ada: gnatbind: Do not generate Ada.Command_Line references when not used

It was previously assumed that configurable runtimes could not return exit
statuses, however this assumption no longer holds. Instead, only import
the required symbols from Ada.Command_Line's support packages if
Ada.Command_Line is in the closure of the partition when a configurable
runtime is used.

gcc/ada/

	* bindgen.adb (Command_Line_Used): New object.
	(Gen_Main): Only generate references to symbols used by
	Ada.Command_Line if the package is used by the partition.
	(Gen_Output_File_Ada): Ditto.
	(Resolve_Binder_Options): Check if Ada.Command_Line is in the
	closure of the partition.

1 files changed, 42 insertions, 13 deletions

diff --git a/gcc/ada/bindgen.adb b/gcc/ada/bindgen.adb
index 03315fe..005ad70 100644
--- a/gcc/ada/bindgen.adb
+++ b/gcc/ada/bindgen.adb
@@ -65,6 +65,15 @@ package body Bindgen is
    --  Number of default-sized primary stacks the binder needs to allocate for
    --  task objects declared in the program.
 
+   Command_Line_Used : Boolean := False;
+   --  Flag indicating whether the unit Ada.Command_Line is in the closure of
+   --  the partition. This is set by Resolve_Binder_Options, and is used to
+   --  determine whether or not to import and use symbols defined in
+   --  Ada.Command_Line's support packages (gnat_argc, gnat_argv, gnat_envp
+   --  and gnat_exit_status). Conservatively, it is always set to True for
+   --  non-configurable run-times as parts of the compiler and run-time assume
+   --  these symbols are available and can be imported directly.
+
    System_Restrictions_Used : Boolean := False;
    --  Flag indicating whether the unit System.Restrictions is in the closure
    --  of the partition. This is set by Resolve_Binder_Options, and is used
@@ -2092,15 +2101,13 @@ package body Bindgen is
 
       WBI ("   begin");
 
-      --  Acquire command-line arguments if present and supported on the
-      --  target. Do not acquire command-line arguments if pragma No_Run_Time
-      --  is in effect as the run-time symbols will not be available.
+      --  Acquire command-line arguments if supported on the target and used
+      --  by the program.
 
       if CodePeer_Mode then
          null;
 
-      elsif Command_Line_Args_On_Target and then not No_Run_Time_Mode then
-
+      elsif Command_Line_Args_On_Target and then Command_Line_Used then
          --  Initialize gnat_argc/gnat_argv only if not already initialized,
          --  to avoid losing the result of any command-line processing done by
          --  earlier GNAT run-time initialization.
@@ -2187,10 +2194,13 @@ package body Bindgen is
          if No_Main_Subprogram
            or else ALIs.Table (ALIs.First).Main_Program = Proc
          then
-            if No_Run_Time_Mode then
-               WBI ("      return (0);");
-            else
+            --  Return gnat_exit_status if Ada.Command_Line is used otherwise
+            --  return 0.
+
+            if Command_Line_Used then
                WBI ("      return (gnat_exit_status);");
+            else
+               WBI ("      return (0);");
             end if;
          else
             WBI ("      return (Result);");
@@ -2589,8 +2599,11 @@ package body Bindgen is
 
          --  A run-time configured to support command line arguments defines
          --  a number of internal symbols that need to be set by the binder.
+         --  We do not do this in cases where the program does not use
+         --  Ada.Command_Line, as the package and it's support files may not be
+         --  present.
 
-         if Command_Line_Args_On_Target and then not No_Run_Time_Mode then
+         if Command_Line_Args_On_Target and then Command_Line_Used then
             WBI ("");
             WBI ("   gnat_argc : Integer;");
             WBI ("   gnat_argv : System.Address;");
@@ -2602,13 +2615,17 @@ package body Bindgen is
             WBI ("   pragma Import (C, gnat_envp);");
          end if;
 
-         --  Define exit status. The exit status is stored in the run-time
-         --  library to allow applications set the state through
-         --  Ada.Command_Line. It is initialized there.
+         --  Define exit status if supported by the target. The exit status is
+         --  stored in the run-time library to allow applications set the state
+         --  through Ada.Command_Line and is initialized in the run-time. Like
+         --  command line arguments, skip if Ada.Command_Line is not used in
+         --  the enclosure of the partition because this package may not be
+         --  available in the runtime.
 
          WBI ("");
 
-         if Exit_Status_Supported_On_Target and then not No_Run_Time_Mode then
+         if Exit_Status_Supported_On_Target and then Command_Line_Used
+         then
             WBI ("   gnat_exit_status : Integer;");
             WBI ("   pragma Import (C, gnat_exit_status);");
          end if;
@@ -3371,6 +3388,18 @@ package body Bindgen is
 
          Check_Package (System_Version_Control_Used,
                         "system.version_control%s");
+
+         --  Ditto for the use of Ada.Command_Line, except we always set
+         --  Command_Line_Used to True if on a non-configurable run-time
+         --  as parts of the compiler and run-time assume the GNAT command
+         --  line symbols are available and can be imported directly (as
+         --  long as No_Run_Time mode is not set).
+
+         if Configurable_Run_Time_On_Target then
+            Check_Package (Command_Line_Used, "ada.command_line%s");
+         elsif not No_Run_Time_Mode then
+            Command_Line_Used := True;
+         end if;
       end loop;
    end Resolve_Binder_Options;