + -- freezing mechanism). + + while Present (Priv_Elmt) loop + Priv_Sub := Node (Priv_Elmt); + + if Present (Full_View (Priv_Sub)) then + + if Scope (Priv_Sub) = P + or else not In_Open_Scopes (Scope (Priv_Sub)) + then + Set_Is_Immediately_Visible (Priv_Sub, False); + end if; + + if Is_Visible_Dependent (Priv_Sub) then + Preserve_Full_Attributes + (Priv_Sub, Full_View (Priv_Sub)); + Replace_Elmt (Priv_Elmt, Full_View (Priv_Sub)); + Exchange_Declarations (Priv_Sub); + end if; + end if; + + Next_Elmt (Priv_Elmt); + end loop; + + -- Now restore the type itself to its private view + + Exchange_Declarations (Id); + + -- If we have installed an underlying full view for a type + -- derived from a private type in a child unit, restore the + -- proper views of private and full view. See corresponding + -- code in Install_Private_Declarations. + -- After the exchange, Full denotes the private type in the + -- visible part of the package. + + if Is_Private_Base_Type (Full) + and then Present (Full_View (Full)) + and then Present (Underlying_Full_View (Full)) + and then In_Package_Body (Current_Scope) + then + Set_Full_View (Full, Underlying_Full_View (Full)); + Set_Underlying_Full_View (Full, Empty); + end if; + + elsif Ekind (Id) = E_Incomplete_Type + and then No (Full_View (Id)) + then + -- Mark Taft amendment types + + Set_Has_Completion_In_Body (Id); + + elsif not Is_Child_Unit (Id) + and then (not Is_Private_Type (Id) + or else No (Full_View (Id))) + then + Set_Is_Hidden (Id); + Set_Is_Potentially_Use_Visible (Id, False); + end if; + + <<Next_Id>> + Next_Entity (Id); + end loop; + end Uninstall_Declarations; + + ------------------------ + -- Unit_Requires_Body -- + ------------------------ + + function Unit_Requires_Body (P : Entity_Id) return Boolean is + E : Entity_Id; + + begin + -- Imported entity never requires body. Right now, only + -- subprograms can be imported, but perhaps in the future + -- we will allow import of packages. + + if Is_Imported (P) then + return False; + + -- Body required if library package with pragma Elaborate_Body + + elsif Has_Pragma_Elaborate_Body (P) then + return True; + + -- Body required if subprogram + + elsif Is_Subprogram (P) or else Is_Generic_Subprogram (P) then + return True; + + -- Treat a block as requiring a body + + elsif Ekind (P) = E_Block then + return True; + + elsif Ekind (P) = E_Package + and then Nkind (Parent (P)) = N_Package_Specification + and then Present (Generic_Parent (Parent (P))) + then + declare + G_P : constant Entity_Id := Generic_Parent (Parent (P)); + begin + if Has_Pragma_Elaborate_Body (G_P) then + return True; + end if; + end; + end if; + + -- Otherwise search entity chain for entity requiring completion + + E := First_Entity (P); + while Present (E) loop + + -- Always ignore child units. Child units get added to the entity + -- list of a parent unit, but are not original entities of the + -- parent, and so do not affect whether the parent needs a body. + + if Is_Child_Unit (E) then + null; + + -- Ignore formal packages and their renamings + + elsif Ekind (E) = E_Package + and then Nkind (Original_Node (Unit_Declaration_Node (E))) = + N_Formal_Package_Declaration + then + null; + + -- Otherwise test to see if entity requires a completion. + -- Note that subprogram entities whose declaration does not come + -- from source are ignored here on the basis that we assume the + -- expander will provide an implicit completion at some point. + + elsif (Is_Overloadable (E) + and then Ekind (E) /= E_Enumeration_Literal + and then Ekind (E) /= E_Operator + and then not Is_Abstract_Subprogram (E) + and then not Has_Completion (E) + and then Comes_From_Source (Parent (E))) + + or else + (Ekind (E) = E_Package + and then E /= P + and then not Has_Completion (E) + and then Unit_Requires_Body (E)) + + or else + (Ekind (E) = E_Incomplete_Type and then No (Full_View (E))) + + or else + ((Ekind (E) = E_Task_Type or else + Ekind (E) = E_Protected_Type) + and then not Has_Completion (E)) + + or else + (Ekind (E) = E_Generic_Package and then E /= P + and then not Has_Completion (E) + and then Unit_Requires_Body (E)) + + or else + (Is_Generic_Subprogram (E) + and then not Has_Completion (E)) + + then + return True; + + -- Entity that does not require completion + + else + null; + end if; + + Next_Entity (E); + end loop; + + return False; + end Unit_Requires_Body; + +end Sem_Ch7; |