1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S E M _ E L A B -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 1997-2019, 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-- This package contains routines which handle access-before-elaboration 27-- run-time checks and compile-time diagnostics. See the body for details. 28 29with Types; use Types; 30 31package Sem_Elab is 32 33 ----------- 34 -- Types -- 35 ----------- 36 37 -- The following type classifies the various enclosing levels used in ABE 38 -- diagnostics. 39 40 type Enclosing_Level_Kind is 41 (Declaration_Level, 42 -- A construct is at the "declaration level" when it appears within the 43 -- declarations of a block statement, an entry body, a subprogram body, 44 -- or a task body, ignoring enclosing packages. Example: 45 46 -- package Pack is 47 -- procedure Proc is -- subprogram body 48 -- package Nested is -- enclosing package ignored 49 -- X ... -- at declaration level 50 51 Generic_Spec_Level, 52 Generic_Body_Level, 53 -- A construct is at the "generic level" when it appears in a 54 -- generic package library unit, ignoring enclosing packages. Example: 55 56 -- generic 57 -- package Pack is -- generic package spec 58 -- package Nested is -- enclosing package ignored 59 -- X ... -- at generic library level 60 61 Instantiation_Level, 62 -- A construct is at the "instantiation library level" when it appears 63 -- in a library unit which is also an instantiation. Example: 64 65 -- package Inst is new Gen; -- at instantiation level 66 67 Library_Spec_Level, 68 Library_Body_Level, 69 -- A construct is at the "library level" when it appears in a package 70 -- library unit, ignoring enclosing packages. Example: 71 72 -- package body Pack is -- package body 73 -- package Nested is -- enclosing package ignored 74 -- X ... -- at library level 75 76 No_Level); 77 -- This value is used to indicate that none of the levels above are in 78 -- effect. 79 80 subtype Generic_Level is Enclosing_Level_Kind range 81 Generic_Spec_Level .. 82 Generic_Body_Level; 83 84 subtype Library_Level is Enclosing_Level_Kind range 85 Library_Spec_Level .. 86 Library_Body_Level; 87 88 subtype Library_Or_Instantiation_Level is Enclosing_Level_Kind range 89 Instantiation_Level .. 90 Library_Body_Level; 91 92 procedure Build_Call_Marker (N : Node_Id); 93 pragma Inline (Build_Call_Marker); 94 -- Create a call marker for call or requeue statement N and record it for 95 -- later processing by the ABE mechanism. 96 97 procedure Build_Variable_Reference_Marker 98 (N : Node_Id; 99 Read : Boolean; 100 Write : Boolean); 101 pragma Inline (Build_Variable_Reference_Marker); 102 -- Create a variable reference marker for arbitrary node N if it mentions a 103 -- variable, and record it for later processing by the ABE mechanism. Flag 104 -- Read should be set when the reference denotes a read. Flag Write should 105 -- be set when the reference denotes a write. 106 107 procedure Check_Elaboration_Scenarios; 108 -- Examine each scenario recorded during analysis/resolution and apply the 109 -- Ada or SPARK elaboration rules taking into account the model in effect. 110 -- This processing detects and diagnoses ABE issues, installs conditional 111 -- ABE checks or guaranteed ABE failures, and ensures the elaboration of 112 -- units. 113 114 function Find_Enclosing_Level (N : Node_Id) return Enclosing_Level_Kind; 115 pragma Inline (Find_Enclosing_Level); 116 -- Determine the enclosing level of arbitrary node N 117 118 procedure Initialize; 119 pragma Inline (Initialize); 120 -- Initialize the internal structures of this unit 121 122 procedure Kill_Elaboration_Scenario (N : Node_Id); 123 -- Determine whether arbitrary node N denotes a scenario which requires 124 -- ABE diagnostics or runtime checks and eliminate it from a region with 125 -- dead code. 126 127 procedure Record_Elaboration_Scenario (N : Node_Id); 128 pragma Inline (Record_Elaboration_Scenario); 129 -- Determine whether atribtray node N denotes a scenario which requires 130 -- ABE diagnostics or runtime checks. If this is the case, store N for 131 -- later processing. 132 133 --------------------------------------------------------------------------- 134 -- -- 135 -- L E G A C Y A C C E S S B E F O R E E L A B O R A T I O N -- 136 -- -- 137 -- M E C H A N I S M -- 138 -- -- 139 --------------------------------------------------------------------------- 140 141 -- This section contains the implementation of the pre-18.x Legacy ABE 142 -- Mechanism. The mechanism can be activated using switch -gnatH (legacy 143 -- elaboration checking mode enabled). 144 145 procedure Check_Elab_Assign (N : Node_Id); 146 -- N is either the left side of an assignment, or a procedure argument for 147 -- a mode OUT or IN OUT formal. This procedure checks for a possible case 148 -- of access to an entity from elaboration code before the entity has been 149 -- initialized, and issues appropriate warnings. 150 151 procedure Check_Elab_Call 152 (N : Node_Id; 153 Outer_Scope : Entity_Id := Empty; 154 In_Init_Proc : Boolean := False); 155 -- Check a call for possible elaboration problems. The node N is either an 156 -- N_Function_Call or N_Procedure_Call_Statement node or an access 157 -- attribute reference whose prefix is a subprogram. 158 -- 159 -- If SPARK_Mode is On, then N can also be a variable reference, since 160 -- SPARK requires the use of Elaborate_All for references to variables 161 -- in other packages. 162 163 -- The Outer_Scope argument indicates whether this is an outer level 164 -- call from Sem_Res (Outer_Scope set to Empty), or an internal recursive 165 -- call (Outer_Scope set to entity of outermost call, see body). The flag 166 -- In_Init_Proc should be set whenever the current context is a type 167 -- init proc. 168 169 -- Note: this might better be called Check_Elab_Reference (to recognize 170 -- the SPARK case), but we prefer to keep the original name, since this 171 -- is primarily used for checking for calls that could generate an ABE). 172 173 procedure Check_Elab_Calls; 174 -- Not all the processing for Check_Elab_Call can be done at the time 175 -- of calls to Check_Elab_Call. This is because for internal calls, we 176 -- need to wait to complete the check until all generic bodies have been 177 -- instantiated. The Check_Elab_Calls procedure cleans up these waiting 178 -- checks. It is called once after the completion of instantiation. 179 180 procedure Check_Elab_Instantiation 181 (N : Node_Id; 182 Outer_Scope : Entity_Id := Empty); 183 -- Check an instantiation for possible elaboration problems. N is an 184 -- instantiation node (N_Package_Instantiation, N_Function_Instantiation, 185 -- or N_Procedure_Instantiation), and Outer_Scope indicates if this is 186 -- an outer level call from Sem_Ch12 (Outer_Scope set to Empty), or an 187 -- internal recursive call (Outer_Scope set to scope of outermost call, 188 -- see body for further details). The returned value is relevant only 189 -- for an outer level call, and is set to False if an elaboration error 190 -- is bound to occur on the instantiation, and True otherwise. This is 191 -- used by the caller to signal that the body of the instance should 192 -- not be generated (see detailed description in body). 193 194 procedure Check_Task_Activation (N : Node_Id); 195 -- At the point at which tasks are activated in a package body, check 196 -- that the bodies of the tasks are elaborated. 197 198end Sem_Elab; 199