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------------------------------------------------------------------------------

--                                                                          --

--                         GNAT COMPILER COMPONENTS                         --

--                                                                          --

--                             L I B . W R I T                              --

--                                                                          --

--                                 S p e c                                  --

--                                                                          --

--          Copyright (C) 1992-2009, Free Software Foundation, Inc.         --

--                                                                          --

-- GNAT is free software;  you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --

-- for  more details.  You should have  received  a copy of the GNU General --

-- Public License  distributed with GNAT; see file COPYING3.  If not, go to --

-- http://www.gnu.org/licenses for a complete copy of the license.          --

--                                                                          --

-- GNAT was originally developed  by the GNAT team at  New York University. --

-- Extensive contributions were provided by Ada Core Technologies Inc.      --

--                                                                          --

------------------------------------------------------------------------------

--  This package contains the routines for writing the library information

package Lib.Writ is

   -----------------------------------

   -- Format of Library Information --

   -----------------------------------

   --  This section describes the format of the library information that is

   --  associated with object files. The exact method of this association is

   --  potentially implementation dependent and is described and implemented in

   --  package ali. From the point of view of the description here, all we need

   --  to know is that the information is represented as a string of characters

   --  that is somehow associated with an object file, and can be retrieved. If

   --  no library information exists for a given object file, then we take this

   --  as equivalent to the non-existence of the object file, as if source file

   --  has not been previously compiled.

   --  The library information is written as a series of lines of the form:

   --    Key_Character parameter parameter ...

   --  The following sections describe the format of these lines in detail

   --------------------------------------

   -- Making Changes to the ALI Format --

   --------------------------------------

   --  A number of tools use ali.adb to parse ali files. This means that

   --  changes to this format can cause old versions of these tools to be

   --  incompatible with new versions of the compiler. Any changes to ali file

   --  formats must be carefully evaluated to understand any such possible

   --  conflicts, and in particular, it is very undesirable to create conflicts

   --  between older versions of GPS and newer versions of the compiler.

   --  If the following guidelines are respected, downward compatibility

   --  problems (old tools reading new ali files) should be minimized:

   --    The basic key character format must be kept

   --    The V line must be the first line, this is checked by ali.adb even in

   --    Ignore_Errors mode, and is used to verify that the file at hand is

   --    indeed likely intended to be an ali file.

   --    The P line must be present, though may be modified in contents

   --    according to remaining guidelines. Again, ali.adb assumes the P

   --    line is present even in Ignore_Errors mode.

   --    New modifiers can generally be added (in particular adding new two

   --    letter modifiers to the P or U lines is always safe)

   --    Adding entirely new lines (with a new key letter) to the ali file is

   --    always safe, at any point (other than before the V line), since such

   --    lines will be ignored.

   --  Following the guidelines in this section should ensure that this problem

   --  is minimized and that old tools will be able to deal successfully with

   --  new ali formats. Note that this does not apply to the compiler itself,

   --  which always requires consistency between the ali files and the binder.

   --  That is because one of the main functions of the binder is to ensure

   --  consistency of the partition, and this can be compromised if the ali

   --  files are inconsistent.

   ------------------

   -- Header Lines --

   ------------------

   --  The initial header lines in the file give information about the

   --  compilation environment, and identify other special information such as

   --  main program parameters.

   --  ----------------

   --  -- V  Version --

   --  ----------------

   --    V "xxxxxxxxxxxxxxxx"

   --

   --      This line indicates the library output version, as defined in

   --      Gnatvsn. It ensures that separate object modules of a program are

   --      consistent. It has to be changed if anything changes which would

   --      affect successful binding of separately compiled modules. Examples

   --      of such changes are modifications in the format of the library info

   --      described in this package, or modifications to calling sequences, or

   --      to the way that data is represented.

   --    Note: the V line absolutely must be the first line, and no change

   --    to the ALI format should change this, since even in Ignore_Errors

   --    mode, Scan_ALI insists on finding a V line.

   --  ---------------------

   --  -- M  Main Program --

   --  ---------------------

   --    M type [priority] [T=time-slice] W=?

   --      This line appears only if the main unit for this file is suitable

   --      for use as a main program. The parameters are:

   --        type

   --          P for a parameterless procedure

   --          F for a function returning a value of integral type

   --            (used for writing a main program returning an exit status)

   --        priority

   --          Present only if there was a valid pragma Priority in the

   --          corresponding unit to set the main task priority. It is an

   --          unsigned decimal integer.

   --        T=time-slice

   --          Present only if there was a valid pragma Time_Slice in the

   --          corresponding unit. It is an unsigned decimal integer in the

   --          range 0 .. 10**9 giving the time slice value in units of

   --          milliseconds. The actual significance of this parameter is

   --          target dependent.

   --        W=?

   --          This parameter indicates the wide character encoding method used

   --          when compiling the main program file. The ? character is the

   --          single character used in the -gnatW? switch. This is used to

   --          provide the default wide-character encoding for Wide_Text_IO

   --          files.

   --  -----------------

   --  -- A  Argument --

   --  -----------------

   --    A argument

   --      One of these lines appears for each of the arguments present in the

   --      call to the gnat1 program. This can be used if it is necessary to

   --      reconstruct this call (e.g. for fix and continue).

   --  -------------------

   --  -- P  Parameters --

   --  -------------------

   --    P <<parameters>>

   --      Indicates various information that applies to the compilation of the

   --      corresponding source file. Parameters is a sequence of zero or more

   --      two letter codes that indicate configuration pragmas and other

   --      parameters that apply:

   --

   --      The arguments are as follows:

   --

   --         CE   Compilation errors. If this is present it means that the ali

   --              file resulted from a compilation with the -gnatQ switch set,

   --              and illegalities were detected. The ali file contents may

   --              not be completely reliable, but the format will be correct

   --              and complete. Note that NO is always present if CE is

   --              present.

   --

   --         DB   Detect_Blocking pragma is in effect for all units in this

   --              file.

   --

   --         FD   Configuration pragmas apply to all the units in this file

   --              specifying a possibly non-standard floating point format

   --              (VAX float with Long_Float using D_Float).

   --

   --         FG   Configuration pragmas apply to all the units in this file

   --              specifying a possibly non-standard floating point format

   --              (VAX float with Long_Float using G_Float).

   --

   --         FI   Configuration pragmas apply to all the units in this file

   --              specifying a possibly non-standard floating point format

   --              (IEEE Float).

   --

   --         Lx   A valid Locking_Policy pragma applies to all the units in

   --              this file, where x is the first character (upper case) of

   --              the policy name (e.g. 'C' for Ceiling_Locking).

   --

   --         NO   No object. This flag indicates that the units in this file

   --              were not compiled to produce an object. This can occur as a

   --              result of the use of -gnatc, or if no object can be produced

   --              (e.g. when a package spec is compiled instead of the body,

   --              or a subunit on its own).

   --

   --         NR   No_Run_Time. Indicates that a pragma No_Run_Time applies

   --              to all units in the file.

   --

   --         NS   Normalize_Scalars pragma in effect for all units in

   --              this file.

   --

   --         Qx   A valid Queueing_Policy pragma applies to all the units

   --              in this file, where x is the first character (upper case)

   --              of the policy name (e.g. 'P' for Priority_Queueing).

   --

   --         SL   Indicates that the unit is an Interface to a Standalone

   --              Library. Note that this indication is never given by the

   --              compiler, but is added by the Project Manager in gnatmake

   --              when an Interface ALI file is copied to the library

   --              directory.

   --         SS   This unit references System.Secondary_Stack (that is,

   --              the unit makes use of the secondary stack facilities).

   --

   --         Tx   A valid Task_Dispatching_Policy pragma applies to all

   --              the units in this file, where x is the first character

   --              (upper case) of the corresponding policy name (e.g. 'F'

   --              for FIFO_Within_Priorities).

   --

   --         UA  Unreserve_All_Interrupts pragma was processed in one or

   --             more units in this file

   --

   --         ZX  Units in this file use zero-cost exceptions and have

   --             generated exception tables. If ZX is not present, the

   --             longjmp/setjmp exception scheme is in use.

   --

   --      Note that language defined units never output policy (Lx, Tx, Qx)

   --      parameters. Language defined units must correctly handle all

   --      possible cases. These values are checked for consistency by the

   --      binder and then copied to the generated binder output file.

   --    Note: The P line must be present. Even in Ignore_Errors mode, Scan_ALI

   --    insists on finding a P line. So if changes are made to the ALI format,

   --    they should not include removing the P line!

   --  ---------------------

   --  -- R  Restrictions --

   --  ---------------------

   --  The first R line records the status of restrictions generated by pragma

   --  Restrictions encountered, as well as information on what the compiler

   --  has been able to determine with respect to restrictions violations.

   --  The format is:

   --    R <<restriction-characters>> <<restriction-param-id-entries>>

   --      The first parameter is a string of characters that records

   --      information regarding restrictions that do not take parameter not

   --      take parameter values. It is a string of characters, one character

   --      for each value (in order) in All_Boolean_Restrictions. There are

   --      three possible settings for each restriction:

   --        r   Restricted. Unit was compiled under control of a pragma

   --            Restrictions for the corresponding restriction. In this case

   --            the unit certainly does not violate the Restriction, since

   --            this would have been detected by the compiler.

   --        n   Not used. The unit was not compiled under control of a pragma

   --            Restrictions for the corresponding restriction, and does not

   --            make any use of the referenced feature.

   --        v   Violated. The unit was not compiled under control of a pragma

   --            Restrictions for the corresponding restriction, and it does

   --            indeed use the referenced feature.

   --      This information is used in the binder to check consistency, i.e. to

   --      detect cases where one unit has "r" and another unit has "v", which

   --      is not permitted, since these restrictions are partition-wide.

   --  The second parameter, which immediately follows the first (with no

   --  separating space) gives restriction information for identifiers for

   --  which a parameter is given.

   --      The parameter is a string of entries, one for each value in

   --      Restrict.All_Parameter_Restrictions. Each entry has two components

   --      in sequence, the first indicating whether or not there is a

   --      restriction, and the second indicating whether or not the compiler

   --      detected violations. In the boolean case it is not necessary to

   --      separate these, since if a restriction is set, and violated, that is

   --      an error. But in the parameter case, this is not true. For example,

   --      we can have a unit with a pragma Restrictions (Max_Tasks => 4),

   --      where the compiler can detect that there are exactly three tasks

   --      declared. Both of these pieces of information must be passed to the

   --      binder. The parameter of 4 is important in case the total number of

   --      tasks in the partition is greater than 4. The parameter of 3 is

   --      important in case some other unit has a restrictions pragma with

   --      Max_Tasks=>2.

   --      The component for the presence of restriction has one of two

   --      possible forms:

   --         n   No pragma for this restriction is present in the set of units

   --             for this ali file.

   --         rN  At least one pragma for this restriction is present in the

   --             set of units for this ali file. The value N is the minimum

   --             parameter value encountered in any such pragma. N is in the

   --             range of Integer (a value larger than N'Last causes the

   --             pragma to be ignored).

   --      The component for the violation detection has one of three

   --      possible forms:

   --         n   No violations were detected by the compiler

   --         vN  A violation was detected. N is either the maximum or total

   --             count of violations (depending on the checking type) in all

   --             the units represented by the ali file). Note that this

   --             setting is only allowed for restrictions that are in

   --             Checked_[Max|Sum]_Parameter_Restrictions. The value here is

   --             known to be exact by the compiler and is in the range of

   --             Natural.

   --         vN+ A violation was detected. The compiler cannot determine

   --             the exact count of violations, but it is at least N.

   --      There are no spaces within the parameter string, so the entry

   --      described above in the header of this section for Max_Tasks would

   --      appear as the string r4v3.

   --      Note: The restrictions line is required to be present. Even in

   --      Ignore_Errors mode, Scan_ALI expects to find an R line and will

   --      signal a fatal error if it is missing. This means that future

   --      changes to the ALI file format must retain the R line.

   --  Subsequent R lines are present only if pragma Restriction No_Dependence

   --  is used. There is one such line for each such pragma appearing in the

   --  extended main unit. The format is

   --    R unit_name

   --      Here the unit name is in all lower case. The components of the unit

   --      name are separated by periods. The names themselves are in encoded

   --      form, as documented in Namet.

   --  -------------------------

   --  -- I  Interrupt States --

   --  -------------------------

   --    I interrupt-number interrupt-state line-number

   --      This line records information from an Interrupt_State pragma. There

   --      is one line for each separate pragma, and if no such pragmas are

   --      used, then no I lines are present.

   --      The interrupt-number is an unsigned positive integer giving the

   --      value of the interrupt as defined in Ada.Interrupts.Names.

   --      The interrupt-state is one of r/s/u for Runtime/System/User

   --      The line number is an unsigned decimal integer giving the line

   --      number of the corresponding Interrupt_State pragma. This is used

   --      in consistency messages.

   --  --------------------------------------

   --  -- S  Priority Specific Dispatching --

   --  --------------------------------------

   --    S policy_identifier first_priority last_priority line-number

   --      This line records information from a Priority_Specific_Dispatching

   --      pragma. There is one line for each separate pragma, and if no such

   --      pragmas are used, then no S lines are present.

   --      The policy_identifier is the first character (upper case) of the

   --      corresponding policy name (e.g. 'F' for FIFO_Within_Priorities).

   --      The first_priority and last_priority fields define the range of

   --      priorities to which the specified dispatching policy apply.

   --      The line number is an unsigned decimal integer giving the line

   --      number of the corresponding Priority_Specific_Dispatching pragma.

   --      This is used in consistency messages.

   ----------------------------

   -- Compilation Unit Lines --

   ----------------------------

   --  Following these header lines, a set of information lines appears for

   --  each compilation unit that appears in the corresponding object file. In

   --  particular, when a package body or subprogram body is compiled, there

   --  will be two sets of information, one for the spec and one for the body,

   --  with the entry for the body appearing first. This is the only case in

   --  which a single ALI file contains more than one unit (in particular note

   --  that subunits do *not* count as compilation units for this purpose, and

   --  generate no library information, since they are inlined).

   --  --------------------

   --  -- U  Unit Header --

   --  --------------------

   --  The lines for each compilation unit have the following form

   --    U unit-name source-name version <<attributes>>

   --

   --      This line identifies the unit to which this section of the library

   --      information file applies. The first three parameters are the unit

   --      name in internal format, as described in package Uname, and the name

   --      of the source file containing the unit.

   --

   --      Version is the version given as eight hexadecimal characters with

   --      upper case letters. This value is the exclusive or of the source

   --      checksums of the unit and all its semantically dependent units.

   --

   --      The <<attributes>> are a series of two letter codes indicating

   --      information about the unit:

   --

   --         BD  Unit does not have pragma Elaborate_Body, but the elaboration

   --             circuit has determined that it would be a good idea if this

   --             pragma were present, since the body of the package contains

   --             elaboration code that modifies one or more variables in the

   --             visible part of the package. The binder will try, but does

   --             not promise, to keep the elaboration of the body close to

   --             the elaboration of the spec.

   --

   --         DE  Dynamic Elaboration. This unit was compiled with the dynamic

   --             elaboration model, as set by either the -gnatE switch or

   --             pragma Elaboration_Checks (Dynamic).

   --

   --         EB  Unit has pragma Elaborate_Body, or is a generic instance that

   --             has a body. Set for instances because RM 12.3(20) requires

   --             that the body be immediately elaborated after the spec (we

   --             would normally do that anyway, because elaborate spec and

   --             body together whenever possible, and for an instance it is

   --             always possible; however setting EB ensures that this is done

   --             even when using the -p gnatbind switch).

   --

   --         EE  Elaboration entity is present which must be set true when

   --             the unit is elaborated. The name of the elaboration entity is

   --             formed from the unit name in the usual way. If EE is present,

   --             then this boolean must be set True as part of the elaboration

   --             processing routine generated by the binder. Note that EE can

   --             be set even if NE is set. This happens when the boolean is

   --             needed solely for checking for the case of access before

   --             elaboration.

   --

   --         GE  Unit is a generic declaration, or corresponding body

   --

   --         IL  Unit source uses a style with identifiers in all lower-case

   --         IU  (IL) or all upper case (IU). If the standard mixed-case usage

   --             is detected, or the compiler cannot determine the style, then

   --             no I parameter will appear.

   --

   --         IS  Initialize_Scalars pragma applies to this unit, or else there

   --             is at least one use of the Invalid_Value attribute.

   --

   --         KM  Unit source uses a style with keywords in mixed case (KM)

   --         KU  or all upper case (KU). If the standard lower-case usage is

   --             is detected, or the compiler cannot determine the style, then

   --             no K parameter will appear.

   --

   --         NE  Unit has no elaboration routine. All subprogram bodies and

   --             specs are in this category. Package bodies and specs may or

   --             may not have NE set, depending on whether or not elaboration

   --             code is required. Set if N_Compilation_Unit node has flag

   --             Has_No_Elaboration_Code set.

   --

   --         OL   The units in this file are compiled with a local pragma

   --              Optimize_Alignment, so no consistency requirement applies

   --              to these units. All internal units have this status since

   --              they have an automatic default of Optimize_Alignment (Off).

   --

   --         OO   Optimize_Alignment (Off) is the default setting for all

   --              units in this file. All files in the partition that specify

   --              a default must specify the same default.

   --

   --         OS   Optimize_Alignment (Space) is the default setting for all

   --              units in this file. All files in the partition that specify

   --              a default must specify the same default.

   --

   --         OT   Optimize_Alignment (Time) is the default setting for all

   --              units in this file. All files in the partition that specify

   --              a default must specify the same default.

   --

   --         PK  Unit is package, rather than a subprogram

   --

   --         PU  Unit has pragma Pure

   --

   --         PR  Unit has pragma Preelaborate

   --

   --         RA  Unit declares a Remote Access to Class-Wide (RACW) type

   --

   --         RC  Unit has pragma Remote_Call_Interface

   --

   --         RT  Unit has pragma Remote_Types

   --

   --         SP  Unit has pragma Shared_Passive.

   --

   --         SU  Unit is a subprogram, rather than a package

   --

   --      The attributes may appear in any order, separated by spaces.

   --  ---------------------

   --  -- W  Withed Units --

   --  ---------------------

   --  Following each U line, is a series of lines of the form

   --    W unit-name [source-name lib-name] [E] [EA] [ED] [AD]

   --

   --      One of these lines is present for each unit that is mentioned in an

   --      explicit with clause by the current unit. The first parameter is the

   --      unit name in internal format. The second parameter is the file name

   --      of the file that must be compiled to compile this unit. It is

   --      usually the file for the body, except for packages which have no

   --      body. For units that need a body, if the source file for the body

   --      cannot be found, the file name of the spec is used instead. The

   --      third parameter is the file name of the library information file

   --      that contains the results of compiling this unit. The optional

   --      modifiers are used as follows:

   --

   --        E   pragma Elaborate applies to this unit

   --

   --        EA  pragma Elaborate_All applies to this unit

   --

   --        ED  Elaborate_Desirable set for this unit, which means that there

   --            is no Elaborate, but the analysis suggests that Program_Error

   --            may be raised if the Elaborate conditions cannot be satisfied.

   --            The binder will attempt to treat ED as E if it can.

   --

   --        AD  Elaborate_All_Desirable set for this unit, which means that

   --            there is no Elaborate_All, but the analysis suggests that

   --            Program_Error may be raised if the Elaborate_All conditions

   --            cannot be satisfied. The binder will attempt to treat AD as

   --            EA if it can.

   --

   --      The parameter source-name and lib-name are omitted for the case of a

   --      generic unit compiled with earlier versions of GNAT which did not

   --      generate object or ali files for generics.

   --  In fact W lines include implicit withs ???

   --  -----------------------

   --  -- L  Linker_Options --

   --  -----------------------

   --  Following the W lines (if any, or the U line if not), are an optional

   --  series of lines that indicates the usage of the pragma Linker_Options in

   --  the associated unit. For each appearance of a pragma Linker_Options (or

   --  Link_With) in the unit, a line is present with the form:

   --    L "string"

   --      where string is the string from the unit line enclosed in quotes.

   --      Within the quotes the following can occur:

   --        c    graphic characters in range 20-7E other than " or {

   --        ""   indicating a single " character

   --        {hh} indicating a character whose code is hex hh (0-9,A-F)

   --        {00} [ASCII.NUL] is used as a separator character

   --             to separate multiple arguments of a single

   --             Linker_Options pragma.

   --      For further details, see Stringt.Write_String_Table_Entry. Note that

   --      wide characters in the form {hhhh} cannot be produced, since pragma

   --      Linker_Option accepts only String, not Wide_String.

   --      The L lines are required to appear in the same order as the

   --      corresponding Linker_Options (or Link_With) pragmas appear in the

   --      source file, so that this order is preserved by the binder in

   --      constructing the set of linker arguments.

   ---------------------

   -- Reference Lines --

   ---------------------

   --  The reference lines contain information about references from any of the

   --  units in the compilation (including, body version and version

   --  attributes, linker options pragmas and source dependencies.

   --  ------------------------------------

   --  -- E  External Version References --

   --  ------------------------------------

   --  One of these lines is present for each use of 'Body_Version or 'Version

   --  in any of the units of the compilation. These are used by the linker to

   --  determine which version symbols must be output. The format is simply:

   --    E name

   --  where name is the external name, i.e. the unit name with either a S or a

   --  B for spec or body version referenced (Body_Version always references

   --  the body, Version references the Spec, except in the case of a reference

   --  to a subprogram with no separate spec). Upper half and wide character

   --  codes are encoded using the same method as in Namet (Uhh for upper half,

   --  Whhhh for wide character, where hh are hex digits).

   --  ---------------------

   --  -- D  Dependencies --

   --  ---------------------

   --  The dependency lines indicate the source files on which the compiled

   --  units depend. This is used by the binder for consistency checking.

   --  These lines are also referenced by the cross-reference information.

   --    D source-name time-stamp checksum [subunit-name] line:file-name

   --      The time-stamp field contains the time stamp of the corresponding

   --      source file. See types.ads for details on time stamp representation.

   --      The checksum is an 8-hex digit representation of the source file

   --      checksum, with letters given in lower case.

   --      The subunit name is present only if the dependency line is for a

   --      subunit. It contains the fully qualified name of the subunit in all

   --      lower case letters.

   --      The line:file-name entry is present only if a Source_Reference

   --      pragma appeared in the source file identified by source-name. In

   --      this case, it gives the information from this pragma. Note that this

   --      allows cross-reference information to be related back to the

   --      original file. Note: the reason the line number comes first is that

   --      a leading digit immediately identifies this as a Source_Reference

   --      entry, rather than a subunit-name.

   --      A line number of zero for line: in this entry indicates that there

   --      is more than one source reference pragma. In this case, the line

   --      numbers in the cross-reference are correct, and refer to the

   --      original line number, but there is no information that allows a

   --      reader of the ALI file to determine the exact mapping of physical

   --      line numbers back to the original source.

   --      Files with a zero checksum and a non-zero time stamp are in general

   --      files on which the compilation depends but which are not Ada files

   --      with further dependencies. This includes preprocessor data files

   --      and preprocessor definition files.

   --      Note: blank lines are ignored when the library information is read,

   --      and separate sections of the file are separated by blank lines to

   --      ease readability. Blanks between fields are also ignored.

   --      For entries corresponding to files that were not present (and thus

   --      resulted in error messages), or for files that are not part of the

   --      dependency set, both the time stamp and checksum are set to all zero

   --      characters. These dummy entries are ignored by the binder in

   --      dependency checking, but must be present for proper interpretation

   --      of the cross-reference data.

   --------------------------

   -- Cross-Reference Data --

   --------------------------

   --  The cross-reference data follows the dependency lines. See the spec of

   --  Lib.Xref for details on the format of this data.

   --  --------------

   --  -- N  Notes --

   --  --------------

   --  The note lines record annotations inserted in source code for processing

   --  by external tools using pragmas. For each occurrence of any of these

   --  pragmas, a line is generated with the following syntax:

   --    N <dep>x<sloc> [<arg_id>:]<arg> ...

   --  x is one of:

   --    A  pragma Annotate

   --    C  pragma Comment

   --    I  pragma Ident

   --    T  pragma Title

   --    S  pragma Subtitle

   --  <dep>  is the source file containing the pragma by its dependency index

   --         (first D line has index 1)

   --  <sloc> is the source location of the pragma

   --  Successive entries record the pragma_argument_associations.

   --  For a named association, the entry is prefixed with the pragma argument

   --  identifier <arg_id> followed by a colon.

   --  <arg> represents the pragma argument, and has the following conventions:

   --   - identifiers are output verbatim

   --   - static string expressions are output as literals encoded as for

   --       L lines

   --   - static integer expressions are output as decimal literals

   --   - any other expression is replaced by the placeholder "<expr>"

   ---------------------------------

   -- Source Coverage Obligations --

   ---------------------------------

   --  The Source Coverage Obligation (SCO) information follows the cross-

   --  reference data. See the spec of Par_SCO for full details of the format.

   ----------------------

   -- Global_Variables --

   ----------------------

   --  The table structure defined here stores one entry for each

   --  Interrupt_State pragma encountered either in the main source or

   --  in an ancillary with'ed source. Since interrupt state values

   --  have to be consistent across all units in a partition, we may

   --  as well detect inconsistencies at compile time when we can.

   type Interrupt_State_Entry is record

      Interrupt_Number : Pos;

      --  Interrupt number value

      Interrupt_State : Character;

      --  Set to r/s/u for Runtime/System/User

      Pragma_Loc : Source_Ptr;

      --  Location of pragma setting this value in place

   end record;

   package Interrupt_States is new Table.Table (

     Table_Component_Type => Interrupt_State_Entry,

     Table_Index_Type     => Nat,

     Table_Low_Bound      => 1,

     Table_Initial        => 30,

     Table_Increment      => 200,

     Table_Name           => "Name_Interrupt_States");

   --  The table structure defined here stores one entry for each

   --  Priority_Specific_Dispatching pragma encountered either in the main

   --  source or in an ancillary with'ed source. Since have to be consistent

   --  across all units in a partition, we may as well detect inconsistencies

   --  at compile time when we can.

   type Specific_Dispatching_Entry is record

      Dispatching_Policy : Character;

      --  First character (upper case) of the corresponding policy name

      First_Priority     : Nat;

      --  Lower bound of the priority range to which the specified dispatching

      --  policy applies.

      Last_Priority      : Nat;

      --  Upper bound of the priority range to which the specified dispatching

      --  policy applies.

      Pragma_Loc         : Source_Ptr;

      --  Location of pragma setting this value in place

   end record;

   package Specific_Dispatching is new Table.Table (

     Table_Component_Type => Specific_Dispatching_Entry,

     Table_Index_Type     => Nat,

     Table_Low_Bound      => 1,

     Table_Initial        => 10,

     Table_Increment      => 100,

     Table_Name           => "Name_Priority_Specific_Dispatching");

   -----------------

   -- Subprograms --

   -----------------

   procedure Ensure_System_Dependency;

   --  This procedure ensures that a dependency is created on system.ads. Even

   --  if there is no semantic dependency, Targparm has read the file to

   --  acquire target parameters, so we need a source dependency.

   procedure Write_ALI (Object : Boolean);

   --  This procedure writes the library information for the current main unit

   --  The Object parameter is true if an object file is created, and false

   --  otherwise.

   --

   --  Note: in the case where we are not generating code (-gnatc mode), this

   --  routine only writes an ALI file if it cannot find an existing up to

   --  date ALI file. If it *can* find an existing up to date ALI file, then

   --  it reads this file and sets the Lib.Compilation_Arguments table from

   --  the A lines in this file.

   procedure Add_Preprocessing_Dependency (S : Source_File_Index);

   --  Indicate that there is a dependency to be added on a preprocessing data

   --  file or on a preprocessing definition file.

end Lib.Writ;