Re: [PATCH] Fix PR ada/111813 (Inconsistent limit in Ada.Calendar.Formatting)

[Simon Wright <simon@pushface.org>]

Pierre-Marie, I’ve CC’d you hoping you’re an appropriate person to ping on this one.
If not, who would be for this sort of change?

I should have said, tested by
- add test case, make -C gcc check-gnat: error reported
- make -C gcc gnatlib_and_tools; make install
- make -C gcc check-gnat: no error reported

FSF copyright assignment RT:1016382

—S

> On 16 Oct 2023, at 14:32, Simon Wright <simon@pushface.org> wrote:
> 
> The description of the second Value function (returning Duration) (ARM 9.6.1(87) 
> doesn't place any limitation on the Elapsed_Time parameter's value, beyond 
> "Constraint_Error is raised if the string is not formatted as described for Image, or 
> the function cannot interpret the given string as a Duration value".
> 
> It would seem reasonable that Value and Image should be consistent, in that any 
> string produced by Image should be accepted by Value. Since Image must produce
> a two-digit representation of the Hours, there's an implication that its 
> Elapsed_Time parameter should be less than 100.0 hours (the ARM merely says
> that in that case the result is implementation-defined).
> 
> The current implementation of Value raises Constraint_Error if the Elapsed_Time
> parameter is greater than or equal to 24 hours.
> 
> This patch removes the restriction, so that the Elapsed_Time parameter must only
> be less than 100.0 hours.
> 
> gcc/ada/Changelog:
> 
>  2023-10-15 Simon Wright <simon@pushface.org>
> 
>  PR ada/111813
> 
>  * gcc/ada/libgnat/a-calfor.adb (Value (2)): Allow values of parameter
>      Elapsed_Time greater than or equal to 24 hours, by doing the
>      hour calculations in Natural rather than Hour_Number (0 .. 23).
>      Calculate the result directly rather than by using Seconds_Of
>      (whose Hour parameter is of type Hour_Number).
> 
>      If an exception occurs of type Constraint_Error, re-raise it
>      rather than raising a new CE.
> 
> gcc/testsuite/Changelog:
> 
>  2023-10-15 Simon Wright <simon@pushface.org>
> 
>  PR ada/111813
> 
>  * gcc/testsuite/gnat.dg/calendar_format_value.adb: New test.
> 
> ---
> gcc/ada/libgnat/a-calfor.adb                  | 11 +++++---
> .../gnat.dg/calendar_format_value.adb         | 26 +++++++++++++++++++
> 2 files changed, 34 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/gnat.dg/calendar_format_value.adb
> 
> diff --git a/gcc/ada/libgnat/a-calfor.adb b/gcc/ada/libgnat/a-calfor.adb
> index 18f4e7388df..493728b490e 100644
> --- a/gcc/ada/libgnat/a-calfor.adb
> +++ b/gcc/ada/libgnat/a-calfor.adb
> @@ -777,7 +777,7 @@ package body Ada.Calendar.Formatting is
> 
>    function Value (Elapsed_Time : String) return Duration is
>       D          : String (1 .. 11);
> -      Hour       : Hour_Number;
> +      Hour       : Natural;
>       Minute     : Minute_Number;
>       Second     : Second_Number;
>       Sub_Second : Second_Duration := 0.0;
> @@ -817,7 +817,7 @@ package body Ada.Calendar.Formatting is
> 
>       --  Value extraction
> 
> -      Hour   := Hour_Number   (Hour_Number'Value   (D (1 .. 2)));
> +      Hour   := Natural       (Natural'Value       (D (1 .. 2)));
>       Minute := Minute_Number (Minute_Number'Value (D (4 .. 5)));
>       Second := Second_Number (Second_Number'Value (D (7 .. 8)));
> 
> @@ -837,9 +837,14 @@ package body Ada.Calendar.Formatting is
>          raise Constraint_Error;
>       end if;
> 
> -      return Seconds_Of (Hour, Minute, Second, Sub_Second);
> +      return Duration (Hour * 3600)
> +        + Duration (Minute * 60)
> +        + Duration (Second)
> +        + Sub_Second;
> 
>    exception
> +      --  CE is mandated, but preserve trace if CE already.
> +      when Constraint_Error => raise;
>       when others => raise Constraint_Error;
>    end Value;
> 
> diff --git a/gcc/testsuite/gnat.dg/calendar_format_value.adb b/gcc/testsuite/gnat.dg/calendar_format_value.adb
> new file mode 100644
> index 00000000000..e98e496fd3b
> --- /dev/null
> +++ b/gcc/testsuite/gnat.dg/calendar_format_value.adb
> @@ -0,0 +1,26 @@
> +-- { dg-do run }
> +-- { dg-options "-O2" }
> +
> +with Ada.Calendar.Formatting;
> +
> +procedure Calendar_Format_Value is
> +   Limit : constant Duration
> +     := 99 * 3600.0 + 59 * 60.0 + 59.0;
> +begin
> +   declare
> +      Image : constant String := Ada.Calendar.Formatting .Image (Limit);
> +      Image_Error : exception;
> +   begin
> +      if Image /= "99:59:59" then
> +         raise Image_Error with "image: " & Image;
> +      end if;
> +      declare
> +         Value : constant Duration := Ada.Calendar.Formatting.Value (Image);
> +         Value_Error : exception;
> +      begin
> +         if Value /= Limit then
> +            raise Value_Error with "duration: " & Value'Image;
> +         end if;
> +      end;
> +   end;
> +end Calendar_Format_Value;
> -- 
> 2.39.3 (Apple Git-145)
>