[COMMITTED] ada: Dimensional analysis when used with elementary functions

Marc Poulhiès poulhies@adacore.com
Tue Sep 26 11:46:18 GMT 2023


From: Derek Schacht <schacht@adacore.com>

gcc/ada/

	* doc/gnat_ugn/gnat_and_program_execution.rst: Add more details on
	using Generic Elementary Functions with dimensional analysis.
	* gnat_ugn.texi: Regenerate.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 .../gnat_ugn/gnat_and_program_execution.rst   | 12 ++++++++++++
 gcc/ada/gnat_ugn.texi                         | 19 +++++++++++++++++--
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst b/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst
index 62abca24f41..35e34772658 100644
--- a/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst
+++ b/gcc/ada/doc/gnat_ugn/gnat_and_program_execution.rst
@@ -3294,6 +3294,18 @@ requires ``DV(Source)`` = ``DV(Target)``, and analogously for parameter
 passing (the dimension vector for the actual parameter must be equal to the
 dimension vector for the formal parameter).
 
+When using dimensioned types with elementary functions it is necessary to
+instantiate the ``Ada.Numerics.Generic_Elementary_Functions`` package using
+the ``Mks_Type`` and not any of the derived subtypes such as ``Distance``.
+For functions such as ``Sqrt`` the dimensional analysis will fail when using
+the subtypes because both the parameter and return are of the same type.
+
+An example instantiation
+
+  .. code-block:: ada
+  
+        package Mks_Numerics is new 
+           Ada.Numerics.Generic_Elementary_Functions (System.Dim.Mks.Mks_Type);
 
 .. _Stack_Related_Facilities:
 
diff --git a/gcc/ada/gnat_ugn.texi b/gcc/ada/gnat_ugn.texi
index 7c5926eba64..1562bee1f64 100644
--- a/gcc/ada/gnat_ugn.texi
+++ b/gcc/ada/gnat_ugn.texi
@@ -19,7 +19,7 @@
 
 @copying
 @quotation
-GNAT User's Guide for Native Platforms , Aug 31, 2023
+GNAT User's Guide for Native Platforms , Sep 26, 2023
 
 AdaCore
 
@@ -15510,7 +15510,6 @@ Linker to be used. The default is @code{bfd} for @code{ld.bfd}; @code{gold}
 (for @code{ld.gold}) and @code{mold} (for @code{ld.mold}) are more
 recent and faster alternatives, but only available on GNU/Linux
 platforms.
-
 @end table
 
 @node Binding with gnatbind,Linking with gnatlink,Linker Switches,Building Executable Programs with GNAT
@@ -22093,6 +22092,22 @@ requires @code{DV(Source)} = @code{DV(Target)}, and analogously for parameter
 passing (the dimension vector for the actual parameter must be equal to the
 dimension vector for the formal parameter).
 
+When using dimensioned types with elementary functions it is necessary to
+instantiate the @code{Ada.Numerics.Generic_Elementary_Functions} package using
+the @code{Mks_Type} and not any of the derived subtypes such as @code{Distance}.
+For functions such as @code{Sqrt} the dimensional analysis will fail when using
+the subtypes because both the parameter and return are of the same type.
+
+An example instantiation
+
+@quotation
+
+@example
+package Mks_Numerics is new
+   Ada.Numerics.Generic_Elementary_Functions (System.Dim.Mks.Mks_Type);
+@end example
+@end quotation
+
 @node Stack Related Facilities,Memory Management Issues,Performing Dimensionality Analysis in GNAT,GNAT and Program Execution
 @anchor{gnat_ugn/gnat_and_program_execution id52}@anchor{14d}@anchor{gnat_ugn/gnat_and_program_execution stack-related-facilities}@anchor{1aa}
 @section Stack Related Facilities
-- 
2.42.0



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