Mercurial > hg > CbC > CbC_gcc
diff gcc/ada/par.adb @ 111:04ced10e8804
gcc 7
| author | kono |
|---|---|
| date | Fri, 27 Oct 2017 22:46:09 +0900 |
| parents | |
| children | 84e7813d76e9 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/gcc/ada/par.adb Fri Oct 27 22:46:09 2017 +0900 @@ -0,0 +1,1700 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT COMPILER COMPONENTS -- +-- -- +-- P A R -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 1992-2017, 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. -- +-- -- +------------------------------------------------------------------------------ + +with Aspects; use Aspects; +with Atree; use Atree; +with Casing; use Casing; +with Debug; use Debug; +with Elists; use Elists; +with Errout; use Errout; +with Fname; use Fname; +with Lib; use Lib; +with Namet; use Namet; +with Namet.Sp; use Namet.Sp; +with Nlists; use Nlists; +with Nmake; use Nmake; +with Opt; use Opt; +with Output; use Output; +with Par_SCO; use Par_SCO; +with Restrict; use Restrict; +with Scans; use Scans; +with Scn; use Scn; +with Sem_Util; use Sem_Util; +with Sinput; use Sinput; +with Sinput.L; use Sinput.L; +with Sinfo; use Sinfo; +with Snames; use Snames; +with Style; +with Stylesw; use Stylesw; +with Table; +with Tbuild; use Tbuild; + +--------- +-- Par -- +--------- + +function Par (Configuration_Pragmas : Boolean) return List_Id is + + Num_Library_Units : Natural := 0; + -- Count number of units parsed (relevant only in syntax check only mode, + -- since in semantics check mode only a single unit is permitted anyway). + + Save_Config_Switches : Config_Switches_Type; + -- Variable used to save values of config switches while we parse the + -- new unit, to be restored on exit for proper recursive behavior. + + Loop_Block_Count : Nat := 0; + -- Counter used for constructing loop/block names (see the routine + -- Par.Ch5.Get_Loop_Block_Name). + + Inside_Record_Definition : Boolean := False; + -- True within a record definition. Used to control warning for + -- redefinition of standard entities (not issued for field names). + + -------------------- + -- Error Recovery -- + -------------------- + + -- When an error is encountered, a call is made to one of the Error_Msg + -- routines to record the error. If the syntax scan is not derailed by the + -- error (e.g. a complaint that logical operators are inconsistent in an + -- EXPRESSION), then control returns from the Error_Msg call, and the + -- parse continues unimpeded. + + -- If on the other hand, the Error_Msg represents a situation from which + -- the parser cannot recover locally, the exception Error_Resync is raised + -- immediately after the call to Error_Msg. Handlers for Error_Resync + -- are located at strategic points to resynchronize the parse. For example, + -- when an error occurs in a statement, the handler skips to the next + -- semicolon and continues the scan from there. + + -- Each parsing procedure contains a note with the heading "Error recovery" + -- which shows if it can propagate the Error_Resync exception. In order + -- not to propagate the exception, a procedure must either contain its own + -- handler for this exception, or it must not call any other routines which + -- propagate the exception. + + -- Note: the arrangement of Error_Resync handlers is such that it should + -- never be possible to transfer control through a procedure which made + -- an entry in the scope stack, invalidating the contents of the stack. + + Error_Resync : exception; + -- Exception raised on error that is not handled locally, see above + + Last_Resync_Point : Source_Ptr; + -- The resynchronization routines in Par.Sync run a risk of getting + -- stuck in an infinite loop if they do not skip a token, and the caller + -- keeps repeating the same resync call. On the other hand, if they skip + -- a token unconditionally, some recovery opportunities are missed. The + -- variable Last_Resync_Point records the token location previously set + -- by a Resync call, and if a subsequent Resync call occurs at the same + -- location, then the Resync routine does guarantee to skip a token. + + -------------------------------------------- + -- Handling Semicolon Used in Place of IS -- + -------------------------------------------- + + -- The following global variables are used in handling the error situation + -- of using a semicolon in place of IS in a subprogram declaration as in: + + -- procedure X (Y : Integer); + -- Q : Integer; + -- begin + -- ... + -- end; + + -- The two contexts in which this can appear are at the outer level, and + -- within a declarative region. At the outer level, we know something is + -- wrong as soon as we see the Q (or begin, if there are no declarations), + -- and we can immediately decide that the semicolon should have been IS. + + -- The situation in a declarative region is more complex. The declaration + -- of Q could belong to the outer region, and we do not know that we have + -- an error until we hit the begin. It is still not clear at this point + -- from a syntactic point of view that something is wrong, because the + -- begin could belong to the enclosing subprogram or package. However, we + -- can incorporate a bit of semantic knowledge and note that the body of + -- X is missing, so we definitely DO have an error. We diagnose this error + -- as semicolon in place of IS on the subprogram line. + + -- There are two styles for this diagnostic. If the begin immediately + -- follows the semicolon, then we can place a flag (IS expected) right + -- on the semicolon. Otherwise we do not detect the error until we hit + -- the begin which refers back to the line with the semicolon. + + -- To control the process in the second case, the following global + -- variables are set to indicate that we have a subprogram declaration + -- whose body is required and has not yet been found. The prefix SIS + -- stands for "Subprogram IS" handling. + + SIS_Entry_Active : Boolean := False; + -- Set True to indicate that an entry is active (i.e. that a subprogram + -- declaration has been encountered, and no body for this subprogram has + -- been encountered). The remaining fields are valid only if this is True. + + SIS_Labl : Node_Id; + -- Subprogram designator + + SIS_Sloc : Source_Ptr; + -- Source location of FUNCTION/PROCEDURE keyword + + SIS_Ecol : Column_Number; + -- Column number of FUNCTION/PROCEDURE keyword + + SIS_Semicolon_Sloc : Source_Ptr; + -- Source location of semicolon at end of subprogram declaration + + SIS_Declaration_Node : Node_Id; + -- Pointer to tree node for subprogram declaration + + SIS_Missing_Semicolon_Message : Error_Msg_Id; + -- Used to save message ID of missing semicolon message (which will be + -- modified to missing IS if necessary). Set to No_Error_Msg in the + -- normal (non-error) case. + + -- Five things can happen to an active SIS entry + + -- 1. If a BEGIN is encountered with an SIS entry active, then we have + -- exactly the situation in which we know the body of the subprogram is + -- missing. After posting an error message, we change the spec to a body, + -- rechaining the declarations that intervened between the spec and BEGIN. + + -- 2. Another subprogram declaration or body is encountered. In this + -- case the entry gets overwritten with the information for the new + -- subprogram declaration. We don't catch some nested cases this way, + -- but it doesn't seem worth the effort. + + -- 3. A nested declarative region (e.g. package declaration or package + -- body) is encountered. The SIS active indication is reset at the start + -- of such a nested region. Again, like case 2, this causes us to miss + -- some nested cases, but it doesn't seen worth the effort to stack and + -- unstack the SIS information. Maybe we will reconsider this if we ever + -- get a complaint about a missed case. + + -- 4. We encounter a valid pragma INTERFACE or IMPORT that effectively + -- supplies the missing body. In this case we reset the entry. + + -- 5. We encounter the end of the declarative region without encountering + -- a BEGIN first. In this situation we simply reset the entry. We know + -- that there is a missing body, but it seems more reasonable to let the + -- later semantic checking discover this. + + ---------------------------------------------------- + -- Handling of Reserved Words Used as Identifiers -- + ---------------------------------------------------- + + -- Note: throughout the parser, the terms reserved word and keyword are + -- used interchangeably to refer to the same set of reserved keywords + -- (including until, protected, etc). + + -- If a reserved word is used in place of an identifier, the parser where + -- possible tries to recover gracefully. In particular, if the keyword is + -- clearly spelled using identifier casing, e.g. Until in a source program + -- using mixed case identifiers and lower case keywords, then the keyword + -- is treated as an identifier if it appears in a place where an identifier + -- is required. + + -- The situation is more complex if the keyword is spelled with normal + -- keyword casing. In this case, the parser is more reluctant to consider + -- it to be intended as an identifier, unless it has some further + -- confirmation. + + -- In the case of an identifier appearing in the identifier list of a + -- declaration, the appearance of a comma or colon right after the keyword + -- on the same line is taken as confirmation. For an enumeration literal, + -- a comma or right paren right after the identifier is also treated as + -- adequate confirmation. + + -- The following type is used in calls to Is_Reserved_Identifier and + -- also to P_Defining_Identifier and P_Identifier. The default for all + -- these functions is that reserved words in reserved word case are not + -- considered to be reserved identifiers. The Id_Check value indicates + -- tokens, which if they appear immediately after the identifier, are + -- taken as confirming that the use of an identifier was expected + + type Id_Check is + (None, + -- Default, no special token test + + C_Comma_Right_Paren, + -- Consider as identifier if followed by comma or right paren + + C_Comma_Colon, + -- Consider as identifier if followed by comma or colon + + C_Do, + -- Consider as identifier if followed by DO + + C_Dot, + -- Consider as identifier if followed by period + + C_Greater_Greater, + -- Consider as identifier if followed by >> + + C_In, + -- Consider as identifier if followed by IN + + C_Is, + -- Consider as identifier if followed by IS + + C_Left_Paren_Semicolon, + -- Consider as identifier if followed by left paren or semicolon + + C_Use, + -- Consider as identifier if followed by USE + + C_Vertical_Bar_Arrow); + -- Consider as identifier if followed by | or => + + -------------------------------------------- + -- Handling IS Used in Place of Semicolon -- + -------------------------------------------- + + -- This is a somewhat trickier situation, and we can't catch it in all + -- cases, but we do our best to detect common situations resulting from + -- a "cut and paste" operation which forgets to change the IS to semicolon. + -- Consider the following example: + + -- package body X is + -- procedure A; + -- procedure B is + -- procedure C; + -- ... + -- procedure D is + -- begin + -- ... + -- end; + -- begin + -- ... + -- end; + + -- The trouble is that the section of text from PROCEDURE B through END; + -- constitutes a valid procedure body, and the danger is that we find out + -- far too late that something is wrong (indeed most compilers will behave + -- uncomfortably on the above example). + + -- We have two approaches to helping to control this situation. First we + -- make every attempt to avoid swallowing the last END; if we can be sure + -- that some error will result from doing so. In particular, we won't + -- accept the END; unless it is exactly correct (in particular it must not + -- have incorrect name tokens), and we won't accept it if it is immediately + -- followed by end of file, WITH or SEPARATE (all tokens that unmistakeably + -- signal the start of a compilation unit, and which therefore allow us to + -- reserve the END; for the outer level.) For more details on this aspect + -- of the handling, see package Par.Endh. + + -- If we can avoid eating up the END; then the result in the absence of + -- any additional steps would be to post a missing END referring back to + -- the subprogram with the bogus IS. Similarly, if the enclosing package + -- has no BEGIN, then the result is a missing BEGIN message, which again + -- refers back to the subprogram header. + + -- Such an error message is not too bad (it's already a big improvement + -- over what many parsers do), but it's not ideal, because the declarations + -- following the IS have been absorbed into the wrong scope. In the above + -- case, this could result for example in a bogus complaint that the body + -- of D was missing from the package. + + -- To catch at least some of these cases, we take the following additional + -- steps. First, a subprogram body is marked as having a suspicious IS if + -- the declaration line is followed by a line which starts with a symbol + -- that can start a declaration in the same column, or to the left of the + -- column in which the FUNCTION or PROCEDURE starts (normal style is to + -- indent any declarations which really belong a subprogram). If such a + -- subprogram encounters a missing BEGIN or missing END, then we decide + -- that the IS should have been a semicolon, and the subprogram body node + -- is marked (by setting the Bad_Is_Detected flag true. Note that we do + -- not do this for library level procedures, only for nested procedures, + -- since for library level procedures, we must have a body. + + -- The processing for a declarative part checks to see if the last + -- declaration scanned is marked in this way, and if it is, the tree + -- is modified to reflect the IS being interpreted as a semicolon. + + --------------------------------------------------- + -- Parser Type Definitions and Control Variables -- + --------------------------------------------------- + + -- The following variable and associated type declaration are used by the + -- expression parsing routines to return more detailed information about + -- the categorization of a parsed expression. + + type Expr_Form_Type is ( + EF_Simple_Name, -- Simple name, i.e. possibly qualified identifier + EF_Name, -- Simple expression which could also be a name + EF_Simple, -- Simple expression which is not call or name + EF_Range_Attr, -- Range attribute reference + EF_Non_Simple); -- Expression that is not a simple expression + + Expr_Form : Expr_Form_Type; + + -- The following type is used for calls to P_Subprogram, P_Package, P_Task, + -- P_Protected to indicate which of several possibilities is acceptable. + + type Pf_Rec is record + Spcn : Boolean; -- True if specification OK + Decl : Boolean; -- True if declaration OK + Gins : Boolean; -- True if generic instantiation OK + Pbod : Boolean; -- True if proper body OK + Rnam : Boolean; -- True if renaming declaration OK + Stub : Boolean; -- True if body stub OK + Pexp : Boolean; -- True if parameterized expression OK + Fil2 : Boolean; -- Filler to fill to 8 bits + end record; + pragma Pack (Pf_Rec); + + function T return Boolean renames True; + function F return Boolean renames False; + + Pf_Decl_Gins_Pbod_Rnam_Stub_Pexp : constant Pf_Rec := + Pf_Rec'(F, T, T, T, T, T, T, F); + Pf_Decl_Pexp : constant Pf_Rec := + Pf_Rec'(F, T, F, F, F, F, T, F); + Pf_Decl_Gins_Pbod_Rnam_Pexp : constant Pf_Rec := + Pf_Rec'(F, T, T, T, T, F, T, F); + Pf_Decl_Pbod_Pexp : constant Pf_Rec := + Pf_Rec'(F, T, F, T, F, F, T, F); + Pf_Pbod_Pexp : constant Pf_Rec := + Pf_Rec'(F, F, F, T, F, F, T, F); + Pf_Spcn : constant Pf_Rec := + Pf_Rec'(T, F, F, F, F, F, F, F); + -- The above are the only allowed values of Pf_Rec arguments + + type SS_Rec is record + Eftm : Boolean; -- ELSIF can terminate sequence + Eltm : Boolean; -- ELSE can terminate sequence + Extm : Boolean; -- EXCEPTION can terminate sequence + Ortm : Boolean; -- OR can terminate sequence + Sreq : Boolean; -- at least one statement required + Tatm : Boolean; -- THEN ABORT can terminate sequence + Whtm : Boolean; -- WHEN can terminate sequence + Unco : Boolean; -- Unconditional terminate after one statement + end record; + pragma Pack (SS_Rec); + + SS_Eftm_Eltm_Sreq : constant SS_Rec := SS_Rec'(T, T, F, F, T, F, F, F); + SS_Eltm_Ortm_Tatm : constant SS_Rec := SS_Rec'(F, T, F, T, F, T, F, F); + SS_Extm_Sreq : constant SS_Rec := SS_Rec'(F, F, T, F, T, F, F, F); + SS_None : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, F, F); + SS_Ortm_Sreq : constant SS_Rec := SS_Rec'(F, F, F, T, T, F, F, F); + SS_Sreq : constant SS_Rec := SS_Rec'(F, F, F, F, T, F, F, F); + SS_Sreq_Whtm : constant SS_Rec := SS_Rec'(F, F, F, F, T, F, T, F); + SS_Whtm : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, T, F); + SS_Unco : constant SS_Rec := SS_Rec'(F, F, F, F, F, F, F, T); + + Goto_List : Elist_Id; + -- List of goto nodes appearing in the current compilation. Used to + -- recognize natural loops and convert them into bona fide loops for + -- optimization purposes. + + Label_List : Elist_Id; + -- List of label nodes for labels appearing in the current compilation. + -- Used by Par.Labl to construct the corresponding implicit declarations. + + ----------------- + -- Scope Table -- + ----------------- + + -- The scope table, also referred to as the scope stack, is used to record + -- the current scope context. It is organized as a stack, with inner nested + -- entries corresponding to higher entries on the stack. An entry is made + -- when the parser encounters the opening of a nested construct (such as a + -- record, task, package etc.), and then package Par.Endh uses this stack + -- to deal with END lines (including properly dealing with END nesting + -- errors). + + type SS_End_Type is + -- Type of end entry required for this scope. The last two entries are + -- used only in the subprogram body case to mark the case of a suspicious + -- IS, or a bad IS (i.e. suspicions confirmed by missing BEGIN or END). + -- See separate section on dealing with IS used in place of semicolon. + -- Note that for many purposes E_Name, E_Suspicious_Is and E_Bad_Is are + -- treated the same (E_Suspicious_Is and E_Bad_Is are simply special cases + -- of E_Name). They are placed at the end of the enumeration so that a + -- test for >= E_Name catches all three cases efficiently. + + (E_Dummy, -- dummy entry at outer level + E_Case, -- END CASE; + E_If, -- END IF; + E_Loop, -- END LOOP; + E_Record, -- END RECORD; + E_Return, -- END RETURN; + E_Select, -- END SELECT; + E_Name, -- END [name]; + E_Suspicious_Is, -- END [name]; (case of suspicious IS) + E_Bad_Is); -- END [name]; (case of bad IS) + + -- The following describes a single entry in the scope table + + type Scope_Table_Entry is record + Etyp : SS_End_Type; + -- Type of end entry, as per above description + + Lreq : Boolean; + -- A flag indicating whether the label, if present, is required to + -- appear on the end line. It is referenced only in the case of Etyp is + -- equal to E_Name or E_Suspicious_Is where the name may or may not be + -- required (yes for labeled block, no in other cases). Note that for + -- all cases except begin, the question of whether a label is required + -- can be determined from the other fields (for loop, it is required if + -- it is present, and for the other constructs it is never required or + -- allowed). + + Ecol : Column_Number; + -- Contains the absolute column number (with tabs expanded) of the + -- expected column of the end assuming normal Ada indentation usage. If + -- the RM_Column_Check mode is set, this value is used for generating + -- error messages about indentation. Otherwise it is used only to + -- control heuristic error recovery actions. This value is zero origin. + + Labl : Node_Id; + -- This field is used to provide the name of the construct being parsed + -- and indirectly its kind. For loops and blocks, the field contains the + -- source name or the generated one. For package specifications, bodies, + -- subprogram specifications and bodies the field holds the correponding + -- program unit name. For task declarations and bodies, protected types + -- and bodies, and accept statements the field hold the name of the type + -- or operation. For if-statements, case-statements, return statements, + -- and selects, the field is initialized to Error. + + -- Note: this is a bit of an odd (mis)use of Error, since there is no + -- Error, but we use this value as a place holder to indicate that it + -- is an error to have a label on the end line. + + -- Whenever the field is a name, it is attached to the parent node of + -- the construct being parsed. Thus the parent node indicates the kind + -- of construct whose parse tree is being built. This is used in error + -- recovery. + + Decl : List_Id; + -- Points to the list of declarations (i.e. the declarative part) + -- associated with this construct. It is set only in the END [name] + -- cases, and is set to No_List for all other cases which do not have a + -- declarative unit associated with them. This is used for determining + -- the proper location for implicit label declarations. + + Node : Node_Id; + -- Empty except in the case of entries for IF and CASE statements, in + -- which case it contains the N_If_Statement or N_Case_Statement node. + -- This is used for setting the End_Span field. + + Sloc : Source_Ptr; + -- Source location of the opening token of the construct. This is used + -- to refer back to this line in error messages (such as missing or + -- incorrect end lines). The Sloc field is not used, and is not set, if + -- a label is present (the Labl field provides the text name of the + -- label in this case, which is fine for error messages). + + S_Is : Source_Ptr; + -- S_Is is relevant only if Etyp is set to E_Suspicious_Is or E_Bad_Is. + -- It records the location of the IS that is considered to be + -- suspicious. + + Junk : Boolean; + -- A boolean flag that is set true if the opening entry is the dubious + -- result of some prior error, e.g. a record entry where the record + -- keyword was missing. It is used to suppress the issuing of a + -- corresponding junk complaint about the end line (we do not want + -- to complain about a missing end record when there was no record). + end record; + + -- The following declares the scope table itself. The Last field is the + -- stack pointer, so that Scope.Table (Scope.Last) is the top entry. The + -- oldest entry, at Scope_Stack (0), is a dummy entry with Etyp set to + -- E_Dummy, and the other fields undefined. This dummy entry ensures that + -- Scope_Stack (Scope_Stack_Ptr).Etyp can always be tested, and that the + -- scope stack pointer is always in range. + + package Scope is new Table.Table ( + Table_Component_Type => Scope_Table_Entry, + Table_Index_Type => Int, + Table_Low_Bound => 0, + Table_Initial => 50, + Table_Increment => 100, + Table_Name => "Scope"); + + ------------------------------------------ + -- Table for Handling Suspicious Labels -- + ------------------------------------------ + + -- This is a special data structure which is used to deal very spefifically + -- with the following error case + + -- label; + -- loop + -- ... + -- end loop label; + + -- Similar cases apply to FOR, WHILE, DECLARE, or BEGIN + + -- In each case the opening line looks like a procedure call because of + -- the semicolon. And the end line looks illegal because of an unexpected + -- label. If we did nothing special, we would just diagnose the label on + -- the end as unexpected. But that does not help point to the real error + -- which is that the semicolon after label should be a colon. + + -- To deal with this, we build an entry in the Suspicious_Labels table + -- whenever we encounter an identifier followed by a semicolon, followed + -- by one of LOOP, FOR, WHILE, DECLARE, BEGIN. Then this entry is used to + -- issue the right message when we hit the END that confirms that this was + -- a bad label. + + type Suspicious_Label_Entry is record + Proc_Call : Node_Id; + -- Node for the procedure call statement built for the label; construct + + Semicolon_Loc : Source_Ptr; + -- Location of the possibly wrong semicolon + + Start_Token : Source_Ptr; + -- Source location of the LOOP, FOR, WHILE, DECLARE, BEGIN token + end record; + + package Suspicious_Labels is new Table.Table ( + Table_Component_Type => Suspicious_Label_Entry, + Table_Index_Type => Int, + Table_Low_Bound => 1, + Table_Initial => 50, + Table_Increment => 100, + Table_Name => "Suspicious_Labels"); + + -- Now when we are about to issue a message complaining about an END label + -- that should not be there because it appears to end a construct that has + -- no label, we first search the suspicious labels table entry, using the + -- source location stored in the scope table as a key. If we find a match, + -- then we check that the label on the end matches the name in the call, + -- and if so, we issue a message saying the semicolon should be a colon. + + -- Quite a bit of work, but really helpful in the case where it helps, and + -- the need for this is based on actual experience with tracking down this + -- kind of error (the eye often easily mistakes semicolon for colon). + + -- Note: we actually have enough information to patch up the tree, but + -- this may not be worth the effort. Also we could deal with the same + -- situation for EXIT with a label, but for now don't bother with that. + + Current_Assign_Node : Node_Id := Empty; + -- This is the node of the current assignment statement being compiled. + -- It is used to record the presence of target_names on its RHS. This + -- context-dependent trick simplifies the analysis of such nodes, where + -- the RHS must first be analyzed with expansion disabled. + + --------------------------------- + -- Parsing Routines by Chapter -- + --------------------------------- + + -- Uncommented declarations in this section simply parse the construct + -- corresponding to their name, and return an ID value for the Node or + -- List that is created. + + ------------- + -- Par.Ch2 -- + ------------- + + package Ch2 is + function P_Pragma (Skipping : Boolean := False) return Node_Id; + -- Scan out a pragma. If Skipping is True, then the caller is skipping + -- the pragma in the context of illegal placement (this is used to avoid + -- some junk cascaded messages). Some pragmas must be dealt with during + -- the parsing phase (e.g. pragma Page, since we can generate a listing + -- in syntax only mode). It is possible that the parser uses the rescan + -- logic (using Save/Restore_Scan_State) with the effect of calling this + -- procedure more than once for the same pragma. All parse-time pragma + -- handling must be prepared to handle such multiple calls correctly. + + function P_Identifier (C : Id_Check := None) return Node_Id; + -- Scans out an identifier. The parameter C determines the treatment + -- of reserved identifiers. See declaration of Id_Check for details. + + function P_Pragmas_Opt return List_Id; + -- This function scans for a sequence of pragmas in other than a + -- declaration sequence or statement sequence context. All pragmas + -- can appear except pragmas Assert and Debug, which are only allowed + -- in a declaration or statement sequence context. + + procedure P_Pragmas_Misplaced; + -- Skips misplaced pragmas with a complaint + + procedure P_Pragmas_Opt (List : List_Id); + -- Parses optional pragmas and appends them to the List + end Ch2; + + ------------- + -- Par.Ch3 -- + ------------- + + package Ch3 is + Missing_Begin_Msg : Error_Msg_Id; + -- This variable is set by a call to P_Declarative_Part. Normally it + -- is set to No_Error_Msg, indicating that no special processing is + -- required by the caller. The special case arises when a statement + -- is found in the sequence of declarations. In this case the Id of + -- the message issued ("declaration expected") is preserved in this + -- variable, then the caller can change it to an appropriate missing + -- begin message if indeed the BEGIN is missing. + + function P_Array_Type_Definition return Node_Id; + function P_Basic_Declarative_Items return List_Id; + function P_Constraint_Opt return Node_Id; + function P_Declarative_Part return List_Id; + function P_Discrete_Choice_List return List_Id; + function P_Discrete_Range return Node_Id; + function P_Discrete_Subtype_Definition return Node_Id; + function P_Known_Discriminant_Part_Opt return List_Id; + function P_Signed_Integer_Type_Definition return Node_Id; + function P_Range return Node_Id; + function P_Range_Constraint return Node_Id; + function P_Record_Definition return Node_Id; + function P_Subtype_Mark return Node_Id; + function P_Subtype_Mark_Resync return Node_Id; + function P_Unknown_Discriminant_Part_Opt return Boolean; + + function P_Access_Definition + (Null_Exclusion_Present : Boolean) return Node_Id; + -- Ada 2005 (AI-231/AI-254): The caller parses the null-exclusion part + -- and indicates if it was present + + function P_Access_Type_Definition + (Header_Already_Parsed : Boolean := False) return Node_Id; + -- Ada 2005 (AI-254): The formal is used to indicate if the caller has + -- parsed the null_exclusion part. In this case the caller has also + -- removed the ACCESS token + + procedure P_Component_Items (Decls : List_Id); + -- Scan out one or more component items and append them to the given + -- list. Only scans out more than one declaration in the case where the + -- source has a single declaration with multiple defining identifiers. + + function P_Defining_Identifier (C : Id_Check := None) return Node_Id; + -- Scan out a defining identifier. The parameter C controls the + -- treatment of errors in case a reserved word is scanned. See the + -- declaration of this type for details. + + function P_Interface_Type_Definition + (Abstract_Present : Boolean) return Node_Id; + -- Ada 2005 (AI-251): Parse the interface type definition part. Abstract + -- Present indicates if the reserved word "abstract" has been previously + -- found. It is used to report an error message because interface types + -- are by definition abstract tagged. We generate a record_definition + -- node if the list of interfaces is empty; otherwise we generate a + -- derived_type_definition node (the first interface in this list is the + -- ancestor interface). + + function P_Null_Exclusion + (Allow_Anonymous_In_95 : Boolean := False) return Boolean; + -- Ada 2005 (AI-231): Parse the null-excluding part. A True result + -- indicates that the null-excluding part was present. + -- + -- Allow_Anonymous_In_95 is True if we are in a context that allows + -- anonymous access types in Ada 95, in which case "not null" is legal + -- if it precedes "access". + + function P_Subtype_Indication + (Not_Null_Present : Boolean := False) return Node_Id; + -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the + -- null-excluding part has been scanned out and it was present. + + function P_Range_Or_Subtype_Mark + (Allow_Simple_Expression : Boolean := False) return Node_Id; + -- Scans out a range or subtype mark, and also permits a general simple + -- expression if Allow_Simple_Expression is set to True. + + function Init_Expr_Opt (P : Boolean := False) return Node_Id; + -- If an initialization expression is present (:= expression), then + -- it is scanned out and returned, otherwise Empty is returned if no + -- initialization expression is present. This procedure also handles + -- certain common error cases cleanly. The parameter P indicates if + -- a right paren can follow the expression (default = no right paren + -- allowed). + + procedure Skip_Declaration (S : List_Id); + -- Used when scanning statements to skip past a misplaced declaration + -- The declaration is scanned out and appended to the given list. + -- Token is known to be a declaration token (in Token_Class_Declk) + -- on entry, so there definition is a declaration to be scanned. + + function P_Subtype_Indication + (Subtype_Mark : Node_Id; + Not_Null_Present : Boolean := False) return Node_Id; + -- This version of P_Subtype_Indication is called when the caller has + -- already scanned out the subtype mark which is passed as a parameter. + -- Ada 2005 (AI-231): The flag Not_Null_Present indicates that the + -- null-excluding part has been scanned out and it was present. + + function P_Subtype_Mark_Attribute (Type_Node : Node_Id) return Node_Id; + -- Parse a subtype mark attribute. The caller has already parsed the + -- subtype mark, which is passed in as the argument, and has checked + -- that the current token is apostrophe. + end Ch3; + + ------------- + -- Par.Ch4 -- + ------------- + + package Ch4 is + function P_Aggregate return Node_Id; + function P_Expression return Node_Id; + function P_Expression_Or_Range_Attribute return Node_Id; + function P_Function_Name return Node_Id; + function P_Name return Node_Id; + function P_Qualified_Simple_Name return Node_Id; + function P_Qualified_Simple_Name_Resync return Node_Id; + function P_Simple_Expression return Node_Id; + function P_Simple_Expression_Or_Range_Attribute return Node_Id; + + function P_Case_Expression return Node_Id; + -- Scans out a case expression. Called with Token pointing to the CASE + -- keyword, and returns pointing to the terminating right parent, + -- semicolon, or comma, but does not consume this terminating token. + + function P_Expression_If_OK return Node_Id; + -- Scans out an expression allowing an unparenthesized case expression, + -- if expression, or quantified expression to appear without enclosing + -- parentheses. However, if such an expression is not preceded by a left + -- paren, and followed by a right paren, an error message will be output + -- noting that parenthesization is required. + + function P_Expression_No_Right_Paren return Node_Id; + -- Scans out an expression in contexts where the expression cannot be + -- terminated by a right paren (gives better error recovery if an errant + -- right paren is found after the expression). + + function P_Expression_Or_Range_Attribute_If_OK return Node_Id; + -- Scans out an expression or range attribute where a conditional + -- expression is permitted to appear without surrounding parentheses. + -- However, if such an expression is not preceded by a left paren, and + -- followed by a right paren, an error message will be output noting + -- that parenthesization is required. + + function P_If_Expression return Node_Id; + -- Scans out an if expression. Called with Token pointing to the + -- IF keyword, and returns pointing to the terminating right paren, + -- semicolon or comma, but does not consume this terminating token. + + function P_Qualified_Expression (Subtype_Mark : Node_Id) return Node_Id; + -- This routine scans out a qualified expression when the caller has + -- already scanned out the name and apostrophe of the construct. + + function P_Quantified_Expression return Node_Id; + -- This routine scans out a quantified expression when the caller has + -- already scanned out the keyword "for" of the construct. + end Ch4; + + ------------- + -- Par.Ch5 -- + ------------- + + package Ch5 is + function P_Condition return Node_Id; + -- Scan out and return a condition. Note that an error is given if + -- the condition is followed by a right parenthesis. + + function P_Condition (Cond : Node_Id) return Node_Id; + -- Similar to the above, but the caller has already scanned out the + -- conditional expression and passes it as an argument. This form of + -- the call does not check for a following right parenthesis. + + function P_Loop_Parameter_Specification return Node_Id; + -- Used in loop constructs and quantified expressions. + + function P_Sequence_Of_Statements (SS_Flags : SS_Rec) return List_Id; + -- The argument indicates the acceptable termination tokens. + -- See body in Par.Ch5 for details of the use of this parameter. + + procedure Parse_Decls_Begin_End (Parent : Node_Id); + -- Parses declarations and handled statement sequence, setting + -- fields of Parent node appropriately. + end Ch5; + + ------------- + -- Par.Ch6 -- + ------------- + + package Ch6 is + function P_Designator return Node_Id; + function P_Defining_Program_Unit_Name return Node_Id; + function P_Formal_Part return List_Id; + function P_Parameter_Profile return List_Id; + function P_Return_Statement return Node_Id; + function P_Subprogram_Specification return Node_Id; + + procedure P_Mode (Node : Node_Id); + -- Sets In_Present and/or Out_Present flags in Node scanning past IN, + -- OUT or IN OUT tokens in the source. + + function P_Subprogram (Pf_Flags : Pf_Rec) return Node_Id; + -- Scans out any construct starting with either of the keywords + -- PROCEDURE or FUNCTION. The parameter indicates which possible + -- possible kinds of construct (body, spec, instantiation etc.) + -- are permissible in the current context. + end Ch6; + + ------------- + -- Par.Ch7 -- + ------------- + + package Ch7 is + function P_Package (Pf_Flags : Pf_Rec) return Node_Id; + -- Scans out any construct starting with the keyword PACKAGE. The + -- parameter indicates which possible kinds of construct (body, spec, + -- instantiation etc.) are permissible in the current context. + end Ch7; + + ------------- + -- Par.Ch8 -- + ------------- + + package Ch8 is + procedure P_Use_Clause (Item_List : List_Id); + end Ch8; + + ------------- + -- Par.Ch9 -- + ------------- + + package Ch9 is + function P_Abort_Statement return Node_Id; + function P_Abortable_Part return Node_Id; + function P_Accept_Statement return Node_Id; + function P_Delay_Statement return Node_Id; + function P_Entry_Body return Node_Id; + function P_Protected return Node_Id; + function P_Requeue_Statement return Node_Id; + function P_Select_Statement return Node_Id; + function P_Task return Node_Id; + function P_Terminate_Alternative return Node_Id; + end Ch9; + + -------------- + -- Par.Ch10 -- + -------------- + + package Ch10 is + function P_Compilation_Unit return Node_Id; + -- Note: this function scans a single compilation unit, and checks that + -- an end of file follows this unit, diagnosing any unexpected input as + -- an error, and then skipping it, so that Token is set to Tok_EOF on + -- return. An exception is in syntax-only mode, where multiple + -- compilation units are permitted. In this case, P_Compilation_Unit + -- does not check for end of file and there may be more compilation + -- units to scan. The caller can uniquely detect this situation by the + -- fact that Token is not set to Tok_EOF on return. + -- + -- What about multiple unit/file capability that now exists??? + -- + -- The Ignore parameter is normally set False. It is set True in the + -- multiple unit per file mode if we are skipping past a unit that we + -- are not interested in. + end Ch10; + + -------------- + -- Par.Ch11 -- + -------------- + + package Ch11 is + function P_Handled_Sequence_Of_Statements return Node_Id; + function P_Raise_Expression return Node_Id; + function P_Raise_Statement return Node_Id; + + function Parse_Exception_Handlers return List_Id; + -- Parses the partial construct EXCEPTION followed by a list of + -- exception handlers which appears in a number of productions, and + -- returns the list of exception handlers. + end Ch11; + + -------------- + -- Par.Ch12 -- + -------------- + + package Ch12 is + function P_Generic return Node_Id; + function P_Generic_Actual_Part_Opt return List_Id; + end Ch12; + + -------------- + -- Par.Ch13 -- + -------------- + + package Ch13 is + function P_Representation_Clause return Node_Id; + + function Aspect_Specifications_Present + (Strict : Boolean := Ada_Version < Ada_2012) return Boolean; + -- This function tests whether the next keyword is WITH followed by + -- something that looks reasonably like an aspect specification. If so, + -- True is returned. Otherwise False is returned. In either case control + -- returns with the token pointer unchanged (i.e. pointing to the WITH + -- token in the case where True is returned). This function takes care + -- of generating appropriate messages if aspect specifications appear + -- in versions of Ada prior to Ada 2012. The parameter strict can be + -- set to True, to be rather strict about considering something to be + -- an aspect specification. If Strict is False, then the circuitry is + -- rather more generous in considering something ill-formed to be an + -- attempt at an aspect specification. The default is more strict for + -- Ada versions before Ada 2012 (where aspect specifications are not + -- permitted). Note: this routine never checks the terminator token + -- for aspects so it does not matter whether the aspect specifications + -- are terminated by semicolon or some other character. + -- + -- Note: This function also handles the case of WHEN used where WITH + -- was intended, and in that case posts an error and returns True. + + procedure P_Aspect_Specifications + (Decl : Node_Id; + Semicolon : Boolean := True); + -- This procedure scans out a series of aspect spefications. If argument + -- Semicolon is True, a terminating semicolon is also scanned. If this + -- argument is False, the scan pointer is left pointing past the aspects + -- and the caller must check for a proper terminator. + -- + -- P_Aspect_Specifications is called with the current token pointing + -- to either a WITH keyword starting an aspect specification, or an + -- instance of what shpould be a terminator token. In the former case, + -- the aspect specifications are scanned out including the terminator + -- token if it is a semicolon, and the Has_Aspect_Specifications + -- flag is set in the given declaration node. A list of aspects + -- is built and stored for this declaration node using a call to + -- Set_Aspect_Specifications. If no WITH keyword is present, then this + -- call has no effect other than scanning out the terminator if it is a + -- semicolon (with the exception that it detects WHEN used in place of + -- WITH). + + -- If Decl is Error on entry, any scanned aspect specifications are + -- ignored and a message is output saying aspect specifications not + -- permitted here. If Decl is Empty, then scanned aspect specifications + -- are also ignored, but no error message is given (this is used when + -- the caller has already taken care of the error message). + + function Get_Aspect_Specifications + (Semicolon : Boolean := True) return List_Id; + -- Parse a list of aspects but do not attach them to a declaration node. + -- Subsidiary to P_Aspect_Specifications procedure. Used when parsing + -- a subprogram specification that may be a declaration or a body. + -- Semicolon has the same meaning as for P_Aspect_Specifications above. + + function P_Code_Statement (Subtype_Mark : Node_Id) return Node_Id; + -- Function to parse a code statement. The caller has scanned out + -- the name to be used as the subtype mark (but has not checked that + -- it is suitable for use as a subtype mark, i.e. is either an + -- identifier or a selected component). The current token is an + -- apostrophe and the following token is either a left paren or + -- RANGE (the latter being an error to be caught by P_Code_Statement. + end Ch13; + + -- Note: the parsing for annexe J features (i.e. obsolescent features) + -- is found in the logical section where these features would be if + -- they were not obsolescent. In particular: + + -- Delta constraint is parsed by P_Delta_Constraint (3.5.9) + -- At clause is parsed by P_At_Clause (13.1) + -- Mod clause is parsed by P_Mod_Clause (13.5.1) + + -------------- + -- Par.Endh -- + -------------- + + -- Routines for handling end lines, including scope recovery + + package Endh is + function Check_End + (Decl : Node_Id := Empty; + Is_Loc : Source_Ptr := No_Location) return Boolean; + -- Called when an end sequence is required. In the absence of an error + -- situation, Token contains Tok_End on entry, but in a missing end + -- case, this may not be the case. Pop_End_Context is used to determine + -- the appropriate action to be taken. The returned result is True if + -- an End sequence was encountered and False if no End sequence was + -- present. This occurs if the END keyword encountered was determined + -- to be improper and deleted (i.e. Pop_End_Context set End_Action to + -- Skip_And_Reject). Note that the END sequence includes a semicolon, + -- except in the case of END RECORD, where a semicolon follows the END + -- RECORD, but is not part of the record type definition itself. + -- + -- If Decl is non-empty, then aspect specifications are permitted + -- following the end, and Decl is the declaration node with which + -- these aspect specifications are to be associated. If Decl is empty, + -- then aspect specifications are not permitted and will generate an + -- error message. + -- + -- Is_Loc is set to other than the default only for the case of a + -- package declaration. It points to the IS keyword of the declaration, + -- and is used to specialize the error messages for misplaced aspect + -- specifications in this case. Note that Decl is always Empty if Is_Loc + -- is set. + + procedure End_Skip; + -- Skip past an end sequence. On entry Token contains Tok_End, and we + -- we know that the end sequence is syntactically incorrect, and that + -- an appropriate error message has already been posted. The mission + -- is simply to position the scan pointer to be the best guess of the + -- position after the end sequence. We do not issue any additional + -- error messages while carrying this out. + + procedure End_Statements + (Parent : Node_Id := Empty; + Decl : Node_Id := Empty; + Is_Sloc : Source_Ptr := No_Location); + -- Called when an end is required or expected to terminate a sequence + -- of statements. The caller has already made an appropriate entry in + -- the Scope.Table to describe the expected form of the end. This can + -- only be used in cases where the only appropriate terminator is end. + -- If Parent is non-empty, then if a correct END line is encountered, + -- the End_Label field of Parent is set appropriately. + -- + -- If Decl is non-null, then it is a declaration node, and aspect + -- specifications are permitted after the end statement. These aspect + -- specifications, if present, are stored in this declaration node. + -- If Decl is null, then aspect specifications are not permitted after + -- the end statement. + -- + -- In the case where Decl is null, Is_Sloc determines the handling. If + -- it is set to No_Location, then aspect specifications are ignored and + -- an error message is given. Is_Sloc is used in the package declaration + -- case to point to the IS, and is used to specialize the error emssages + -- issued in this case. + end Endh; + + -------------- + -- Par.Sync -- + -------------- + + -- These procedures are used to resynchronize after errors. Following an + -- error which is not immediately locally recoverable, the exception + -- Error_Resync is raised. The handler for Error_Resync typically calls + -- one of these recovery procedures to resynchronize the source position + -- to a point from which parsing can be restarted. + + -- Note: these procedures output an information message that tokens are + -- being skipped, but this message is output only if the option for + -- Multiple_Errors_Per_Line is set in Options. + + package Sync is + procedure Resync_Choice; + -- Used if an error occurs scanning a choice. The scan pointer is + -- advanced to the next vertical bar, arrow, or semicolon, whichever + -- comes first. We also quit if we encounter an end of file. + + procedure Resync_Cunit; + -- Synchronize to next token which could be the start of a compilation + -- unit, or to the end of file token. + + procedure Resync_Expression; + -- Used if an error is detected during the parsing of an expression. + -- It skips past tokens until either a token which cannot be part of + -- an expression is encountered (an expression terminator), or if a + -- comma or right parenthesis or vertical bar is encountered at the + -- current parenthesis level (a parenthesis level counter is maintained + -- to carry out this test). + + procedure Resync_Past_Malformed_Aspect; + -- Used when parsing aspect specifications to skip a malformed aspect. + -- The scan pointer is positioned next to a comma, a semicolon or "is" + -- when the aspect applies to a body. + + procedure Resync_Past_Semicolon; + -- Used if an error occurs while scanning a sequence of declarations. + -- The scan pointer is positioned past the next semicolon and the scan + -- resumes. The scan is also resumed on encountering a token which + -- starts a declaration (but we make sure to skip at least one token + -- in this case, to avoid getting stuck in a loop). + + procedure Resync_Past_Semicolon_Or_To_Loop_Or_Then; + -- Used if an error occurs while scanning a sequence of statements. The + -- scan pointer is positioned past the next semicolon, or to the next + -- occurrence of either then or loop, and the scan resumes. + + procedure Resync_Semicolon_List; + -- Used if an error occurs while scanning a parenthesized list of items + -- separated by semicolons. The scan pointer is advanced to the next + -- semicolon or right parenthesis at the outer parenthesis level, or + -- to the next is or RETURN keyword occurrence, whichever comes first. + + procedure Resync_To_Semicolon; + -- Similar to Resync_Past_Semicolon, except that the scan pointer is + -- left pointing to the semicolon rather than past it. + + procedure Resync_To_When; + -- Used when an error occurs scanning an entry index specification. The + -- scan pointer is positioned to the next WHEN (or to IS or semicolon if + -- either of these appear before WHEN, indicating another error has + -- occurred). + end Sync; + + -------------- + -- Par.Tchk -- + -------------- + + -- Routines to check for expected tokens + + package Tchk is + + -- Procedures with names of the form T_xxx, where Tok_xxx is a token + -- name, check that the current token matches the required token, and + -- if so, scan past it. If not, an error is issued indicating that + -- the required token is not present (xxx expected). In most cases, the + -- scan pointer is not moved in the not-found case, but there are some + -- exceptions to this, see for example T_Id, where the scan pointer is + -- moved across a literal appearing where an identifier is expected. + + procedure T_Abort; + procedure T_Arrow; + procedure T_At; + procedure T_Body; + procedure T_Box; + procedure T_Colon; + procedure T_Colon_Equal; + procedure T_Comma; + procedure T_Dot_Dot; + procedure T_For; + procedure T_Greater_Greater; + procedure T_Identifier; + procedure T_In; + procedure T_Is; + procedure T_Left_Paren; + procedure T_Loop; + procedure T_Mod; + procedure T_New; + procedure T_Of; + procedure T_Or; + procedure T_Private; + procedure T_Range; + procedure T_Record; + procedure T_Right_Paren; + procedure T_Semicolon; + procedure T_Then; + procedure T_Type; + procedure T_Use; + procedure T_When; + procedure T_With; + + -- Procedures having names of the form TF_xxx, where Tok_xxx is a token + -- name check that the current token matches the required token, and + -- if so, scan past it. If not, an error message is issued indicating + -- that the required token is not present (xxx expected). + + -- If the missing token is at the end of the line, then control returns + -- immediately after posting the message. If there are remaining tokens + -- on the current line, a search is conducted to see if the token + -- appears later on the current line, as follows: + + -- A call to Scan_Save is issued and a forward search for the token + -- is carried out. If the token is found on the current line before a + -- semicolon, then it is scanned out and the scan continues from that + -- point. If not the scan is restored to the point where it was missing. + + procedure TF_Arrow; + procedure TF_Is; + procedure TF_Loop; + procedure TF_Return; + procedure TF_Semicolon; + procedure TF_Then; + procedure TF_Use; + + -- Procedures with names of the form U_xxx, where Tok_xxx is a token + -- name, are just like the corresponding T_xxx procedures except that + -- an error message, if given, is unconditional. + + procedure U_Left_Paren; + procedure U_Right_Paren; + end Tchk; + + -------------- + -- Par.Util -- + -------------- + + package Util is + function Bad_Spelling_Of (T : Token_Type) return Boolean; + -- This function is called in an error situation. It checks if the + -- current token is an identifier whose name is a plausible bad + -- spelling of the given keyword token, and if so, issues an error + -- message, sets Token from T, and returns True. Otherwise Token is + -- unchanged, and False is returned. + + procedure Check_Bad_Layout; + -- Check for bad indentation in RM checking mode. Used for statements + -- and declarations. Checks if current token is at start of line and + -- is exdented from the current expected end column, and if so an + -- error message is generated. + + procedure Check_Misspelling_Of (T : Token_Type); + pragma Inline (Check_Misspelling_Of); + -- This is similar to the function above, except that it does not + -- return a result. It is typically used in a situation where any + -- identifier is an error, and it makes sense to simply convert it + -- to the given token if it is a plausible misspelling of it. + + procedure Check_95_Keyword (Token_95, Next : Token_Type); + -- This routine checks if the token after the current one matches the + -- Next argument. If so, the scan is backed up to the current token + -- and Token_Type is changed to Token_95 after issuing an appropriate + -- error message ("(Ada 83) keyword xx cannot be used"). If not, + -- the scan is backed up with Token_Type unchanged. This routine + -- is used to deal with an attempt to use a 95 keyword in Ada 83 + -- mode. The caller has typically checked that the current token, + -- an identifier, matches one of the 95 keywords. + + procedure Check_Future_Keyword; + -- Emit a warning if the current token is a valid identifier in the + -- language version in use, but is a reserved word in a later language + -- version (unless the language version in use is Ada 83). + + procedure Check_Simple_Expression (E : Node_Id); + -- Given an expression E, that has just been scanned, so that Expr_Form + -- is still set, outputs an error if E is a non-simple expression. E is + -- not modified by this call. + + procedure Check_Simple_Expression_In_Ada_83 (E : Node_Id); + -- Like Check_Simple_Expression, except that the error message is only + -- given when operating in Ada 83 mode, and includes "in Ada 83". + + function Check_Subtype_Mark (Mark : Node_Id) return Node_Id; + -- Called to check that a node representing a name (or call) is + -- suitable for a subtype mark, i.e, that it is an identifier or + -- a selected component. If so, or if it is already Error, then + -- it is returned unchanged. Otherwise an error message is issued + -- and Error is returned. + + function Comma_Present return Boolean; + -- Used in comma delimited lists to determine if a comma is present, or + -- can reasonably be assumed to have been present (an error message is + -- generated in the latter case). If True is returned, the scan has been + -- positioned past the comma. If False is returned, the scan position + -- is unchanged. Note that all comma-delimited lists are terminated by + -- a right paren, so the only legitimate tokens when Comma_Present is + -- called are right paren and comma. If some other token is found, then + -- Comma_Present has the job of deciding whether it is better to pretend + -- a comma was present, post a message for a missing comma and return + -- True, or return False and let the caller diagnose the missing right + -- parenthesis. + + procedure Discard_Junk_Node (N : Node_Id); + procedure Discard_Junk_List (L : List_Id); + pragma Inline (Discard_Junk_Node); + pragma Inline (Discard_Junk_List); + -- These procedures do nothing at all, their effect is simply to discard + -- the argument. A typical use is to skip by some junk that is not + -- expected in the current context. + + procedure Ignore (T : Token_Type); + -- If current token matches T, then give an error message and skip + -- past it, otherwise the call has no effect at all. T may be any + -- reserved word token, or comma, left or right paren, or semicolon. + + function Is_Reserved_Identifier (C : Id_Check := None) return Boolean; + -- Test if current token is a reserved identifier. This test is based + -- on the token being a keyword and being spelled in typical identifier + -- style (i.e. starting with an upper case letter). The parameter C + -- determines the special treatment if a reserved word is encountered + -- that has the normal casing of a reserved word. + + procedure Merge_Identifier (Prev : Node_Id; Nxt : Token_Type); + -- Called when the previous token is an identifier (whose Token_Node + -- value is given by Prev) to check if current token is an identifier + -- that can be merged with the previous one adding an underscore. The + -- merge is only attempted if the following token matches Nxt. If all + -- conditions are met, an error message is issued, and the merge is + -- carried out, modifying the Chars field of Prev. + + function Next_Token_Is (Tok : Token_Type) return Boolean; + -- Looks at token after current one and returns True if the token type + -- matches Tok. The scan is unconditionally restored on return. + + procedure No_Constraint; + -- Called in a place where no constraint is allowed, but one might + -- appear due to a common error (e.g. after the type mark in a procedure + -- parameter. If a constraint is present, an error message is posted, + -- and the constraint is scanned and discarded. + + procedure Push_Scope_Stack; + pragma Inline (Push_Scope_Stack); + -- Push a new entry onto the scope stack. Scope.Last (the stack pointer) + -- is incremented. The Junk field is preinitialized to False. The caller + -- is expected to fill in all remaining entries of the new top stack + -- entry at Scope.Table (Scope.Last). + + procedure Pop_Scope_Stack; + -- Pop an entry off the top of the scope stack. Scope_Last (the scope + -- table stack pointer) is decremented by one. It is a fatal error to + -- try to pop off the dummy entry at the bottom of the stack (i.e. + -- Scope.Last must be non-zero at the time of call). + + function Separate_Present return Boolean; + -- Determines if the current token is either Tok_Separate, or an + -- identifier that is a possible misspelling of "separate" followed + -- by a semicolon. True is returned if so, otherwise False. + + procedure Signal_Bad_Attribute; + -- The current token is an identifier that is supposed to be an + -- attribute identifier but is not. This routine posts appropriate + -- error messages, including a check for a near misspelling. + + function Token_Is_At_Start_Of_Line return Boolean; + pragma Inline (Token_Is_At_Start_Of_Line); + -- Determines if the current token is the first token on the line + + function Token_Is_At_End_Of_Line return Boolean; + -- Determines if the current token is the last token on the line + + procedure Warn_If_Standard_Redefinition (N : Node_Id); + -- Issues a warning if Warn_On_Standard_Redefinition is set True, and + -- the Node N (which is a Defining_Identifier node with the Chars field + -- set) is a renaming of an entity in package Standard. + + end Util; + + -------------- + -- Par.Prag -- + -------------- + + -- The processing for pragmas is split off from chapter 2 + + function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id; + -- This function is passed a tree for a pragma that has been scanned out. + -- The pragma is syntactically well formed according to the general syntax + -- for pragmas and the pragma identifier is for one of the recognized + -- pragmas. It performs specific syntactic checks for specific pragmas. + -- The result is the input node if it is OK, or Error otherwise. The + -- reason that this is separated out is to facilitate the addition + -- of implementation defined pragmas. The second parameter records the + -- location of the semicolon following the pragma (this is needed for + -- correct processing of the List and Page pragmas). The returned value + -- is a copy of Pragma_Node, or Error if an error is found. Note that + -- at the point where Prag is called, the right paren ending the pragma + -- has been scanned out, and except in the case of pragma Style_Checks, + -- so has the following semicolon. For Style_Checks, the caller delays + -- the scanning of the semicolon so that it will be scanned using the + -- settings from the Style_Checks pragma preceding it. + + -------------- + -- Par.Labl -- + -------------- + + procedure Labl; + -- This procedure creates implicit label declarations for all labels that + -- are declared in the current unit. Note that this could conceptually be + -- done at the point where the labels are declared, but it is tricky to do + -- it then, since the tree is not hooked up at the point where the label is + -- declared (e.g. a sequence of statements is not yet attached to its + -- containing scope at the point a label in the sequence is found). + + -------------- + -- Par.Load -- + -------------- + + procedure Load; + -- This procedure loads all subsidiary units that are required by this + -- unit, including with'ed units, specs for bodies, and parents for child + -- units. It does not load bodies for inlined procedures and generics, + -- since we don't know till semantic analysis is complete what is needed. + + ----------- + -- Stubs -- + ----------- + + -- The package bodies can see all routines defined in all other subpackages + + use Ch2; + use Ch3; + use Ch4; + use Ch5; + use Ch6; + use Ch7; + use Ch8; + use Ch9; + use Ch10; + use Ch11; + use Ch12; + use Ch13; + + use Endh; + use Tchk; + use Sync; + use Util; + + package body Ch2 is separate; + package body Ch3 is separate; + package body Ch4 is separate; + package body Ch5 is separate; + package body Ch6 is separate; + package body Ch7 is separate; + package body Ch8 is separate; + package body Ch9 is separate; + package body Ch10 is separate; + package body Ch11 is separate; + package body Ch12 is separate; + package body Ch13 is separate; + + package body Endh is separate; + package body Tchk is separate; + package body Sync is separate; + package body Util is separate; + + function Prag (Pragma_Node : Node_Id; Semi : Source_Ptr) return Node_Id + is separate; + + procedure Labl is separate; + procedure Load is separate; + + Result : List_Id := Empty_List; + +-- Start of processing for Par + +begin + Compiler_State := Parsing; + + -- Deal with configuration pragmas case first + + if Configuration_Pragmas then + declare + Pragmas : constant List_Id := Empty_List; + P_Node : Node_Id; + + begin + loop + if Token = Tok_EOF then + Result := Pragmas; + exit; + + elsif Token /= Tok_Pragma then + Error_Msg_SC ("only pragmas allowed in configuration file"); + Result := Error_List; + exit; + + else + P_Node := P_Pragma; + + if Nkind (P_Node) = N_Pragma then + + -- Give error if bad pragma + + if not Is_Configuration_Pragma_Name + (Pragma_Name_Unmapped (P_Node)) + and then + Pragma_Name_Unmapped (P_Node) /= Name_Source_Reference + then + if Is_Pragma_Name (Pragma_Name_Unmapped (P_Node)) then + Error_Msg_N + ("only configuration pragmas allowed " & + "in configuration file", P_Node); + else + Error_Msg_N + ("unrecognized pragma in configuration file", + P_Node); + end if; + + -- Pragma is OK config pragma, so collect it + + else + Append (P_Node, Pragmas); + end if; + end if; + end if; + end loop; + end; + + -- Normal case of compilation unit + + else + Save_Opt_Config_Switches (Save_Config_Switches); + + -- The following loop runs more than once in syntax check mode + -- where we allow multiple compilation units in the same file + -- and in Multiple_Unit_Per_file mode where we skip units till + -- we get to the unit we want. + + for Ucount in Pos loop + Set_Opt_Config_Switches + (Is_Internal_Unit (Current_Source_Unit), + Main_Unit => Current_Source_Unit = Main_Unit); + + -- Initialize scope table and other parser control variables + + Compiler_State := Parsing; + Scope.Init; + Scope.Increment_Last; + Scope.Table (0).Etyp := E_Dummy; + SIS_Entry_Active := False; + Last_Resync_Point := No_Location; + + Goto_List := New_Elmt_List; + Label_List := New_Elmt_List; + + -- If in multiple unit per file mode, skip past ignored unit + + if Ucount < Multiple_Unit_Index then + + -- We skip in syntax check only mode, since we don't want to do + -- anything more than skip past the unit and ignore it. This means + -- we skip processing like setting up a unit table entry. + + declare + Save_Operating_Mode : constant Operating_Mode_Type := + Operating_Mode; + + Save_Style_Check : constant Boolean := Style_Check; + + begin + Operating_Mode := Check_Syntax; + Style_Check := False; + Discard_Node (P_Compilation_Unit); + Operating_Mode := Save_Operating_Mode; + Style_Check := Save_Style_Check; + + -- If we are at an end of file, and not yet at the right unit, + -- then we have a fatal error. The unit is missing. + + if Token = Tok_EOF then + Error_Msg_SC ("file has too few compilation units"); + raise Unrecoverable_Error; + end if; + end; + + -- Here if we are not skipping a file in multiple unit per file mode. + -- Parse the unit that we are interested in. Note that in check + -- syntax mode we are interested in all units in the file. + + else + declare + Comp_Unit_Node : constant Node_Id := P_Compilation_Unit; + + begin + -- If parsing was successful and we are not in check syntax + -- mode, check that language-defined units are compiled in GNAT + -- mode. For this purpose we do NOT consider renamings in annex + -- J as predefined. That allows users to compile their own + -- versions of these files. Another exception is System.RPC + -- and its children. This allows a user to supply their own + -- communication layer. + -- Similarly, we do not generate an error in CodePeer mode, + -- to allow users to analyze third-party compiler packages. + + if Comp_Unit_Node /= Error + and then Operating_Mode = Generate_Code + and then Current_Source_Unit = Main_Unit + and then not GNAT_Mode + and then not CodePeer_Mode + then + declare + Uname : constant String := + Get_Name_String + (Unit_Name (Current_Source_Unit)); + Name : String (1 .. Uname'Length - 2); + + begin + -- Because Unit_Name includes "%s"/"%b", we need to strip + -- the last two characters to get the real unit name. + + Name := Uname (Uname'First .. Uname'Last - 2); + + if Name = "ada" or else + Name = "interfaces" or else + Name = "system" + then + Error_Msg + ("language-defined units cannot be recompiled", + Sloc (Unit (Comp_Unit_Node))); + + elsif Name'Length > 4 + and then + Name (Name'First .. Name'First + 3) = "ada." + then + Error_Msg + ("user-defined descendants of package Ada " & + "are not allowed", + Sloc (Unit (Comp_Unit_Node))); + + elsif Name'Length > 11 + and then + Name (Name'First .. Name'First + 10) = "interfaces." + then + Error_Msg + ("user-defined descendants of package Interfaces " & + "are not allowed", + Sloc (Unit (Comp_Unit_Node))); + + elsif Name'Length > 7 + and then Name (Name'First .. Name'First + 6) = "system." + and then Name /= "system.rpc" + and then + (Name'Length < 11 + or else Name (Name'First .. Name'First + 10) /= + "system.rpc.") + then + Error_Msg + ("user-defined descendants of package System " & + "are not allowed", + Sloc (Unit (Comp_Unit_Node))); + end if; + end; + end if; + end; + + -- All done if at end of file + + exit when Token = Tok_EOF; + + -- If we are not at an end of file, it means we are in syntax + -- check only mode, and we keep the loop going to parse all + -- remaining units in the file. + + end if; + + Restore_Opt_Config_Switches (Save_Config_Switches); + end loop; + + -- Now that we have completely parsed the source file, we can complete + -- the source file table entry. + + Complete_Source_File_Entry; + + -- An internal error check, the scope stack should now be empty + + pragma Assert (Scope.Last = 0); + + -- Here we make the SCO table entries for the main unit + + if Generate_SCO then + SCO_Record_Raw (Main_Unit); + end if; + + -- Remaining steps are to create implicit label declarations and to load + -- required subsidiary sources. These steps are required only if we are + -- doing semantic checking. + + if Operating_Mode /= Check_Syntax or else Debug_Flag_F then + Par.Labl; + Par.Load; + end if; + + -- Restore settings of switches saved on entry + + Restore_Opt_Config_Switches (Save_Config_Switches); + Set_Comes_From_Source_Default (False); + end if; + + Compiler_State := Analyzing; + Current_Source_File := No_Source_File; + return Result; +end Par;