[Ada] Restrict initialization of External_Tag and Expanded_Name

2018-05-23  Javier Miranda  <miranda@adacore.com>

gcc/ada/

	* exp_disp.adb (Make_DT): Restrict the initialization of
	External_Tag and Expanded_Name to an empty string to the case where
	both pragmas apply (i.e. No_Tagged_Streams and Discard_Names), since
	restricted runtimes are compiled with pragma Discard_Names.
	* doc/gnat_rm/implementation_defined_pragmas.rst,
	doc/gnat_rm/implementation_defined_characteristics.rst: Add
	documentation.
	* gnat_rm.texi: Regenerate.

From-SVN: r260584

gcc/ada/ChangeLog

+2018-05-23  Javier Miranda  <miranda@adacore.com>
+
+	* exp_disp.adb (Make_DT): Restrict the initialization of
+	External_Tag and Expanded_Name to an empty string to the case where
+	both pragmas apply (i.e. No_Tagged_Streams and Discard_Names), since
+	restricted runtimes are compiled with pragma Discard_Names.
+	* doc/gnat_rm/implementation_defined_pragmas.rst,
+	doc/gnat_rm/implementation_defined_characteristics.rst: Add
+	documentation.
+	* gnat_rm.texi: Regenerate.
+
 2018-05-23  Maroua Maalej  <maalej@adacore.com>
 
 	* sem_spark.adb: Fix of some permission rules of pointers in SPARK.

gcc/ada/doc/gnat_rm/implementation_defined_characteristics.rst

@@ -875,6 +875,11 @@ be suppressed.  In the presence of this pragma, the Image attribute
 provides the image of the Pos of the literal, and Value accepts
 Pos values.
 
+For tagged types, when pragmas ``Discard_Names`` and ``No_Tagged_Streams``
+simultaneously apply, their Expanded_Name and External_Tag are initialized
+with empty strings. This is useful to avoid exposing entity names at binary
+level.
+
 *
   "The result of the ``Task_Identification.Image``
   attribute.  See C.7.1(7)."

gcc/ada/doc/gnat_rm/implementation_defined_pragmas.rst

@@ -3892,6 +3892,11 @@ and derived types of this type inherit the pragma automatically, so the effect
 applies to a complete hierarchy (this is necessary to deal with the class-wide
 dispatching versions of the stream routines).
 
+When pragmas ``Discard_Names`` and ``No_Tagged_Streams`` are simultaneously
+applied to a tagged type its Expanded_Name and External_Tag are initialized
+with empty strings. This is useful to avoid exposing entity names at binary
+level but has a negative impact on the debuggability of tagged types.
+
 Pragma Normalize_Scalars
 ========================
 

gcc/ada/gnat_rm.texi

@@ -21,7 +21,7 @@
 
 @copying
 @quotation
-GNAT Reference Manual , Apr 20, 2018
+GNAT Reference Manual , Apr 23, 2018
 
 AdaCore
 
@@ -5328,6 +5328,11 @@ and derived types of this type inherit the pragma automatically, so the effect
 applies to a complete hierarchy (this is necessary to deal with the class-wide
 dispatching versions of the stream routines).
 
+When pragmas @code{Discard_Names} and @code{No_Tagged_Streams} are simultaneously
+applied to a tagged type its Expanded_Name and External_Tag are initialized
+with empty strings. This is useful to avoid exposing entity names at binary
+level but has a negative impact on the debuggability of tagged types.
+
 @node Pragma Normalize_Scalars,Pragma Obsolescent,Pragma No_Tagged_Streams,Implementation Defined Pragmas
 @anchor{gnat_rm/implementation_defined_pragmas pragma-normalize-scalars}@anchor{a8}
 @section Pragma Normalize_Scalars
@@ -17143,6 +17148,11 @@ be suppressed.  In the presence of this pragma, the Image attribute
 provides the image of the Pos of the literal, and Value accepts
 Pos values.
 
+For tagged types, when pragmas @code{Discard_Names} and @code{No_Tagged_Streams}
+simultaneously apply, their Expanded_Name and External_Tag are initialized
+with empty strings. This is useful to avoid exposing entity names at binary
+level.
+
 
 @itemize *