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Commit 51c40324 by Arnaud Charlet
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Add section for gnatcheck. 

        Add documentation for restriction No_Dispatching_Calls
        Add documentation for pragma Ada_2005
        Remove mention of obsolete pragma Propagate_Exceptions

From-SVN: r111105
parent 7e3d710b
Showing with 132 additions and 81 deletions
gcc/ada/gnat_rm.texi
...@@ -48,7 +48,7 @@ entitled ``GNU Free Documentation License''. ...@@ -48,7 +48,7 @@ entitled ``GNU Free Documentation License''.
@title GNAT Reference Manual @title GNAT Reference Manual
@subtitle GNAT, The GNU Ada 95 Compiler @subtitle GNAT, The GNU Ada 95 Compiler
@subtitle GCC version @value{version-GCC} @subtitle GCC version @value{version-GCC}
@author Ada Core Technologies, Inc. @author AdaCore
@page @page
@vskip 0pt plus 1filll @vskip 0pt plus 1filll
...@@ -103,6 +103,7 @@ Implementation Defined Pragmas ...@@ -103,6 +103,7 @@ Implementation Defined Pragmas
* Pragma Ada_83:: * Pragma Ada_83::
* Pragma Ada_95:: * Pragma Ada_95::
* Pragma Ada_05:: * Pragma Ada_05::
* Pragma Ada_2005::
* Pragma Annotate:: * Pragma Annotate::
* Pragma Assert:: * Pragma Assert::
* Pragma Ast_Entry:: * Pragma Ast_Entry::
...@@ -166,7 +167,6 @@ Implementation Defined Pragmas ...@@ -166,7 +167,6 @@ Implementation Defined Pragmas
* Pragma Polling:: * Pragma Polling::
* Pragma Profile (Ravenscar):: * Pragma Profile (Ravenscar)::
* Pragma Profile (Restricted):: * Pragma Profile (Restricted)::
* Pragma Propagate_Exceptions::
* Pragma Psect_Object:: * Pragma Psect_Object::
* Pragma Pure_Function:: * Pragma Pure_Function::
* Pragma Restriction_Warnings:: * Pragma Restriction_Warnings::
...@@ -643,6 +643,7 @@ consideration, the use of these pragmas should be minimized. ...@@ -643,6 +643,7 @@ consideration, the use of these pragmas should be minimized.
* Pragma Ada_83:: * Pragma Ada_83::
* Pragma Ada_95:: * Pragma Ada_95::
* Pragma Ada_05:: * Pragma Ada_05::
* Pragma Ada_2005::
* Pragma Annotate:: * Pragma Annotate::
* Pragma Assert:: * Pragma Assert::
* Pragma Ast_Entry:: * Pragma Ast_Entry::
...@@ -706,7 +707,6 @@ consideration, the use of these pragmas should be minimized. ...@@ -706,7 +707,6 @@ consideration, the use of these pragmas should be minimized.
* Pragma Polling:: * Pragma Polling::
* Pragma Profile (Ravenscar):: * Pragma Profile (Ravenscar)::
* Pragma Profile (Restricted):: * Pragma Profile (Restricted)::
* Pragma Propagate_Exceptions::
* Pragma Psect_Object:: * Pragma Psect_Object::
* Pragma Pure_Function:: * Pragma Pure_Function::
* Pragma Restriction_Warnings:: * Pragma Restriction_Warnings::
...@@ -819,6 +819,19 @@ contexts. This pragma is useful when writing a reusable component that ...@@ -819,6 +819,19 @@ contexts. This pragma is useful when writing a reusable component that
itself uses Ada 2005 features, but which is intended to be usable from itself uses Ada 2005 features, but which is intended to be usable from
either Ada 83 or Ada 95 programs. either Ada 83 or Ada 95 programs.
@node Pragma Ada_2005
@unnumberedsec Pragma Ada_2005
@findex Ada_2005
@noindent
Syntax:
@smallexample @c ada
pragma Ada_2005;
@end smallexample
@noindent
This configuration pragma is a synonym for pragma Ada_05 and has the
same syntax and effect.
@node Pragma Annotate @node Pragma Annotate
@unnumberedsec Pragma Annotate @unnumberedsec Pragma Annotate
@findex Annotate @findex Annotate
...@@ -2916,21 +2929,25 @@ also has no effect in DEC Ada 83 for OpenVMS Alpha Systems. ...@@ -2916,21 +2929,25 @@ also has no effect in DEC Ada 83 for OpenVMS Alpha Systems.
Syntax: Syntax:
@smallexample @c ada @smallexample @c ada
pragma No_Return (procedure_local_NAME); pragma No_Return (procedure_local_NAME @{, procedure_local_NAME@});
@end smallexample @end smallexample
@noindent @noindent
@var{procedure_local_NAME} must refer to one or more procedure Each @var{procedure_local_NAME} argument must refer to one or more procedure
declarations in the current declarative part. A procedure to which this declarations in the current declarative part. A procedure to which this
pragma is applied may not contain any explicit @code{return} statements, pragma is applied may not contain any explicit @code{return} statements.
and also may not contain any implicit return statements from falling off In addition, if the procedure contains any implicit returns from falling
the end of a statement sequence. One use of this pragma is to identify off the end of a statement sequence, then execution of that implicit
procedures whose only purpose is to raise an exception. return will cause Program_Error to be raised.
Another use of this pragma is to suppress incorrect warnings about One use of this pragma is to identify procedures whose only purpose is to raise
missing returns in functions, where the last statement of a function an exception. Another use of this pragma is to suppress incorrect warnings
about missing returns in functions, where the last statement of a function
statement sequence is a call to such a procedure. statement sequence is a call to such a procedure.
Note that in Ada 2005 mode, this pragma is part of the language, and is
identical in effect to the pragma as implemented in Ada 95 mode.
@node Pragma No_Strict_Aliasing @node Pragma No_Strict_Aliasing
@unnumberedsec Pragma No_Strict_Aliasing @unnumberedsec Pragma No_Strict_Aliasing
@findex No_Strict_Aliasing @findex No_Strict_Aliasing
...@@ -3340,46 +3357,6 @@ This set of restrictions causes the automatic selection of a simplified ...@@ -3340,46 +3357,6 @@ This set of restrictions causes the automatic selection of a simplified
version of the run time that provides improved performance for the version of the run time that provides improved performance for the
limited set of tasking functionality permitted by this set of restrictions. limited set of tasking functionality permitted by this set of restrictions.
@node Pragma Propagate_Exceptions
@unnumberedsec Pragma Propagate_Exceptions
@findex Propagate_Exceptions
@cindex Zero Cost Exceptions
@noindent
Syntax:
@smallexample @c ada
pragma Propagate_Exceptions (subprogram_local_NAME);
@end smallexample
@noindent
This pragma indicates that the given entity, which is the name of an
imported foreign-language subprogram may receive an Ada exception,
and that the exception should be propagated. It is relevant only if
zero cost exception handling is in use, and is thus never needed if
the alternative @code{longjmp} / @code{setjmp} implementation of
exceptions is used (although it is harmless to use it in such cases).
The implementation of fast exceptions always properly propagates
exceptions through Ada code, as described in the Ada Reference Manual.
However, this manual is silent about the propagation of exceptions
through foreign code. For example, consider the
situation where @code{P1} calls
@code{P2}, and @code{P2} calls @code{P3}, where
@code{P1} and @code{P3} are in Ada, but @code{P2} is in C@.
@code{P3} raises an Ada exception. The question is whether or not
it will be propagated through @code{P2} and can be handled in
@code{P1}.
For the @code{longjmp} / @code{setjmp} implementation of exceptions,
the answer is always yes. For some targets on which zero cost exception
handling is implemented, the answer is also always yes. However, there
are some targets, notably in the current version all x86 architecture
targets, in which the answer is that such propagation does not
happen automatically. If such propagation is required on these
targets, it is mandatory to use @code{Propagate_Exceptions} to
name all foreign language routines through which Ada exceptions
may be propagated.
@node Pragma Psect_Object @node Pragma Psect_Object
@unnumberedsec Pragma Psect_Object @unnumberedsec Pragma Psect_Object
@findex Psect_Object @findex Psect_Object
...@@ -3450,6 +3427,11 @@ applies to the underlying renamed function. This can be used to ...@@ -3450,6 +3427,11 @@ applies to the underlying renamed function. This can be used to
disambiguate cases of overloading where some but not all functions disambiguate cases of overloading where some but not all functions
in a set of overloaded functions are to be designated as pure. in a set of overloaded functions are to be designated as pure.
If pragma @code{Pure_Function} is applied to a library level function, the
function is also considered pure from an optimization point of view, but the
unit is not a Pure unit in the categorization sense. So for example, a function
thus marked is free to @code{with} non-pure units.
@node Pragma Restriction_Warnings @node Pragma Restriction_Warnings
@unnumberedsec Pragma Restriction_Warnings @unnumberedsec Pragma Restriction_Warnings
@findex Restriction_Warnings @findex Restriction_Warnings
...@@ -4115,7 +4097,10 @@ effects. ...@@ -4115,7 +4097,10 @@ effects.
If @code{local_NAME} identifies more than one matching homonym in the If @code{local_NAME} identifies more than one matching homonym in the
current scope, then the entity most recently declared is the one to which current scope, then the entity most recently declared is the one to which
the pragma applies. the pragma applies. Note that in the case of accept formals, the pragma
Unreferenced may appear immediately after the keyword @code{do} which
allows the indication of whether or not accept formals are referenced
or not to be given individually for each accept statement.
The left hand side of an assignment does not count as a reference for the The left hand side of an assignment does not count as a reference for the
purpose of this pragma. Thus it is fine to assign to an entity for which purpose of this pragma. Thus it is fine to assign to an entity for which
...@@ -5153,6 +5138,17 @@ would preclude their use as numbers). This is used internally for the ...@@ -5153,6 +5138,17 @@ would preclude their use as numbers). This is used internally for the
construction of values of the floating-point attributes from the file construction of values of the floating-point attributes from the file
@file{ttypef.ads}, but may also be used by user programs. @file{ttypef.ads}, but may also be used by user programs.
For example, the following program prints the first 50 digits of pi:
@smallexample @c ada
with Text_IO; use Text_IO;
with Ada.Numerics;
procedure Pi is
begin
Put (Ada.Numerics.Pi'Universal_Literal_String);
end;
@end smallexample
@node Unrestricted_Access @node Unrestricted_Access
@unnumberedsec Unrestricted_Access @unnumberedsec Unrestricted_Access
@cindex @code{Access}, unrestricted @cindex @code{Access}, unrestricted
...@@ -7376,6 +7372,57 @@ from Boolean). This is intended for use in safety critical programs ...@@ -7376,6 +7372,57 @@ from Boolean). This is intended for use in safety critical programs
where the certification protocol requires the use of short-circuit where the certification protocol requires the use of short-circuit
(and then, or else) forms for all composite boolean operations. (and then, or else) forms for all composite boolean operations.
@item No_Dispatching_Calls
@findex No_Dispatching_Calls
This restriction ensures at compile time that the code generated by the
compiler involves no dispatching calls. The use of this restriction allows the
safe use of record extensions and membership tests and ensures that the code
contains no indirect calls through a dispatching mechanism. (Note that this
includes internally-generated calls created by the compiler, for example in
the implementation of the predefined attributes on class-wide objects.) The
membership test is allowed in the presence of this restriction, because its
implementation requires no dispatching. The following example indicates
constructs that violate this restriction.
@smallexample
package Pkg is
type T is tagged record
Data : Natural;
end record;
procedure P (X : T);
type DT is new T with record
More_Data : Natural;
end record;
procedure Q (X : DT);
end Pkg;
with Pkg; use Pkg;
procedure Example is
procedure Test (O : T'Class) is
N : Natural := O'Size; -- Error: Dispatching call
begin
if O in DT'Class then -- OK : Membership test
Q (DT (O)); -- OK : Type conversion plus direct call
else
P (O); -- Error: Dispatching call
end if;
end Test;
Obj : DT;
begin
P (Obj); -- OK : Direct call
P (T (Obj)); -- OK : Type conversion plus direct call
P (T'Class (Obj)); -- Error: Dispatching call
Test (Obj); -- OK : Type conversion
if Obj in T'Class then -- OK : Membership test
null;
end if;
end Example;
@end smallexample
@item No_Dynamic_Attachment @item No_Dynamic_Attachment
@findex No_Dynamic_Attachment @findex No_Dynamic_Attachment
This restriction ensures that there is no call to any of the operations This restriction ensures that there is no call to any of the operations
...@@ -7429,7 +7476,8 @@ or by rejecting any construct that would otherwise generate an implicit ...@@ -7429,7 +7476,8 @@ or by rejecting any construct that would otherwise generate an implicit
conditional. Note that this check does not include run time constraint conditional. Note that this check does not include run time constraint
checks, which on some targets may generate implicit conditionals as checks, which on some targets may generate implicit conditionals as
well. To control the latter, constraint checks can be suppressed in the well. To control the latter, constraint checks can be suppressed in the
normal manner. normal manner. Constructs generating implicit conditionals include comparisons
of composite objects and the Max/Min attributes.
@item No_Implicit_Dynamic_Code @item No_Implicit_Dynamic_Code
@findex No_Implicit_Dynamic_Code @findex No_Implicit_Dynamic_Code
...@@ -7513,15 +7561,6 @@ the partition. It is similar in effect to the use of @code{Max_Tasks => 0} ...@@ -7513,15 +7561,6 @@ the partition. It is similar in effect to the use of @code{Max_Tasks => 0}
except that violations are caught at compile time and cause an error message except that violations are caught at compile time and cause an error message
to be output either by the compiler or binder. to be output either by the compiler or binder.
@item No_Wide_Characters
@findex No_Wide_Characters
This restriction ensures at compile time that no uses of the types
@code{Wide_Character} or @code{Wide_String} or corresponding wide
wide types
appear, and that no wide or wide wide string or character literals
appear in the program (that is literals representing characters not in
type @code{Character}.
@item Static_Priorities @item Static_Priorities
@findex Static_Priorities @findex Static_Priorities
This restriction ensures at compile time that all priority expressions This restriction ensures at compile time that all priority expressions
...@@ -7605,6 +7644,15 @@ identifiers (other than @code{No_Implementation_Restrictions} itself) ...@@ -7605,6 +7644,15 @@ identifiers (other than @code{No_Implementation_Restrictions} itself)
are present. With this restriction, the only other restriction identifiers are present. With this restriction, the only other restriction identifiers
that can be used are those defined in the Ada 95 Reference Manual. that can be used are those defined in the Ada 95 Reference Manual.
@item No_Wide_Characters
@findex No_Wide_Characters
This restriction ensures at compile time that no uses of the types
@code{Wide_Character} or @code{Wide_String} or corresponding wide
wide types
appear, and that no wide or wide wide string or character literals
appear in the program (that is literals representing characters not in
type @code{Character}.
@end table @end table
@sp 1 @sp 1
...@@ -8945,9 +8993,12 @@ task definition a pragma of the form: ...@@ -8945,9 +8993,12 @@ task definition a pragma of the form:
@noindent @noindent
Then @code{Default_Stack_Size} can be defined in a global package, and Then @code{Default_Stack_Size} can be defined in a global package, and
modified as required. Any tasks requiring stack sizes different from the modified as required. Any tasks requiring stack sizes different from the
default can have an appropriate alternative reference in the pragma. default can have an appropriate alternative reference in the pragma.
You can also use the @code{-d} binder switch to modify the default stack
size.
For access types, the @code{Storage_Size} clause specifies the maximum For access types, the @code{Storage_Size} clause specifies the maximum
space available for allocation of objects of the type. If this space is space available for allocation of objects of the type. If this space is
exceeded then @code{Storage_Error} will be raised by an allocation attempt. exceeded then @code{Storage_Error} will be raised by an allocation attempt.
...@@ -11089,8 +11140,8 @@ There is no internal buffering of any kind at the Ada library level. The only ...@@ -11089,8 +11140,8 @@ There is no internal buffering of any kind at the Ada library level. The only
buffering is that provided at the system level in the implementation of the buffering is that provided at the system level in the implementation of the
library routines that support streams. This facilitates shared use of these library routines that support streams. This facilitates shared use of these
streams by mixed language programs. Note though that system level buffering is streams by mixed language programs. Note though that system level buffering is
explictly enabled at elaboration of the standard I/O packages and that can have explicitly enabled at elaboration of the standard I/O packages and that can
an impact on mixed language programs, in particular those using I/O before have an impact on mixed language programs, in particular those using I/O before
calling the Ada elaboration routine (e.g. adainit). It is recommended to call calling the Ada elaboration routine (e.g. adainit). It is recommended to call
the Ada elaboration routine before performing any I/O or when impractical, the Ada elaboration routine before performing any I/O or when impractical,
flush the common I/O streams and in particular Standard_Output before flush the common I/O streams and in particular Standard_Output before
...@@ -12504,7 +12555,7 @@ is common to both bindings. ...@@ -12504,7 +12555,7 @@ is common to both bindings.
@cindex @code{GNAT.Altivec.Vector_Types} (@file{g-alvety.ads}) @cindex @code{GNAT.Altivec.Vector_Types} (@file{g-alvety.ads})
@cindex AltiVec @cindex AltiVec
@noindent @noindent
This package exposes the various vector types part of the Ada binding This package exposes the various vector types part of the Ada binding
to AltiVec facilities. to AltiVec facilities.
...@@ -14025,23 +14076,23 @@ except for OpenVMS. ...@@ -14025,23 +14076,23 @@ except for OpenVMS.
@menu @menu
* Static constant aggregates with static bounds:: * Static constant aggregates with static bounds::
* Constant aggregates with an unconstrained nominal types:: * Constant aggregates with unconstrained nominal types::
* Aggregates with static bounds:: * Aggregates with static bounds::
* Aggregates with non-static bounds:: * Aggregates with non-static bounds::
* Aggregates in assignment statements:: * Aggregates in assignment statements::
@end menu @end menu
@noindent @noindent
Aggregate have a rich syntax and allow the user to specify the values of Aggregates have a rich syntax and allow the user to specify the values of
complex data structures by means of a single construct. As a result, the complex data structures by means of a single construct. As a result, the
code generated for aggregates can be quite complex and involve loops, case code generated for aggregates can be quite complex and involve loops, case
statements and multiple assignments. In the simplest cases, however, the statements and multiple assignments. In the simplest cases, however, the
compiler will recognize aggregates whose components and constraints are compiler will recognize aggregates whose components and constraints are
fully static, and in those cases the compiler will generate little or no fully static, and in those cases the compiler will generate little or no
executable code. The following is an outline of the code that GNAT generates executable code. The following is an outline of the code that GNAT generates
for various aggregate constructs. For further details, the user will find it for various aggregate constructs. For further details, you will find it
useful to examine the output produced by the -gnatG flag to see the expanded useful to examine the output produced by the -gnatG flag to see the expanded
source that is input to the code generator. The user will also want to examine source that is input to the code generator. You may also want to examine
the assembly code generated at various levels of optimization. the assembly code generated at various levels of optimization.
The code generated for aggregates depends on the context, the component values, The code generated for aggregates depends on the context, the component values,
...@@ -14056,7 +14107,7 @@ component values and static subtypes also lead to simpler code. ...@@ -14056,7 +14107,7 @@ component values and static subtypes also lead to simpler code.
For the declarations: For the declarations:
@smallexample @c ada @smallexample @c ada
type One_Dim is array (1..10) of integer; type One_Dim is array (1..10) of integer;
ar0 : constant One_Dim := ( 1, 2, 3, 4, 5, 6, 7, 8, 9, 0); ar0 : constant One_Dim := (1, 2, 3, 4, 5, 6, 7, 8, 9, 0);
@end smallexample @end smallexample
@noindent @noindent
...@@ -14064,7 +14115,7 @@ GNAT generates no executable code: the constant ar0 is placed in static memory. ...@@ -14064,7 +14115,7 @@ GNAT generates no executable code: the constant ar0 is placed in static memory.
The same is true for constant aggregates with named associations: The same is true for constant aggregates with named associations:
@smallexample @c ada @smallexample @c ada
Cr1 : constant One_Dim := (4 => 16, 2 => 4, 3 => 9, 1=> 1); Cr1 : constant One_Dim := (4 => 16, 2 => 4, 3 => 9, 1 => 1, 5 .. 10 => 0);
Cr3 : constant One_Dim := (others => 7777); Cr3 : constant One_Dim := (others => 7777);
@end smallexample @end smallexample
...@@ -14098,8 +14149,8 @@ Zero1: constant two_dim := (1..3 => (1..3 => 0)); ...@@ -14098,8 +14149,8 @@ Zero1: constant two_dim := (1..3 => (1..3 => 0));
Zero2: constant two_dim := (others => (others => 0)); Zero2: constant two_dim := (others => (others => 0));
@end smallexample @end smallexample
@node Constant aggregates with an unconstrained nominal types @node Constant aggregates with unconstrained nominal types
@subsection Constant aggregates with an unconstrained nominal types @subsection Constant aggregates with unconstrained nominal types
@noindent @noindent
In such cases the aggregate itself establishes the subtype, so that In such cases the aggregate itself establishes the subtype, so that
...@@ -14122,7 +14173,7 @@ for it as a combination of individual assignments and loops over the target ...@@ -14122,7 +14173,7 @@ for it as a combination of individual assignments and loops over the target
object. The declarations object. The declarations
@smallexample @c ada @smallexample @c ada
Cr_Var1 : One_Dim := (2, 5, 7, 11); Cr_Var1 : One_Dim := (2, 5, 7, 11, 0, 0, 0, 0, 0, 0);
Cr_Var2 : One_Dim := (others > -1); Cr_Var2 : One_Dim := (others > -1);
@end smallexample @end smallexample
...@@ -14624,14 +14675,14 @@ for building shared libraries. ...@@ -14624,14 +14675,14 @@ for building shared libraries.
Expression must be a path name. The attribute defines the Expression must be a path name. The attribute defines the
directory in which the sources of the interfaces of a Stand-alone Library will directory in which the sources of the interfaces of a Stand-alone Library will
be copied. The directory must exist, must be distinct from the project's be copied. The directory must exist, must be distinct from the project's
object directory and source directories of all project in the project tree, object directory and source directories of all projects in the project tree,
and must be writable. and must be writable.
@item Library_Src_Dir @item Library_Src_Dir
Expression must be a path name. The attribute defines the Expression must be a path name. The attribute defines the
directory in which the ALI files of a Library will directory in which the ALI files of a Library will
be copied. The directory must exist, must be distinct from the project's be copied. The directory must exist, must be distinct from the project's
object directory and source directoriesof all project in the project tree, object directory and source directories of all projects in the project tree,
and must be writable. and must be writable.
@item Library_Symbol_File @item Library_Symbol_File
...@@ -14665,7 +14716,7 @@ object files of the interfaces that are not in the reference symbol file, ...@@ -14665,7 +14716,7 @@ object files of the interfaces that are not in the reference symbol file,
these symbols are put at the end of the list in the newly created symbol file these symbols are put at the end of the list in the newly created symbol file
and the minor ID is increased. and the minor ID is increased.
"controlled": the attribute Library_Reference_Symbol_File must be difined. "controlled": the attribute Library_Reference_Symbol_File must be defined.
The library will fail to build if the exported symbols in the object files of The library will fail to build if the exported symbols in the object files of
the interfaces do not match exactly the symbol in the symbol file. the interfaces do not match exactly the symbol in the symbol file.
...@@ -15037,7 +15088,7 @@ specified. ...@@ -15037,7 +15088,7 @@ specified.
This is an associative array attribute. Its domain is This is an associative array attribute. Its domain is
a set of file names. Its range is a string list that specifies a set of file names. Its range is a string list that specifies
options to be used when binding the named main file. If a main file options to be used when binding the named main file. If a main file
is not specified in the Switches attribute, it is boundt with the is not specified in the Switches attribute, it is bound with the
options specified by Default_Switches of its language, if defined. options specified by Default_Switches of its language, if defined.
@end table @end table
...@@ -15065,7 +15116,7 @@ options specified by Default_Switches of its language, if defined. ...@@ -15065,7 +15116,7 @@ options specified by Default_Switches of its language, if defined.
@item Linker_Options @item Linker_Options
This is a string list attribute. Its value specifies additional options that This is a string list attribute. Its value specifies additional options that
be givent to the linker when linking an executable. This attribute is not be given to the linker when linking an executable. This attribute is not
used in the main project, only in projects imported directly or indirectly. used in the main project, only in projects imported directly or indirectly.
@end table @end table
......
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