[Ada] Warn about obsolete uses of renamed Ada 83 packages

[Ada] Warn about obsolete uses of renamed Ada 83 packages

[Pierre-Marie de Rodat]

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Ada 83 packages like Unchecked_Conversion or Text_IO are obsolete since
Ada 95. GNAT now warns about their uses when warnings on obsolescent
featured (Annex J) is active.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* doc/gnat_ugn/building_executable_programs_with_gnat.rst
	(Warning Message Control): Update description of switch -gnatwj.
	* gnat_ugn.texi: Regenerate.
	* sem_ch10.adb (Analyze_With_Clause): Warn on WITH clauses for
	obsolete renamed units; in Ada 83 mode do not consider
	predefined renamings to be obsolete.

gcc/testsuite/

	* gnat.dg/renaming1.adb: Update WITH clause.
	* gnat.dg/renaming1.ads: Likewise.
	* gnat.dg/warn29.adb: Likewise.

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diff --git a/gcc/ada/doc/gnat_ugn/building_executable_programs_with_gnat.rst b/gcc/ada/doc/gnat_ugn/building_executable_programs_with_gnat.rst
--- a/gcc/ada/doc/gnat_ugn/building_executable_programs_with_gnat.rst
+++ b/gcc/ada/doc/gnat_ugn/building_executable_programs_with_gnat.rst
@@ -3277,8 +3277,7 @@ of the pragma in the :title:`GNAT_Reference_manual`).
   If this warning option is activated, then warnings are generated for
   calls to subprograms marked with ``pragma Obsolescent`` and
   for use of features in Annex J of the Ada Reference Manual. In the
-  case of Annex J, not all features are flagged. In particular use
-  of the renamed packages (like ``Text_IO``) and use of package
+  case of Annex J, not all features are flagged. In particular, uses of package
   ``ASCII`` are not flagged, since these are very common and
   would generate many annoying positive warnings. The default is that
   such warnings are not generated.


diff --git a/gcc/ada/gnat_ugn.texi b/gcc/ada/gnat_ugn.texi
--- a/gcc/ada/gnat_ugn.texi
+++ b/gcc/ada/gnat_ugn.texi
@@ -11383,8 +11383,7 @@ This switch disables warnings on overlapping actuals in a call.
 If this warning option is activated, then warnings are generated for
 calls to subprograms marked with @code{pragma Obsolescent} and
 for use of features in Annex J of the Ada Reference Manual. In the
-case of Annex J, not all features are flagged. In particular use
-of the renamed packages (like @code{Text_IO}) and use of package
+case of Annex J, not all features are flagged. In particular, uses of package
 @code{ASCII} are not flagged, since these are very common and
 would generate many annoying positive warnings. The default is that
 such warnings are not generated.


diff --git a/gcc/ada/sem_ch10.adb b/gcc/ada/sem_ch10.adb
--- a/gcc/ada/sem_ch10.adb
+++ b/gcc/ada/sem_ch10.adb
@@ -2597,11 +2597,19 @@ package body Sem_Ch10 is
       --  Note: this is not quite right if the user defines one of these units
       --  himself, but that's a marginal case, and fixing it is hard ???
 
-      if Restriction_Check_Required (No_Obsolescent_Features) then
-         if In_Predefined_Renaming (U) then
+      if Ada_Version >= Ada_95
+        and then In_Predefined_Renaming (U)
+      then
+         if Restriction_Check_Required (No_Obsolescent_Features) then
             Check_Restriction (No_Obsolescent_Features, N);
             Restriction_Violation := True;
          end if;
+
+         if Warn_On_Obsolescent_Feature then
+            Error_Msg_N
+              ("renamed predefined unit is an obsolescent feature "
+               & "(RM J.1)?j?", N);
+         end if;
       end if;
 
       --  Check No_Implementation_Units violation


diff --git a/gcc/testsuite/gnat.dg/renaming1.adb b/gcc/testsuite/gnat.dg/renaming1.adb
--- a/gcc/testsuite/gnat.dg/renaming1.adb
+++ b/gcc/testsuite/gnat.dg/renaming1.adb
@@ -1,12 +1,12 @@
 -- { dg-do compile}
 -- { dg-options "-gnatwa" }
 
-with Text_IO;
-use Text_IO;
+with Ada.Text_IO;
+use Ada.Text_IO;
 package body renaming1 is
-   procedure Fo (A : Text_IO.File_Access) is
+   procedure Fo (A : Ada.Text_IO.File_Access) is
    begin
-      if A = Text_IO.Standard_Output then
+      if A = Ada.Text_IO.Standard_Output then
          null;
       end if;
    end Fo;


diff --git a/gcc/testsuite/gnat.dg/renaming1.ads b/gcc/testsuite/gnat.dg/renaming1.ads
--- a/gcc/testsuite/gnat.dg/renaming1.ads
+++ b/gcc/testsuite/gnat.dg/renaming1.ads
@@ -1,4 +1,4 @@
-with Text_IO;
+with Ada.Text_IO;
 package renaming1 is
-   procedure Fo (A : Text_IO.File_Access);
+   procedure Fo (A : Ada.Text_IO.File_Access);
 end;


diff --git a/gcc/testsuite/gnat.dg/warn29.adb b/gcc/testsuite/gnat.dg/warn29.adb
--- a/gcc/testsuite/gnat.dg/warn29.adb
+++ b/gcc/testsuite/gnat.dg/warn29.adb
@@ -1,7 +1,7 @@
 --  { dg-do compile }
 --  { dg-options "-gnatwa" }
 
-with Text_IO; use Text_IO;
+with Ada.Text_IO; use Ada.Text_IO;
 
 package body Warn29 is
    procedure P (X : T; Y : Integer) is