gcc/ada/warnsw.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                               W A R N S W                                --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1999-2023, 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 unit contains the routines used to handle setting of warning options
  27 --  in the GNAT compiler.
  28
  29 package Warnsw is
  30
  31    -------------------
  32    -- Warning Flags --
  33    -------------------
  34
  35    --  These flags are activated or deactivated by -gnatw switches and control
  36    --  whether warnings of a given class will be generated or not.
  37
  38    package Warnings_Package is
  39       type Opt_Warnings_Enum is
  40         --  List of all warnings that can be enabled, plus the two null-ish
  41         --  values.
  42         (No_Such_Warning, Special_Case, -- see body
  43
  44          Address_Clause_Overlay_Warnings,
  45          Check_Unreferenced,
  46          Check_Unreferenced_Formals,
  47          Check_Withs,
  48          Constant_Condition_Warnings,
  49          Elab_Info_Messages,
  50          Elab_Warnings,
  51          Implementation_Unit_Warnings,
  52          Ineffective_Inline_Warnings,
  53          List_Body_Required_Info,
  54          List_Inherited_Aspects,
  55          Warning_Doc_Switch,
  56          Warn_On_Ada_2005_Compatibility,
  57          Warn_On_Ada_2012_Compatibility,
  58          Warn_On_Ada_2022_Compatibility,
  59          Warn_On_All_Unread_Out_Parameters,
  60          Warn_On_Anonymous_Allocators,
  61          Warn_On_Assertion_Failure,
  62          Warn_On_Assumed_Low_Bound,
  63          Warn_On_Atomic_Synchronization,
  64          Warn_On_Bad_Fixed_Value,
  65          Warn_On_Biased_Representation,
  66          Warn_On_Component_Order,
  67          Warn_On_Constant,
  68          Warn_On_Deleted_Code,
  69          Warn_On_Dereference,
  70          Warn_On_Elab_Access,
  71          Warn_On_Export_Import,
  72          Warn_On_Hiding,
  73          Warn_On_Ignored_Equality,
  74          Warn_On_Ineffective_Predicate_Test,
  75          Warn_On_Late_Primitives,
  76          Warn_On_Modified_Unread,
  77          Warn_On_No_Value_Assigned,
  78          Warn_On_Non_Local_Exception,
  79          No_Warn_On_Non_Local_Exception,
  80          Warn_On_Object_Renames_Function,
  81          Warn_On_Obsolescent_Feature,
  82          Warn_On_Overlap,
  83          Warn_On_Overridden_Size,
  84          Warn_On_Parameter_Order,
  85          Warn_On_Pedantic_Checks,
  86          Warn_On_Questionable_Layout,
  87          Warn_On_Questionable_Missing_Parens,
  88          Warn_On_Record_Holes,
  89          Warn_On_Redundant_Constructs,
  90          Warn_On_Reverse_Bit_Order,
  91          Warn_On_Size_Alignment,
  92          Warn_On_Standard_Redefinition,
  93          Warn_On_Suspicious_Contract,
  94          Warn_On_Suspicious_Modulus_Value,
  95          Warn_On_Unchecked_Conversion,
  96          Warn_On_Unknown_Compile_Time_Warning,
  97          Warn_On_Unordered_Enumeration_Type,
  98          Warn_On_Unrecognized_Pragma,
  99          Warn_On_Unrepped_Components,
 100          Warn_On_Warnings_Off); -- Opt_Warnings_Enum
 101
 102       subtype Warnings_Enum is Opt_Warnings_Enum
 103         range Opt_Warnings_Enum'Succ (Special_Case) .. Opt_Warnings_Enum'Last;
 104       --  Just the warning switches, without the null-ish values
 105    end Warnings_Package;
 106    use Warnings_Package;
 107
 108    type Warnings_State is array (Warnings_Enum) of Boolean;
 109    pragma Pack (Warnings_State);
 110    --  Without Pack, we can have bootstrapping failures, because the compiler
 111    --  generates calls to System.Boolean_Array_Operations, which is not
 112    --  currently part of the compiler.
 113
 114    Warning_Flags : Warnings_State :=
 115    --  Current state of warnings -- True/False means enabled/disabled.
 116    --  The following initializes the flags to their default values,
 117    --  and warning switches modify them.
 118      (Address_Clause_Overlay_Warnings |
 119       Elab_Warnings |
 120       Implementation_Unit_Warnings |
 121       Warning_Doc_Switch |
 122       Warn_On_Ada_2005_Compatibility |
 123       Warn_On_Ada_2012_Compatibility |
 124       Warn_On_Ada_2022_Compatibility |
 125       Warn_On_Assertion_Failure |
 126       Warn_On_Assumed_Low_Bound |
 127       Warn_On_Biased_Representation |
 128       Warn_On_Export_Import |
 129       Warn_On_No_Value_Assigned |
 130       Warn_On_Questionable_Missing_Parens |
 131       Warn_On_Reverse_Bit_Order |
 132       Warn_On_Size_Alignment |
 133       Warn_On_Suspicious_Contract |
 134       Warn_On_Suspicious_Modulus_Value |
 135       Warn_On_Unchecked_Conversion |
 136       Warn_On_Unknown_Compile_Time_Warning |
 137       Warn_On_Unrecognized_Pragma =>
 138         True,
 139
 140       Check_Unreferenced |
 141       Check_Unreferenced_Formals |
 142       Check_Withs |
 143       Constant_Condition_Warnings |
 144       Elab_Info_Messages |
 145       Ineffective_Inline_Warnings |
 146       List_Body_Required_Info |
 147       List_Inherited_Aspects |
 148       Warn_On_All_Unread_Out_Parameters |
 149       Warn_On_Anonymous_Allocators |
 150       Warn_On_Atomic_Synchronization |
 151       Warn_On_Bad_Fixed_Value |
 152       Warn_On_Component_Order |
 153       Warn_On_Constant |
 154       Warn_On_Deleted_Code |
 155       Warn_On_Dereference |
 156       Warn_On_Elab_Access |
 157       Warn_On_Hiding |
 158       Warn_On_Ignored_Equality |
 159       Warn_On_Ineffective_Predicate_Test |
 160       Warn_On_Late_Primitives |
 161       Warn_On_Modified_Unread |
 162       Warn_On_Non_Local_Exception |
 163       No_Warn_On_Non_Local_Exception |
 164       Warn_On_Object_Renames_Function |
 165       Warn_On_Obsolescent_Feature |
 166       Warn_On_Overlap |
 167       Warn_On_Overridden_Size |
 168       Warn_On_Parameter_Order |
 169       Warn_On_Pedantic_Checks |
 170       Warn_On_Questionable_Layout |
 171       Warn_On_Record_Holes |
 172       Warn_On_Redundant_Constructs |
 173       Warn_On_Standard_Redefinition |
 174       Warn_On_Unordered_Enumeration_Type |
 175       Warn_On_Unrepped_Components |
 176       Warn_On_Warnings_Off =>
 177         False);
 178
 179    package X renames Warnings_Package;
 180    F : Warnings_State renames Warning_Flags;
 181    --  Short-hand names used only locally to this package
 182
 183    --  The following rename all the components of Warning_Flags for convenient
 184    --  access throughout the compiler.
 185
 186    pragma Style_Checks ("M120");
 187    Address_Clause_Overlay_Warnings : Boolean renames F (X.Address_Clause_Overlay_Warnings);
 188    --  Set False to disable address clause warnings. Modified by use of
 189    --  -gnatwo/O.
 190
 191    Check_Unreferenced : Boolean renames F (X.Check_Unreferenced);
 192    --  Set to True to enable checking for unreferenced entities other
 193    --  than formal parameters (for which see Check_Unreferenced_Formals)
 194    --  Modified by use of -gnatwu/U.
 195
 196    Check_Unreferenced_Formals : Boolean renames F (X.Check_Unreferenced_Formals);
 197    --  Set to True to check for unreferenced formals. This is turned on by
 198    --  -gnatwa/wf/wu and turned off by -gnatwA/wF/wU.
 199
 200    Check_Withs : Boolean renames F (X.Check_Withs);
 201    --  Set to True to enable checking for unused withs, and also the case
 202    --  of withing a package and using none of the entities in the package.
 203    --  Modified by use of -gnatwu/U.
 204
 205    Constant_Condition_Warnings : Boolean renames F (X.Constant_Condition_Warnings);
 206    --  Set to True to activate warnings on constant conditions. Modified by
 207    --  use of -gnatwc/C.
 208
 209    Elab_Info_Messages : Boolean renames F (X.Elab_Info_Messages);
 210    --  Set to True to output info messages for static elabmodel (-gnatel)
 211
 212    Elab_Warnings : Boolean renames F (X.Elab_Warnings);
 213    --  Set to True to generate elaboration warnings (-gnatwl). The warnings are
 214    --  enabled by default because they carry the same importance as errors. The
 215    --  compiler cannot emit actual errors because elaboration diagnostics need
 216    --  dataflow analysis, which is not available. This behavior parallels that
 217    --  of the old ABE mechanism.
 218
 219    Implementation_Unit_Warnings : Boolean renames F (X.Implementation_Unit_Warnings);
 220    --  Set True to activate warnings for use of implementation internal units.
 221    --  Modified by use of -gnatwi/-gnatwI.
 222
 223    Ineffective_Inline_Warnings : Boolean renames F (X.Ineffective_Inline_Warnings);
 224    --  Set True to activate warnings if front-end inlining (-gnatN) is not able
 225    --  to actually inline a particular call (or all calls). Can be controlled
 226    --  by use of -gnatwp/-gnatwP. Also set True to activate warnings if
 227    --  frontend inlining is not able to inline a subprogram expected to
 228    --  be inlined in GNATprove mode.
 229
 230    List_Body_Required_Info : Boolean renames F (X.List_Body_Required_Info);
 231    --  List info messages about why a package requires a body. Modified by use
 232    --  of -gnatw.y/.Y.
 233
 234    List_Inherited_Aspects : Boolean renames F (X.List_Inherited_Aspects);
 235    --  List inherited invariants, preconditions, and postconditions from
 236    --  Invariant'Class, Pre'Class, and Post'Class aspects. Also list inherited
 237    --  subtype predicates. Modified by use of -gnatw.l/.L.
 238
 239    Warning_Doc_Switch : Boolean renames F (X.Warning_Doc_Switch);
 240    --  If this is set True, then the ??/?*?/?$?/?x?/?.x?/?_x? insertion
 241    --  sequences in error messages generate appropriate tags for the output
 242    --  error messages. If this switch is False, then these sequences are still
 243    --  recognized (for the purposes of implementing the pattern matching in
 244    --  pragmas Warnings (Off,..) and Warning_As_Error(...) but do not result
 245    --  in adding the error message tag. The -gnatw.d switch sets this flag
 246    --  True, -gnatw.D sets this flag False.
 247
 248    Warn_On_Ada_2005_Compatibility : Boolean renames F (X.Warn_On_Ada_2005_Compatibility);
 249    --  Set to True to generate all warnings on Ada 2005 compatibility issues,
 250    --  including warnings on Ada 2005 obsolescent features used in Ada 2005
 251    --  mode. Set by default, modified by use of -gnatwy/Y.
 252
 253    Warn_On_Ada_2012_Compatibility : Boolean renames F (X.Warn_On_Ada_2012_Compatibility);
 254    --  Set to True to generate all warnings on Ada 2012 compatibility issues,
 255    --  including warnings on Ada 2012 obsolescent features used in Ada 2012
 256    --  mode. Modified by use of -gnatwy/Y.
 257
 258    Warn_On_Ada_2022_Compatibility : Boolean renames F (X.Warn_On_Ada_2022_Compatibility);
 259    --  Set to True to generate all warnings on Ada 2022 compatibility issues,
 260    --  including warnings on Ada 2022 obsolescent features used in Ada 2022
 261    --  mode. There is no switch controlling this option.
 262
 263    Warn_On_All_Unread_Out_Parameters : Boolean renames F (X.Warn_On_All_Unread_Out_Parameters);
 264    --  Set to True to generate warnings in all cases where a variable is
 265    --  modified by being passed as to an OUT formal, but the resulting value is
 266    --  never read. The default is that this warning is suppressed. Modified
 267    --  by use of gnatw.o/.O.
 268
 269    Warn_On_Anonymous_Allocators : Boolean renames F (X.Warn_On_Anonymous_Allocators);
 270    --  Warn when allocators for anonymous access types are present, which,
 271    --  although not illegal in Ada, may be confusing to users due to how
 272    --  accessibility checks get generated. Off by default, modified by use
 273    --  of -gnatw_a/_A and set as part of -gnatwa.
 274
 275    Warn_On_Assertion_Failure : Boolean renames F (X.Warn_On_Assertion_Failure);
 276    --  Set to True to activate warnings on assertions that can be determined
 277    --  at compile time will always fail. Modified by use of -gnatw.a/.A.
 278
 279    Warn_On_Assumed_Low_Bound : Boolean renames F (X.Warn_On_Assumed_Low_Bound);
 280    --  Set to True to activate warnings for string parameters that are indexed
 281    --  with literals or S'Length, presumably assuming a lower bound of one.
 282    --  Modified by use of -gnatww/W.
 283
 284    Warn_On_Atomic_Synchronization : Boolean renames F (X.Warn_On_Atomic_Synchronization);
 285    --  Set to True to generate information messages for atomic synchronization.
 286    --  Modified by use of -gnatw.n/.N.
 287
 288    Warn_On_Bad_Fixed_Value : Boolean renames F (X.Warn_On_Bad_Fixed_Value);
 289    --  Set to True to generate warnings for static fixed-point expression
 290    --  values that are not an exact multiple of the small value of the type.
 291    --  Odd by default, modified by use of -gnatwb/B.
 292
 293    Warn_On_Biased_Representation : Boolean renames F (X.Warn_On_Biased_Representation);
 294    --  Set to True to generate warnings for size clauses, component clauses
 295    --  and component_size clauses that force biased representation. Modified
 296    --  by use of -gnatw.b/.B.
 297
 298    Warn_On_Component_Order : Boolean renames F (X.Warn_On_Component_Order);
 299    --  Warn when record component clauses are out of order with respect to the
 300    --  component declarations, or if the memory layout is out of order with
 301    --  respect to component declarations and clauses.  Off by default, set by
 302    --  -gnatw_r (but not -gnatwa).
 303
 304    Warn_On_Constant : Boolean renames F (X.Warn_On_Constant);
 305    --  Set to True to generate warnings for variables that could be declared
 306    --  as constants. Modified by use of -gnatwk/K.
 307
 308    Warn_On_Deleted_Code : Boolean renames F (X.Warn_On_Deleted_Code);
 309    --  Set to True to generate warnings for code deleted by the front end
 310    --  for conditional statements whose outcome is known at compile time.
 311    --  Modified by use of -gnatwt/T.
 312
 313    Warn_On_Dereference : Boolean renames F (X.Warn_On_Dereference);
 314    --  Set to True to generate warnings for implicit dereferences for array
 315    --  indexing and record component access. Modified by use of -gnatwd/D.
 316
 317    Warn_On_Elab_Access : Boolean renames F (X.Warn_On_Elab_Access);
 318    --  Set to True to generate warnings for P'Access in the case where
 319    --  subprogram P is in the same package as the P'Access, and the P'Access is
 320    --  evaluated at package elaboration time, and occurs before the body of P
 321    --  has been elaborated. Modified by use of -gnatw.f/.F.
 322
 323    Warn_On_Export_Import : Boolean renames F (X.Warn_On_Export_Import);
 324    --  Set to True to generate warnings for suspicious use of export or
 325    --  import pragmas. Modified by use of -gnatwx/X.
 326
 327    Warn_On_Hiding : Boolean renames F (X.Warn_On_Hiding);
 328    --  Set to True to generate warnings if a declared entity hides another
 329    --  entity. The default is that this warning is suppressed. Modified by
 330    --  use of -gnatwh/H.
 331
 332    Warn_On_Ignored_Equality : Boolean renames F (X.Warn_On_Ignored_Equality);
 333    --  Warn when a user-defined "=" function does not compose (i.e. is ignored
 334    --  for a predefined "=" for a composite type containing a component of
 335    --  whose type has the user-defined "=" as primitive). Off by default, and
 336    --  set by -gnatw_q (but not -gnatwa).
 337
 338    Warn_On_Ineffective_Predicate_Test : Boolean renames F (X.Warn_On_Ineffective_Predicate_Test);
 339    --  Set to True to generate warnings if a static predicate is testing for
 340    --  values that do not belong to the parent subtype. Modified by use of
 341    --  -gnatw_s/S.
 342
 343    Warn_On_Late_Primitives : Boolean renames F (X.Warn_On_Late_Primitives);
 344    --  Warn when tagged type public primitives are defined after its private
 345    --  extensions.
 346
 347    Warn_On_Modified_Unread : Boolean renames F (X.Warn_On_Modified_Unread);
 348    --  Set to True to generate warnings if a variable is assigned but is never
 349    --  read. Also controls warnings for similar cases involving out parameters,
 350    --  but only if there is only one out parameter for the procedure involved.
 351    --  The default is that this warning is suppressed, modified by use of
 352    --  -gnatwm/M.
 353
 354    Warn_On_No_Value_Assigned : Boolean renames F (X.Warn_On_No_Value_Assigned);
 355    --  Set to True to generate warnings if no value is ever assigned to a
 356    --  variable that is at least partially uninitialized. Set to false to
 357    --  suppress such warnings. The default is that such warnings are enabled.
 358    --  Modified by use of -gnatwv/V.
 359
 360    Warn_On_Non_Local_Exception : Boolean renames F (X.Warn_On_Non_Local_Exception);
 361    --  Set to True to generate warnings for non-local exception raises and also
 362    --  handlers that can never handle a local raise. This warning is only ever
 363    --  generated if pragma Restrictions (No_Exception_Propagation) is set. The
 364    --  default is not to generate the warnings except that if the source has
 365    --  at least one exception handler, and this restriction is set, and the
 366    --  warning was not explicitly turned off, then it is turned on by default.
 367    --  Modified by use of -gnatw.x/.X.
 368
 369    No_Warn_On_Non_Local_Exception : Boolean renames F (X.No_Warn_On_Non_Local_Exception);
 370    --  This is set to True if the above warning is explicitly suppressed. We
 371    --  use this to avoid turning it on by default when No_Exception_Propagation
 372    --  restriction is set and an exception handler is present.
 373
 374    Warn_On_Object_Renames_Function : Boolean renames F (X.Warn_On_Object_Renames_Function);
 375    --  Set to True to generate warnings when a function result is renamed as
 376    --  an object. The default is that this warning is disabled. Modified by
 377    --  use of -gnatw.r/.R.
 378
 379    Warn_On_Obsolescent_Feature : Boolean renames F (X.Warn_On_Obsolescent_Feature);
 380    --  Set to True to generate warnings on use of any feature in Annex or if a
 381    --  subprogram is called for which a pragma Obsolescent applies. Modified
 382    --  by use of -gnatwj/J.
 383
 384    Warn_On_Overlap : Boolean renames F (X.Warn_On_Overlap);
 385    --  Set to True to generate warnings when a writable actual overlaps with
 386    --  another actual in a subprogram call. This applies only in modes before
 387    --  Ada 2012. Starting with Ada 2012, such overlaps are illegal.
 388    --  Modified by use of -gnatw.i/.I.
 389
 390    Warn_On_Overridden_Size : Boolean renames F (X.Warn_On_Overridden_Size);
 391    --  Warn when explicit record component clause or array component_size
 392    --  clause specifies a size that overrides a size for the type which was
 393    --  set with an explicit size clause. Off by default, modified by use of
 394    --  -gnatw.s/.S (but not -gnatwa).
 395
 396    Warn_On_Parameter_Order : Boolean renames F (X.Warn_On_Parameter_Order);
 397    --  Set to True to generate warnings for cases where the argument list for
 398    --  a call is a sequence of identifiers that match the formal identifiers,
 399    --  but are in the wrong order.
 400
 401    Warn_On_Pedantic_Checks : Boolean renames F (X.Warn_On_Pedantic_Checks);
 402    --  Warn for violation of miscellaneous pedantic rules (such as when the
 403    --  subtype of a formal parameter given in a subprogram body's specification
 404    --  comes from a different subtype declaration that the subtype of the
 405    --  formal in the subprogram declaration). Off by default, and set by
 406    --  -gnatw_p (but not -gnatwa).
 407
 408    Warn_On_Questionable_Layout : Boolean renames F (X.Warn_On_Questionable_Layout);
 409    --  Warn when default layout of a record type is questionable for run-time
 410    --  efficiency reasons and would be improved by reordering the components.
 411    --  Off by default, modified by use of -gnatw.q/.Q (but not -gnatwa).
 412
 413    function Get_Warn_On_Questionable_Layout return Boolean is
 414      (Warn_On_Questionable_Layout);
 415    --  WARNING: There is a matching C declaration of this function in fe.h
 416
 417    Warn_On_Questionable_Missing_Parens : Boolean renames F (X.Warn_On_Questionable_Missing_Parens);
 418    --  Set to True to generate warnings for cases where parentheses are missing
 419    --  and the usage is questionable, because the intent is unclear. On by
 420    --  default, modified by use of -gnatwq/Q.
 421
 422    Warn_On_Record_Holes : Boolean renames F (X.Warn_On_Record_Holes);
 423    --  Warn when explicit record component clauses leave uncovered holes (gaps)
 424    --  in a record layout. Off by default, set by -gnatw.h (but not -gnatwa).
 425
 426    Warn_On_Redundant_Constructs : Boolean renames F (X.Warn_On_Redundant_Constructs);
 427    --  Set to True to generate warnings for redundant constructs (e.g. useless
 428    --  assignments/conversions). The default is that this warning is disabled.
 429    --  Modified by use of -gnatwr/R.
 430
 431    Warn_On_Reverse_Bit_Order : Boolean renames F (X.Warn_On_Reverse_Bit_Order);
 432    --  Set to True to generate warning (informational) messages for component
 433    --  clauses that are affected by non-standard bit-order. The default is
 434    --  that this warning is enabled. Modified by -gnatw.v/.V.
 435
 436    Warn_On_Size_Alignment : Boolean renames F (X.Warn_On_Size_Alignment);
 437    --  Warn when explicit Size and Alignment clauses are given for a type, and
 438    --  the size is not a multiple of the alignment. Off by default, modified
 439    --  by use of -gnatw.z/.Z and set as part of -gnatwa.
 440
 441    Warn_On_Standard_Redefinition : Boolean renames F (X.Warn_On_Standard_Redefinition);
 442    --  Warn when a program defines an identifier that matches a name in
 443    --  Standard. Off by default, modified by use of -gnatw.k/.K (but not
 444    --  by -gnatwa).
 445
 446    Warn_On_Suspicious_Contract : Boolean renames F (X.Warn_On_Suspicious_Contract);
 447    --  Set to True to generate warnings for suspicious contracts expressed as
 448    --  pragmas or aspects precondition and postcondition, as well as other
 449    --  suspicious cases of expressions typically found in contracts like
 450    --  quantified expressions and uses of Update attribute. The default is that
 451    --  this warning is enabled. Modified by use of -gnatw.t/.T.
 452
 453    Warn_On_Suspicious_Modulus_Value : Boolean renames F (X.Warn_On_Suspicious_Modulus_Value);
 454    --  Set to True to generate warnings for suspicious modulus values, as well
 455    --  as negative literals of a modular type. The default is that this warning
 456    --  is enabled. Modified by -gnatw.m/.M.
 457
 458    Warn_On_Unchecked_Conversion : Boolean renames F (X.Warn_On_Unchecked_Conversion);
 459    --  Set to True to generate warnings for unchecked conversions that may have
 460    --  non-portable semantics (e.g. because sizes of types differ). Modified
 461    --  by use of -gnatwz/Z.
 462
 463    Warn_On_Unknown_Compile_Time_Warning : Boolean renames F (X.Warn_On_Unknown_Compile_Time_Warning);
 464    --  Warn on a pragma Compile_Time_Warning whose condition has a value that
 465    --  is not known at compile time. On by default, modified by use
 466    --  of -gnatw_c/_C and set as part of -gnatwa.
 467
 468    Warn_On_Unordered_Enumeration_Type : Boolean renames F (X.Warn_On_Unordered_Enumeration_Type);
 469    --  Set to True to generate warnings for inappropriate uses (comparisons
 470    --  and explicit ranges) on unordered enumeration types (which includes
 471    --  all enumeration types for which pragma Ordered is not given). The
 472    --  default is that this warning is disabled. Modified by -gnat.u/.U.
 473
 474    Warn_On_Unrecognized_Pragma : Boolean renames F (X.Warn_On_Unrecognized_Pragma);
 475    --  Set to True to generate warnings for unrecognized pragmas. The default
 476    --  is that this warning is enabled. Modified by use of -gnatwg/G.
 477
 478    Warn_On_Unrepped_Components : Boolean renames F (X.Warn_On_Unrepped_Components);
 479    --  Set to True to generate warnings for the case of components of record
 480    --  which have a record representation clause but this component does not
 481    --  have a component clause. Modified by use of -gnatw.c/.C.
 482
 483    Warn_On_Warnings_Off : Boolean renames F (X.Warn_On_Warnings_Off);
 484    --  Set to True to generate warnings for use of Pragma Warnings (Off, ent),
 485    --  where either the pragma is never used, or it could be replaced by a
 486    --  pragma Unmodified or Unreferenced. Also generates warnings for pragma
 487    --  Warning (Off, string) which either has no matching pragma Warning On,
 488    --  or where no warning has been suppressed by the use of the pragma.
 489    --  Modified by use of -gnatw.w/.W.
 490    pragma Style_Checks ("M79");
 491
 492    -----------------------------------
 493    -- Saving and Restoring Warnings --
 494    -----------------------------------
 495
 496    function Save_Warnings return Warnings_State;
 497    --  Returns current settings of warnings
 498
 499    procedure Restore_Warnings (W : Warnings_State);
 500    --  Restores current settings of warning flags from W
 501
 502    -----------------
 503    -- Subprograms --
 504    -----------------
 505
 506    type Warning_Family is
 507      --  The "family" indicates the form of warning switch:
 508      (Plain, -- form "-gnatwx"
 509       '.',   -- form "-gnatw.x"
 510       '_');  -- form "-gnatw_x"
 511      --  where "x" is a lowercase letter that enables a particular warning.
 512      --  Typically, uppercase of "x" disables the warning, but there are some
 513      --  switches that do not follow that pattern.
 514
 515    function Set_Warning_Switch
 516      (Family : Warning_Family; C : Character) return Boolean;
 517    --  Set the warning switch or switches corresponding to the given family and
 518    --  character. Returns True for valid warning switch, False for invalid.
 519    --  Called for -gnatw... switches, and for pragma Warnings.
 520
 521    procedure Set_GNAT_Mode_Warnings;
 522    --  Called for -gnatg and -gnatw.g to set GNAT mode warnings. This set of
 523    --  warnings is neither a subset nor a superset of -gnatwa.
 524
 525 end Warnsw;