gcc/ada/errout.ads

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT COMPILER COMPONENTS                         --
   4 --                                                                          --
   5 --                               E R R O U T                                --
   6 --                                                                          --
   7 --                                 S p e c                                  --
   8 --                                                                          --
   9 --          Copyright (C) 1992-2018, 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 the routines to output error messages. They are
  27 --  basically system independent, however in some environments, e.g. when the
  28 --  parser is embedded into an editor, it may be appropriate to replace the
  29 --  implementation of this package.
  30
  31 with Err_Vars;
  32 with Erroutc;
  33 with Namet;    use Namet;
  34 with Table;
  35 with Types;    use Types;
  36 with Uintp;    use Uintp;
  37
  38 with System;
  39
  40 package Errout is
  41
  42    Current_Error_Source_File : Source_File_Index
  43      renames Err_Vars.Current_Error_Source_File;
  44    --  Id of current messages. Used to post file name when unit changes. This
  45    --  is initialized to Main_Source_File at the start of a compilation, which
  46    --  means that no file names will be output unless there are errors in
  47    --  units other than the main unit. However, if the main unit has a pragma
  48    --  Source_Reference line, then this is initialized to No_Source_File, to
  49    --  force an initial reference to the real source file name.
  50
  51    Raise_Exception_On_Error : Nat renames Err_Vars.Raise_Exception_On_Error;
  52    --  If this value is non-zero, then any attempt to generate an error
  53    --  message raises the exception Error_Msg_Exception, and the error message
  54    --  is not output. This is used for defending against junk resulting from
  55    --  illegalities, and also for substitution of more appropriate error
  56    --  messages from higher semantic levels. It is a counter so that the
  57    --  increment/decrement protocol nests neatly.
  58
  59    Error_Msg_Exception : exception renames Err_Vars.Error_Msg_Exception;
  60    --  Exception raised if Raise_Exception_On_Error is true
  61
  62    Warning_Doc_Switch : Boolean renames Err_Vars.Warning_Doc_Switch;
  63    --  If this is set True, then the ??/?*?/?$?/?x?/?X? insertion sequences in
  64    --  error messages generate appropriate tags for the output error messages.
  65    --  If this switch is False, then these sequences are still recognized (for
  66    --  the purposes of implementing the pattern matching in pragmas Warnings
  67    --  (Off,..) and Warning_As_Pragma(...) but do not result in adding the
  68    --  error message tag. The -gnatw.d switch sets this flag True, -gnatw.D
  69    --  sets this flag False.
  70
  71    Current_Node : Node_Id := Empty;
  72    --  Used by Error_Msg as a default Node_Id.
  73    --  Relevant only when Opt.Include_Subprogram_In_Messages is set.
  74
  75    -----------------------------------
  76    -- Suppression of Error Messages --
  77    -----------------------------------
  78
  79    --  In an effort to reduce the impact of redundant error messages, the
  80    --  error output routines in this package normally suppress certain
  81    --  classes of messages as follows:
  82
  83    --    1.  Identical messages placed at the same point in the text. Such
  84    --        duplicate error message result for example from rescanning
  85    --        sections of the text that contain lexical errors. Only one of
  86    --        such a set of duplicate messages is output, and the rest are
  87    --        suppressed.
  88
  89    --    2.  If more than one parser message is generated for a single source
  90    --        line, then only the first message is output, the remaining
  91    --        messages on the same line are suppressed.
  92
  93    --    3.  If a message is posted on a node for which a message has been
  94    --        previously posted, then only the first message is retained. The
  95    --        Error_Posted flag is used to detect such multiple postings. Note
  96    --        that this only applies to semantic messages, since otherwise
  97    --        for parser messages, this would be a special case of case 2.
  98
  99    --    4.  If a message is posted on a node whose Etype or Entity
 100    --        fields reference entities on which an error message has
 101    --        already been placed, as indicated by the Error_Posted flag
 102    --        being set on these entities, then the message is suppressed.
 103
 104    --    5.  If a message attempts to insert an Error node, or a direct
 105    --        reference to the Any_Type node, then the message is suppressed.
 106
 107    --    6.  Note that cases 2-5 only apply to error messages, not warning
 108    --        messages. Warning messages are only suppressed for case 1, and
 109    --        when they come from other than the main extended unit.
 110
 111    --    7.  If an error or warning references an internal name, and we have
 112    --        already placed an error (not warning) message at that location,
 113    --        then we assume this is cascaded junk and delete the message.
 114
 115    --  This normal suppression action may be overridden in cases 2-5 (but not
 116    --  in case 1 or 7 by setting All_Errors mode, or by setting the special
 117    --  unconditional message insertion character (!) as described below.
 118
 119    ---------------------------------------------------------
 120    -- Error Message Text and Message Insertion Characters --
 121    ---------------------------------------------------------
 122
 123    --  Error message text strings are composed of lower case letters, digits
 124    --  and the special characters space, comma, period, colon and semicolon,
 125    --  apostrophe and parentheses. Special insertion characters can also
 126    --  appear which cause the error message circuit to modify the given
 127    --  string as follows:
 128
 129    --    Insertion character % (Percent: insert name from Names table)
 130    --      The character % is replaced by the text for the name specified by
 131    --      the Name_Id value stored in Error_Msg_Name_1. A blank precedes the
 132    --      name if it is preceded by a non-blank character other than left
 133    --      parenthesis. The name is enclosed in quotes unless manual quotation
 134    --      mode is set. If the Name_Id is set to No_Name, then no insertion
 135    --      occurs; if the Name_Id is set to Error_Name, then the string
 136    --      <error> is inserted. A second and third % may appear in a single
 137    --      message, similarly replaced by the names which are specified by the
 138    --      Name_Id values stored in Error_Msg_Name_2 and Error_Msg_Name_3. The
 139    --      names are decoded and cased according to the current identifier
 140    --      casing mode. Note: if a unit name ending with %b or %s is passed
 141    --      for this kind of insertion, this suffix is simply stripped. Use a
 142    --      unit name insertion ($) to process the suffix.
 143    --
 144    --      Note: the special names _xxx (xxx = Pre/Post/Invariant) are changed
 145    --      to insert the string xxx'Class into the message.
 146
 147    --    Insertion character %% (Double percent: insert literal name)
 148    --      The character sequence %% acts as described above for %, except
 149    --      that the name is simply obtained with Get_Name_String and is not
 150    --      decoded or cased, it is inserted literally from the names table.
 151    --      A trailing %b or %s is not treated specially.
 152    --
 153    --      Note: the special names _xxx (xxx = Pre/Post/Invariant) are changed
 154    --      to insert the string xxx'Class into the message.
 155
 156    --    Insertion character $ (Dollar: insert unit name from Names table)
 157    --      The character $ is treated similarly to %, except that the name is
 158    --      obtained from the Unit_Name_Type value in Error_Msg_Unit_1 and
 159    --      Error_Msg_Unit_2, as provided by Get_Unit_Name_String in package
 160    --      Uname. Note that this name includes the postfix (spec) or (body)
 161    --      strings. If this postfix is not required, use the normal % insertion
 162    --      for the unit name.
 163
 164    --    Insertion character { (Left brace: insert file name from names table)
 165    --      The character { is treated similarly to %, except that the input
 166    --      value is a File_Name_Type value stored in Error_Msg_File_1 or
 167    --      Error_Msg_File_2 or Error_Msg_File_3. The value is output literally,
 168    --      enclosed in quotes as for %, but the case is not modified, the
 169    --      insertion is the exact string stored in the names table without
 170    --      adjusting the casing.
 171
 172    --    Insertion character * (Asterisk: insert reserved word name)
 173    --      The insertion character * is treated exactly like % except that the
 174    --      resulting name is cased according to the default conventions for
 175    --      reserved words (see package Scans).
 176
 177    --    Insertion character & (Ampersand: insert name from node)
 178    --      The insertion character & is treated similarly to %, except that
 179    --      the name is taken from the Chars field of the given node, and may
 180    --      refer to a child unit name, or a selected component. The casing is,
 181    --      if possible, taken from the original source reference, which is
 182    --      obtained from the Sloc field of the given node or nodes. If no Sloc
 183    --      is available (happens e.g. for nodes in package Standard), then the
 184    --      default case (see Scans spec) is used. The nodes to be used are
 185    --      stored in Error_Msg_Node_1, Error_Msg_Node_2. No insertion occurs
 186    --      for the Empty node, and the Error node results in the insertion of
 187    --      the characters <error>. In addition, if the special global variable
 188    --      Error_Msg_Qual_Level is non-zero, then the reference will include
 189    --      up to the given number of levels of qualification, using the scope
 190    --      chain.
 191    --
 192    --      Note: the special names _xxx (xxx = Pre/Post/Invariant) are changed
 193    --      to insert the string xxx'Class into the message.
 194
 195    --    Insertion character # (Pound: insert line number reference)
 196    --      The character # is replaced by the string indicating the source
 197    --      position stored in Error_Msg_Sloc. There are three cases:
 198    --
 199    --        for package Standard:           in package Standard
 200    --        for locations in current file:  at line nnn:ccc
 201    --        for locations in other files:   at filename:nnn:ccc
 202    --
 203    --      By convention, the # insertion character is only used at the end of
 204    --      an error message, so the above strings only appear as the last
 205    --      characters of an error message. The only exceptions to this rule
 206    --      are that an RM reference may follow in the form (RM .....) and a
 207    --      right parenthesis may immediately follow the #. In the case of
 208    --      continued messages, # can only appear at the end of a group of
 209    --      continuation messages, except that \\ messages which always start
 210    --      a new line end the sequence from the point of view of this rule.
 211    --      The idea is that for any use of -gnatj, it will still be the case
 212    --      that a location reference appears only at the end of a line.
 213
 214    --      Note: the output of the string "at " is suppressed if the string
 215    --      " from" or " from " immediately precedes the insertion character #.
 216    --      Certain messages read better with from than at.
 217
 218    --    Insertion character } (Right brace: insert type reference)
 219    --      The character } is replaced by a string describing the type
 220    --      referenced by the entity whose Id is stored in Error_Msg_Node_1.
 221    --      The string gives the name or description of the type, and also
 222    --      where appropriate the location of its declaration. Special cases
 223    --      like "some integer type" are handled appropriately. Only one } is
 224    --      allowed in a message, since there is not enough room for two (the
 225    --      insertion can be quite long, including a file name). In addition, if
 226    --      the special global variable Error_Msg_Qual_Level is non-zero, then
 227    --      the reference will include up to the given number of levels of
 228    --      qualification, using the scope chain.
 229
 230    --    Insertion character @ (At: insert column number reference)
 231    --      The character @ is replaced by null if the RM_Column_Check mode is
 232    --      off (False). If the switch is on (True), then @ is replaced by the
 233    --      text string " in column nnn" where nnn is the decimal
 234    --      representation of the column number stored in Error_Msg_Col plus
 235    --      one (the plus one is because the number is stored 0-origin and
 236    --      displayed 1-origin).
 237
 238    --    Insertion character ^ (Caret: insert integer value)
 239    --      The character ^ is replaced by the decimal conversion of the Uint
 240    --      value stored in Error_Msg_Uint_1, with a possible leading minus.
 241    --      A second ^ may occur in the message, in which case it is replaced
 242    --      by the decimal conversion of the Uint value in Error_Msg_Uint_2.
 243
 244    --    Insertion character > (Greater Than: run time name)
 245    --      The character > is replaced by a string of the form (name) if
 246    --      Targparm scanned out a Run_Time_Name (see package Targparm for
 247    --      details). The name is enclosed in parentheses and output in mixed
 248    --      case mode (upper case after any space in the name). If no run time
 249    --      name is defined, this insertion character has no effect.
 250
 251    --    Insertion character ! (Exclamation: unconditional message)
 252    --      The character ! appearing anywhere in the text of a message makes
 253    --      the message unconditional which means that it is output even if it
 254    --      would normally be suppressed. See section above for a description
 255    --      of the cases in which messages are normally suppressed. Note that
 256    --      in the case of warnings, the meaning is that the warning should not
 257    --      be removed in dead code (that's the only time that the use of !
 258    --      has any effect for a warning).
 259    --
 260    --      Note: the presence of ! is ignored in continuation messages (i.e.
 261    --      messages starting with the \ insertion character). The effect of the
 262    --      use of ! in a parent message automatically applies to all of its
 263    --      continuation messages (since we clearly don't want any case in which
 264    --      continuations are separated from the main message). It is allowable
 265    --      to put ! in continuation messages, and the usual style is to include
 266    --      it, since it makes it clear that the continuation is part of an
 267    --      unconditional message.
 268
 269    --    Insertion character !! (Double exclamation: unconditional warning)
 270    --      Normally warning messages issued in other than the main unit are
 271    --      suppressed. If the message contains !! then this suppression is
 272    --      avoided. This is currently used by the Compile_Time_Warning pragma
 273    --      to ensure the message for a with'ed unit is output, and for warnings
 274    --      on ineffective back-end inlining, which is detected in units that
 275    --      contain subprograms to be inlined in the main program. It is also
 276    --      used by the Compiler_Unit_Warning pragma for similar reasons.
 277
 278    --    Insertion character ? (Question: warning message)
 279    --      The character ? appearing anywhere in a message makes the message
 280    --      warning instead of a normal error message, and the text of the
 281    --      message will be preceded by "warning:" in the normal case. The
 282    --      handling of warnings if further controlled by the Warning_Mode
 283    --      option (-w switch), see package Opt for further details, and also by
 284    --      the current setting from pragma Warnings. This pragma applies only
 285    --      to warnings issued from the semantic phase (not the parser), but
 286    --      currently all relevant warnings are posted by the semantic phase
 287    --      anyway. Messages starting with (style) are also treated as warning
 288    --      messages.
 289    --
 290    --      Note: when a warning message is output, the text of the message is
 291    --      preceded by "warning: " in the normal case. An exception to this
 292    --      rule occurs when the text of the message starts with "info: " in
 293    --      which case this string is not prepended. This allows callers to
 294    --      label certain warnings as informational messages, rather than as
 295    --      warning messages requiring some action.
 296    --
 297    --      Note: the presence of ? is ignored in continuation messages (i.e.
 298    --      messages starting with the \ insertion character). The warning
 299    --      status of continuations is determined only by the parent message
 300    --      which is being continued. It is allowable to put ? in continuation
 301    --      messages, and the usual style is to include it, since it makes it
 302    --      clear that the continuation is part of a warning message, but it is
 303    --      not necessary to go through any computational effort to include it.
 304    --
 305    --      Note: this usage is obsolete, use ?? ?*? ?$? ?x? ?X? to specify
 306    --      the string to be added when Warn_Doc_Switch is set to True. If this
 307    --      switch is True, then for simple ? messages it has no effect. This
 308    --      simple form is to ease transition and will be removed later.
 309
 310    --    Insertion character ?? (Two question marks: default warning)
 311    --      Like ?, but if the flag Warn_Doc_Switch is True, adds the string
 312    --      "[enabled by default]" at the end of the warning message. For
 313    --      continuations, use this in each continuation message.
 314
 315    --    Insertion character ?x? (warning with switch)
 316    --      Like ?, but if the flag Warn_Doc_Switch is True, adds the string
 317    --      "[-gnatwx]" at the end of the warning message. x is a lower case
 318    --      letter. For continuations, use this on each continuation message.
 319
 320    --    Insertion character ?X? (warning with dot switch)
 321    --      Like ?, but if the flag Warn_Doc_Switch is True, adds the string
 322    --      "[-gnatw.x]" at the end of the warning message. X is an upper case
 323    --      letter corresponding to the lower case letter x in the message.
 324    --      For continuations, use this on each continuation message.
 325
 326    --    Insertion character ?*? (restriction warning)
 327    --      Like ?, but if the flag Warn_Doc_Switch is True, adds the string
 328    --      "[restriction warning]" at the end of the warning message. For
 329    --      continuations, use this on each continuation message.
 330
 331    --    Insertion character ?$? (elaboration informational messages)
 332    --      Like ?, but if the flag Warn_Doc_Switch is True, adds the string
 333    --      "[-gnatel]" at the end of the info message. This is used for the
 334    --      messages generated by the switch -gnatel. For continuations, use
 335    --      this on each continuation message.
 336
 337    --    Insertion character < (Less Than: conditional warning message)
 338    --      The character < appearing anywhere in a message is used for a
 339    --      conditional error message. If Error_Msg_Warn is True, then the
 340    --      effect is the same as ? described above, and in particular << <X<
 341    --      <x< <$< <*< have the effect of ?? ?X? ?x? ?$? ?*? respectively. If
 342    --      Error_Msg_Warn is False, then the < << or <X< sequence is ignored
 343    --      and the message is treated as a error rather than a warning.
 344
 345    --    Insertion character A-Z (Upper case letter: Ada reserved word)
 346    --      If two or more upper case letters appear in the message, they are
 347    --      taken as an Ada reserved word, and are converted to the default
 348    --      case for reserved words (see Scans package spec). Surrounding
 349    --      quotes are added unless manual quotation mode is currently set.
 350    --      RM and SPARK are special exceptions, they are never treated as
 351    --      keywords, and just appear verbatim, with no surrounding quotes.
 352    --      As a special case, 'R'M is used instead of RM (which is not treated
 353    --      as a keyword) to indicate when the reference to the RM is possibly
 354    --      not useful anymore, and could possibly be replaced by a comment
 355    --      in the source.
 356
 357    --    Insertion character ` (Backquote: set manual quotation mode)
 358    --      The backquote character always appears in pairs. Each backquote of
 359    --      the pair is replaced by a double quote character. In addition, any
 360    --      reserved keywords, or name insertions between these backquotes are
 361    --      not surrounded by the usual automatic double quotes. See the
 362    --      section below on manual quotation mode for further details.
 363
 364    --    Insertion character ' (Quote: literal character)
 365    --      Precedes a character which is placed literally into the message.
 366    --      Used to insert characters into messages that are one of the
 367    --      insertion characters defined here. Also used for insertion of
 368    --      upper case letter sequences not to be treated as keywords.
 369
 370    --    Insertion character \ (Backslash: continuation message)
 371    --      Indicates that the message is a continuation of a message
 372    --      previously posted. This is used to ensure that such groups of
 373    --      messages are treated as a unit. The \ character must be the first
 374    --      character of the message text.
 375
 376    --    Insertion character \\ (Two backslashes: continuation with new line)
 377    --      This differs from \ only in -gnatjnn mode (Error_Message_Line_Length
 378    --      set non-zero). This sequence forces a new line to start even when
 379    --      continuations are being gathered into a single message.
 380
 381    --    Insertion character | (Vertical bar: non-serious error)
 382    --      By default, error messages (other than warning messages) are
 383    --      considered to be fatal error messages which prevent expansion or
 384    --      generation of code in the presence of the -gnatQ switch. If the
 385    --      insertion character | appears, the message is considered to be
 386    --      non-serious, and does not cause Serious_Errors_Detected to be
 387    --      incremented (so expansion is not prevented by such a msg). This
 388    --      insertion character is ignored in continuation messages.
 389
 390    --    Insertion character ~ (Tilde: insert string)
 391    --      Indicates that Error_Msg_String (1 .. Error_Msg_Strlen) is to be
 392    --      inserted to replace the ~ character. The string is inserted in the
 393    --      literal form it appears, without any action on special characters.
 394
 395    --    Insertion character [ (Left bracket: will/would be raised at run time)
 396    --      This is used in messages about exceptions being raised at run-time.
 397    --      If the current message is a warning message, then if the code is
 398    --      executed, the exception will be raised, and [ inserts:
 399    --
 400    --        will be raised at run time
 401    --
 402    --      If the current message is an error message, then it is an error
 403    --      because the exception would have been raised and [ inserts:
 404    --
 405    --        would have been raised at run time
 406    --
 407    --      Typically the message contains a < insertion which means that the
 408    --      message is a warning or error depending on Error_Msg_Warn. This is
 409    --      most typically used in the context of messages which are normally
 410    --      warnings, but are errors in GNATprove mode, corresponding to the
 411    --      permission in the definition of SPARK that allows an implementation
 412    --      to reject a program as illegal if a situation arises in which the
 413    --      compiler can determine that it is certain that a run-time check
 414    --      would have fail if the statement was executed.
 415
 416    --    Insertion character ] (Right bracket: may/might be raised at run time)
 417    --      This is like [ except that the insertion messages say may/might,
 418    --      instead of will/would.
 419
 420    --    Insertion sequence "(style)" (style message)
 421    --      This appears only at the start of the message (and not any of its
 422    --      continuations, if any), and indicates that the message is a style
 423    --      message. Style messages are also considered to be warnings, but
 424    --      they do not get a tag.
 425
 426    --    Insertion sequence "info: " (informational message)
 427    --      This appears only at the start of the message (and not any of its
 428    --      continuations, if any), and indicates that the message is an info
 429    --      message. The message will be output with this prefix, and if there
 430    --      are continuations that are not printed using the -gnatj switch they
 431    --      will also have this prefix. Informational messages are usually also
 432    --      warnings, but they don't have to be.
 433
 434    --    Insertion sequence "low: " or "medium: " or "high: " (check message)
 435    --      This appears only at the start of the message (and not any of its
 436    --      continuations, if any), and indicates that the message is a check
 437    --      message. The message will be output with this prefix. Check
 438    --      messages are not fatal (so are like info messages in that respect)
 439    --      and are not controlled by pragma Warnings.
 440
 441    -----------------------------------------------------
 442    -- Global Values Used for Error Message Insertions --
 443    -----------------------------------------------------
 444
 445    --  The following global variables are essentially additional parameters
 446    --  passed to the error message routine for insertion sequences described
 447    --  above. The reason these are passed globally is that the insertion
 448    --  mechanism is essentially an untyped one in which the appropriate
 449    --  variables are set depending on the specific insertion characters used.
 450
 451    --  Note that is mandatory that the caller ensure that global variables
 452    --  are set before the Error_Msg call, otherwise the result is undefined.
 453
 454    Error_Msg_Col : Column_Number renames Err_Vars.Error_Msg_Col;
 455    --  Column for @ insertion character in message
 456
 457    Error_Msg_Uint_1 : Uint renames Err_Vars.Error_Msg_Uint_1;
 458    Error_Msg_Uint_2 : Uint renames Err_Vars.Error_Msg_Uint_2;
 459    --  Uint values for ^ insertion characters in message
 460
 461    Error_Msg_Sloc : Source_Ptr renames Err_Vars.Error_Msg_Sloc;
 462    --  Source location for # insertion character in message
 463
 464    Error_Msg_Name_1 : Name_Id renames Err_Vars.Error_Msg_Name_1;
 465    Error_Msg_Name_2 : Name_Id renames Err_Vars.Error_Msg_Name_2;
 466    Error_Msg_Name_3 : Name_Id renames Err_Vars.Error_Msg_Name_3;
 467    --  Name_Id values for % insertion characters in message
 468
 469    Error_Msg_File_1 : File_Name_Type renames Err_Vars.Error_Msg_File_1;
 470    Error_Msg_File_2 : File_Name_Type renames Err_Vars.Error_Msg_File_2;
 471    Error_Msg_File_3 : File_Name_Type renames Err_Vars.Error_Msg_File_3;
 472    --  File_Name_Type values for { insertion characters in message
 473
 474    Error_Msg_Unit_1 : Unit_Name_Type renames Err_Vars.Error_Msg_Unit_1;
 475    Error_Msg_Unit_2 : Unit_Name_Type renames Err_Vars.Error_Msg_Unit_2;
 476    --  Unit_Name_Type values for $ insertion characters in message
 477
 478    Error_Msg_Node_1 : Node_Id renames Err_Vars.Error_Msg_Node_1;
 479    Error_Msg_Node_2 : Node_Id renames Err_Vars.Error_Msg_Node_2;
 480    --  Node_Id values for & insertion characters in message
 481
 482    Error_Msg_Qual_Level : Nat renames Err_Vars.Error_Msg_Qual_Level;
 483    --  Number of levels of qualification required for type name (see the
 484    --  description of the } insertion character). Note that this value does
 485    --  not get reset by any Error_Msg call, so the caller is responsible
 486    --  for resetting it.
 487
 488    Error_Msg_Warn : Boolean renames Err_Vars.Error_Msg_Warn;
 489    --  Used if current message contains a < insertion character to indicate
 490    --  if the current message is a warning message. Must be set appropriately
 491    --  before any call to Error_Msg_xxx with a < insertion character present.
 492    --  Setting is irrelevant if no < insertion character is present.
 493
 494    Error_Msg_String : String  renames Err_Vars.Error_Msg_String;
 495    Error_Msg_Strlen : Natural renames Err_Vars.Error_Msg_Strlen;
 496    --  Used if current message contains a ~ insertion character to indicate
 497    --  insertion of the string Error_Msg_String (1 .. Error_Msg_Strlen).
 498
 499    -----------------------------------------------------
 500    -- Format of Messages and Manual Quotation Control --
 501    -----------------------------------------------------
 502
 503    --  Messages are generally all in lower case, except for inserted names
 504    --  and appear in one of the following three forms:
 505
 506    --    error: text
 507    --    warning: text
 508
 509    --  The prefixes error and warning are supplied automatically (depending
 510    --  on the use of the ? insertion character), and the call to the error
 511    --  message routine supplies the text. The "error: " prefix is omitted
 512    --  in brief error message formats.
 513
 514    --  Reserved Ada keywords in the message are in the default keyword case
 515    --  (determined from the given source program), surrounded by quotation
 516    --  marks. This is achieved by spelling the reserved word in upper case
 517    --  letters, which is recognized as a request for insertion of quotation
 518    --  marks by the error text processor. Thus for example:
 519
 520    --    Error_Msg_AP ("IS expected");
 521
 522    --  would result in the output of one of the following:
 523
 524    --    error: "is" expected
 525    --    error: "IS" expected
 526    --    error: "Is" expected
 527
 528    --  the choice between these being made by looking at the casing convention
 529    --  used for keywords (actually the first compilation unit keyword) in the
 530    --  source file.
 531
 532    --  Note: a special exception is that RM is never treated as a keyword
 533    --  but instead is copied literally into the message, this avoids the
 534    --  need for writing 'R'M for all reference manual quotes. A similar
 535    --  exception is applied to the occurrence of the string SPARK used in
 536    --  error messages about the SPARK subset of Ada.
 537
 538    --  In the case of names, the default mode for the error text processor
 539    --  is to surround the name by quotation marks automatically. The case
 540    --  used for the identifier names is taken from the source program where
 541    --  possible, and otherwise is the default casing convention taken from
 542    --  the source file usage.
 543
 544    --  In some cases, better control over the placement of quote marks is
 545    --  required. This is achieved using manual quotation mode. In this mode,
 546    --  one or more insertion sequences is surrounded by backquote characters.
 547    --  The backquote characters are output as double quote marks, and normal
 548    --  automatic insertion of quotes is suppressed between the double quotes.
 549    --  For example:
 550
 551    --    Error_Msg_AP ("`END &;` expected");
 552
 553    --  generates a message like
 554
 555    --    error: "end Open_Scope;" expected
 556
 557    --  where the node specifying the name Open_Scope has been stored in
 558    --  Error_Msg_Node_1 prior to the call. The great majority of error
 559    --  messages operates in normal quotation mode.
 560
 561    --  Note: the normal automatic insertion of spaces before insertion
 562    --  sequences (such as those that come from & and %) is suppressed in
 563    --  manual quotation mode, so blanks, if needed as in the above example,
 564    --  must be explicitly present.
 565
 566    ----------------------------
 567    -- Message ID Definitions --
 568    ----------------------------
 569
 570    subtype Error_Msg_Id is Erroutc.Error_Msg_Id;
 571    function "=" (Left, Right : Error_Msg_Id) return Boolean
 572      renames Erroutc."=";
 573    --  A type used to represent specific error messages. Used by the clients
 574    --  of this package only in the context of the Get_Error_Id and
 575    --  Change_Error_Text subprograms.
 576
 577    No_Error_Msg : constant Error_Msg_Id := Erroutc.No_Error_Msg;
 578    --  A constant which is different from any value returned by Get_Error_Id.
 579    --  Typically used by a client to indicate absense of a saved Id value.
 580
 581    Warning_Msg : Error_Msg_Id := No_Error_Msg;
 582    --  This is set if a warning message is generated to the ID of the resulting
 583    --  message. Continuation messages have no effect. It is legitimate for the
 584    --  client to set this to No_Error_Msg and then test it to see if a warning
 585    --  message has been issued.
 586
 587    procedure Delete_Warning_And_Continuations (Msg : Error_Msg_Id);
 588    --  Deletes the given warning message and all its continuations. This is
 589    --  typically used in conjunction with reading the value of Warning_Msg.
 590
 591    function Get_Msg_Id return Error_Msg_Id renames Erroutc.Get_Msg_Id;
 592    --  Returns the Id of the message most recently posted using one of the
 593    --  Error_Msg routines.
 594
 595    function Get_Location (E : Error_Msg_Id) return Source_Ptr
 596      renames Erroutc.Get_Location;
 597    --  Returns the flag location of the error message with the given id E
 598
 599    ------------------------
 600    -- List Pragmas Table --
 601    ------------------------
 602
 603    --  When a pragma Page or pragma List is encountered by the parser, an
 604    --  entry is made in the following table. This table is then used to
 605    --  control the full listing if one is being generated. Note that the
 606    --  reason we do the processing in the parser is so that we get proper
 607    --  listing control even in syntax check only mode.
 608
 609    type List_Pragma_Type is (List_On, List_Off, Page);
 610
 611    type List_Pragma_Record is record
 612       Ptyp : List_Pragma_Type;
 613       Ploc : Source_Ptr;
 614    end record;
 615
 616    --  Note: Ploc points to the terminating semicolon in the List_Off and Page
 617    --  cases, and to the pragma keyword for List_On. In the case of a pragma
 618    --  List_Off, a List_On entry is also made in the table, pointing to the
 619    --  pragma keyword. This ensures that, as required, a List (Off) pragma is
 620    --  listed even in list off mode.
 621
 622    package List_Pragmas is new Table.Table (
 623      Table_Component_Type => List_Pragma_Record,
 624      Table_Index_Type     => Int,
 625      Table_Low_Bound      => 1,
 626      Table_Initial        => 50,
 627      Table_Increment      => 200,
 628      Table_Name           => "List_Pragmas");
 629
 630    ---------------------------
 631    -- Ignore_Errors Feature --
 632    ---------------------------
 633
 634    --  In certain cases, notably for optional subunits, the compiler operates
 635    --  in a mode where errors are to be ignored, and the whole unit is to be
 636    --  considered as not present. To implement this we provide the following
 637    --  flag to enable special handling, where error messages are suppressed,
 638    --  but the Fatal_Error flag will still be set in the normal manner.
 639
 640    Ignore_Errors_Enable : Nat := 0;
 641    --  Triggering switch. If non-zero, then ignore errors mode is activated.
 642    --  This is a counter to allow convenient nesting of enable/disable.
 643
 644    -----------------------
 645    --  CODEFIX Facility --
 646    -----------------------
 647
 648    --  The GPS and GNATBench IDE's have a codefix facility that allows for
 649    --  automatic correction of a subset of the errors and warnings issued
 650    --  by the compiler. This is done by recognizing the text of specific
 651    --  messages using appropriate matching patterns.
 652
 653    --  The text of such messages should not be altered without coordinating
 654    --  with the codefix code. All such messages are marked by a specific
 655    --  style of comments, as shown by the following example:
 656
 657    --     Error_Msg_N -- CODEFIX
 658    --       (parameters ....)
 659
 660    --  Any message marked with this -- CODEFIX comment should not be modified
 661    --  without appropriate coordination.
 662
 663    ------------------------------
 664    -- Error Output Subprograms --
 665    ------------------------------
 666
 667    procedure Initialize;
 668    --  Initializes for output of error messages. Must be called for each
 669    --  source file before using any of the other routines in the package.
 670
 671    procedure Finalize (Last_Call : Boolean);
 672    --  Finalize processing of error message list. Includes processing for
 673    --  duplicated error messages, and other similar final adjustment of the
 674    --  list of error messages. Note that this procedure must be called before
 675    --  calling Compilation_Errors to determine if there were any errors. It
 676    --  is perfectly fine to call Finalize more than once, providing that the
 677    --  parameter Last_Call is set False for every call except the last call.
 678
 679    --  This multiple call capability is used to do some processing that may
 680    --  generate messages. Call Finalize to eliminate duplicates and remove
 681    --  deleted warnings. Test for compilation errors using Compilation_Errors,
 682    --  then generate some more errors/warnings, call Finalize again to make
 683    --  sure that all duplicates in these new messages are dealt with, then
 684    --  finally call Output_Messages to output the final list of messages. The
 685    --  argument Last_Call must be set False on all calls except the last call,
 686    --  and must be set True on the last call (a value of True activates some
 687    --  processing that must only be done after all messages are posted).
 688
 689    procedure Output_Messages;
 690    --  Output list of messages, including messages giving number of detected
 691    --  errors and warnings.
 692
 693    procedure Error_Msg
 694      (Msg : String; Flag_Location : Source_Ptr);
 695    procedure Error_Msg
 696      (Msg : String; Flag_Location : Source_Ptr; N : Node_Id);
 697    --  Output a message at specified location. Can be called from the parser
 698    --  or the semantic analyzer. If N is set, points to the relevant node for
 699    --  this message.
 700
 701    procedure Error_Msg_S (Msg : String);
 702    --  Output a message at current scan pointer location. This routine can be
 703    --  called only from the parser, since it references Scan_Ptr.
 704
 705    procedure Error_Msg_AP (Msg : String);
 706    --  Output a message just after the previous token. This routine can be
 707    --  called only from the parser, since it references Prev_Token_Ptr.
 708
 709    procedure Error_Msg_BC (Msg : String);
 710    --  Output a message just before the current token. Note that the important
 711    --  difference between this and the previous routine is that the BC case
 712    --  posts a flag on the current line, whereas AP can post a flag at the
 713    --  end of the preceding line. This routine can be called only from the
 714    --  parser, since it references Token_Ptr.
 715
 716    procedure Error_Msg_SC (Msg : String);
 717    --  Output a message at the start of the current token, unless we are at
 718    --  the end of file, in which case we always output the message after the
 719    --  last real token in the file. This routine can be called only from the
 720    --  parser, since it references Token_Ptr.
 721
 722    procedure Error_Msg_SP (Msg : String);
 723    --  Output a message at the start of the previous token. This routine can
 724    --  be called only from the parser, since it references Prev_Token_Ptr.
 725
 726    procedure Error_Msg_N (Msg : String; N : Node_Or_Entity_Id);
 727    --  Output a message at the Sloc of the given node. This routine can be
 728    --  called from the parser or the semantic analyzer, although the call from
 729    --  the latter is much more common (and is the most usual way of generating
 730    --  error messages from the analyzer). The message text may contain a
 731    --  single & insertion, which will reference the given node. The message is
 732    --  suppressed if the node N already has a message posted, or if it is a
 733    --  warning and N is an entity node for which warnings are suppressed.
 734
 735    procedure Error_Msg_F (Msg : String; N : Node_Id);
 736    --  Similar to Error_Msg_N except that the message is placed on the first
 737    --  node of the construct N (First_Node (N)). Note that this procedure uses
 738    --  Original_Node to look at the original source tree, since that's what we
 739    --  want for placing an error message flag in the right place.
 740
 741    procedure Error_Msg_NE
 742      (Msg : String;
 743       N   : Node_Or_Entity_Id;
 744       E   : Node_Or_Entity_Id);
 745    --  Output a message at the Sloc of the given node N, with an insertion of
 746    --  the name from the given entity node E. This is used by the semantic
 747    --  routines, where this is a common error message situation. The Msg text
 748    --  will contain a & or } as usual to mark the insertion point. This
 749    --  routine can be called from the parser or the analyzer.
 750
 751    procedure Error_Msg_FE
 752      (Msg : String;
 753       N   : Node_Id;
 754       E   : Node_Or_Entity_Id);
 755    --  Same as Error_Msg_NE, except that the message is placed on the first
 756    --  node of the construct N (First_Node (N)).
 757
 758    procedure Error_Msg_NEL
 759      (Msg           : String;
 760       N             : Node_Or_Entity_Id;
 761       E             : Node_Or_Entity_Id;
 762       Flag_Location : Source_Ptr);
 763    --  Exactly the same as Error_Msg_NE, except that the flag is placed at
 764    --  the specified Flag_Location instead of at Sloc (N).
 765
 766    procedure Error_Msg_NW
 767      (Eflag : Boolean;
 768       Msg   : String;
 769       N     : Node_Or_Entity_Id);
 770    --  This routine is used for posting a message conditionally. The message
 771    --  is posted (with the same effect as Error_Msg_N (Msg, N) if and only
 772    --  if Eflag is True and if the node N is within the main extended source
 773    --  unit and comes from source. Typically this is a warning mode flag.
 774    --  This routine can only be called during semantic analysis. It may not
 775    --  be called during parsing.
 776
 777    procedure Change_Error_Text (Error_Id : Error_Msg_Id; New_Msg : String);
 778    --  The error message text of the message identified by Id is replaced by
 779    --  the given text. This text may contain insertion characters in the
 780    --  usual manner, and need not be the same length as the original text.
 781
 782    function First_Node (C : Node_Id) return Node_Id;
 783    --  Given a construct C, finds the first node in the construct, i.e. the one
 784    --  with the lowest Sloc value. This is useful in placing error msgs. Note
 785    --  that this procedure uses Original_Node to look at the original source
 786    --  tree, since that's what we want for placing an error message flag in
 787    --  the right place.
 788
 789    function First_Sloc (N : Node_Id) return Source_Ptr;
 790    --  Given the node for an expression, return a source pointer value that
 791    --  points to the start of the first token in the expression. In the case
 792    --  where the expression is parenthesized, an attempt is made to include
 793    --  the parentheses (i.e. to return the location of the initial paren).
 794
 795    function Get_Ignore_Errors return Boolean;
 796    --  Return True if all error calls are ignored.
 797
 798    procedure Purge_Messages (From : Source_Ptr; To : Source_Ptr)
 799      renames Erroutc.Purge_Messages;
 800    --  All error messages whose location is in the range From .. To (not
 801    --  including the end points) will be deleted from the error listing.
 802
 803    procedure Remove_Warning_Messages (N : Node_Id);
 804    --  Remove any warning messages corresponding to the Sloc of N or any
 805    --  of its descendant nodes. No effect if no such warnings. Note that
 806    --  style messages (identified by the fact that they start with "(style)")
 807    --  are not removed by this call. Basically the idea behind this procedure
 808    --  is to remove warnings about execution conditions from known dead code.
 809
 810    procedure Remove_Warning_Messages (L : List_Id);
 811    --  Remove warnings on all elements of a list (Calls Remove_Warning_Messages
 812    --  on each element of the list, see above).
 813
 814    procedure Reset_Warnings;
 815    --  Reset the counts related to warnings. This is used both to initialize
 816    --  these counts and to reset them after each phase of analysis for a given
 817    --  value of Opt.Warning_Mode in gnat2why.
 818
 819    procedure Set_Ignore_Errors (To : Boolean);
 820    --  Following a call to this procedure with To=True, all error calls are
 821    --  ignored. A call with To=False restores the default treatment in which
 822    --  error calls are treated as usual (and as described in this spec).
 823
 824    procedure Set_Warnings_Mode_Off (Loc : Source_Ptr; Reason : String_Id)
 825      renames Erroutc.Set_Warnings_Mode_Off;
 826    --  Called in response to a pragma Warnings (Off) to record the source
 827    --  location from which warnings are to be turned off. Reason is the
 828    --  Reason from the pragma, or the null string if none is given.
 829
 830    procedure Set_Warnings_Mode_On (Loc : Source_Ptr)
 831      renames Erroutc.Set_Warnings_Mode_On;
 832    --  Called in response to a pragma Warnings (On) to record the source
 833    --  location from which warnings are to be turned back on.
 834
 835    procedure Set_Specific_Warning_Off
 836      (Loc    : Source_Ptr;
 837       Msg    : String;
 838       Reason : String_Id;
 839       Config : Boolean;
 840       Used   : Boolean := False)
 841      renames Erroutc.Set_Specific_Warning_Off;
 842    --  This is called in response to the two argument form of pragma Warnings
 843    --  where the first argument is OFF, and the second argument is a string
 844    --  which identifies a specific warning to be suppressed. The first argument
 845    --  is the start of the suppression range, and the second argument is the
 846    --  string from the pragma. Loc is the location of the pragma (which is the
 847    --  start of the range to suppress). Reason is the reason string from the
 848    --  pragma, or the null string if no reason is given. Config is True for the
 849    --  configuration pragma case (where there is no requirement for a matching
 850    --  OFF pragma). Used is set True to disable the check that the warning
 851    --  actually has the effect of suppressing a warning.
 852
 853    procedure Set_Specific_Warning_On
 854      (Loc : Source_Ptr;
 855       Msg : String;
 856       Err : out Boolean)
 857      renames Erroutc.Set_Specific_Warning_On;
 858    --  This is called in response to the two argument form of pragma Warnings
 859    --  where the first argument is ON, and the second argument is the prefix
 860    --  of a specific warning to be suppressed. The first argument is the end
 861    --  of the suppression range, and the second argument is the string from
 862    --  the pragma. Err is set to True on return to report the error of no
 863    --  matching Warnings Off pragma preceding this one.
 864
 865    function Compilation_Errors return Boolean;
 866    --  Returns True if errors have been detected, or warnings in -gnatwe (treat
 867    --  warnings as errors) mode. Note that it is mandatory to call Finalize
 868    --  before calling this routine. To account for changes to Warning_Mode in
 869    --  gnat2why between phases, the past or current presence of an error is
 870    --  recorded in a global variable at each call.
 871
 872    procedure Error_Msg_CRT (Feature : String; N : Node_Id);
 873    --  Posts a non-fatal message on node N saying that the feature identified
 874    --  by the Feature argument is not supported in either configurable
 875    --  run-time mode or no run-time mode (as appropriate). In the former case,
 876    --  the name of the library is output if available.
 877
 878    procedure Error_Msg_PT (E : Entity_Id; Iface_Prim : Entity_Id);
 879    --  Posts an error on protected type entry or subprogram E (referencing its
 880    --  overridden interface primitive Iface_Prim) indicating wrong mode of the
 881    --  first formal (RM 9.4(11.9/3)).
 882
 883    procedure Error_Msg_Ada_2012_Feature (Feature : String; Loc : Source_Ptr);
 884    --  If not operating in Ada 2012 mode, posts errors complaining that Feature
 885    --  is only supported in Ada 2012, with appropriate suggestions to fix this.
 886    --  Loc is the location at which the flag is to be posted. Feature, which
 887    --  appears at the start of the first generated message, may contain error
 888    --  message insertion characters in the normal manner, and in particular
 889    --  may start with | to flag a non-serious error.
 890
 891    procedure dmsg (Id : Error_Msg_Id) renames Erroutc.dmsg;
 892    --  Debugging routine to dump an error message
 893
 894    ------------------------------------
 895    -- SPARK Error Output Subprograms --
 896    ------------------------------------
 897
 898    --  The following routines are intended to report semantic errors in SPARK
 899    --  constructs subject to aspect/pragma SPARK_Mode. Note that syntax errors
 900    --  must be reported using the Error_Msg_XXX routines. This allows for the
 901    --  partial analysis of SPARK features when they are disabled via SPARK_Mode
 902    --  set to "off".
 903
 904    procedure SPARK_Msg_N (Msg : String; N : Node_Or_Entity_Id);
 905    pragma Inline (SPARK_Msg_N);
 906    --  Same as Error_Msg_N, but the error is suppressed if SPARK_Mode is Off.
 907    --  The routine is inlined because it acts as a simple wrapper.
 908
 909    procedure SPARK_Msg_NE
 910      (Msg : String;
 911       N   : Node_Or_Entity_Id;
 912       E   : Node_Or_Entity_Id);
 913    pragma Inline (SPARK_Msg_NE);
 914    --  Same as Error_Msg_NE, but the error is suppressed if SPARK_Mode is Off.
 915    --  The routine is inlined because it acts as a simple wrapper.
 916
 917    ------------------------------------------
 918    -- Utility Interface for Casing Control --
 919    ------------------------------------------
 920
 921    procedure Adjust_Name_Case
 922      (Buf : in out Bounded_String;
 923       Loc : Source_Ptr);
 924    --  Given a name stored in Buf, set proper casing. Loc is an associated
 925    --  source position, and if we can find a match between the name in Buf and
 926    --  the name at that source location, we copy the casing from the source,
 927    --  otherwise we set appropriate default casing.
 928
 929    procedure Adjust_Name_Case (Loc : Source_Ptr);
 930    --  Uses Buf => Global_Name_Buffer. There are no calls to this in the
 931    --  compiler, but it is called in SPARK 2014.
 932
 933    procedure Set_Identifier_Casing
 934      (Identifier_Name : System.Address;
 935       File_Name       : System.Address);
 936    --  This subprogram can be used by the back end for the purposes of
 937    --  concocting error messages that are not output via Errout, e.g.
 938    --  the messages generated by the gcc back end.
 939    --
 940    --  The identifier is a null terminated string that represents the name of
 941    --  an identifier appearing in the source program. File_Name is a null
 942    --  terminated string giving the corresponding file name for the identifier
 943    --  as obtained from the front end by the use of Full_Debug_Name to the
 944    --  source file referenced by the corresponding source location value. On
 945    --  return, the name is in Name_Buffer, null terminated with Name_Len set.
 946    --  This name is the identifier name as passed, cased according to the
 947    --  default identifier casing for the given file.
 948
 949 end Errout;