[Ada] Parametrized expressions must be parenthesized
Arnaud Charlet
charlet@adacore.com
Thu Oct 7 12:46:00 GMT 2010
This patch implements the restriction that parametrized expressions
must be parenthesized, which was missed in the original implementation.
The following test program is compiled first with -gnat2012 then with
-gnat2005.
1. package PexpParen is
2. function F (A : Integer)
3. return Integer is A * A;
|
>>> parametrized expression must be enclosed in parentheses
4. function G (A : Integer)
5. return Integer is (A * A);
6. end;
1. package PexpParen is
2. function F (A : Integer)
3. return Integer is A * A;
|
>>> parametrized expression must be enclosed in parentheses
>>> parametrized expression is an Ada 2012 feature
>>> unit must be compiled with -gnat2012 switch
4. function G (A : Integer)
5. return Integer is (A * A);
|
>>> parametrized expression is an Ada 2012 feature
>>> unit must be compiled with -gnat2012 switch
6. end;
Tested on x86_64-pc-linux-gnu, committed on trunk
2010-10-07 Robert Dewar <dewar@adacore.com>
* par-ch3.adb, par-ch6.adb, par-ch7.adb, par-ch9.adb, par-ch10.adb: Add
Pexp to Pf_Rec constants
(P_Subprogram): Expression is always enclosed in parentheses
* par.adb (Pf_Rec): add Pexp flag for parametrized expression
* sinfo.ads (N_Parametrized_Expression): Expression must be in parens
-------------- next part --------------
Index: par-ch9.adb
===================================================================
--- par-ch9.adb (revision 165080)
+++ par-ch9.adb (working copy)
@@ -651,7 +651,7 @@ package body Ch9 is
Set_Must_Not_Override (Decl, Not_Overriding);
elsif Token = Tok_Function or else Token = Tok_Procedure then
- Decl := P_Subprogram (Pf_Decl);
+ Decl := P_Subprogram (Pf_Decl_Pexp);
Set_Must_Override (Specification (Decl), Is_Overriding);
Set_Must_Not_Override (Specification (Decl), Not_Overriding);
@@ -682,7 +682,7 @@ package body Ch9 is
return P_Entry_Declaration;
elsif Token = Tok_Function or else Token = Tok_Procedure then
- return P_Subprogram (Pf_Decl);
+ return P_Subprogram (Pf_Decl_Pexp);
elsif Token = Tok_Identifier then
L := New_List;
@@ -754,7 +754,7 @@ package body Ch9 is
or else
Token = Tok_Not or else Bad_Spelling_Of (Tok_Not)
then
- Append (P_Subprogram (Pf_Decl_Pbod), Item_List);
+ Append (P_Subprogram (Pf_Decl_Pbod_Pexp), Item_List);
elsif Token = Tok_Pragma or else Bad_Spelling_Of (Tok_Pragma) then
P_Pragmas_Opt (Item_List);
Index: sinfo.ads
===================================================================
--- sinfo.ads (revision 165098)
+++ sinfo.ads (working copy)
@@ -4435,10 +4435,7 @@ package Sinfo is
-- and put in its proper section when we know exactly where that is!
-- PARAMETRIZED_EXPRESSION ::=
- -- FUNCTION SPECIFICATION IS EXPRESSION;
-
- -- Note: there are no separate nodes for the profiles, instead the
- -- information appears directly in the following nodes.
+ -- FUNCTION SPECIFICATION IS (EXPRESSION);
-- N_Parametrized_Expression
-- Sloc points to FUNCTION
Index: par.adb
===================================================================
--- par.adb (revision 165097)
+++ par.adb (working copy)
@@ -352,7 +352,7 @@ function Par (Configuration_Pragmas : Bo
Pbod : Boolean; -- True if proper body OK
Rnam : Boolean; -- True if renaming declaration OK
Stub : Boolean; -- True if body stub OK
- Fil1 : Boolean; -- Filler to fill to 8 bits
+ Pexp : Boolean; -- True if parametried expression OK
Fil2 : Boolean; -- Filler to fill to 8 bits
end record;
pragma Pack (Pf_Rec);
@@ -360,18 +360,18 @@ function Par (Configuration_Pragmas : Bo
function T return Boolean renames True;
function F return Boolean renames False;
- Pf_Decl_Gins_Pbod_Rnam_Stub : constant Pf_Rec :=
- Pf_Rec'(F, T, T, T, T, T, F, F);
- Pf_Decl : constant Pf_Rec :=
- Pf_Rec'(F, T, F, F, F, F, F, F);
- Pf_Decl_Gins_Pbod_Rnam : constant Pf_Rec :=
- Pf_Rec'(F, T, T, T, T, F, F, F);
- Pf_Decl_Pbod : constant Pf_Rec :=
- Pf_Rec'(F, T, F, T, F, F, F, F);
- Pf_Pbod : constant Pf_Rec :=
- Pf_Rec'(F, F, F, T, F, F, F, F);
- Pf_Spcn : constant Pf_Rec :=
- Pf_Rec'(T, F, F, F, F, F, F, F);
+ 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
Index: par-ch6.adb
===================================================================
--- par-ch6.adb (revision 165099)
+++ par-ch6.adb (working copy)
@@ -124,7 +124,7 @@ package body Ch6 is
-- other subprogram constructs.
-- PARAMETRIZED_EXPRESSION ::=
- -- FUNCTION SPECIFICATION IS EXPRESSION;
+ -- FUNCTION SPECIFICATION IS (EXPRESSION);
-- The value in Pf_Flags indicates which of these possible declarations
-- is acceptable to the caller:
@@ -134,6 +134,7 @@ package body Ch6 is
-- Pf_Flags.Pbod Set if proper body OK
-- Pf_Flags.Rnam Set if renaming declaration OK
-- Pf_Flags.Stub Set if body stub OK
+ -- Pf_Flags.Pexp Set if parametrized expression OK
-- If an inappropriate form is encountered, it is scanned out but an
-- error message indicating that it is appearing in an inappropriate
@@ -221,17 +222,17 @@ package body Ch6 is
-- already been given, so no need to give another message here.
-- An overriding indicator is allowed for subprogram declarations,
- -- bodies (including subunits), renamings, stubs, and
- -- instantiations. The test against Pf_Decl_Pbod is added to account
- -- for the case of subprograms declared in a protected type, where
- -- only subprogram declarations and bodies can occur. The Pf_Pbod
- -- case is for subunits.
+ -- bodies (including subunits), renamings, stubs, and instantiations.
+ -- The test against Pf_Decl_Pbod is added to account for the case of
+ -- subprograms declared in a protected type, where only subprogram
+ -- declarations and bodies can occur. The Pf_Pbod case is for
+ -- subunits.
- if Pf_Flags /= Pf_Decl_Gins_Pbod_Rnam_Stub
+ if Pf_Flags /= Pf_Decl_Gins_Pbod_Rnam_Stub_Pexp
and then
- Pf_Flags /= Pf_Decl_Pbod
+ Pf_Flags /= Pf_Decl_Pbod_Pexp
and then
- Pf_Flags /= Pf_Pbod
+ Pf_Flags /= Pf_Pbod_Pexp
then
Error_Msg_SC ("overriding indicator not allowed here!");
@@ -583,12 +584,9 @@ package body Ch6 is
end if;
end if;
- -- Processing for subprogram body or parametrized expression
+ -- Processing for stub or subprogram body or parametrized expression
<<Subprogram_Body>>
- if not Pf_Flags.Pbod then
- Error_Msg_SP ("subprogram body not allowed here!");
- end if;
-- Subprogram body stub case
@@ -614,28 +612,24 @@ package body Ch6 is
-- Subprogram body or parametrized expression case
else
- -- Here we must distinguish a body and a parametrized expression
-
- Parse_Body_Or_Parametrized_Expression : declare
- function Is_Parametrized_Expression return Boolean;
- -- Returns True if we have case of parametrized epression
+ Scan_Body_Or_Parametrized_Expression : declare
- --------------------------------
- -- Is_Parametrized_Expression --
- --------------------------------
+ function Likely_Parametrized_Expression return Boolean;
+ -- Returns True if we have a probably case of a parametrized
+ -- expression omitting the parentheses, if so, returns True
+ -- and emits an appropriate error message, else returns False.
+
+ ------------------------------------
+ -- Likely_Parametrized_Expression --
+ ------------------------------------
- function Is_Parametrized_Expression return Boolean is
+ function Likely_Parametrized_Expression return Boolean is
begin
- -- Parametrized expression only allowed in Ada 2012
-
- if Ada_Version < Ada_12 then
- return False;
-
-- If currently pointing to BEGIN or a declaration keyword
-- or a pragma, then we definitely have a subprogram body.
-- This is a common case, so worth testing first.
- elsif Token = Tok_Begin
+ if Token = Tok_Begin
or else Token in Token_Class_Declk
or else Token = Tok_Pragma
then
@@ -652,42 +646,79 @@ package body Ch6 is
or else Token = Tok_New
or else Token = Tok_Not
then
- return True;
+ null;
- -- Anything other than an identifier must be a body at
- -- this stage. Probably we could do a little better job of
- -- distingushing some more error cases, but it seems right
- -- to err on the side of favoring a body over the
- -- new-fangled parametrized expression.
+ -- Anything other than an identifier must be a body
elsif Token /= Tok_Identifier then
return False;
- -- For identifier we have to scan ahead if identifier is
- -- followed by a colon or a comma, it is a declaration and
- -- hence we have a subprogram body. Otherwise we have an
- -- expression.
+ -- Here for an identifier
else
- declare
- Scan_State : Saved_Scan_State;
- Tok : Token_Type;
- begin
- Save_Scan_State (Scan_State);
- Scan; -- past identifier
- Tok := Token;
- Restore_Scan_State (Scan_State);
- return Tok /= Tok_Colon and then Tok /= Tok_Comma;
- end;
+ -- If the identifier is the first token on its line, then
+ -- let's assume that we have a missing begin and this is
+ -- intended as a subprogram body.
+
+ if Token_Is_At_Start_Of_Line then
+ return False;
+
+ -- Otherwise we have to scan ahead. If the identifier is
+ -- followed by a colon or a comma, it is a declaration
+ -- and hence we have a subprogram body. Otherwise assume
+ -- a parametrized expression.
+
+ else
+ declare
+ Scan_State : Saved_Scan_State;
+ Tok : Token_Type;
+ begin
+ Save_Scan_State (Scan_State);
+ Scan; -- past identifier
+ Tok := Token;
+ Restore_Scan_State (Scan_State);
+
+ if Tok = Tok_Colon or else Tok = Tok_Comma then
+ return False;
+ end if;
+ end;
+ end if;
end if;
- end Is_Parametrized_Expression;
- -- Start of processing for Parse_Body_Or_Parametrized_Expression
+ -- Fall through if we have a likely parametrized expression
+
+ Error_Msg_SC
+ ("parametrized expression must be "
+ & "enclosed in parentheses");
+ return True;
+ end Likely_Parametrized_Expression;
+
+ -- Start of processing for Scan_Body_Or_Parametrized_Expression
begin
- -- Parametrized_Expression case, parse expression
+ -- Parametrized_Expression case
+
+ if Token = Tok_Left_Paren
+ or else Likely_Parametrized_Expression
+ then
+ -- Check parametrized expression allowed here
+
+ if not Pf_Flags.Pexp then
+ Error_Msg_SC
+ ("parametrized expression not allowed here!");
+ end if;
+
+ -- Check we are in Ada 2012 mode
+
+ if Ada_Version < Ada_12 then
+ Error_Msg_SC
+ ("parametrized expression is an Ada 2012 feature!");
+ Error_Msg_SC
+ ("\unit must be compiled with -gnat2012 switch!");
+ end if;
+
+ -- Parse out expression and build parametrized expression
- if Is_Parametrized_Expression then
Body_Node :=
New_Node
(N_Parametrized_Expression, Sloc (Specification_Node));
@@ -699,10 +730,16 @@ package body Ch6 is
-- Subprogram body case
else
- -- Here is the test for a suspicious IS (i.e. one that looks
- -- like it might more properly be a semicolon). See separate
- -- section discussing use of IS instead of semicolon in
- -- package Parse.
+ -- Check body allowed here
+
+ if not Pf_Flags.Pbod then
+ Error_Msg_SP ("subprogram body not allowed here!");
+ end if;
+
+ -- Here is the test for a suspicious IS (i.e. one that
+ -- looks like it might more properly be a semicolon).
+ -- See separate section describing use of IS instead
+ -- of semicolon in package Parse.
if (Token in Token_Class_Declk
or else
@@ -715,7 +752,7 @@ package body Ch6 is
end if;
-- Build and return subprogram body, parsing declarations
- -- an statement sequence that belong to the body.
+ -- and statement sequence that belong to the body.
Body_Node :=
New_Node (N_Subprogram_Body, Sloc (Specification_Node));
@@ -724,7 +761,7 @@ package body Ch6 is
end if;
return Body_Node;
- end Parse_Body_Or_Parametrized_Expression;
+ end Scan_Body_Or_Parametrized_Expression;
end if;
-- Processing for subprogram declaration
Index: par-ch10.adb
===================================================================
--- par-ch10.adb (revision 165097)
+++ par-ch10.adb (working copy)
@@ -347,10 +347,10 @@ package body Ch10 is
Error_Msg_BC -- CODEFIX
("keyword BODY expected here [see file name]");
Restore_Scan_State (Scan_State);
- Set_Unit (Comp_Unit_Node, P_Package (Pf_Pbod));
+ Set_Unit (Comp_Unit_Node, P_Package (Pf_Pbod_Pexp));
else
Restore_Scan_State (Scan_State);
- Set_Unit (Comp_Unit_Node, P_Package (Pf_Decl_Gins_Pbod_Rnam));
+ Set_Unit (Comp_Unit_Node, P_Package (Pf_Decl_Gins_Pbod_Rnam_Pexp));
end if;
elsif Token = Tok_Generic then
@@ -364,7 +364,7 @@ package body Ch10 is
or else Token = Tok_Overriding
or else Token = Tok_Procedure
then
- Set_Unit (Comp_Unit_Node, P_Subprogram (Pf_Decl_Gins_Pbod_Rnam));
+ Set_Unit (Comp_Unit_Node, P_Subprogram (Pf_Decl_Gins_Pbod_Rnam_Pexp));
-- A little bit of an error recovery check here. If we just scanned
-- a subprogram declaration (as indicated by an SIS entry being
@@ -1034,10 +1034,10 @@ package body Ch10 is
or else Token = Tok_Overriding
or else Token = Tok_Procedure
then
- Body_Node := P_Subprogram (Pf_Pbod);
+ Body_Node := P_Subprogram (Pf_Pbod_Pexp);
elsif Token = Tok_Package then
- Body_Node := P_Package (Pf_Pbod);
+ Body_Node := P_Package (Pf_Pbod_Pexp);
elsif Token = Tok_Protected then
Scan; -- past PROTECTED
Index: par-ch3.adb
===================================================================
--- par-ch3.adb (revision 165097)
+++ par-ch3.adb (working copy)
@@ -4142,7 +4142,7 @@ package body Ch3 is
when Tok_Function =>
Check_Bad_Layout;
- Append (P_Subprogram (Pf_Decl_Gins_Pbod_Rnam_Stub), Decls);
+ Append (P_Subprogram (Pf_Decl_Gins_Pbod_Rnam_Stub_Pexp), Decls);
Done := False;
when Tok_For =>
@@ -4186,7 +4186,7 @@ package body Ch3 is
Error_Msg_SC ("\unit must be compiled with -gnat05 switch");
Token := Tok_Overriding;
- Append (P_Subprogram (Pf_Decl_Gins_Pbod_Rnam_Stub), Decls);
+ Append (P_Subprogram (Pf_Decl_Gins_Pbod_Rnam_Stub_Pexp), Decls);
Done := False;
-- Normal case, no overriding, or overriding followed by colon
@@ -4201,17 +4201,17 @@ package body Ch3 is
when Tok_Not =>
Check_Bad_Layout;
- Append (P_Subprogram (Pf_Decl_Gins_Pbod_Rnam_Stub), Decls);
+ Append (P_Subprogram (Pf_Decl_Gins_Pbod_Rnam_Stub_Pexp), Decls);
Done := False;
when Tok_Overriding =>
Check_Bad_Layout;
- Append (P_Subprogram (Pf_Decl_Gins_Pbod_Rnam_Stub), Decls);
+ Append (P_Subprogram (Pf_Decl_Gins_Pbod_Rnam_Stub_Pexp), Decls);
Done := False;
when Tok_Package =>
Check_Bad_Layout;
- Append (P_Package (Pf_Decl_Gins_Pbod_Rnam_Stub), Decls);
+ Append (P_Package (Pf_Decl_Gins_Pbod_Rnam_Stub_Pexp), Decls);
Done := False;
when Tok_Pragma =>
@@ -4220,7 +4220,7 @@ package body Ch3 is
when Tok_Procedure =>
Check_Bad_Layout;
- Append (P_Subprogram (Pf_Decl_Gins_Pbod_Rnam_Stub), Decls);
+ Append (P_Subprogram (Pf_Decl_Gins_Pbod_Rnam_Stub_Pexp), Decls);
Done := False;
when Tok_Protected =>
Index: par-ch7.adb
===================================================================
--- par-ch7.adb (revision 165080)
+++ par-ch7.adb (working copy)
@@ -109,7 +109,7 @@ package body Ch7 is
-- Case of package body. Note that we demand a package body if that
-- is the only possibility (even if the BODY keyword is not present)
- if Token = Tok_Body or else Pf_Flags = Pf_Pbod then
+ if Token = Tok_Body or else Pf_Flags = Pf_Pbod_Pexp then
if not Pf_Flags.Pbod then
Error_Msg_SC ("package body cannot appear here!");
end if;
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