Ada Programming/Pragmas/Restrictions

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Summary

The pragma Restrictions is used to forbid the utilization of some language features.

List of language defined restrictions identifiers

Some restrictions are specially marked:

Ada 2005: This is a new Ada 2005 restrictions identifier.
Ada 2012: This is a new Ada 2012 restrictions identifier.

Immediate_Reclamation
Max_Asynchronous_Select_Nesting
Max_Entry_Queue_Length (Ada 2005)
Max_Protected_Entries
Max_Select_Alternatives
Max_Storage_At_Blocking
Max_Task_Entries
Max_Tasks
No_Abort_Statements
No_Access_Parameter_Allocators (Ada 2012)
No_Access_Subprograms
No_Allocators
No_Anonymous_Allocators (Ada 2012)
No_Asynchronous_Control
No_Coextensions (Ada 2012)
No_Delay
No_Dependence (Ada 2005)
No_Dispatch
No_Dynamic_Attachment (Ada 2005)
No_Dynamic_Priorities
No_Exceptions
No_Fixed_Point
No_Floating_Point
No_Implementation_Aspect_Specifications (Ada 2012)
No_Implementation_Attributes (Ada 2005)
No_Implementation_Identifiers (Ada 2012)
No_Implementation_Pragmas (Ada 2005)
No_Implementation_Units (Ada 2012)
No_Implicit_Heap_Allocations
No_IO
No_Local_Allocators
No_Local_Protected_Objects (Ada 2005)
No_Local_Timing_Events (Ada 2005)
No_Nested_Finalization
No_Obsolescent_Features (Ada 2005)
No_Protected_Type_Allocators (Ada 2005)
No_Protected_Types
No_Recursion
No_Reentrancy
No_Relative_Delay (Ada 2005)
No_Requeue_Statements (Ada 2005)
No_Select_Statements (Ada 2005)
No_Specific_Termination_Handlers (Ada 2005)
No_Specification_of_Aspect (Ada 2012)
No_Standard_Allocators_After_Elaboration (Ada 2012)
No_Task_Allocators
No_Task_Hierarchy
No_Task_Termination (Ada 2005)
No_Terminate_Alternatives
No_Unchecked_Access
No_Unchecked_Conversion
No_Unchecked_Deallocation
No_Use_of_Attribute (Ada 2012)
No_Use_of_Pragma (Ada 2012)
Simple_Barriers (Ada 2005)

List of implementation defined restrictions identifiers

The following restrictions are not available in all Ada compilers, only in those that had implemented them:

GNAT: This is an implementation defined restriction identifier of the GNAT compiler.

No_Calendar (GNAT)
No_Default_Initialization (GNAT)
No_Direct_Boolean_Operators (GNAT)
No_Dispatching_Calls (GNAT)
No_Elaboration_Code (GNAT)
No_Enumeration_Maps (GNAT)
No_Entry_Calls_In_Elaboration_Code (GNAT)
No_Entry_Queue (GNAT)
No_Exception_Handlers (GNAT)
No_Exception_Propagation (GNAT)
No_Exception_Registration, previously named 'No_Exception_Streams' (GNAT)
No_Implementation_Restrictions (GNAT)
No_Implicit_Aliasing (GNAT)
No_Implicit_Conditionals (GNAT)
No_Implicit_Dynamic_Code (GNAT)
No_Implicit_Loops (GNAT)
No_Initialize_Scalars (GNAT)
No_Secondary_Stack (GNAT)
No_Select_Statements (GNAT)
No_Standard_Storage_Pools (GNAT)
No_Streams (GNAT)
No_Task_Attributes_Package (GNAT)
No_Tasking (GNAT)
No_Wide_Characters (GNAT)
SPARK (GNAT)
Static_Priorities (GNAT)
Static_Storage_Size (GNAT)

"Hello, world!" with restrictions

The following sample demonstrates the use of pragma . Note that on Windows, Linux and macOS the given restrictions won't change the generated code.

File: hello_world_restricted.adb, Crate: pragmas_restrictions (view, plain text, download with Alire, Alire crate info)

Code:

pragma Restrictions (
   Simple_Barriers,
   No_Abort_Statements,
   No_Asynchronous_Control,
   No_Calendar,
   No_Delay,
   No_Dynamic_Attachment,
   No_Dynamic_Priorities,
   No_Enumeration_Maps,
   No_Entry_Calls_In_Elaboration_Code,
   No_Entry_Queue,
   No_Exception_Registration,
   No_Initialize_Scalars,
   No_Local_Protected_Objects,
   No_Protected_Type_Allocators,
   No_Protected_Types,
   No_Relative_Delay,
   No_Requeue_Statements,
   No_Select_Statements,
   No_Streams,
   No_Task_Allocators,
   No_Task_Attributes_Package,
   No_Task_Hierarchy,
   No_Task_Termination,
   No_Tasking,
   No_Terminate_Alternatives,
   No_Wide_Characters,
   Static_Priorities,
   Static_Storage_Size,
   Immediate_Reclamation,
   No_Implementation_Restrictions,
   Max_Protected_Entries => 0,
   Max_Protected_Entries => 0,
   Max_Select_Alternatives => 0,
   Max_Task_Entries => 0,
   Max_Tasks => 0,
   Max_Asynchronous_Select_Nesting => 0);

with Ada.Text_IO;

procedure Hello_World_Restricted is
begin
   Ada.Text_IO.Put_Line ("Hello World!");
   Ada.Text_IO.New_Line;
   Ada.Text_IO.Put_Line ("This is a program with restricted runtime.");
end Hello_World_Restricted;

Output:

>alr run hello_world_restricted
ⓘ Building pragmas_restrictions=1.0.1/pragmas_restrictions.gpr...          
Compile
   [Ada]          hello_world_restricted.adb
Bind
   [gprbind]      hello_world_restricted.bexch
   [Ada]          hello_world_restricted.ali
Link
   [link]         hello_world_restricted.adb
✓ Build finished successfully in 0.83 seconds.
Hello World!

This is a program with restricted runtime.

Ada Programming/Pragmas/Restrictions

Summary

List of language defined restrictions identifiers

List of implementation defined restrictions identifiers

"Hello, world!" with restrictions

See also

Wikibook

Ada Reference Manual

Ada Quality and Style Guide